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MPEG_CD 2.0.5
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MANUAL
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MPEG/CDェ Features:
・ Easy to use CD player and document metaphor.
・ Realtime MPEG-1 Layer I/II decompression.
・ MPEG-1 Layer I/II to AIFF file encode/decode.
・ Automatic encode/decode on document double click.
・ Background audio encode/decode.
・ Decompression playlist queues multiple tunes for play.
・ Apple Event Aware provides browser support.
・ Audio CD to AIFF file copy.
・ Mic to AIFF recording.
・ □MPEG audio encoding of AIFF files.
Our Home...
Please visit our home page for new product announcements:
http://www.kauai.com/~bbal
CD-Audio Encoding
With a PowerMac or supported 68K based Mac with compatible
CD-ROM drive, you can immediately begin compressing your existing
audio CD's into MPEG files. Follow these steps:
1) Place an audio CD in your CD-ROM drive.
2) Select "Record/Audio CD to AIFF...". A file open dialog will appear.
Navigate to your CD drive (Audio CD 1) and select a given
audio track from the CD (e.g., Track 1).
3) Another file open dialog will appear. Navigate back to your hard
disk and click "Save".
4) The entire CD track will be preserved in AIFF format on your hard
disk (make certain you have the space...).
5) Double click the icon of the newly created AIFF file, the file should begin
to play.
6) Now, select "List/Encode" or Command-E to MPEG encode the file at the default
encoder settings. MPEG audio software-only compression takes time, be patient.
7) A ".m1a" file is now created in the same directory as the AIFF file.
8) Double click the newly created .m1a MPEG audio file. The file should now
decompress in realtime.
-- WARNING --
Be aware, much audio material is copyrighted. Check with the content originator
regarding rights to translation and distribution of said audio material in MPEG
format.
Microphone Input Encoding
1) Select "Record/Mic to AIFF". A file open dialog box will appear wherein
you should navigate to where you want to save the AIFF file being created.
2) The standard mac microphone transport functions appear. Select "record"
and start recording your mic input (be certain to verify your Sound control
panel "Sound In" Options are set to the Microphone as input).
3) Click stop when done recording, then Save.
4) Double-click the newly created AIFF file to listen.
5) Enter "Command-E" to MPEG encode the file which will appear in the same
folder as the AIFF file.
6) Double click the newly created .m1a MPEG audio file. The file should now
decompress in realtime.
This feature is very useful for voice-mail. Speak into your microphone,
encode, and send the compressed audio as a Eudora attachment.
-- To obtain the fully authorized version of MPEG/CDE with unlimited encoding
and decoding capability requires a full license. See below for instructions on
obtaining a full MPEG/CDE license or registering your MPEG/CD copy. --
Evaluating Fidelity vs. Size Tradeoff issues
1) Select File->Preferences Encoder (2/2) and enable the checkbox
"Encode all Bitrates in Layer".
2) Perform the sequence of steps outlined in CD-Audio Encoding above.
This encodes your AIFF file in all bitrates applicable to your Preferences
Encoder (1/2) settings based on the selected Mode and Layer. Be patient,
as encoding can take a long time based on your AIFF filesize.
To abort from this batch encoding mode use the Command-, sequence - i.e.
hold down the Command and comma keys together.
Decoder Preferences
MPEG/CDェ maintains a default set of Preferences in the System Folder
called MPEGDefaultConfig which are written on exit from the
application.
From within MPEG/CDェ, pull down the "Edit" menu and select "Preferences".
Read the following discussion to determine default settings based
on your playback requirements.
Realtime playback of full quality stereo MPEG Layer II audio requires
a sufficiently strong machine, i.e. high end Quadra or PowerMac.
However, MPEG/CDェ provides several options to lighten processing load
at the expense of time, memory, disk space, and audio quality, allowing
realtime playback on lesser machines.
Upon initial MPEG/CD launch, the Decoder Preferences are set for "Realtime"
decompression. If, when you double-click the Astor-Basia file, sound
is emitted but has intermittent gaps in play, your machine isn't fast enough
for realtime decompression. You can reduce processor requirements in one
of three ways to possibly squeeze realtime decompression from your
machine:
1) Try using one of the Decoder Preferences downsampling modes. First,
2x, then 4x, etc. This effectively drops audio samples - trading audio quality
for decompression speed.
2) If Channels is set to "Both", set instead to either "Left" or "Right. This
effectively halves the amount of decompression processing required by your
machine.
3) If the above at 16x still can't decompress your audio realtime, then set your
Downsampling back to "None" and select the "Decompress to AIFF file" checkbox.
This will decompress the MPEG encoded audio file to an AIFF file (make certain
you have enough hard disk space...). You can then double click the new AIFF file
and you'll here the audio clip at the selected fidelity (full fidelity if licensed).
Encoder Preferences
MPEG audio has three layers, I, II, and III. Currently only Layers
I and II are supported. Within a given layer a number of bitrates
are supported, expressed in kilobits per second or Kbps. Assuming
32 Kbps bitrate is selected, each second of audio is compressed
to 32,000 bits or 4,000 bytes. Normally, an input 44.1 kHz sampled
mono channel would contain 44,100 * 16 (bits/sample) = 705,600 bits.
Thus, at the 32 Kbps rate this stream compresses to 705,600/32,000
or appx 22:1.
As another example, a standard 44.1 kHz sampled stereo stream uses
44,100 * 16 (bits/sample) * 2 (channels) = 1,411,200 bits/second.
Compressing this at a 64 Kbps bitrate yields 64,000 bits.
Thus, the compression ratio in this case is again appx. 22:1.
You can perform similar calculations to determine the effective
compression ratios of the other bitrates.
Some additional checkboxes exist to select the desired psychoacoustic
model, emphasis, input audio sampling frequency, and encoding mode.
When selecting the 32 Kbps bitrate, you can elect one of the
MPEG-LBR rates to achieve two lower bitrates which are a superset of
MPEG, and can "stream" over 14,400 and 28,800 baud modems using
the MPEG/CDS client software.
The List
MPEG/CDェ maintains a default List in the System Folder called
"MPEGDefaultPlayList". If enterring MPEG/CDェ through double-clicking
the application, the default List is read. Any changes made to the
List from inside MPEG/CD are written to MPEGDefaultPlayList upon
exit.
When double-clicking an .m1a or AIFF sound file from the Finder, the
default List is not read (this also applies when clicking on an
.mp2 or .AIFF file from within Netscape). This allows you to use the
"Command-/" and "Command-r" commands (described below) to replay
the tune following play, or cancel the tune during play.
Adding a List entry
Selecting "List/Show..." presents the current List. Enter "File/Add to List"
to add a file to the List. Now you can do a "List/Show..." and see the
tune in the list. Additonal entries can be added in a similar manner.
All Highlighted entries in the List will be decompressed and/or encoded
depending on whether it is an ".m1a" or "aiff" file. By default, an entry
is selected when enterred into the List.
Deleting a List entry
To remove a List entry, first deselect all current entries that may be
highlighted and select (highlight) only the entry(s) to be deleted by Command
clicking the entry(s). Now, press the Delete key. The entry(s) is cleared from the
List. Multiple entries can be deleted in this manner. Enter, "OK" to complete
the deletion sequence.
Deselecting a List entry
By default each entry is selected for play when added to a List indicated
by the highlighted entry. You can deselect the tune yet keep it in the List
forcing MPEG/CDェ to bypass the tune when selecting "Special/Decompress".
To deselect a tune hold down the Command key and click the List entry.
The text will no longer be highlighted indicating decompression for this file
is disabled.
Managing Multiple Lists
The default List is managed by MPEG/CDェ and preserved in the System
Folder Preferences area and serves the needs of the typical user. However,
any number of Lists can be created and preserved using "File/Save List".
This "Disc Jockey" friendly feature allows numerous Lists to be preserved
and recalled for subsequent use.
Lists of AIFF files can be created for batch encoding or decoding. Lists of
m1a files can be made for back-to-back decode/play.
Decompression
When the "MPEG Decompress" progress dialog appears, you can abort the
current file decompression at any time by enterring "Command-.",
that's the Apple key and the period together - or use the "Cancel"
button. To abort the current file decompression and quit the application,
enter "Command-," - that's the Apple key and the comma together.
Decompression status window
By selecting the "Status/Show Window" pull down, a blank status
window appears. When a file is decompressed or played, the MPEG
audio header information is displayed in the window to allow examining
the utilized MPEG coding constraints. Following file decompression, the
number of samples "clipped" during processing are displayed as Errors.
If multiple files are queued in a playlist, information for each file is
echoed and can be scrolled through following decompression. Clicking
the window's close box or selecting "Status/Hide Window" removes the
status window from the screen.
Admittedly, the Status window is primitive. You can't type into the
window or printing becomes "askew". Also, the status window
isn't refreshed once another window (including the decompression
status window) overlays it. Use this window as a reference and a
progress monitor.
File Creators and files
m1a
After completely playing an MPEG encoded audio file the first time,
MPEG/CD stamps the file creator as KAU1 with a filetype of M1A.
From this point on you can double-click the file in the Finder to start
audio playback - similar to Macintosh Finder sound files.
When properly configured, Netscape stamps an MPEG .m1a audio file
with the KAU1 creator and M1A file type when using "File/Save
Next Link as..." from within Netscape. Users should be aware Netscape
always implicitly places downloaded audio files in the System Folder, i.e.
if you click on a .m1a file hyperlink, the file is transferred to your
System Folder and subsequently realtime played (if MPEG/CD Preferences
are appropriately set). Thus, you're required to have enough space on
your hard disk to minimally hold the audio file for subsequent play.
When "File/Save Next Link as..." is not used, the temporary audio files in
the System Folder are deleted when exitting Netscape. Files
downloaded by Netscape are directly double-click playable by MPEG/CDェ.
If, however, you download the .m1a audio files to your machine using
ftp, Fetch, or another method, the file appears as a document with
the standard TeachText document icon. To stamp the file creator
with KAU1 and filetype M1A you must first add the downloaded
file to an MPEG/CDェ List using "File/Add to List" and
completely decompress the file. When the m1a file is closed by MPEG/CDェ
the creator and file type are set to the appropriate values and the file
is now eligible for subsequent double-click play and has the familiar
MPEG/CDェ icon.
AIFF
Double clicking an MPEG/CDェ created AIFF file from the Finder launches
MPEG/CDェ and plays the audio file. The application remains open
following play. Set your default Preferences for realtime decompression
prior to double clicking.
Drag and Drop Play
Dropping an MPEG/CDェ tagged m1a or AIFF file onto the MPEG/CDェ application
initiates audio play of the sound file. Keep the MPEG/CDェ application icon
(or alias) on your desktop and drop CD's into the player when you
want background music while you work in other applications!
An .m1a or .AIFF file dropped on the MPEG/CDェ application forces MPEG/CDェ to
temporarily create a list with only the requested AIFF tune(s). Thus,
replay (Command-R) will replay only the currently playing tune.
Drag and Drop Encode
AIFF file(s) created by MPEG/CD through "Mic to AIFF" or "Audio CD to AIFF"
can be encoded by dragging the AIFF files on top of the MPEG/CD application
icon. The files will be successively encoded each using the current Encoder
Preference settings. This allows for overnite batch MPEG audio encoding of
several tunes.
It's beyond the scope of this document to describe MPEG. Experiment with the
encoder bitrate settings and encode the same file under several settings. For
lower bitrates, files will be smaller and of lesser fidelity. The reverse is
true for the larger bitrates.
Eventually I'll write a description of the encoder settings, and will provide
licensed MPEG/CDE users with the in-depth information.
Aborting Encode/Decode
Both encode and decode progress bar windows have a cancel key which can
be clicked at any time to abort encode or play. The resulting file created to
the point of cancel is "valid" and is playable (m1a or aiff). You can also use the
standard Mac Command-. to kill the encode/decode.
Sample Audio Site
A good place to locate MPEG encoded music on the net is
at the "Internet Underground Music Archive" (IUMA):
http://www.iuma.com/
With MPEG/CDE you can now join the ranks of a growing number of
audio web sites...
Difficulties
If you're having difficulty decompressing a file, download the file once
again to rule out transmission errors over your service provider's line. If
still unsuccessful, send the audio file URL to our email address below
and we'll look into it as time permits.
Modern Memory Manager
There's been reports that MPEG/CDェ doesn't operate correctly on
PowerMac platforms when the Memory Control Panel "Modern Memory
Manager" Radio Button is set to "Off". A temporary workaround is to
keep this setting to "On" until further notice.
Scriptability
Let us know your requirements.
Command Reference
File
Command-O Open List
Command-A Add to List
Command-I Import to List
Command-S Save List
Command-K Create File Alias
Command-Q Quit
Status
Command-W Show/Hide Window
Record
Command-M Mic to AIFF
Command-C Audio CD to AIFF
List
Command-E Encode
Command-D Decode
Command-L Show
During Play Operation
Command-/ Skip current PlayList entry
Command-R Replay current PlayList entry
Command-. Abort current encode/decode in progress
Command-, Abort current batch encode/decode in progress
Send any suggestions and/or questions to bbal@kauai.com
Send all orders and registration fees to:
Kauai Media
c/o MPEG/CD Registration
3790 Via de la Valle
Suite 204
Del Mar, CA 92014