Media Share 13/mediashare_13.zip/mediashare_13/ZIPPED/MMEDIA/PMSNDX3D.ZIP/pmsndx.hlp

OS/2 Help File | 1994-04-04 | 64KB | 1,517 lines

ΓòÉΓòÉΓòÉ 1. Introduction ΓòÉΓòÉΓòÉ

First off, what is PMsndX?  PMsndX is the acronym that I created to mean
Presentation Manager sound eXchange. PMsndX was written specifically for OS/2
to provide the functionality of the SOX sound manipulation program.  The
advantage to this program over the program is that it fully utilizes the
presentation facilities of the OS/2 environment.  This program was written to
provide all of the functionality of SOX while taking advantage the object
oriented approach offered by C++. The advantage of writing this program from
scratch is that it is easy to tailor it to OS/2 and C++.  The obvious
diadvantage is that it does not benefit from the extensive testing that SOX has
had.

Obviously if I intended to have this program remain as simply a SOX port to the
OS/2 environment, I would not have taken the time to rewrite it based on its
functionality.  The intent of this venture (other than to give me something to
do during this long icy winter) is to provide a platform for me to use some
signal processing from my college days to enhance the functions of the program.

Wow, you are still reading!  Well, now for some information on the user
interface.  There is nothing more frustrating than trying to use a program with
a difficult or complex user interface.  Twelve years ago I started programming
a TI99/4A in assembly language and from the start I have put more effort into a
clean user interface than anything.  It wasn't till I ran across JOEVIEW that I
realized that OS/2 could had one of the most capable environments that I had
seen in a while.  Presentation Manager programming has got to be one of the
easiest environments use and is a breeze compared to Windows or the X
environment.

In any case, I spent more time on the user interface of this program than I
ever thought possible.  It is designed around a single coordinating window
populated by bitmaps.  Each bitmaps has some sort of image that might change
when the button is pushed.  To make sure that the literate people out there (or
the icon impaired) understand the buttons too, I put a bit of text on them too
to describe the function.

Now, I have used programs on a lot of platforms and I have my favorites and the
more annoying ones too.  My pet peeves are the applications like Procomm for
Windows which just assumes that you want the darn thing to fill up your screen.
Or something like Microsoft Word which has so many menus and submenus that it
is hard to remember where a function is.  So, taking this into account, I
designed the interface such that the main functions of the program are
accessible from the main pannel.  Pressing the button for the function will
then bring up a dialog box which asks the user for the necessary information.
Pushing the button again will remove the dialog box.  I prefer this interface
because it provides a single point of control.  Well, you just need to play
with it for a bit to get an understanding of what I am talking about here.


ΓòÉΓòÉΓòÉ 2. Conventions ΓòÉΓòÉΓòÉ

Throughout the documentation provided with PMsndX a number of terms are used
which may be common to Presentation Manager programs but uncommon to
conversational English.  There are also terms which are specific to PMsndX
which may be new to a user of this program.  The intent of this section is not
to recreate the OS/2 documentation; rather, it is intended to identify some
basic terms necessary to understand the language used in this documentation.

Presentation Manager:
   The Presentation Manager is the Graphical User Interface (GUI) for most OS/2
   systems.  There are other GUIs available for OS/2 but this is the most
   common and the one that comes with OS/2 out of the box.  In general mose
   people refer to the Presentation Manager by the acronym PM.

SYSTEM MENU:
   Every PM program for OS/2 generally provides a SYSTEM MENU through an icon
   in the upper left corner of the window interface to the user.  By default,
   the system menu will contain the basic functions necessary to control the
   window for on the OS/2 PM desktop.

TITLE BAR:
   In order for a window to be moved about the desktop with the mouse, a window
   must have a titlebar.  This is the thick bar at the top of the window.  The
   titlebar provides another function in that it allows the program to display
   relevant messages to the user.

MINIMIZE BUTTON:
   A PM program may provide various control buttons for a window in the top
   right corner of a window.  One of these buttons is the MINIMIZE button. When
   the user selects this button, the window will be removed from the desktop
   and replaced by a small icon somewhere on the screen.  In most cases, the
   icon is placed at the bottom of the screen.  To restore the window the user
   can double click on the icon or can use a mouse button to bring up a menu
   and select Restore.

MAIN CONTROL PANEL:
   The main control panel for PMsndX is the window that is initially displayed
   when the program is executed.  This window is the main point of control for
   the program and provides access to all of the above mentioned controls as
   well as access to all of the functions of the program.


ΓòÉΓòÉΓòÉ 3. Mouse Pointer ΓòÉΓòÉΓòÉ

The mouse pointer is used as an indication to the state of the program.  When
the program is processing, the mouse pointer will be changed to a small dial
with 10 markers on the dial.  The percentage of work completed is then
displayed as the work is done.  When the dial reaches the vertical position,
the work will be complete.

There is one exception to this operation.  When the echo effect is used, the
dial on the pointer will rotate more than once. This is because the results of
the echo effect change the length of the data depending on the markers and
volumes such that the resulting length is unpredictable.  The dial will turn
for twice as the samples increases to another multiple of the initial sample
length.


ΓòÉΓòÉΓòÉ 4. System Menu ΓòÉΓòÉΓòÉ

As with any OS/2 program written for the Presentation Manager, this PMsndX has
an icon in the top left corner of the control window.  Pressing this icon will
bring up a menu of system operations.  With the exception of the About menu
item, each of the functions of the system menu may be performed without using
the menu through some other means provided by this program.  However, the
system menu has been provided to allow the program to be used without a mouse
if necessary.

The menu items provided in the system menu are:

Restore   Restore the windows after being minimized
Move      Move the control window
Minimize  Minimize all of the windows of PMsndx to an icon
Close     Close the all windows and exit
About     Display information about the author and version
Help      Bring up the help system


ΓòÉΓòÉΓòÉ 4.1. Restore ΓòÉΓòÉΓòÉ

During the use of PMsndX, the user may select to Minimize the windows to an
icon on the desktop.  To restore the window from the icon the user may either
double click on the icon or may press a mouse button while the pointer is over
the icon to bring up the system menu and select the restore item.


ΓòÉΓòÉΓòÉ 4.2. Move ΓòÉΓòÉΓòÉ

PMsndX provides the standard controls for moving the windows around on the
desktop.  It is generally easiest to use the mouse to select the titlebar of
the window and drag the window to the new location.  If the user uses the
system menu to move the window, the mouse will be centered in the control
window and any movement of the mouse will move the window until a mouse button
is pressed.

Note:  The system menu is only provided on the control window an the Help
       window.  None of the dialog boxes for the various buttons provide a
       system menu since it would only have two options (i.e. move and close).


ΓòÉΓòÉΓòÉ 4.3. Minimize ΓòÉΓòÉΓòÉ

All of the windows of PMsndX can be minimized quickly by either selecting the
minimize button on the upper right corner of the control panel or by using the
Minimize menu item of the system menu.  Either action performs the same
function.  The minimize operation is only provided on the control window.  The
dialogs cannot be individually minimized and are removed from the screen
through either one of the dialog action items (i.e. Load, or Dismiss) or
through the buttons of the main control panel.


ΓòÉΓòÉΓòÉ 4.4. Close ΓòÉΓòÉΓòÉ

To exit PMsndX the user can select the Close menu item from the system menu.
This is the default selection of the menu which enables the user to double
click on the PMsndX icon in the top left corner of the control panel to exit
the program.  The user may also use the Exit button on the control panel to
perform the same function.


ΓòÉΓòÉΓòÉ 4.5. About ΓòÉΓòÉΓòÉ

To find out the current version and other information about PMsndX the About
menu item can be selected from the system menu.

PMsndX is just one of the programs written by the Author for Intel based
machines.  All programs developed under the WiSHware Inc. name have been
developed solely by the author (duhh, the Author is the sole member of the
company) and are copyrighted by US Copyright laws.

Note:  This is the only item on the system menu for which there is no other
       means to access.


ΓòÉΓòÉΓòÉ 4.6. Help ΓòÉΓòÉΓòÉ

Selecting this option from the system menu performs the same function as
pressing the Help button on the main control panel.  This brings up the only
line help system for PMsndX.


ΓòÉΓòÉΓòÉ 5. Buttons ΓòÉΓòÉΓòÉ

The main control panel provides the user with access to all tools and functions
trough a set of buttons.  Each button contains an icon and a single word which
describes the function of the button. The buttons have been designed as toggle
type push buttons.  To select a particular button, the mouse must be positioned
over the button and the first mouse button pressed.  This will depress the
button and activate a dialog for the desired function.  The dialogs will
present information to the user about the desired operation and request input
from the user to complete the operation.

The control panel is the main point of control for both activating and
deactivating a particular function.  The dialog boxes can be removed from the
screen by positioning the mouse over a depressed button and pressing the first
mouse button.  The dialog box will be removed and the button will return to the
non-depressed position. It is important to note that when a dialog box is
removed through this means, any information in the dialog is ignored and the
function is canceled.  For each dialog box, the user must enter all of the
information required and then select the appropriate action on the push buttons
at the bottom of the dialog box. The dialog boxes do not have system menus so
that user cannot close the box from a menu as can be done with the main control
panel.  Dialog boxes may also be removed once valid information has been
obtained from the user or when the user dismisses or cancels the operation of
the box.

Now for the buttons.  There are six buttons on the main control pannel.  These
are listed below with a brief explanation of their function.

Open      Opens and reads a new sample file
Save      Saves the current sample to a file
Help      Displays general help about PMsndX
Tools     Displays a notebook of tools
Settings  Displays options to save between sessions
MMPM      Use MMPM to manipulate a sample
Exit      Exit PMsndX


ΓòÉΓòÉΓòÉ 5.1. Open ΓòÉΓòÉΓòÉ

The dialog box for opening a file and reading the sample into memory is
accessed from the OPEN button on the main control panel.  When reading in a
file, PMsndX will attempt to open the file as the type indicated by the
extension on the filename.  However, in the event that the file cannot be
loaded by the extension, PMsndX will automatically try to determine the type of
the file as it reads it.  If the sample header does not match any of the known
header types, PMsndX will refuse to load the file.  If the extension specified
for the file does not match any of the known extensions, PMsndX will
automatically try to determine the file type by reading the header.

This dialog box requests the user to provide a  Filename, Drive, File Type,
Directory, Files, and Save Directory.  Additionally, the user may select Load,
Dismiss, or Help to manage the dialog box.


ΓòÉΓòÉΓòÉ 5.1.1. Open Filename ΓòÉΓòÉΓòÉ

This is a text input field in which the user may type the name of the file to
be opened.  The user may specify a full path or just the file name. If a full
path is specified, the other user input fields will automatically be updated
accordingly if the path is valid.  If a file name is entered without a
qualified path, the path displayed in the other input windows will be used for
the file.  This window is case insensitive and will automatically convert all
input to upper case.


ΓòÉΓòÉΓòÉ 5.1.2. Drive ΓòÉΓòÉΓòÉ

To change the drive to be displayed for the various user input fields the user
may use the DRIVE pulldown field.  The current drive (with volume label) is
automatically displayed in this field.  If the "file Open path" has been
selected in the Settings dialog box, then this will be set to the last drive
used.  To change the default drive, the user can use the pushbutton at the end
of the drive field to display a list of available drives.  Once the user has
selected a new drive, the system will automatically update the other input
fields to reflect the contents of the drive.


ΓòÉΓòÉΓòÉ 5.1.3. File Type ΓòÉΓòÉΓòÉ

The user may specify a filter for the types of files displayed in the Files
input field.  The file types are accessed through a pulldown field.  By default
all files are displayed.  Once a new file type filter has been selected, the
Files display is updated with the list automatically.


ΓòÉΓòÉΓòÉ 5.1.4. Directory ΓòÉΓòÉΓòÉ

By default the last directory used to open a file will be displayed in this
entry field.  The user may select a new directory by positioning the mouse over
the desired directory and either double clicking the mouse.  If the "file Open
path" has been selected in the Settings dislog box, this field will display the
path used at the last session.  If no previous file path has been saved, then
this will display the current directory.


ΓòÉΓòÉΓòÉ 5.1.5. Files ΓòÉΓòÉΓòÉ

To select a file from the list of files displayed in the FILES entry field, the
user can position the mouse pointer over the desired file name and double click
on the first mouse button.  The Open Filename field is then automatically
updated to reflect the new file name.


ΓòÉΓòÉΓòÉ 5.1.6. Save Directory ΓòÉΓòÉΓòÉ

This is a checkbox to allow the user to save the current open path between
sessions without having to open the Settings dialog box.  When this box is
selected, if the Load button is selected, the specified directory path will be
saved when the program has been exited.  If the Save Directory is deselected
before the program is terminated, the path will not be saved.  All file paths
are remembered during each session and the SAVE DIRECTORY box allows the user
to store this path between session.

Note:  The file path is not saved until the program has been terminated.


ΓòÉΓòÉΓòÉ 5.1.7. Load ΓòÉΓòÉΓòÉ

Once the necessary information has been entered by the user to specify a valid
file name and path, the user may select the LOAD button to load the file into
memory.  If the dialog box is dismissed in any way other than through the LOAD
button, the file will not be loaded into memory.


ΓòÉΓòÉΓòÉ 5.1.8. Dismiss ΓòÉΓòÉΓòÉ

At any time when the OPEN dialog box is displayed the user may select the
DISMISS button to cancel the Open operation.  When this button is selected, the
operation is canceled and the file is not loaded, but the information in the
windows is maintained.  If the Save Directory button has been checked, the
specified directory is NOT saved between sessions.


ΓòÉΓòÉΓòÉ 5.1.9. Help ΓòÉΓòÉΓòÉ

To display help specifically for the OPEN dialog box, select the HELP button.
The help page for the box will be displayed.


ΓòÉΓòÉΓòÉ 5.2. Save ΓòÉΓòÉΓòÉ

The dialog box for saving a file to disk is accessed from the SAVE button on
the main control panel.  When saving a file, the extension of the file will
automatically determine the type of output to write for the file (e.g. if the
extension entered by the user is .wav, then the file will be saved in WAVE
format.) or the user may override the file type by selecting one of the buttons
for the type of file.

This dialog box requests the user to provide a Filename, Drive, File Type,
Directory, Files, Format, and Save Directory.  The dialog box also provides OK,
Cancel, and Help buttons to control the dialog box.


ΓòÉΓòÉΓòÉ 5.2.1. Save Filename ΓòÉΓòÉΓòÉ

This is a text input field in which the user may type the name of the file to
be saved.  The user may specify a full path or just the file name. If a full
path is specified, the other user input fields will automatically be updated
accordingly if the path is valid.  if a file name is entered without a
qualidifed path, the path displayed in the other input windows will used for
the file.  This window is case insensitive and will automatically be converted
to upper case.


ΓòÉΓòÉΓòÉ 5.2.2. Drive ΓòÉΓòÉΓòÉ

To change the drive to be displayed for the various user input fields the user
may use the DRIVE pulldown field.  The current drive (with volume label) is
automatically displayed in this field.  If the "file Save path" has been
selected in the Settings dialog box or the Save Directory button has been
selected in this dialog box, then this will be set to the drive used.  To
change the default drive, the user can use the pushbutton at the end of the
drive field to display a list of available drives.  Once the user has selected
a new drive, the system will automatically update the other input fields to
reflect the contents of the drive.


ΓòÉΓòÉΓòÉ 5.2.3. File Type ΓòÉΓòÉΓòÉ

The user may specify a filter for the types of files displayed in the Files
input field.  The file types are accessed through a pulldown field.  By
default, all files are displayed.  Once a new file type filter has been
selected, the Files display is updated with the list automatically.


ΓòÉΓòÉΓòÉ 5.2.4. Directory ΓòÉΓòÉΓòÉ

By default, the last directory used to save a file will be displayed in this
entry field.  The user may select a new directory by by positioning the mouse
over the desired directory and double clicking the mouse.  If the "file Save
path" of the Settings dialog box or the SAVE DIRECTORY box has been selected,
this field will display the path used at the last session.  If no previous file
path has been saved, then this will display the current directory.


ΓòÉΓòÉΓòÉ 5.2.5. Files ΓòÉΓòÉΓòÉ

To select a file from the list of files displayed in the FILES entry field, the
user can position the mouse pointer over the desired file name and double click
on the first mouse button.  The Save Filename field is then automatically
updated to reflect the new file name.


ΓòÉΓòÉΓòÉ 5.2.6. Format ΓòÉΓòÉΓòÉ

When saving a file, the extension of the file normally determines the format to
save the file in.  The forseen primary usage of this program will be to convert
sound samples from one format to another and so this is the default operation
of this program.  However, the user may specify that the information is stored
in a particular format regardless of the file extension.  In the event that no
extension is specified for the file, the PMsndX will automatically save the
file under the specified name under the format currently selected in the FORMAT
field.  The available formats for file operations are listed below. If the file
type of Undefined is selected, then the extension of the file will be used to
determine the file type.

APPLE (.aif)   Not implemented
SUN (.au)      Sun/DEC/NeXT 8 or 16 bit signed data samples or 8 bit ULaw
               samples.
MAC (.hcm)     Not implemented
RAW (.raw)     Not implemented
RAW (.ub)      Not implemented
RAW (.sb)      Not implemented
RAW (.uw)      Not implemented
RAW (.sw)      Not implemented
RAW (.ul)      Not implemented
IRACAM (.sf)   Not implemented
PC (.voc)      Creative Voice file format, 8 bit unsigned samples
SAMP (.smp)    Not implemented
PC (.wav)      Windows or OS/2 8, 16, or 32 bit unsigned data samples
Undefined      This field cannot be selected by the user.  It is only selected
               when there is no file in memory at the time that the SAVE dialog
               box is activated.


ΓòÉΓòÉΓòÉ 5.2.7. Save Directory ΓòÉΓòÉΓòÉ

This is a checkbox to allow the user to save the current save path between
sessions without having to open the Settings dialog box.  when this box is
selected, if the OK button is selected, the specified directory path will be
saved when the program has is terminated. If the SAVE DIRECTORY is deselected
before the program is terminated, the path will not be saved.  All file paths
are remembered during each session and the SAVE DIRECTORY box allows the user
to store this path between sessions.

Note:  The file path is not saved until the program has been terminated.


ΓòÉΓòÉΓòÉ 5.2.8. OK ΓòÉΓòÉΓòÉ

To save the file to disk, the user must select the OK button.  Exiting the
dialog box in any other way will not save the file to disk.


ΓòÉΓòÉΓòÉ 5.2.9. Cancel ΓòÉΓòÉΓòÉ

To cancel the save operation without writing the file to disk the the CANCEL
button is used.  If this button is selected, the current path will not be saved
when the program is terminated.


ΓòÉΓòÉΓòÉ 5.2.10. Help ΓòÉΓòÉΓòÉ

To display help specifically for the SAVE dialog box, select teh HELP button.
The help page for the box will be displayed.


ΓòÉΓòÉΓòÉ 5.3. Help ΓòÉΓòÉΓòÉ

PMsndX is equipped with extensive on line help that can be accessed by pressing
the HELP button from the main control panel.  When this button is selected a
window will appear which will display the table of contents for the system.

Links to other text is displayed in a blue-green color and can be selected to
jump to that description in the text.


ΓòÉΓòÉΓòÉ 5.4. Tools ΓòÉΓòÉΓòÉ

The heart of manipulating the samples is accessed from the TOOLS notebook.
This method of presentation provides a logical an concise method of accessing
the different types of manipulations that can be performed on a sound sample.
some of the pages of the notebook provide information while others let the user
apply a particular effect on the current sound sample.  A third class of pages
are used to launch dialog boxes for particular functions which require more
than the notebook can provide.  The TOOLS notebook can be dismissed by pressing
the TOOLS button on the main control panel.  The tabs on the notebook provide
access to the Info, Type, Average, Duplicate, Echo, Band Pass, Low Pass, Rate,
Speed, Reverse, Vibro, and Volume functions for manipulating the samples.

Using a notebook to display the TOOLS has some unique presentation advantages.
Primarily the notebook allows the effects to be displayed in a single dialog
window.  Since each effect is mutually exclusive of any other tool this
approach displays the maximum information that the user can utilize at any
time.  Another approach would have been to develop a dialog box for each tool.
This approach has the disadvantage that it would require a second control panel
to select the specific tools.  This would violate the approach of providing a
single control panel for the user and would necessitate managing a number of
different windows which could potentially clutter the screen.  The notebook is
a clean and aesthetically pleasing means for managing the tools.

The notebook may be navigated by either selecting the tab on the right of the
book for the desired function or by using the small Plus and Minus buttons at
the bottom of the notebook.  Using the Plus and Minus buttongs will move
through the notebook a single page at a time.  The information for each
function are divided into the following categories.

The notebook can be displayed regardless of the presense of sample data in
memory.  When no sample is present, the pages of the notebook will be
invalidated but can still be viewed.


ΓòÉΓòÉΓòÉ 5.4.1. Info ΓòÉΓòÉΓòÉ

The Info page displays all of the relevant information about the samples
currently in memory.  This includes the following categories:

Load Format     One of the formats which the program can save or open (see
                FORMAT under the Save Dialog).
Data Type       The default extension for this file format.
Data Style      SIGNED, UNSIGNED, ULAW, or ALAW
Channels        Number of channels in the sample
Sampling Rate   The number of samples taken each second
Data Size       BYTE (8 bits), WORD (16 bits), LONG (32 bits)
Samples         The number of samples that make the file
Comments        Some sample files may contain comments.  Any comments found are
                displayed in this window
Byte Order      The natural order of the bytes in each sample.  This field can
                display either Big Endian or Little Endian


ΓòÉΓòÉΓòÉ 5.4.2. Type ΓòÉΓòÉΓòÉ

The type of the file is determined by the header written to the beginning of
the file.  See Save for information how the file type is determined when a file
is saved to disk.  Additionally, the user may use the this tool to change the
Load Format in the Info page of the tools notebook.  When the file is saved,
the file format will automatically be set to whatever has been chosen on this
page of the notebook.

Each file format utilizes different sample formats for the actual data.  By
selecting one of the standard formats on this page the info page will show the
user how the samples will be save.  The fields that are most likely to change
are the Load Format, Data Type, Data Style, and Data Size.

Do not be too concerned with trying to use this page as the file format and
related information will automatically be determined when the file is saved.


ΓòÉΓòÉΓòÉ 5.4.3. Average ΓòÉΓòÉΓòÉ

A sample with an even number of channels may be averaged to produce a sample
with half the initial number of channels. For example, a sample with four
channels can be averaged to produce a sample with two channels and a sample
with two samples can be averaged to produce a sample with one channel.

Channels may be averaged in three ways.  The simplest is to take the left or
right channel data as the final data.  A more complex method is to average the
samples of the left and right to produce a center sample. The results of these
operations are significantly different and can result in very different output
samples.

When a sample contains four channels, it is composed of four sound sources at
45 degrees in each quadrant.  This corresponds to the Front Left, Front Right,
Rear Left, or Rear Right.  To average these into two channels the user can
select to use any of the four channels or to average based on the left or
right. Each of these results in very different output samples.  The individual
control of the four channel sound samples is an enhancement to SOX but is
provided to allow a source sample to be broken into its individual components.
Have you looked at the page for this effect?  If you have, then you might be
confused.  The question is, how do you provide the ability to average channels
from any combination of four possible sources to either one or two possible
outputs.  The answer that I have implemented is simply a column of check boxes
for each output channel.  To select or average any combination of the channels
into either of the output channels, check the box for the channels from the
source sample.  To aid in this, two radio buttons have been provided which
enable or disable the selection of check boxes in the second channel depending
on the number of output channels selected.

To guide the user, when a radio button is selected the check boxes are
automatically set to produce the same results as SOX.


ΓòÉΓòÉΓòÉ 5.4.4. Dupe ΓòÉΓòÉΓòÉ

This function will duplicate channels.

Note:  Not implemented yet.


ΓòÉΓòÉΓòÉ 5.4.5. Reverse ΓòÉΓòÉΓòÉ

This effect allows the user to reverse a section (or all) of a sample.

To select the entire sample, select the Entire Sample button on the notebook
page for the reverse effect.  To select a portion of the sample, the user may
either enter the timemarks for the start and end of the effect or may use the
mouse pointer in the graphical display to select the start and end.

If the button for Select Part is pressed, the Start and End fields will be
enabled. The timemarks must be entered using the format mm:ss.ssss where mm is
the number of minutes into the sample, and ss.ssss is the number of seconds
into the sample.  When the entry field is selected with the mouse, the current
marker will be displayed.  When a new value is entered and another dialog item
is selected, the display will be updated.

To select the begin or end of the reverse effect using the display, either
select the desired marker and drag it to the desired position or simply click
the new position for the marker.  Mouse button 1 selects the Start an Mouse
button 2 is used to select the end. It may be necessary to zoom out on the
sample to view both markers.  The display indicates the current timemarker at
the left of the display, the current timemark for the position of the mouse,
and the zoom factor for the display.  The vertical scroll bar to the right of
the display is used to adjust the zoom factor for the display.  When the mouse
is used to select part of a sample, the Select Part button is automatically
selected.


ΓòÉΓòÉΓòÉ 5.4.6. Echo ΓòÉΓòÉΓòÉ

The echo effect will modify a sample to provide attenuation at specific points
in a sample.  The operator must specify the points where the echo effects are
to start and an attenuation or Volume for the echo.  The attenuation determines
the length of time that it takes for the echo to die away.  If the Attenuation
specified for all of the echo points is greater than 1, then the echo will
"melt" rather than fading away.  If an attenuation is set to 0 or less, the
Echo point is ignored.  I found it very difficult to figure out exactly what
SOX was trying to do here, but the results of the effect seem to be similar.
When playing with SOX to figure out what it was doing, I found that the echo
effect was one of the most difficult to get to work because of the complex user
interface.  Hopefully the echo notebook page will overcome this limitation and
make this effect simple and understandable.

The echo effect presents an interesting challenge to the user interface.  How
do you provide the user with an intuitive method to set the echo locations and
the strength of the echo from a dialog box?  Well, look at the ECHO notebook
page and follow along in the explanation of the operation.  This notebook page
includes a graphical display of the current sample, a text entry field for
editing (e.g. adding or deleting) time marks, and a volume control for setting
the strength of the echo.


ΓòÉΓòÉΓòÉ 5.4.6.1. Echo Graphical Display ΓòÉΓòÉΓòÉ

The ECHO notebook is centered around the graph at the top of the page.  This
display is the primary point of control. However, to allow for a bit more
direct control, the user may use the entry fields to add and delete echo points
too. To explain it all, I will start with the graphical display first and then
lead to the secondary controls.

Once a sample has been loaded into memory, the graphical display will become
active.  The display is controlled through two slider bars for the position in
the sample and for the magnification. The sample is normalized so that the
largest sample value will hit the limit of the display.  This makes the display
volume independent but gives maximum clarity of the actual waveform in memory.
Markers may be added or moved to set the echo points in the waveform.  To aid
the operator in locating the desired echo point, the display contains a status
bar for the starting timemark for the sample in the window, the current
timemark under the mouse, and the magnification factor.


ΓòÉΓòÉΓòÉ 5.4.6.1.1. Echo Display Scrolling ΓòÉΓòÉΓòÉ

To move to the right or left in the display, the horizontal slider bar may be
used.  Pressing the end arrows moves the display one displayed sample to the
left or right.  When the slider bar is pressed, the display will move one half
screen to the right or left.  The user may move the display to a region quickly
by selecting the slider button and dragging it to the appropriate position.
The display is immediately updated to display the current position.

The display area at the bottom of the graph provides a timemark indicator for
the first sample appearing at the left of the graph.  This provides a reference
for moving through the data.  The time marker is displayed in the form of
m:ss.ssss where m is the number of minutes into the sample and ss.ssss is the
number of seconds into the sample.


ΓòÉΓòÉΓòÉ 5.4.6.1.2. Echo Display Zoom ΓòÉΓòÉΓòÉ

Even the smallest sample contains more data than can fit on the graphical
display.  For this reason the vertical slider to the right of the graphical
display is used to adjust the viewing magnification of the samples.  The
maximum magnification of the samples is determined by the length of the sample
and is calculated by dividing the total sample length by the largest number of
data points which may be scrolled through on the display.  The display is
limited to the maximum size of an signed 16 bit value due to the limitations of
the signals for the horizontal slider bar. This results in a maximum of 32767
data points which can be displayed and scolled through.

Initially, the magnification is set for the maximum displayable.  To decrease
the magnification (i.e. zoom out) on the sample, move the slider down the bar.
The arrows on the ends of the bar can be used to increase or decrease the
magnification in increments of 1.  Selecting between the button and the arrows
doubles or halves the magnification. If the button is selected, the
magnification can be set immediately to a value.  Markers are displayed for the
nearest point in the zoom.  However, markers can only be set on exact multiples
of the zoom.  Therefore, when trying to move a marker, if it is set at a
different magnification, it may not be possible to move the marker without
returning to that zoom.  Essentially, the marker is displayed but cannot be
selected because that exact sample point is not visible. I considered making
the mouse select the nearest marker, but this is a point of confusion if many
markers are displayed at the same location for a specific magnification.

The current magnification is displayed in the status area of the display in the
form of "x1/nnnnn" where "nnnnn" is replaced by the current magnification
number (i.e. number of points represented by a single point on the display).
If the display says that the zoom is x1/2, then the magnification of the
display is halved.  If this sounds confusing, then just play with the notebook
page for a bit to get a feel for the operation of the zoom.


ΓòÉΓòÉΓòÉ 5.4.6.1.3. Echo Display Status Bar ΓòÉΓòÉΓòÉ

Before going on, another area of the display needs to be described.  The center
number on the status area of the display indicates the timemark for the current
(or last) mouse position. Whenever the mouse is moved into the display area,
this number will be updated to indicate the time offset for that particular
point.  This takes into account the magnification.


ΓòÉΓòÉΓòÉ 5.4.6.1.4. Echo Adding Echo Points ΓòÉΓòÉΓòÉ

Now for the fun part.  To add an echo point to the sample, move the mouse to
the place where you desire the echo.  The status display will provide a
reference for the timemark. When the proper position has been selected, click
the mouse and a blue marker will be placed.  If the mouse is released, the
marker will be set at that location in the sample.  If the mouse is not
released, the marker may be dragged across the display. This marker may be
moved later if necessary by other means too.

Note:  If at any time the mouse pointer is moved outside of the display before
       the mouse button is released, the marker will not be set and the blue
       mark will be erased from the display.


ΓòÉΓòÉΓòÉ 5.4.6.1.5. Echo Moving Echo Points ΓòÉΓòÉΓòÉ

A echo marker may be moved by positioning the mouse pointer over the marker and
pressing the mouse button.  If the marker is on a multiple of the zoom level,
it will be selected and will follow the mouse as long as the button is pressed.
When the button is released, the marker will be placed at that position.

A marker may be moved to another time delay by entering the desired delay
directly through the Time Mark entry field.

Note:  If the mouse is moved off the display area, the marker will be restored
       to its original position.


ΓòÉΓòÉΓòÉ 5.4.6.2. Echo Time Mark entry field ΓòÉΓòÉΓòÉ

For each marker displayed, the timemark is stored in a Combo Box.  This box is
like an entry field in that the user can edit the time directly; however, it
also has a drop down box that can scroll vertically through all of the
different markers.  This type of box provides a great deal of flexibility for
the user.

To add a marker at a specific time, position the cursor in the Timemark box and
edit the time index.  The format is the same as that used to display the time
marks in the main display.  Enter the number of minutes followed by the
seconds.  The granularity of the seonds is on the order of 1/10000 of a second.
For example, entering 6:54.4253 would accept a time mark at 6 minutes, 54.4253
seconds.  If a value is entered with is beyond the maximum sample of the file
or less than 0, then the data is ignored.

Once the desired time mark has been entered, the user may press the Add button
to place the marker in the current database.  All timemarks added to the
display use the volume specified for the last timemark, or 0 if no volume has
been set yet.

When the listbox is pulled down for the timemarks, each of the timemarks that
have been entered are displayed in a vertically and horizontally scrollable
window.  Up to 32 markers may be placed in the file and any markers which are
unused are displayed with the word "EMPTY".  The markers are placed in the
database in the order that they are entered unless a free slot is open (from
being deleted).  The user may select any of the time marks using the combo box.
If the selected timemark is not empty, the the display will be updated to
display the selected timemark in the center of the graph.  In the event that
the timemark is too close to the end or beginning of the sample to display in
the center of the graph, the timemark will be displayed without being centered.
Once a timemark has been selected, the Del button may be pressed to delete the
marker from the database.  The entry field is not cleared in order to allow the
user to directly edit the timemark which was deleted and add it later.


ΓòÉΓòÉΓòÉ 5.4.6.3. Echo Volume Entry Field ΓòÉΓòÉΓòÉ

The volume for each timemark may be set by specifying a value in the volume
entry field.  This is a simple entry field in which the user can type or delete
numbers.  Since the volume (attenuation) for each timemark may range from 0 to
infinity, the only method for entering the volume is through the keyboard.
Sorry, no sliders here.  As each character is typed, it is stored.  The user
does not have to press enter or any key to accept the value.

I have not found a big use for numbers greater than 1, but I could not find any
reason to limit the user to a specific range of numbers.  Anyone who has
experience with this effect and knows of a reason for a limitation should
contact the author and I will be happy to set up something to make entry of the
Volume easier.

Note:  The most common mistake for the echo effect is in forgetting to enter a
       value in the Volume field.  Remember that you must provide an
       attenuation for the echo in the Volume entry field to make the echo
       point valid.


ΓòÉΓòÉΓòÉ 5.4.7. Band Pass ΓòÉΓòÉΓòÉ

This tool provides the ability to apply a band-pass filter to a sample. The
frequency response for the filter is designed to drop logarithmically around a
center frequency.  The slope of the drop at the desired start (Wp) and end (Ws)
of the filter varies with the distance between the Wp and Ws.  This width is
used to determine the slope of the dropoff at the edges of the filter.  The
frequencies at Wp and Ws will be approximately half of their original
amplitudes and all frequencies outside of the Center - Wp and the Center + Ws
will be eliminated.  The bandpass filter can be mode oriented to pitched
signals (i.e. voice, singing, or instrumental music) or can be modified by
adding noise to the filter so that un-pitched signals can be effectively
processed.

Note:  SOX limits the use of the bandpass filter such that the center frequency
       must be less than or equal to half the sampling rate for the wave.
       Although PMsndX does not enforce this limitation, the results of
       filtering beyond this limit prevents the filter from having much effect.
       To aid the user in locating the maximum effective center frequency, a
       light blue vertical bar is placed at half the sampling rate for the
       data.

The transormation for the Bandpass filter was taken from a a program called
MUSIC56K (as documented in the MUSIC56K source code) and implemented in C++ for
this program.


ΓòÉΓòÉΓòÉ 5.4.7.1. Filter Display ΓòÉΓòÉΓòÉ

Operation of the bandpass filter tool is probably one of the most complex
interfaces in the toolbox.  It is based on a simple principle.  The entire
display of the filter represents the frequency response of the filter and is
operated like a slider.  However, since the Start frequency and the Stop
frequency are independent, the sliding bar is divided into identical controls
for each filter edge. Before getting into the operation of the controls the
display needs to be explained to establish the terms that will be used.

As mentioned, the display is designed to illustrate the frequency response of
the bandpass filter (independent of any added noise).  The center of the Start
(Wp) and End (Ws) of the filter are marked by vertical BLUE bars.  The Center
(Wc) of the filter is marked by a vertical RED bar.  These three markers
provide the means for the user to modify the filter.  The region to the left of
the RED center frequency is always the start of the filter.  The user may click
the mouse to the left of Wp to decrease Wp by 1000 Hz.  Clicking between Wp and
Wc increases Wp by 1000 Hz.  Likewise, clicking between Wc and Ws decreases Ws
by 1000 Hz and clicking to the right of Ws increases Ws by 1000 Hz.  The user
may also click the mouse near Ws or Wp to drag the respective ends of the
filter quickly.

To provide fine control of the filter, Right and Left arrows are provided for
both Wp and Ws.  Clicking on either the right or left arrow will increase the
indicated filter edge by 1 Hz.  To increase or decrease the filter edges by 10
Hz, the user may select the plus or minus corresponding to the filter edges.
The left set of controls affects Wp and the right set of controls affects Ws.


ΓòÉΓòÉΓòÉ 5.4.7.2. Entry Fields ΓòÉΓòÉΓòÉ

As the mouse is used to adjust Wp and Ws, the exact frequencies for Wp, Ws, Wc,
and the filter Width are updated in the text input fields.  The user can use
the mouse to select one of the input fields and modify it directly.  To accept
a value in the entry field and recalculated the dependant frequencies select
another window or click on another item which moves the focus from the
notebook.  The rules for the fields are as follows:

 1. If the Center frequency is modified, new values for Wp and Ws are
    immediately calculated using the current Width. If Wp or Ws are outside of
    the possible ranges, then Wp or Ws are set to the limit of the acceptable
    range and the Width and Center are recalculated.
 2. If the Width of the filter is modified, new values for Wp and Ws are
    immediately calculated using the current Center frequency.  If Wp or Ws are
    then outside of the acceptable ranges, Wp or Ws is then set to its limit
    and the Center and Width are recalculated.
 3. If Wp is changed, the Width and Center are automatically recalculated to
    reflect the new start of the filter.
 4. If Ws is changed, the Width and Center are automatically recalculated to
    reflect the new end of the filter.


ΓòÉΓòÉΓòÉ 5.4.7.3. Noise ΓòÉΓòÉΓòÉ

The bandpass filter has been selected because of the desirable effect on
typical sounds that will be processed by PMsndX such as voice or music.
However, if other types of noise are to be filtered, noise can be added to the
filter which results in a sharper peak of the filter.  To add this noise,
select the checkbox for "Add filter noise". Selecting the checkbox again will
disable the filter noise.

Note:  The display of the frequency response for the filter does not reflect
       added noise.


ΓòÉΓòÉΓòÉ 5.4.8. Low Pass ΓòÉΓòÉΓòÉ

A Low Pass filter can be applied to a sample to eliminate high frequencies.
Filtering is accomplished in the digital domain through the use of a very
simple second order digital Fourier transform.  Future implementation may have
a more complex Fourier transform; however, the chosen function is desirable
because it provides a smooth dropoff without significant ringing. The
performance of the filter is determined by the cutoff frequency and the rate of
drop.  If the dropoff is made too quickly, the filter will exhibit a ringing
effect at the begin and end of the dropoff.  If the dropoff is performed too
slowly, the filter will supress more frequencies toward the end of the desired
range.  The more orders of the filter (more stages), the better the frequency
response; however, more orders increase the time for filtering significantly. A
two order filter works adaquately.


ΓòÉΓòÉΓòÉ 5.4.8.1. Gain ΓòÉΓòÉΓòÉ

When performing the digital convolution of the sample with the step function a
Gain factor is used to normalize the output data.  This acts as a Volume
control for the sample to prevent losses due to numerical overflow.  Values for
the gain range from 0 to 1 in increments of 0.01.  A slider bar is used to set
the gain of the low pass filter.  When the low pass filter is first brought up,
the Gain will default to a value of 0.8.  If this is changed, it will remain at
the new setting until the session is terminated.


ΓòÉΓòÉΓòÉ 5.4.8.2. Frequency ΓòÉΓòÉΓòÉ

The Frequency response of the low pass filter is determined by a the
centerpoint of the dropoff at the end of the step function.  When performing a
digital filter, it is not possible to prevent the gradual drop at the end of
the step function due to the convolution of the samples used in the
transformation.  This is true for analog components also. The centerpoint of
the dropoff can be set in three ways. The user may enter the specific fruquency
in the text entry box in the lower right corner or may use the filter display
like a sliding bar.  As is typical of a sliding bar, the mouse may be used to
capture the cutoff frequency by pressing the mouse button while the mouse is
near the cutoff frequency.  By holding the button down, the user may drag the
frequency to the desired range.  Additionally, the user may click to the right
or the left of the frequency cutoff to increase or decrease the frequency by
1000 Hz. The right and left arros in the corners of the display may be used to
increase or decrease the frequency by 1 Hz. The plus and minus buttons in the
corners of the display may be used to increase or decrease the frequency by 10
Hz. The frequency response curve illustrates the dropoff that occurs at the end
of the step function.


ΓòÉΓòÉΓòÉ 5.4.9. Rate ΓòÉΓòÉΓòÉ

Once a sample has been loaded into memory, the current rate information is
displayed on the RATE page of the notebook. The user can change the rate of the
sample using this page of the tools notebook.

The rate information page is dividied into groups of buttons and slider bars.
These are for Standard Rates, Non-Standard Rates, Quality, Do It, and Help.

Note:  Changing the sampling rate may degrade the quality of the sound.


ΓòÉΓòÉΓòÉ 5.4.9.1. Standard Rates ΓòÉΓòÉΓòÉ

The user may select from a set of standard sampling rates for common computer
formats or may specify a specific rate. OS/2 and Windows use standard rates
which are multiples of 11025 Hz.  Sun, DEC, and NeXT computers commonly use a
sampling rate of 8000 Hz.  Standard rates of 8000, 11025, 22050, and 44100 Hz
have been provided for the user to select.


ΓòÉΓòÉΓòÉ 5.4.9.2. Non-Standard Rates ΓòÉΓòÉΓòÉ

If the user wishes to use a sampling rate which is not one of these, the button
for Non-Standard should be pressed.  This will activate the slider bar and user
input windows to allow the user to specify the rate.  The slider bar can be
used to quickly change the rate in the input window or the user may select the
input window and type in the desired rate.


ΓòÉΓòÉΓòÉ 5.4.9.3. Quality ΓòÉΓòÉΓòÉ

When changing the sampling rate, each new sample point must be interpolated
from the current set of samples.  This can be done in a number of ways.  PMsndX
allows the user to specify the quality of this interpolation between samples.
Choosing a value of 1 will use linear interpolation which is quick, but causes
distortion.  Choosing a higher value will take longer to perform, but will
create a better approximation to the original waveform.


ΓòÉΓòÉΓòÉ 5.4.9.4. Do It ΓòÉΓòÉΓòÉ

If the rate specified by the user is the same as the sampling rate for the data
currently in memory, the DO IT button is disabled.  If the sampling rate is
changed, the DO IT button will be activated.  Pressing this button will convert
the change the data in memory to reflect the information specified by the user.


ΓòÉΓòÉΓòÉ 5.4.9.5. Help ΓòÉΓòÉΓòÉ

To open the HELP engine with for information on the Rate page, select the HELP
button.


ΓòÉΓòÉΓòÉ 5.4.10. Speed ΓòÉΓòÉΓòÉ

This function will change the playback speed of a sample. This is the same
thing as setting a phonograph to a different speed such that the sound is
played too fast or too slow.  The controls for this effect simply specify the
new playback speed.  Once a new speed is selected, the sample is resampled to
interpolate the new playback points. As a result, a sample is still played at
the same rate, but the data is modified to play at the new rate.  This allows
the sample to be stored in a file which is of a standard rate.

The user may select any of the standard rates including 8000 Hz, 11025 Hz,
22050 Hz, and 44100 Hz.  Additionally, the user may specify the playback speed
to be either double (x2) or half (x1/2) or may specify a specify playback speed
by selecting the User button.  If a speed other than the current speed is
specified, the DOIT button will be activated which will allow the user to
perform the change.


ΓòÉΓòÉΓòÉ 5.4.11. Vibro ΓòÉΓòÉΓòÉ

This function is in SOX and has been added to PMsndX to maintain compatibility
with the functions of SOX.  This function performs the "world-famous" Fender
Vibro-Champ sound effect to a sound sample by using a sine wave as the
amplitude of the volume at each sample.  This tool requires that the user set
the Speed, and the Depth of the sine wave.

The code for this effect was taken directly from source code from Lance Norskog
and Sundry and converted to C++ for this program.


ΓòÉΓòÉΓòÉ 5.4.11.1. Speed ΓòÉΓòÉΓòÉ

The speed setting gives the frequency of the sine wave in Hertz.  The range of
values for the slider are from 0 to 30 in increments of 1 Hertz.  A value of 0
would be useless for a frequency so this is automatically changed to 0.001.  By
default, the speed is initially set to 0.001.


ΓòÉΓòÉΓòÉ 5.4.11.2. Depth ΓòÉΓòÉΓòÉ

The depth setting gives the the amount by which the volume will be cut into by
the sine wave.  The range of values for the slider are from 0.0 to 1.0 in
increments of 0.01.  The initial value of the slider is 0.5.


ΓòÉΓòÉΓòÉ 5.4.12. Volume ΓòÉΓòÉΓòÉ

Most anyone who has received a sound sample from different sources has had the
problem that the recorded volume is inconsistent between different samples.
After all, there is no standard recording level for the different machines that
sound can be recorded from.  To allow the user to adjust the volume of a
sample, PMsndX provides a tool to adjust the volume.  Volume can be adjusted by
either specifying the Maximum or by simply multiplying by a fixed value.


ΓòÉΓòÉΓòÉ 5.4.12.1. Maximum Volume ΓòÉΓòÉΓòÉ

By specifying a maximum value for the sound sample, all sound samples can be
set to have a similar maximum.  The obvious use for this function is to allow a
library of sounds to be set at the same volume.  The value used for the maximum
volume is based on a percentage of the maximum data that can be held in a
single sample.  As an example, a value of 100% for the volume represents a
value of 127 for a signed byte sample.

When the button for the Maximum is selected, the slider bar directly beneath
the button is activated.  Initially, this will be set to the current volume in
terms of the percentage of the maximum value for the sample.  The volume may be
adjusted by setting the slider to a value between 0 and 100 percent of the
maximum.

Since the value is based on a percentage of the maximum value of the data that
can be stored in a sample, clipping is not possible.


ΓòÉΓòÉΓòÉ 5.4.12.2. Fixed Volume ΓòÉΓòÉΓòÉ

When the button for the Fixed value is selected, the slider bar directly
beneath the button is activated as well as the checkbox for clipping.  The
fixed bar provides the means to multiply all sound samples by a fixed value
between 0 and 2 in increments of 0.1. A value of 1 makes no change.  Any value
greater than 1 increases the volume and any value less than 1 decreases the
volume.  A value of 2 doubles the volume of the sample.

When using fixed sampling it is possible to exceed the maximum data that may be
stored for a sample.  The checkbox for clipping may be selected to prevent this
clipping.  If the checkbox is set, if the fixed multiple will result in
clipping, then the maximum multiple will be set to the maximum value that will
not result in clipping.  If the clipping box is not set, data may exceed the
maximum that may be stored for the sample.


ΓòÉΓòÉΓòÉ 5.5. Settings ΓòÉΓòÉΓòÉ

The window positions and file paths are maintained as long as PMsndX is
running.  When PMsndX is terminated, it will not save the current positions and
paths for file operations unless the boxes are checked in the SETTINGS dialog
box.  Selecting these buttons has no effect on remembering the current window
positions during a single session; rather, they only affect saving the
information between sessions.

From the SETTINGS dialog box the user may select to save the current window
positions, open file path, save file path, maximum memory and enable MMPM/2
Support requirements of the program.

The SETTINGS information is stored in the file pmsndx??.ini in the directory
where PMsndX was started.  The question marks in the file name represent the
version number for the program.  This is intended to allow future versions of
the program to avoid conflicts in the event that the initialization file format
changes.

Note:  The information in the SETTINGS dialog box is only saved when the
       program is terminated.  If the SAVE CURRENT items are deselected, then
       the information will not be saved between sessions.


ΓòÉΓòÉΓòÉ 5.5.1. Window Positions ΓòÉΓòÉΓòÉ

During a session, the user can move any of the dialog boxes around on the
screen.  If the WINDOW POSITIONS box is checked, these window positions will be
saved when the program is terminated.  If this button is deselected before the
program is terminated, the next session will revert to the previous window
positions saved by the program.  By default, if no window position has been
saved for a particular window, the window will be opened in the lower left
corner of the desktop.


ΓòÉΓòÉΓòÉ 5.5.2. file Open path ΓòÉΓòÉΓòÉ

The file path for loading samples into memory may be saved between sessions by
selecting the FILE OPEN PATH button.  If this button is selected, the last file
open path will be saved when PMsndX is terminated.  If this button is
deselected before the program is terminated, the next session will revert to
the path from the previous session. If no information is saved for the program
at any time, the current path will become the default path for open operations.

Note:  This box may be selected from either the SETTINGS dialog box or from the
       SAVE DIRECTORY button on the OPEN dialog box.


ΓòÉΓòÉΓòÉ 5.5.3. file Save path ΓòÉΓòÉΓòÉ

The file path for saving samples to a file may be saved between sessions by
selecting the FILE SAVE PATH button.  If this button is selected, the last file
save path will be saved when PMsndX is terminated.  If this button is
deselected before the program is terminated, the next session will rever to the
path from the previous session. If no information has not been saved between
sessions, the current path will become the default path for save operations.


ΓòÉΓòÉΓòÉ 5.5.4. Maximum Sample Memory ΓòÉΓòÉΓòÉ

PMsndX takes advantage of OS/2's advanced memory management facilities.  When
the program is started, it only takes up the memory required for the executable
to load.  PMsndX then reserves the amount of memory specified by the SETTINGS
box from OS/2 but does not commit this memory.  This means that the program has
requested that OS/2 allocate the necessary resources to manage the amount of
memory specified.  Until the memory is actually committed it is not taken from
the system's memory pool.  When a sound sample is loaded into memory, PMsndX
then requests that OS/2 commit the necessary memory before it loads the sample.
When a new sample is loaded, the previous memory is decommitted and the
procedure is repeated.

Although this minimizes the actual amount of physical memory required by
PMsndX, it still provides the potential to cause OS/2 to have to commit more
memory than is available on the system.  To avoid this problem, PMsndX provides
the user with the ability to limit the amount of memory which can be committed
by OS/2.  The user may either specify that the program automatically determine
the maximum or that it set the maximum at a specific value.

Memory is primarily used to hold samples for operations; however, whenever the
sound is manipulated in such a way that either the output has a different
number of samples or the operation requires the samples to remain in tact
during the entire operation, additional memory is used to hold the new data.
Once the operation has been completed, the memory is freed.  When setting the
maximum memory, the user must take into account the size of the data in memory
as well as the size of the results of any operations. With the exception of
Sampling Rate changes, the maximum memory requirements will not exceed twice
the size of a sample.  When changing rate, the size is dependent on the new
sampling rate.  If the new rate is higher than the current rate, the memory
requirements will increase.  If the new rate is lower than the original rate,
the memory requirements will shrink.


ΓòÉΓòÉΓòÉ 5.5.4.1. Auto ΓòÉΓòÉΓòÉ

If the user selects the AUTO mode for memory (the default), PMsndX will limit
the memory usage to 32 megabytes.  This is generally more memory than most
systems have but allows for a very large sample file to be loaded.


ΓòÉΓòÉΓòÉ 5.5.4.2. Value ΓòÉΓòÉΓòÉ

Since the minimum OS/2 memory block size is 4096 (4k) bytes, the user may
specify the number of 4k pages for the limit.  The user may either use the up
and down arrows to increment or decrement the amount of memory or may place the
cursor in the window and type the specific value.


ΓòÉΓòÉΓòÉ 5.5.5. MMPM ΓòÉΓòÉΓòÉ

PMsndX supports playing samples from memory directly to the MMPM digital audio
device of OS/2.  This allows samples to be played without having to save the
sample to disk in the native .WAV format.  The settings dialog box provides
controls for disabling or enabling MMPM support and for controlling the actions
taken when a file is loaded (e.g. Play sample on load, convert to a standard
rate when loaded, and exit after play from the command line).  Additionally,
the digital audio device  may be specified.


ΓòÉΓòÉΓòÉ 5.5.5.1. Enable MMPM/2 Support ΓòÉΓòÉΓòÉ

If the MMPM/2 capabilities of the program are not needed or if MMPM support is
not installed on a particular system, the MMPM may be disabled from the
settings dialog box.  By disabling the MMPM/2 support, the button on the main
control panel for MMPM is disabled.  By default the program will disable MMPM
support; however, if the MMPM button is selected, a message is displayed to the
user to indicate that the setting should be turned on from the settings box.

The controls for MMPM and the ability to play the "playlist" using MMPM utilize
the files SW.DLL and MDM.DLL.  These are part of the standard MMPM distribution
and must be present in the DLL path for the MMPM portion of this program to
operate.  The MMPM support is not linked into the executable of this program.
Rather, it is only loaded when the user enables it.  This allows the program to
run on machines which do not have MMPM installed.

The MMPM/2 functionality of PMsndX has been implemented to share the audio
device with other programs on the system. By disabling the MMPM/2 support, the
audio device is freed up completely and all of the tasks (six in total) are
released.


ΓòÉΓòÉΓòÉ 5.5.5.2. Play sample on load ΓòÉΓòÉΓòÉ

If this box is selected, a sample is immediately played when it is loaded into
memory.  To provide control during playback, the MMPM dialog box is opened
after the file has been loaded.  When this feature is used in conjunction with
the exit after play feature, PMsndX provides the ability to play any supported
sample file format from the command line and have the program exit when it is
finished.

If this parameter is not specified, the sample will still be loaded from the
command line; however, it will not be played until the user accesses the MMPM
dialog.

Note:   When a filename is specified on the command line, the control panel and
       the dialog boxes are not opened.  The intention of this operation is to
       allow the program to play without being intrusive.


ΓòÉΓòÉΓòÉ 5.5.5.3. Standard rate on load ΓòÉΓòÉΓòÉ

Not implemented yet!

If a sample is sampled at a rate other than one supported by the MMPM/2 module
of OS/2, this feature will allow the program to resample the file at the
nearest supported rate as it loads the file.  If this option is not selected,
the file will simply refuse to play if it is at a different sampling rate than
supported by OS/2.


ΓòÉΓòÉΓòÉ 5.5.5.4. Exit after Command line play ΓòÉΓòÉΓòÉ

This option provides the ability for PMsndX to exit after playing the sample
when the file is loaded from the command line.  This is primarily intended to
provide a means to play any of the supported formats from the command line.


ΓòÉΓòÉΓòÉ 5.5.5.5. Device ΓòÉΓòÉΓòÉ

Obviously not every machine has the same digital audio device.  PMsndX provides
a means to use a different audio device than the default digital audio
interface.  By default the device name is Waveaudio01.  Any Waveaudio device
may be selected by entering the device name in the Device entry field.


ΓòÉΓòÉΓòÉ 5.5.6. Do It ΓòÉΓòÉΓòÉ

After the user has set all of the information in the SETTINGS dialog box can be
applied by pushing the DO IT button.  When this button is pressed, the dialog
box is inactivated and the settings are applied.

Note:  If a sample is currently loaded into memory and the Maximum Sample
       Memory is changed, the sample data will be flushed from memory.  To warn
       the user of this, a warning box will be displayed.


ΓòÉΓòÉΓòÉ 5.5.7. Oops ΓòÉΓòÉΓòÉ

To dismiss the SETTINGS box without using the values set by the user, the OOPS
button can be used.  This has the same effect as pushing the SETTINGS button on
the main control panel when the SETTINGS box is displayed.  All information
entered by the user is cleared and the SETTINGS remain unchanged.


ΓòÉΓòÉΓòÉ 5.5.8. Help ΓòÉΓòÉΓòÉ

Pressing the HELP button displays help on teh SETTINGS dialog box.


ΓòÉΓòÉΓòÉ 5.6. MMPM ΓòÉΓòÉΓòÉ

So, you are interested in playing some samples from my little program?  Good.

The ability to play a sample is not intended to provide the full capabilities
of the digital audio player.  It is intended to allow samples to be played
without having to save them to disk.  Additionally, this feature allows the
user to play a file of any format currently supported by PMsndX.  The sample
rates are limited to those supported by the MMPM device and if a sample is
loaded with an odd sample rate which is not supported, it must be converted to
a useable sample rate before it can be played.

If you don't have MMPM/2 installed with your OS/2, don't worry.  If you disable
the MMPM support from the settings dialog box, it will not attempt to open the
audio device.

The controls for the MMPM player are basically the same as those used on the
digital audio player so no additional explanation is provided.

O.K., let's face it.  MMPM is pretty cool and it is not extremely difficult to
program.  However, to take advantage of the advanced features of the system, a
great deal needs to be done.  I was not able to find a good reference book for
programming MMPM code, so I winged it and got something going.  No doubt this
will be a problem in the future.  The current implementation is very simple and
uses about 6 tasks to handle the queueing of data and running the little
buttons to look like the IBM buttons for the digital audio player.

Note:  Recording has not been implemented at this time.


ΓòÉΓòÉΓòÉ 5.7. Exit ΓòÉΓòÉΓòÉ

When the EXIT button is pressed, the program terminates.  If the Settings box
or the SAVE DIRECTORY from the Open or Save dialog boxes have been set to save
information, the data will be saved to the initialization file before the
program exits.  all windows of PMsndX including any dialog boxes are removed
from the screen when the program terminates.


ΓòÉΓòÉΓòÉ 6. Technical Issues ΓòÉΓòÉΓòÉ

Memory Usage: I have worked with means for storing and converting from one
format to another efficiently.  Initially I tried to store things in a data
structure which was a union of all of the types of data that are used by the
sound types.  However, converting from one format to another was difficult and
each effect had to be able to understand the initial and final format.  This
became unwildly considering that there can be either signed or unsigned samples
of sizes byte or word.  As new effects were added, it became unmanagable.  At a
sacrafice to memory efficiency, I have changed it to store all data as a signed
SHORT (2 byte) sample.  The effects then operate genericly on the samples and
the only time that the type of data is important is when reading or writing the
samples.  The savings in complexity justified the memory requirements.  As a
result, if a sample is 1k of bytes (.wav format), then in memory it will take
up 2k.  Currently the program will only read and write 8 and 16 bit samples.
Since I don't know of any sound cards that can sample at greater bit sizes,
this is the limit.  In the future, this approach to memory usage can be easily
extended to 32 bits without rewriting every part of the program.  In fact, to
change the storage sizes, two definitions have to be changed and then the
proper input/output routines written.  Simple? I think so.

Additional known faults:

 1. Currently, the Quality setting in the Rate only supports a linear
    approximation.  This appears to be the same that SOX supports as they
    result in similar output.
 2. The buttons for Play and Record have no function at this time.  This
    functionality will be added later.
 3. There is no drag and drop capability yet.
 4. A file must be loaded through the Open button.  PMsndX ignores any
    additional parameters on the command line.
 5. There is currently no means to override the load file type.
 6. Volume changes affect both channels equally.  If one channel is sampled at
    a higher volume, there is no method currently available to mormalize the
    two channels.


ΓòÉΓòÉΓòÉ 7. About the Author ΓòÉΓòÉΓòÉ

My name is William Scott Hiles but I usually go by the name Scott.  I have a
masters degree in signal processing and satellite communications.
Unfortunately, my occupation utilizes very little of my formal education and
takes more advantage of my less formally learned talents.  I work as an
electrical engineer for the Navy in the area of LAN and WAN research. My job is
centered around promoting open systems in networking within the Navy and I am a
Navy expert on fiber optic networking.  I have worked with the ANSI X3
committees for the past 5 years and currently (1993-1994) am the chairman of
the FDDI Repeater specification.  Enough of that dribble...the point is that I
don't use my education in my job.

Which leads me into the purpose of this program.  I am an electrical engineer,
and my heart lies in hardware design and programming.  Well, with this program
I can at least satisfy my need to create software.  So, this program came about
because I was playing with sampling and recreating sound with my Sound Blaster
16 when I had the need to convert from the .wav format to the Sun .au format.
SOX is the only thing that I was able to find that could do what I needed.
However, I quickly realized that SOX is great for the general case, but not so
great in more specific cases such as changing the sampling rate of a file. SOX
is good enough for the human ear, but not good enough for the computer.  So,
rather than live with SOX or just write a resampling program, I wrote PMsndX to
provide the functionality of SOX but enhance it to provide the capabilities I
needed.

My resources are modest.  I am 29 (1993) and have programmed everything from a
PC to a 286 for the past 10 years.  I dumped my 286 in February of 1993 and got
me a nice 486.  I decked the thing out and got OS/2.  I had been playing with
OS/2 since 1.3 on machines that I did not own, but this was the first time I
had it at home to play with as I pleased. Programming under OS/2 provided a
unique challenge with unlimited creative abilities.  The company called
WiSHware which is listed in the About box was formed as a shareware/freeware
incorporated name for anything I write.  I have a significant library of
programs for DOS and even a couple for Windows.  PMsndX is the second program
for OS/2 that I have written.  The first one was not well received as it did
not provide a significant function to the community.  Big deal.  I use it at
home and I don't care.

So that is my history and my qualification.  I am a bit surprised that you read
this far.  Congratulations. By the way, did you wonder why I chose a little
blue motorcycle for the icon? I can easily be reached by my current email
address ([e-mail]) or through US mail at:

Scott Hiles
4421 Savannah St.
King George, VA 22485


ΓòÉΓòÉΓòÉ 8. Shareware ΓòÉΓòÉΓòÉ

During the development stages of PMsndX (i.e. until version 1.0 is available)
PMsndX is free to all for distribution. After version 1.0 is finished, the
program will then be distributed as shareware.

I have put a lot of effort into making this program robust and very pleasing.
In actuality, 90 percent of the work on the program has been around the user
interface because the code for doing the actual effects is only about 500 lines
compared with roughly 10,000 lines of code for the user interface.  It has
taken me more than three months to get this program to where it is now, and I
would hope that if you like the program and use it, you will appreciate it
enough to send me a little cash to help fund future work.  I don't expect much.
I think a round number like $25.00 would be nice, but you can do whatever you
feel like.  Just don't insult me by sending me a penny or something like that.
With my current financial status (i.e. poor) I cannot afford a optimizing
compiler.  With a few donations the program could benefit nicely.  (hint, hint)
The section describing the Author provides my email and US postal mail
addresses.

Note:   If you tested the program during the development stages, you will get a
       FREE copy of the final program.


ΓòÉΓòÉΓòÉ 9. Future Work ΓòÉΓòÉΓòÉ

The scope and goals for PMsndX are growing day by day. Currently I plan to have
all of the functions of SOX as well as a few others listed below.

 1. Drag, Drop, Cut, and Paste operations
 2. Add a scripting language for automating operations
 3. Command line overrides/initialization
 4. Playback, Recording, and Cut/Paste editing
 5. Normalization across channels
 6. Add other filters such as Butterworth, Chebyshev and others.
 7. Add High pass filtering
 8. Add a Band Stop filter


ΓòÉΓòÉΓòÉ 10. Tradeoffs ΓòÉΓòÉΓòÉ

Although SOX has a difficult command line, it is very effective for large
samples because it processes the samples in managable blocks.  As a result, SOX
does not require much memory to operate.  PMsndX provides the user with a
simpler interface at the expense of reqources on the host computer. This can be
a significant factor when manipulating large files on a system that is limited
in memory resources.  This should be taken into consideration.  PMsndX is
useless if it does not have the resources necessary to operate.  When OS/2 uses
its swap file to provide more memory, the performance of PMsndX as well as any
other programs on the system will suffer significantly.


ΓòÉΓòÉΓòÉ <hidden>  ΓòÉΓòÉΓòÉ

SOX originated on Unix and provides a means to convert sound from one format to
another and to add effects to sound samples.  The interface to this program is
the command line with various options and flags.


ΓòÉΓòÉΓòÉ <hidden>  ΓòÉΓòÉΓòÉ

Unix is a registered trademark of ATT laboratories.


ΓòÉΓòÉΓòÉ <hidden>  ΓòÉΓòÉΓòÉ

JoeView is an excellent program written by Joe Burkley.  If you ever need to
view a graphics image of virtually any format, this is the program for you!!!


ΓòÉΓòÉΓòÉ <hidden>  ΓòÉΓòÉΓòÉ

Now, here is where my creativity is somewhat lacking.  Unlike the makers of
BMW, I don't have the resources to hire a company to find the best icons for a
the buttons, so I did it the easy way.  I just made a stab at it and figured
that if anyone had any complaints or comments, they would let me know and I
would change them.  Come on, one of the easiest things to do to a program is to
recompile the resource bitmaps.  If you have suggestions, just let me know and
maybe you might influence me to change them.


ΓòÉΓòÉΓòÉ <hidden>  ΓòÉΓòÉΓòÉ

The bits in a word are stored such that the leftmost bit is stored first in the
first byte and the rightmost bit is stored last in the last byte.  If a word is
composed of 16 bits, the word would be written to a file starting with bit 16
and ending in bit 0.

The number 0x1234 (0001 0010 0011 0100) is actually stored as 0001 0010 0011
0100.


ΓòÉΓòÉΓòÉ <hidden>  ΓòÉΓòÉΓòÉ

The bits in a word are stored such that the leftmost bit is stored first in the
last byte and the rightmost bit is stored last in the first byte.  If a word is
composed of 16 bits, the word would be written to a file starting with bit 7
and ending in bit 8.

The number 0x1234 (0001 0010 0011 0100) is actually stored as 0011 0100 0001
0010.