This Technical Note contains a collection of Q&As relating to a specific topic—questions you’ve sent the Developer Support Center (DSC) along with answers from the DSC engineers. While DSC engineers have checked the Q&A content for accuracy, the Q&A Technical Notes don’t have the editing and organization of other Technical Notes. The Q&A function is to get new technical information and updates to you quickly, saving the polish for when the information migrates into reference manuals.
Q&As are now included with Technical Notes to make access to technical updates easier for you. If you have comments or suggestions about Q&A content or distribution, please let us know by sending an AppleLink to DEVFEEDBACK. Apple Partners may send technical questions about Q&A content to DEVSUPPORT for resolution.
New Q&As and Q&As revised this month are marked with a bar in the side margin.
QuickTime fills in image descriptor when data is compressed
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When I send compressed images over Ethernet, CompressSequenceBegin doesn’t fill in the ImageDescription, which is needed at the other end of the conference link to DecompressSequenceBegin. Is this a bug?
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CompressSequenceBegin doesn’t actually modify the handle that you pass. Instead, QuickTime makes a note of the handle that’s passed and doesn’t actually modify the contents until the first call that actually compresses data, such as CompressSequenceFrame. At that point, the handle will be changed.
If you can postpone dealing with the image descriptor until after the first call that compresses data, whatever you are writing should work just fine.
Decompressing to partial window: Bug & workaround
Written: 6/18/92
Last reviewed: 9/15/92
Under System 7, decompressing directly to a window that is partially “off the screen” (that is, not completely visible) results in a -50 (invalid param) QuickTime error. We can special case when windows are off the screen and decompress into an offscreen GWorld but we would prefer a fix to either QuickTime or System 7.
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The problem you are having is due to a bug in the Image Compression Manager. It fails to clear QDError when starting a decompression job and later checks it to see if it is OK to continue the operation. Something else is setting QDErr and your call fails.
The solution that you can implement now consists of clearing QDErr before calling any of the decompression routines. You can accomplish this by calling QDError (which clears the error after it passes the current value to you) or zeroing the low mem QDerr (0xD6E) by hand.
Future versions of QuickTime will have the fix and will not require that you work around the problem.
Movie Toolbox Q&As
QuickTime M.QT.MovieTB.Q&As
Revised by: Developer Support Center December 1992
Written by: Developer Support Center October 1990
This Technical Note contains a collection of Q&As relating to a specific topic—questions you’ve sent the Developer Support Center (DSC) along with answers from the DSC engineers. While DSC engineers have checked the Q&A content for accuracy, the Q&A Technical Notes don’t have the editing and organization of other Technical Notes. The Q&A function is to get new technical information and updates to you quickly, saving the polish for when the information migrates into reference manuals.
Q&As are now included with Technical Notes to make access to technical updates easier for you. If you have comments or suggestions about Q&A content or distribution, please let us know by sending an AppleLink to DEVFEEDBACK. Apple Partners may send technical questions about Q&A content to DEVSUPPORT for resolution.
New Q&As this month:
How to get more recent MovieRecorder version
Getting movie from movie controller component
Determining QuickDraw video media pixel depth
How to get more recent MovieRecorder version
Date written: 9/21/92
Last reviewed: 11/1/92
I purchased the QuickTime Developer’s Kit, which contains the Starter’s Kit with MovieRecorder version 1.0a1. This seems to have a lot of bugs. How can I get a later version of MovieRecorder that works with QuickTime 1.0?
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The only way to obtain the current version of MovieRecorder (version 1.0 final) is to purchase the QuickTime Starter Kit. Because the Starter Kit is focused on end users, it is available through your local Apple reseller. It’s not available through APDA.
Getting movie from movie controller component
Date written: 7/22/92
Last reviewed: 11/1/92
Is there a way that the action filter proc of a QuickTime movie controller component can have a user reference field so that I can know which movie-“object” the movie controller is referring to? There are local variables associated with a particular movie that I would like to access from the action filter proc; currently there’s no way to reference back to the variables in my program except through globals.
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The movie controller action filter does not have a reference field. As a workaround, you might store your movie data in the userData area of the movie and then call MCGetMovie from an action filter. Once you get a reference to the movie, you can then retrieve the user data. Here are code snippets to do it:
QuickTime Movie Toolbox “globals” are stored in system heap
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According to the QuickTime Movie Toolbox documentation, “The Movie Toolbox maintains a set of global variables for every application using it.” How much global memory is required? Our application is shy on global data space.
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The information maintained is not kept with the application’s global variables. The handle created by the EnterMovies call is stored in the system heap, not in the application heap. You don’t have to worry about how much space to allocate in your application. This initialization does not affect your A5 world either.
EnterMovies initializes everything, including setting up the necessary data space and creating a handle to it. When you’re done, be sure to make a call to ExitMovies to clean up the QuickTime data.
If an application makes multiple calls to EnterMovies, a different set of “globals,” or data area, is set up for each call. A call to ExitMovies should be made before exiting the area that made the call to EnterMovies. For example, an application that uses QuickTime will call EnterMovies and set up the QuickTime world. Then an external may be called upon that wants to use QuickTime. This external would have to make a call to EnterMovies to set up another QuickTime world for its use. Before leaving, the external should call ExitMovies to clean up after itself. The application can then continue to use QuickTime with the original world it set up.
QuickTime file audio retrieval
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How can I retrieve audio from QuickTime files in 1-second chunks? I need a sound equivalent of GetMoviePict.
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You will have to write your own audio extraction routine. The Movie Toolbox does not provide a simple call to, say, GetMovieSound(movie, time, duration). To get around this limitation, use GetMediaSample and collect the sound data by hand. The format for the final result is up to you; in the case of a 'snd ' resource you’d create the handle fill in the other fields and put the sample data in it.
You can use the QuickTime SoundDescription data structure (1) to find frequency, format, and other details, (2) to help you figure out how many samples you need for a second, and (3) to fill in the resource data fields.
Of course, this scheme gets more complicated in the case when there are more than a single sound track. The best source of information on sound resources and such is the Sound Manager chapter in Inside Macintosh Volume VI.
Current QuickTime supports only video and sound media
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Can I add a media to a QuickTime movie that is not video or audio? If so is there anything special I need to do to add text notes that can potentially accompany each frame in my “movie,” which can follow the video frames if a user edits the movie in any way.
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The current release of QuickTime only allows for video and sound media. There is no way to install your own type. This is a high QuickTime priority and is likely to make it in a future release, but at the present there is no mechanism to do it.
Status of rotating matrix support
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What is the status of RotateMatrix and its use with SetMovieMatrix and SetTrackMatrix?
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RotateMatrix works fine. But rotating matrixes are not supported for movies or images. So, although RotateMatrix will give you the correct mathematical result, unless you are using the matrix to transform something else (as with TransformFixedPoints) it has little use.
Rotation is a very important future direction that will get more attention in the future.
How to get the first video frame
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Stepping through QuickTime movie video frames in the order they appear in the movie is simple using GetMovieNextInterestingTime, except for getting the first frame. If I set the time to zero and rate to 1, then I get the second frame, not the first. In addition, the video may start later than at 0. How do you suggest finding this first frame of video?
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To get the first frame in the conditions you describe you have to pass the flag nextTimeEdgeOK = $2000 to GetMovieInterestingTime. What this flag does is to make the call return the current interesting time instead of the next, if the current time is an interesting time. You need to do this since there is no way to go negative and then ask for the next interesting time.
QuickTime interfaces for Think Pascal
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Has Apple created QuickTime headers/interfaces for Think Pascal? The MPW Pascal headers don’t seem to be compatible.
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There are no Think Pascal interfaces, but your Pascal Package comes with a program called Pascal Source Converter, which converts MPW Pascal sources to Think. This should be all you need to be able to use the provided interfaces with your favorite development package.
Standard controller with MCCut or MCClear
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When I select all frames, then do an MCCut or MCClear, the standard controller gets larger and redraws itself at the top of the movie. Is this a situation I should be prepared to handle or a bug? Does the controller behave strangely when the selectionTime of a movie is -1 or when the duration of the movie is 0?
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The behavior you are observing is to be expected if the controller is attached to the movie. In this case, the controller goes to wherever the bottom-left corner of the movie box takes it. If the movie loses all of its “visible” parts, the movie controller will jump to the top of the window.
The only way to get around this is to detach the controller when the movie box is empty; this is also something to keep in mind for the cases when the movie contains only sound, since pure sound movies have no dimensions.
QuickTime and sound channel deallocation
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Our QuickTime application gets a Sound Manager error -201 after playing movies in succession, apparently because sound channels used in the previous movies have not been reclaimed. How does QuickTime decide to deallocate sound channels? It doesn’t seem to happen in my “while (!IsMovieDone(theMovie) && !Button()” play loop.
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Sound channels are released by active movies when they notice that some other movie needs them. This is currently only done at MoviesTask time. Before entering your loop to play a single movie, you can do one or both of the following:
• Preroll the movie you are about to play and check the error. If preroll returns -201 then do a MoviesTask(0,0) to give the other active movies a chance to give up their sound channels. A subsequent preroll of theMovie should return noErr.
• SetMovieActive(othermovies, false). Deactivate the movies that you aren’t playing to force them to give up their resources.
Clipping QuickTime movie posters
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Our application uses the movie poster as a still frame in a cell, similar to using a PICT. If a user sizes the cell width so it’s narrower than the poster, even though we clip the drawing to the cell size, QuickTime posters draw their full width, writing over whatever is in the way. Pictures clip through DrawPicture; why doesn’t ShowMoviePoster stay within clip region?
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ShowMoviePoster, as well as the movie and preview showing calls, uses the movie clipping characteristics rather than the destination port cliprgn. You must set the movie’s clip to obtain the results you want. An easier way to do this is to get the picture for the poster, by calling GetMoviePosterPict, and then simply use DrawPicture to display the poster. Because this is just a picture, the clip region of the port is honored. This way you don’t need different code for movies and pictures.
PutMovieIntoHandle and data forks
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I save PICTs to my document’s data fork by writing the contents of the PicHandle. To save movies, do I convert the movie to a handle, and then save that like I would with PICTs? I just want the file references, not the data itself.
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To save movies that are suitable for storage in a file, use PutMovieIntoHandle. The result of this call can then be saved in the data fork of your files, and then you can call NewMovieFromHandle to reconstruct the movie for playback or editing.
You should also read the documentation regarding Movie Toolbox FlattenMovie, which creates a file that contains the 'moov' resource and the data all in the data fork. The advantage here is that the movie file you create using FlattenMovie can be read by any other QuickTime-capable application.
SetMovieRate and controlling movie playback rate
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QuickTime is a joy! But I’ve run aground with SetMovieRate. I am trying to change the rate at which a movie plays back, but if I call SetMovieRate the movie starts playing immediately, the controller goes wild and the next time I hit the play button it ignores the previous rate.
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SetMovieRate takes effect immediately; that’s why the movie starts playing as soon as you make the call, with a rate other than zero. Also, calling SetMovieRate behind the controller’s back can only cause confusion because you are changing the state of the movie without letting the movie controller know about the change. Note that in normal operation the movie controller plays back movies at the standard speed, rate = 1; this is the current behavior. It is possible that in a future release the movie controller will use the rate the movie was saved with or the one set with SetPreferredMovieRate.
A little-known fact is that the standard controller does contain a primitive mechanism for controlling the rate of playback. If you hold the control key down and then click the mouse over the stepping buttons, you can, for example, play the movie backwards. Furthermore, if you hold the mouse down you’ll get a slider control that does let you play the movie at different rates backward or forward.
The slider provided by the standard controller is not intended to set the rate, so if you play once at low speed the rate does not stick and, as you have found, the next time you click on the play button you go back to the normal speed. If you need the selected rate to remain for the session, you’ll have to provide your own method of selection.
Once you know your desired speed, you’ll need to provide your own filter procedure and install it calling MCSetActionFilter. Upon receiving any mcActionPlay actions for rate changes, you’ll need to call SetMovieRate to set the movie in motion at the desired rate (and return true). Using a filter proc is the legal way of doing this because the controller can keep in sync with the actions regardless of the fact that it’s your code that actually affects the action.
Note that you will have to do some extra work to mimic the normal behavior of the standard controller. For example, when you’re at the end of the movie and the user hits the play button, the controller goes back to the beginning and plays the movie.
QuickTime track and movie sound volume
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What do the values of a movie’s or track’s volume represent? Is there no way to make a track louder?
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Here’s the scoop:
The volume is described as a small fract 8:8 and its values go from -1 to 1 with negative values as placeholders. The maximum volume you can get is 0x0100 with the minimum being 0 (or any negative value). The advantage of using negative volumes is that you can turn off sound while maintaining the level of volume. For example, -1 and 0 both equate to no volume, but the -1 implies that 1 should be the volume when sound is turned back on, whereas the 0 does not.
The volume for a track is scaled to the movie’s volume, and the movie’s volume is scaled to the value the user specifies for the speaker volume using the Sound control panel. This means that the movie volume represents the maximum loudness of any track in the movie.
QuickTime 1.0 FS6Patch elucidation
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The FS6Patch description in the QuickTime 1.0 CD Read Me file says, “There is a known bug with HFS on System 6.” What specifically is this bug? According to the Read Me file, “The exact situation under which the problem occurs is somewhat rare.” What is the exact situation? “If the patch is not necessary, it will not install itself.” What criteria is used to determine necessity?
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When closing or flushing a file that has multiple open paths to a given fork, it is possible that the blocks marked as available for the other paths can also be allocated to the other fork. If this happens before the other paths are closed, blocks will be mapped to more than one fork, potentially trashing at least one of them.
The condition that can trigger this condition is multiple writeable paths to the same fork. Once this is satisfied you would need to make some changes to the fork, close the path, use any of the other paths to modify the fork, access the other fork and modify data. If all these things happen you could see the damage to one of the forks (the second-to-last being accessed).
The code that loads the patch checks the system first; the range where the patch is used is 6.0.4 < system < 7.0. The version of the ROM is also used to decide when to install. If the ROM indicates the machine is later than the Macintosh IIfx, then a fix in ROM is assumed. The last check is to see if the code being patched is already in RAM (the assumption is that being in RAM means fixed). If so, the patch doesn’t get used.
QuickTime alias and FSSpec system services under System 6
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I recall reading that QuickTime includes an implementation of the Alias Manager for System 6, but I haven’t found any precise description of just what is included. Is it a bare minimum to support QuickTime? Or is the full Alias Manager there? Also, is there any way I can use the FSSpec interface to the File Manager, or must I revert to the System 6 interface?
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Here is some information on the alias and FSSpec system services that QuickTime supplies under System 6:
1. QuickTime support for aliases on System 6:
Most of the Alias Manager is available, with these few exceptions:
• NewAlias will accept a fromFile parameter, but it never creates a relative alias.
• NewAliasMinimalFromFullPath is not available.
• ResolveAlias will accept a fromFile parameter, but it ignores it.
• ResolveAliasFile is not present.
• MatchAlias may be called, but the kARMSearchMore, kARMSearchRelFirst, and kARMMultVols flags are not available. If you pass them in, they will be ignored. Furthermore, if you pass in a matchProc, it will never be called.
• UpdateAlias will accept a fromFile parameter, but ignores it.
• The System 6 Alias Manager will not mount network volumes.
So to summarize, on System 6 the Alias Manager doesn’t handle relative aliases, multiple volume searches, searchMore searches, and network volume mounting.
On the good side, nearly all calls are present. Aliases created on System 6 are compatible with System 7 aliases. And aliases made on System 7 will work on System 6.
Unfortunately, QuickTime does not currently install an Alias Manager Gestalt selector as it is only a partial implementation. You can check for the Alias Manager using Gestalt and if it is not present, look for QuickTime (using Gestalt) and if QuickTime is present, assume you have an Alias Manager, subject to the limitations above.
2. FSp file system calls and System 6
QuickTime also makes extensive use of the FSSpec data structure introduced in the System 7 File Manager. Nearly all the FSSpec calls are available on System 6 when QuickTime is installed. The following calls are available on System 6, and should behave as documented for System 7:
FSMakeFSSpec
FSpOpenDF
FSpOpenRF
FSpCreate
FSpDirCreate
FSpDelete
FSpGetFInfo
FSpSetFInfo
FSpSetFLock
FSpRstFLock
FSpRename
FSpCatMove
FSpOpenResFile
FSpCreateResFile
FSpGetCatInfo
The following call is not available when using the QuickTime System 6 version of the FSp calls:
FSpExchangeFiles
Again, the Gestalt selector for the FSp calls is not installed when QuickTime is there. This means that the gestaltFSAttr Gestalt selector may not be present, and gestaltHasFSSpecCalls may not be set, even if gestaltFSAttr is present.
'pnot' resource format for QuickTime-like preview in dialog box
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I would like to implement the preview/thumbnail feature in the Standard File dialog, just like the extension included with QuickTime. Is that code available separate from QuickTime? If not, could I at least get information on how the preview is created?
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To implement your own preview/thumbnail feature, simply duplicate the Standard File dialog, add the necessary 'DITL' resources, and install a custom filter procedure for handling preview commands. On the System 7 CD there’s an example, StdFileSample, that shows exactly how to create a custom file dialog. The Macintosh Technical Note “Customizing Standard File” (formerly #47) describes how to do this as well. For generating and displaying the preview, you can use the following PreviewResourceRecord, found at the end of the ImageCompression.h file:
This is the format for the 'pnot' resource, which defines the preview for the movie file, usually pointing to a 'PICT' resource. It’s all you need to generate QuickTime-compatible preview without using QuickTime.
MCSetClip and clipping with the movie controller
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I use SetMovieDisplayClipRgn to set my movie clip, but the movie doesn’t obey my clipping. Does the movie controller component ignore this clipping?
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You probably are directly modifying a movie that is attached to a controller without notifying the controller of the changes. The controller uses the display clip for its own purposes, such as for badges.
If you want to do clipping with the movie controller you must use MCSetClip. MCSetClip takes two regions. The first clips both the movie and the controller. The second clips just the movie, and is equivalent to the movie display clip. If both clips are set, the controller does the right thing and merges them as appropriate. If you don’t want one or the other of the clips, set them to zero.
In general, if you are going to do something to a movie that is attached to a controller you must either do it through the controller, using the action calls, or you must call MCMovieChanged. Otherwise, the controller would need to constantly poll the movie to see if its state changed. Clearly this would be Evil and Slow.
Problem with disabling a movie video track
Written: 5/29/92
Last reviewed: 9/15/92
When I disable a track in a movie, another random track becomes disabled as well. Is this a QuickTime bug?
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Yes, this problem will be fixed in the next QuickTime release. But, there’s no apparent workaround in the meantime. You’ll need to remove the track since disable doesn’t work.
Determining whether a movie is set to loop or not
Written: 8/11/92
Last reviewed: 9/15/92
How does Simple Player determine whether a movie is set to loop or not? Movie files that are set to loop seem to have a string of 'LOOP' at the end of the 'moov' resource. Does Simple Player check 'LOOP'?
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Simple Player identifies whether movies are set to loop by looking within the user data atoms for the 'LOOP' atom, as you’ve noticed. It’s a 4-byte Boolean in which a value of 1 means standard looping and a value of 0 means palindrome looping. Your applications should add the user data 'LOOP' atom to the end of the movie when a user chooses to loop. We recommend this method as a standard mechanism for determining the looping status of a movie. If the 'LOOP' atom doesn’t exist, there’s no looping. The calls you need to access this information are GetMovieUserData, GetUserData, AddUserData, and RemoveUserData, as defined in the Movie Toolbox chapter of the QuickTime documentation.
Determining QuickDraw video media pixel depth
Written: 8/18/92
Last reviewed: 10/11/92
How do I get the pixel depth of a QuickTime video media for a given track?
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The following sample code does the trick:
#include <QuickDraw.h>
#include <Movies.h>
#include <ImageCompression.h>
Media GetFirstVideoMedia(Movie coolMovie,long *trackIndex)
{
Track coolTrack=nil;
Media coolMedia=nil;
long numTracks;
OSType mediaType;
numTracks = GetMovieTrackCount(coolMovie);
for (*trackIndex=1; *trackIndex <= numTracks; (*trackIndex)++) {
Trying to read any single frame (except the first) from a grayscale (4, 16, or 256 grays), QuickTime movie gives a -157 error (invalid pixel depth). I do “framehandle = GetMoviePict(damovie,daunitnum)” and test if it’s 0. If so, then I do “io = GetMoviesError()” and it gives me the -157 error. GetMoviePict is working fine for all color and black/white movies. It just doesn’t work on “Animation” grayscale and “Video” grayscale movies. Is this a bug?
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It is true that grayscale images will cause a -157 error with GetMoviePict using QuickTime 1.0. QuickTime 1.5 will fix this problem. Some grayscale images may work, if the color tables are custom made. To check for this situation, you can look at the clutID of the ImageDescription structure. If the clutId is 0, then there is a custom color table attached. For these images, GetMoviePict may work.
Movies ‘LOOP’ Atom and Friends
QuickTime M.QT.MoviesLOOP
Written by: John Wang November 1992
This Technical Note discusses entertaining uses for QuickTime user data atoms, Apple defined and otherwise.
Topics
• User Data Types
• Sample Code
• Inside the User Data Atom
Introduction
It is often desirable for an application to preserve the window position and looping state of a movie. This Technical Note describes the “Apple Sanctified” method of doing this using user data atoms.
User data atoms allow applications to store custom information which can be easily accessed using QuickTime Movie Toolbox calls. These user data atoms are text or data which can be associated and stored in any movie, track, or media. A reference to the list of user data atoms for each of these locations can be accessed with the following routines: GetMovieUserData(), GetTrackUserData(), and GetMediaUserData(). Once a reference to a list of user data atoms is obtained, an application can store, retrieve, and manage items in the list using the following routines: GetNextUserDataType(), CountUserDataType(), AddUserData(), GetUserData(), RemoveUserData(), AddUserDataText(), GetUserDataText, and RemoveUserDataText(). A complete description of these routines can be found in Inside Macintosh: QuickTime in the “Working With Movie User Data” section of chapter 2.
User Data Types
Every user data atom carries a type identifier. This identifier is stored in a long integer, similar to a Resource Manager type. Apple has reserved all lowercase user data types values. Applications are free to use types values containing at least one uppercase letter.
MoviePlayer™ has also defined two movie data atoms which are used to indicate looping and window location which applications can implement for compatibility with MoviePlayer™. They are:
'LOOP' If this 4 byte user data atom exists in the movie's user data list, then looping is performed according to its value: 0 for normal looping and 1 for palindrome looping
'WLOC' Handle to a point record indicating the last saved window position
Another variation on this which originated before MoviePlayer™ that applications should be aware of, is the following:
'LOOP' If this zero length data atom exists in the movie's user data list, then normal looping is performed.
In summary, if a 'LOOP' atom exists, then looping should be performed. If the returned data is a long integer of value 1, then palindrome looping should be performed. Normal looping should be performed if data returned is of zero length or if the returned data is a long integer of value 0.
Sample Code
The following example demonstrates how to get looping information from a movie:
short loopInfo; // 0=no looping,1=normal looping,2=palindrome looping
Handle theLoop;
Movie theMovie;
UserData theUserData;
loopInfo = 0;
theLoop = NewHandle(0);
theUserData = GetMovieUserData(theMovie);
if (CountUserDataType(theUserData, 'LOOP')) {
loopInfo = 1;
GetUserData(theUserData, theLoop, 'LOOP', 1);
if (GetHandleSize(theLoop))
if ((** (long **) theLoop) == 1)
loopInfo = 2;
}
The following example demonstrates how to add a looping atom to a movie to indicate that user has selected looping:
Those of you who parse user data atoms directly by accessing the 'moov' handle rather than with the appropriate movie toolbox calls, will notice a trailing long integer of value 0 after all user data atoms in the list. This is required for backward compatibility with QuickTime 1.0 which has a bug that requires the trailer. The size of the 'udta' atom does reflect this extra trailing long integer. QuickTime 1.0 and future versions will automatically handle this when manipulating user data atoms with the movie toolbox calls.
Further Reference:
• Inside Macintosh: QuickTime, Movie Toolbox Reference
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While DSC ° d ONLN dˇˇ )9Lengineers have checked the Q&A content for accuracy, the Q&A Technical Notes ° d ONLN dˇˇ ( Z don’t have ° d ONLN dˇˇ )5Qthe editing and organization of other Technical Notes. The Q&A function is to get ° d ONLN dˇˇ ( Z new technical information and ° d ONLN dˇˇ )ù6updates to you quickly, saving the polish for when the ° d ONLN dˇˇ (# Z,information migrates into reference manuals. ° d ONLN dˇˇ *:Q&As are now included with Technical Notes to make access ° d ONLN dˇˇ (;â to technical updates easier for ° d ONLN dˇˇ (G Z/you. If you have comments or suggestions about ° d ONLN dˇˇ )Ú*Q&A content or distribution, please let us ° d ONLN dˇˇ (S Zknow ° d ONLN dˇˇ ) Iby sending an AppleLink to DEVFEEDBACK. Apple Partners may send technical ° d ONLN dˇˇ (_ Z9questions about Q&A content to DEVSUPPORT for resolution. ° d ONLN dˇˇ *NNew Q&As and Q&As revised this month are marked with a bar in the side margin. "n Ü XÜ
° d ONLN dˇˇ *4;QuickTime fills in image descriptor when data is compressed
° d ONLN dˇˇ * Written: ° d ONLN dˇˇ * Last reviewed: ° d ONLN dˇˇ *When I send compressed ° d ONLN dˇˇ )~?images over Ethernet, CompressSequenceBegin doesn’t fill in the ° d ONLN dˇˇ (Á Z"ImageDescription, which is needed ° d ONLN dˇˇ )≈*at the other end of the conference link to ° d ONLN dˇˇ (Û Z'DecompressSequenceBegin. Is this a bug? ° d ONLN dˇˇ * ___ ° d ONLN dˇˇ *HCompressSequenceBegin doesn’t actually modify the handle that you pass. ° d ONLN dˇˇ (ˆInstead, ° d ONLN dˇˇ (# Z
QuickTime ° d ONLN dˇˇ )7Qmakes a note of the handle that’s passed and doesn’t actually modify the contents ° d ONLN dˇˇ (/ Z<until the first call that actually compresses data, such as ° d ONLN dˇˇ (/u CompressSequenceFrame. At that ° d ONLN dˇˇ (; Z"point, the handle will be changed. ° d ONLN dˇˇ *If you ° d ONLN dˇˇ ) Ycan postpone dealing with the image descriptor until after the first call that compresses ° d ONLN dˇˇ (_ Z5data, whatever you are writing should work just fine. ◊ X◊
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. +6-Macintosh Technical Notes / 4 /˘
° d ONLN dˇˇ *'1Decompressing to partial window: Bug & workaround " H 3
° d ONLN dˇˇ * Written: ° d ONLN dˇˇ )L6/18/92 " W 3 ° d ONLN dˇˇ ( l 6Last reviewed: ° d ONLN dˇˇ )L9/15/92 " c 3 " o 3 ° d ONLN dˇˇ ( Ñ 63Under System 7, decompressing directly to a window ° d ONLN dˇˇ ( Ñ8,that is partially “off the screen” (that is, " { 3 ° d ONLN dˇˇ ( ê 6Ynot completely visible) results in a -50 (invalid param) QuickTime error. We can special ° d ONLN dˇˇ ( ê‰case " á 3 ° d ONLN dˇˇ ( ú 6 when windows are off the screen ° d ONLN dˇˇ )¶4and decompress into an offscreen GWorld but we would " ì 3 ° d ONLN dˇˇ ( ® 6-prefer a fix to either QuickTime or System 7. " ü 3 ° d ONLN dˇˇ * ___ " ´ 3 " ∑ 3 ° d ONLN dˇˇ *YThe problem you are having is due to a bug in the Image Compression Manager. It fails to ° d ONLN dˇˇ ( Âclear " √ 3 ° d ONLN dˇˇ ( ÿ 6NQDError when starting a decompression job and later checks it to see if it is ° d ONLN dˇˇ ( ÿúOK to continue the " œ 3 ° d ONLN dˇˇ ( ‰ 6?operation. Something else is setting QDErr and your call fails. " € 3 " Á 3 ° d ONLN dˇˇ *The solution that you can ° d ONLN dˇˇ )zBimplement now consists of clearing QDErr before calling any of the " Û 3 ° d ONLN dˇˇ ( 6Jdecompression routines. You can accomplish this by calling QDError (which ° d ONLN dˇˇ (Æclears the error " ˇ 3 ° d ONLN dˇˇ ( 6Wafter it passes the current value to you) or zeroing the low mem QDerr (0xD6E) by hand. " 3 " 3 ° d ONLN dˇˇ * Future versions of QuickTime ° d ONLN dˇˇ )ë?will have the fix and will not require that you work around the "# 3 ° d ONLN dˇˇ (8 6problem. "/ 3 ◊ 4◊˘
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IR . ° d ONLN d n < Å Û ( õ ZMovie Toolbox Q&As
° d ONLN d Ä < è Ö * QuickTime ° d ONLN d Äh è˛ ( ´ÜM.QT.MovieTB.Q&As
° d ONLN d / õ < ß t ( √ Z Revised by: ° d ONLN d ; õ Ñ ß ˇ )HDeveloper Support Center ° d ONLN d T õ¥ ߲ ( √“
December 1992 ° d ONLN d b ß < ≥ q ( œ Z Written by: ° d ONLN d n ß Ñ ≥ ˇ )HDeveloper Support Center ° d ONLN d á ßæ ≥˛ ( œ‹ October 1990 ° d ONLN d î ø < À ⁄ ( Á Z This Technical Note contains a ° d ONLN d ≥ ø ⁄ À˛ )û9collection of Q&As relating to a specific topic—questions ° d ONLN d Ì À < ◊† ( Û ZGyou’ve sent the Developer Support Center (DSC) along with answers from ° d ONLN d4 À† ◊˛ ( Ûæthe DSC engineers. ° d ONLN dG ◊ < „ u ( ˇ Z
° d ONLN dX§ <≥z *4,How to get more recent MovieRecorder version
° d ONLN dÖ≥ <ø x *
Date written: ° d ONLN dì≥ àø ¨ )L9/21/92 ° d ONLN dõø <À Å (Á ZLast reviewed: ° d ONLN d™ø àÀ ¨ )L11/1/92 ° d ONLN d≤◊ <„ H (ˇ ZI ° d ONLN d¥◊ H„˛ ) Npurchased the QuickTime Developer’s Kit, which contains the Starter’s Kit with ° d ONLN d„ <ÔQ ( Z9MovieRecorder version 1.0a1. This seems to have a lot of ° d ONLN d<„QÔ˛ ( o#bugs. How can I get a later version ° d ONLN d`Ô <˚. ( Z/of MovieRecorder that works with QuickTime 1.0? ° d ONLN dê˚ < N * ___ ° d ONLN dî < ä *EThe only way to obtain the current version of MovieRecorder (version ° d ONLN dŸä ˛ (;®1.0 final) is to purchase ° d ONLN dÛ <+ª (G ZLthe QuickTime Starter Kit. Because the Starter Kit is focused on end users, ° d ONLN d? ª+˛ (GŸit is available ° d ONLN dO+ <7z (S ZCthrough your local Apple reseller. It’s not available through APDA. ◊ X◊
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. +6-Macintosh Technical Notes / 4 /˘
° d ONLN d ) 8] *'-Getting movie from movie controller component
° d ONLN d . 8 D T *
Date written: ° d ONLN d < 8 d D à )L7/22/92 ° d ONLN d D D P ] ( l 6Last reviewed: ° d ONLN d S D d P à )L11/1/92 ° d ONLN d [ \ h> ( Ñ 6@Is there a way that the action filter proc of a QuickTime movie ° d ONLN d õ \> h⁄ ( Ñ\ controller component can have a ° d ONLN d ª h t ] ( ê 6user reference ° d ONLN d h ] t⁄ )EOfield so that I can know which movie-“object” the movie controller is referring ° d ONLN d t Ä@ ( ú 6Ato? There are local variables associated with a particular movie ° d ONLN d[ t@ Ä⁄ ( ú^ that I would like to access from ° d ONLN d| Ä åE ( ® 6Cthe action filter proc; currently there’s no way to reference back ° d ONLN dø ÄE å⁄ ( ®c to the variables in my program ° d ONLN dfi å ò á ( ¥ 6except through globals. ° d ONLN dˆ ò § * * ___ ° d ONLN d˙ ∞ º *3The movie controller action filter does not have a ° d ONLN d- ∞ º⁄ )È+reference field. As a workaround, you might ° d ONLN dY º ») ( ‰ 68store your movie data in the userData area of the movie ° d ONLN dë º) »⁄ ( ‰G and then call MCGetMovie from an ° d ONLN d≤ » ‘ 7 ( 6action ° d ONLN dπ » 7 ‘⁄ ) Xfilter. Once you get a reference to the movie, you can then retrieve the user data. Here ° d ONLN d ‘ ‡ ê ( ¸ 6are code snippets to do it: ,
Courier
° d ONLN d. Ï ˜ | * Handle movieNameH; ° d ONLN dC ˆ | *
Str255 movieName; ° d ONLN dX | *
Movie coolMovie; ° d ONLN dm r * // Get coolMovie ° d ONLN dÄ ) Â *
) movieNameH = NewHandle(sizeof(Str255)); ° d ONLN d™( 3 Â *
) strcpy(*movieNameH,PtoCstr(movieName)); ° d ONLN d‘2 =P *
5return false; // let mc component handle all actions ° d ONLN dZ¥ ø *
}
° d ONLN d\÷ Â_ *&-Determining QuickDraw video media pixel depth
° d ONLN däÂ Ò T *
Date written: ° d ONLN dòÂ dÒ à )L8/18/92 ° d ONLN d†Ò ˝ ] ( 6Last reviewed: ° d ONLN dØÒ d˝ à )L11/1/92 ° d ONLN d∑ | (1 6JHow do I get the pixel depth of a QuickTime video media for a given track? ° d ONLN d ! * * ___ ° d ONLN d- 9 › *)The following sample code does the trick:
° d ONLN d0E P Ü *#include <QuickDraw.h> ° d ONLN dGO Z w *
>imageDescH=(SampleDescriptionHandle)NewHandle(sizeof(Handle)); ° d ONLN d] Ω < » » *
long trackIndex=0; ° d ONLN dz « < “ Õ *
Media coolMedia=nil; ° d ONLN dò € < ÊJ *6coolMedia = GetFirstVideoMedia(coolMovie,&trackIndex); ° d ONLN dœ  < ^ *
:if (!trackIndex || !coolMedia) return -1; // we need both ° d ONLN d
Ô < ˙c *
;GetMediaSampleDescription(coolMedia,trackIndex,imageDescH); ° d ONLN dF <@ *4return (*(ImageDescriptionHandle)imageDescH)->depth; ° d ONLN d{
< A *
}
° d ONLN d}/ <>fl *&;QuickTime Movie Toolbox “globals” are stored in system heap
° d ONLN dπ> <J b * Written: ° d ONLN d√J <V Å * Last reviewed: ° d ONLN d”b <n ƒ *According to the QuickTime ° d ONLN dÓb ƒn˛ )à;Movie Toolbox documentation, “The Movie Toolbox maintains a ° d ONLN d*n <z Y (ñ Zset of ° d ONLN d1n Yz˛ ) Uglobal variables for every application using it.” How much global memory is required? ° d ONLN dáz <Ü (¢ Z,Our application is shy on global data space. ° d ONLN d¥Ü <í N * ___ ° d ONLN d∏û <™. *0The information maintained is not kept with the ° d ONLN dËû.™˛ )Ú*application’s global variables. The handle ° d ONLN d™ <∂ Ä (“ Zcreated by the ° d ONLN d"™ Ä∂˛ )DOEnterMovies call is stored in the system heap, not in the application heap. You ° d ONLN dr∂ <¬o (fi Z=don’t have to worry about how much space to allocate in your ° d ONLN dØ∂o¬˛ (fiç application. This initialization ° d ONLN d–¬ <Œ Î (Í Z%does not affect your A5 world either. ° d ONLN dˆ⁄ <ÊT *=EnterMovies initializes everything, including setting up the ° d ONLN d3⁄TÊ˛ (r#necessary data space and creating a ° d ONLN dWÊ <Ú ( ZUhandle to it. When you’re done, be sure to make a call to ExitMovies to clean up the ° d ONLN d¨Ê Ú˛ (Ë QuickTime ° d ONLN d∂Ú <˛ S ( Zdata. ° d ONLN dº
<o *CIf an application makes multiple calls to EnterMovies, a different ° d ONLN dˇ
o˛ (2ç set of “globals,” or data area, ° d ONLN d <" W (> Zis set ° d ONLN d& W"˛ )Wup for each call. A call to ExitMovies should be made before exiting the area that made ° d ONLN d~" <.ò (J ZIthe call to EnterMovies. For example, an application that uses QuickTime ° d ONLN d«"ò.˛ (J∂will call EnterMovies ° d ONLN d›. <:V (V Z5and set up the QuickTime world. Then an external may ° d ONLN d.V:˛ (Vt be called upon that wants to use ° d ONLN d3: <F. (b Z,QuickTime. This external would have to make ° d ONLN d_:.F˛ )Ú'a call to EnterMovies to set up another ° d ONLN dáF <R’ (n ZTQuickTime world for its use. Before leaving, the external should call ExitMovies to ° d ONLN d€F’R˛ (nÛclean up ° d ONLN d‰R <^≈ (z ZSafter itself. The application can then continue to use QuickTime with the original ° d ONLN d 7R≈^˛ (z„ world it set ° d ONLN d D^ <j L (Ü Zup.
° d ONLN d HÇ <ë *' QuickTime file audio retrieval
° d ONLN d ) 5 *$1How can I retrieve audio from QuickTime files in ° d ONLN d 1 ) 5⁄ )Ï*1-second chunks? I need a sound equivalent ° d ONLN d \ 5 A j ( ] 6of GetMoviePict. ° d ONLN d m A M * * ___ ° d ONLN d q Y e q *You will have to ° d ONLN d Ç Y q e⁄ )YCwrite your own audio extraction routine. The Movie Toolbox does not ° d ONLN d Δ e q Ø ( ç 6 provide a simple call to, say, ° d ONLN d  e Ø q⁄ )ó8GetMovieSound(movie, time, duration). To get around this ° d ONLN d q }{ ( ô 6Glimitation, use GetMediaSample and collect the sound data by hand. The ° d ONLN de q{ }⁄ ( ôôformat for the final ° d ONLN dz } âí ( • 6Vresult is up to you; in the case of a 'snd ' resource you’d create the handle fill in ° d ONLN d– }í â⁄ ( •∞the other fields ° d ONLN d· â ï ü ( ± 6 and put the sample data in it. ° d ONLN d ° ≠T *AYou can use the QuickTime SoundDescription data structure (1) to ° d ONLN dA °T ≠⁄ ( …rfind frequency, format, and ° d ONLN d] ≠ π å ( ’ 6other details, (2) to help ° d ONLN dx ≠ å π⁄ )tAyou figure out how many samples you need for a second, and (3) to ° d ONLN d∫ π ≈ § ( · 6!fill in the resource data fields. ° d ONLN d‹ — ›O *>Of course, this scheme gets more complicated in the case when ° d ONLN d —O ›⁄ ( ˘m there are more than a single ° d ONLN d7 › È : ( 6sound ° d ONLN d= › : È⁄ )"Ntrack. The best source of information on sound resources and such is the Sound ° d ONLN då È ı u ( 6Manager chapter in ° d ONLN dü È u ı Δ )]Inside Macintosh ° d ONLN dØ È Δ ı )Q Volume VI.
° d ONLN dª
ï (8 65Current QuickTime supports only video and sound media
° d ONLN dÒ ( > * Written: ° d ONLN d˚( 4 ] * Last reviewed: ° d ONLN d @ L */Can I add a media to a QuickTime movie that is ° d ONLN d:@L⁄ )Ì+not video or audio? If so is there anything ° d ONLN dfL Xè (t 6Qspecial I need to do to add text notes that can potentially accompany each frame ° d ONLN d∑LèX⁄ (t≠in my “movie,” ° d ONLN dΔX di (Ä 6Gwhich can follow the video frames if a user edits the movie in any way. ° d ONLN dd p * * ___ ° d ONLN d| à ∏ *!The current release of QuickTime ° d ONLN d3| ∏à⁄ )†9only allows for video and sound media. There is no way to ° d ONLN dmà î- (∞ 69install your own type. This is a high QuickTime priority ° d ONLN d¶à-î⁄ (∞K$and is likely to make it in a future ° d ONLN dÀî †# (º 6;release, but at the present there is no mechanism to do it.
° d ONLN d∏ « Ù *'!Status of rotating matrix support
° d ONLN d)« ” > * Written: ° d ONLN d3” fl ] * Last reviewed: ° d ONLN dCÎ ˜π *VWhat is the status of RotateMatrix and its use with SetMovieMatrix and SetTrackMatrix? ° d ONLN dö˜ * * ___ ° d ONLN dû V *ARotateMatrix works fine. But rotating matrixes are not supported ° d ONLN dflV⁄ (7tfor movies or images. So, ° d ONLN d˘ '≠ (C 6Talthough RotateMatrix will give you the correct mathematical result, unless you are ° d ONLN dM≠'⁄ (CÀ using the ° d ONLN dW' 3° (O 6Tmatrix to transform something else (as with TransformFixedPoints) it has little use. ° d ONLN d¨? K¶ *YRotation is a very important future direction that will get more attention in the future.
° d ONLN dc r *' How to get the first video frame
° d ONLN d'r ~ > * Written: ° d ONLN d1~ ä ] * Last reviewed: ◊ 4◊˘
° d ONLN d < )∞ ( E ZGStepping through QuickTime movie video frames in the order they appear ° d ONLN d G ∞ )˛ ( EŒin the movie is ° d ONLN d W ) < 5g ( Q Z=simple using GetMovieNextInterestingTime, except for getting ° d ONLN d î )g 5˛ ( QÖ"the first frame. If I set the time ° d ONLN d ∑ 5 < A& ( ] Z4to zero and rate to 1, then I get the second frame, ° d ONLN d Î 5& A˛ )Í/not the first. In addition, the video may start ° d ONLN d A < MÅ ( i ZFlater than at 0. How do you suggest finding this first frame of video? ° d ONLN db M < Y N * ___ ° d ONLN df e < q } * To get the ° d ONLN dq e } q˛ )ADfirst frame in the conditions you describe you have to pass the flag ° d ONLN d∂ q < }‹ ( ô ZRnextTimeEdgeOK = $2000 to GetMovieInterestingTime. What this flag does is to make ° d ONLN d q‹ }˛ ( ô˙the call ° d ONLN d } < â € ( • Z$return the current interesting time ° d ONLN d5 } € Ⲡ)ü@instead of the next, if the current time is an interesting time. ° d ONLN dv â < ï x ( ± Z You need to ° d ONLN dÇ â x ï˛ )<Rdo this since there is no way to go negative and then ask for the next interesting ° d ONLN d’ ï < ° T ( Ω Ztime.
° d ONLN d€ π < »? *'%QuickTime interfaces for Think Pascal
° d ONLN d » < ‘ b * Written: ° d ONLN d ‘ < ‡ Å * Last reviewed: ° d ONLN d Ï < ¯∑ *IHas Apple created QuickTime headers/interfaces for Think Pascal? The MPW ° d ONLN dd Ï∑ ¯˛ (’Pascal headers ° d ONLN ds ¯ < ƒ ( Z don’t seem to be compatible. ° d ONLN dê < N * ___ ° d ONLN dî <(C *6There are no Think Pascal interfaces, but your Pascal ° d ONLN d C(˛ (Da#Package comes with a program called ° d ONLN dÓ( <4q (P Z;Pascal Source Converter, which converts MPW Pascal sources ° d ONLN d)(q4˛ (Pè to Think. This should be all ° d ONLN dF4 <@Ë (\ ZZyou need to be able to use the provided interfaces with your favorite development package.
° d ONLN d°X <gg *')Standard controller with MCCut or MCClear
° d ONLN dÀg <s b * Written: ° d ONLN d’s < Å * Last reviewed: ° d ONLN dÂã <óÌ *[When I select all frames, then do an MCCut or MCClear, the standard controller gets larger ° d ONLN d@ãÌó˛ (≥ and ° d ONLN dDó <£z (ø ZEredraws itself at the top of the movie. Is this a situation I should ° d ONLN dâóz£˛ (øòbe prepared to handle or a ° d ONLN d§£ <Ø∂ (À ZObug? Does the controller behave strangely when the selectionTime of a movie is ° d ONLN dÛ£∂Ø˛ (À‘-1 or when the ° d ONLN dØ <ª ∫ (◊ Zduration of the movie is 0? ° d ONLN d ª <« N * ___ ° d ONLN d"” <fl í *The behavior you ° d ONLN d3” ífl˛ )VNare observing is to be expected if the controller is attached to the movie. In ° d ONLN dÇfl <Ή ( Z]this case, the controller goes to wherever the bottom-left corner of the movie box takes it. ° d ONLN dflfl‰Î˛ (If the ° d ONLN dÊÎ <˜Û ( Z`movie loses all of its “visible” parts, the movie controller will jump to the top of the window. ° d ONLN dG <± *OThe only way to get around this is to detach the controller when the movie box ° d ONLN dñ±˛ (+œis empty; this is ° d ONLN d® < “ (7 Z also something to keep in mind ° d ONLN d« “˛ )ñ<for the cases when the movie contains only sound, since pure ° d ONLN d <' „ (C Z sound movies have no dimensions.
° d ONLN d%? <NX *'(QuickTime and sound channel deallocation
° d ONLN dNN <Z b * Written: ° d ONLN dXZ <f Å * Last reviewed: ° d ONLN dhr <~F */Our QuickTime application gets a Sound Manager ° d ONLN dórF~˛ (öd"error -201 after playing movies in ° d ONLN d∫~ <äË (¶ ZSsuccession, apparently because sound channels used in the previous movies have not ° d ONLN d
~Ëä˛ (¶been ° d ONLN d ä <ñ „ (≤ Z reclaimed. How does QuickTime ° d ONLN d 0ä „ñ˛ )ß7decide to deallocate sound channels? It doesn’t seem to ° d ONLN d hñ <¢ô (æ ZDhappen in my “while (!IsMovieDone(theMovie) && !Button()” play loop. ◊ X◊
° d ONLN d ) * *___ ° d ONLN d 5 Aù *NSound channels are released by active movies when they notice that some other ° d ONLN d R 5ù A⁄ ( ]ª movie needs ° d ONLN d ^ A M ä ( i 6them. This is currently ° d ONLN d v A ä M⁄ )rAonly done at MoviesTask time. Before entering your loop to play a ° d ONLN d ∏ M Y ( u 66single movie, you can do one or both of the following: ° d ONLN d Ô e q ¬ *%• Preroll the movie you are about to ° d ONLN d e ¬ q⁄ )™;play and check the error. If preroll returns -201 then do a ° d ONLN dP q } m ( ô 6MoviesTask(0,0) ° d ONLN d` q m }⁄ )UKto give the other active movies a chance to give up their sound channels. A ° d ONLN d¨ } â ( • 63subsequent preroll of theMovie should return noErr. ° d ONLN d‡ â ï? * <• SetMovieActive(othermovies, false). Deactivate the movies ° d ONLN d â? ï⁄ ( ±] that you aren’t playing to force ° d ONLN d= ï ° ≠ ( Ω 6 them to give up their resources.
° d ONLN d^ π » *' Clipping QuickTime movie posters
( * * ___ ° d ONLN d4 @¥ *PShowMoviePoster, as well as the movie and preview showing calls, uses the movie ° d ONLN da4¥@⁄ (\“clipping ° d ONLN dj@ L í (h 6 characteristics rather than ° d ONLN dÜ@ íL⁄ )zEthe destination port cliprgn. You must set the movie’s clip to obtain ° d ONLN dÃL X^ (t 6Ethe results you want. An easier way to do this is to get the picture ° d ONLN dL^X⁄ (t|for the poster, by calling ° d ONLN d,X d0 (Ä 67GetMoviePosterPict, and then simply use DrawPicture to ° d ONLN dcX0d⁄ (ÄN#display the poster. Because this is ° d ONLN dád p≤ (å 6Zjust a picture, the clip region of the port is honored. This way you don’t need different ° d ONLN d·d≤p⁄ (å–code for ° d ONLN dÍp | z (ò 6movies and pictures.
° d ONLN dˇî £ *'!PutMovieIntoHandle and data forks
° d ONLN d!£ Ø > * Written: ° d ONLN d+Ø ª ] * Last reviewed: ° d ONLN d;« ”y *GI save PICTs to my document’s data fork by writing the contents of the ° d ONLN dÇ«y”⁄ (ÔóPicHandle. To save ° d ONLN dï” fl (˚ 65movies, do I convert the movie to a handle, and then ° d ONLN d ”fl⁄ )˚)save that like I would with PICTs? I just ° d ONLN dÙfl Î ‡ ( 6.want the file references, not the data itself. ° d ONLN d#Î ˜ * * ___ ° d ONLN d' ± *TTo save movies that are suitable for storage in a file, use PutMovieIntoHandle. The ° d ONLN d{±⁄ (+œ result of ° d ONLN dÖ ñ (7 6Ethis call can then be saved in the data fork of your files, and then ° d ONLN d ñ⁄ (7¥ you can call ° d ONLN d◊ 'o (C 6DNewMovieFromHandle to reconstruct the movie for playback or editing. ° d ONLN d 3 ?ô *MYou should also read the documentation regarding Movie Toolbox FlattenMovie, ° d ONLN di3ô?⁄ ([∑
which creates ° d ONLN dw? K “ (g 6)a file that contains the 'moov' resource ° d ONLN d†? “K⁄ )∫8and the data all in the data fork. The advantage here is ° d ONLN dŸK W Ñ (s 6that the movie file you ° d ONLN dÒK ÑW⁄ )lDcreate using FlattenMovie can be read by any other QuickTime-capable ° d ONLN d 6W c O ( 6 application.
° d ONLN d C{ äh *'0SetMovieRate and controlling movie playback rate
° d ONLN d tä ñ > * Written: ° d ONLN d ~ñ ¢ ] * Last reviewed: ◊ 4◊˘
° d ONLN d ) < 5k ( Q Z>QuickTime is a joy! But I’ve run aground with SetMovieRate. I ° d ONLN d > )k 5˛ ( Qâ am trying to change the rate at ° d ONLN d ^ 5 < A8 ( ] Z5which a movie plays back, but if I call SetMovieRate ° d ONLN d ì 58 A˛ )¸)the movie starts playing immediately, the ° d ONLN d Ω A < M– ( i ZZcontroller goes wild and the next time I hit the play button it ignores the previous rate. ° d ONLN d M < Y N * ___ ° d ONLN d e < q û *SetMovieRate takes ° d ONLN d/ e û q˛ )bFeffect immediately; that’s why the movie starts playing as soon as you ° d ONLN dv q < }µ ( ô ZNmake the call, with a rate other than zero. Also, calling SetMovieRate behind ° d ONLN dƒ qµ }˛ ( ô”the controller’s ° d ONLN d’ } < â ( • Z*back can only cause confusion because you ° d ONLN dˇ } Ⲡ)–3are changing the state of the movie without letting ° d ONLN d3 â < ïû ( ± ZJthe movie controller know about the change. Note that in normal operation ° d ONLN d} âû ï˛ ( ±ºthe movie controller ° d ONLN dí ï < °¬ ( Ω ZWplays back movies at the standard speed, rate = 1; this is the current behavior. It is ° d ONLN dÈ ï¬ °˛ ( Ω‡
possible that ° d ONLN d˜ ° < ≠ ( … ZWin a future release the movie controller will use the rate the movie was saved with or ° d ONLN dN ° ≠˛ ( …Ë the one set ° d ONLN dZ ≠ < π Δ ( ’ Zwith SetPreferredMovieRate. ° d ONLN dw ≈ < — ™ *A little-known fact is ° d ONLN dé ≈ ™ —˛ )nCthat the standard controller does contain a primitive mechanism for ° d ONLN d“ — < ›L ( ˘ Z:controlling the rate of playback. If you hold the control ° d ONLN d —L ›˛ ( ˘j!key down and then click the mouse ° d ONLN d. › < È≥ ( ZKover the stepping buttons, you can, for example, play the movie backwards. ° d ONLN dy ›≥ È˛ (—Furthermore, if ° d ONLN dâ È < ı÷ ( ZXyou hold the mouse down you’ll get a slider control that does let you play the movie at ° d ONLN d· È÷ ı˛ (Ù different ° d ONLN dÎ ı < Ω ( Zrates backward or forward. ° d ONLN d
<– *ZThe slider provided by the standard controller is not intended to set the rate, so if you ° d ONLN d`
Splaceholders. The maximum volume you can get is 0x0100 with the minimum being 0 (or ° d ONLN ds º »Ω ( ‰ 6Vany negative value). The advantage of using negative volumes is that you can turn off ° d ONLN d… ºΩ »⁄ ( ‰€sound ° d ONLN dœ » ‘à ( 6[while maintaining the level of volume. For example, -1 and 0 both equate to no volume, but ° d ONLN d* »Ã ‘⁄ ( Íthe ° d ONLN d. ‘ ‡‘ ( ¸ 6\-1 implies that 1 should be the volume when sound is turned back on, whereas the 0 does not. ° d ONLN dã Ï ¯Ã *\The volume for a track is scaled to the movie’s volume, and the movie’s volume is scaled to ° d ONLN dÁ Ïà ¯⁄ (Íthe ° d ONLN dÎ ¯ % ( 6:value the user specifies for the speaker volume using the ° d ONLN d% ¯%⁄ ( C$Sound control panel. This means that ° d ONLN dJ ã (, 6Kthe movie volume represents the maximum loudness of any track in the movie.
° d ONLN dñ( 7 *'"QuickTime 1.0 FS6Patch elucidation
° d ONLN dπ7 C > * Written: ° d ONLN d√C O ] * Last reviewed: ° d ONLN d”[ gj *DThe FS6Patch description in the QuickTime 1.0 CD Read Me file says, ° d ONLN d[jg⁄ (Éà“There is a known bug ° d ONLN d-g s´ (è 6Owith HFS on System 6.” What specifically is this bug? According to the Read Me ° d ONLN d|g´s⁄ (è…
file, “The ° d ONLN dás 7 (õ 6;exact situation under which the problem occurs is somewhat ° d ONLN d¬s7⁄ (õU#rare.” What is the exact situation? ° d ONLN dÊ ãM (ß 6B“If the patch is not necessary, it will not install itself.” What ° d ONLN d(Mã⁄ (ßk criteria is used to determine ° d ONLN dFã ó H (≥ 6
necessity? ° d ONLN dQó £ * * ___ ° d ONLN dUØ ª ≠ * When closing or flushing a file ° d ONLN duØ ≠ª⁄ )ïAthat has multiple open paths to a given fork, it is possible that ° d ONLN d∑ª «f („ 6Ithe blocks marked as available for the other paths can also be allocated ° d ONLN d ªf«⁄ („Ñto the other fork. If this ° d ONLN d« ”d (Ô 6Ahappens before the other paths are closed, blocks will be mapped ° d ONLN d\«d”⁄ (ÔÇto more than one fork, ° d ONLN ds” fl ‘ (˚ 6*potentially trashing at least one of them. ° d ONLN dûÎ ˜ π *$The condition that can trigger this ° d ONLN d¬Î π˜⁄ )°<condition is multiple writeable paths to the same fork. Once ° d ONLN dˇ˜ ó ( 6 this is satisfied you would ° d ONLN d˜ ó⁄ )Aneed to make some changes to the fork, close the path, use any of ° d ONLN d] g (+ 6Ethe other paths to modify the fork, access the other fork and modify ° d ONLN d¢g⁄ (+Ödata. If all these things ° d ONLN dº ª (7 6Xhappen you could see the damage to one of the forks (the second-to-last being accessed). ° d ONLN d' 3ö *TThe code that loads the patch checks the system first; the range where the patch is ° d ONLN di'ö3⁄ (O∏
used is 6.0.4 ° d ONLN dw3 ?≠ ([ 6R< system < 7.0. The version of the ROM is also used to decide when to install. If ° d ONLN d…3≠?⁄ ([Àthe ROM ° d ONLN d—? K ° (g 6 indicates the machine is later ° d ONLN d? °K⁄ )â?than the Macintosh IIfx, then a fix in ROM is assumed. The last ° d ONLN d 0K W= (s 6<check is to see if the code being patched is already in RAM ° d ONLN d lK=W⁄ (s[ (the assumption is that being in ° d ONLN d çW c ( 64RAM means fixed). If so, the patch doesn’t get used. ◊ 4◊˘
° d ONLN d ) < 8Œ ( T Z9QuickTime alias and FSSpec system services under System 6
° d ONLN d : 8 < D b * Written: ° d ONLN d D D < P Å * Last reviewed: ° d ONLN d T \ < h` *>I recall reading that QuickTime includes an implementation of ° d ONLN d í \` h˛ ( Ñ~ the Alias Manager for System 6, ° d ONLN d ≤ h < t™ ( ê ZNbut I haven’t found any precise description of just what is included. Is it a ° d ONLN d h™ t˛ ( ê»bare minimum to ° d ONLN d t < ÄΔ ( ú ZPsupport QuickTime? Or is the full Alias Manager there? Also, is there any way I ° d ONLN d` tΔ Ä˛ ( ú‰ can use the ° d ONLN dl Ä < å∂ ( ® ZQFSSpec interface to the File Manager, or must I revert to the System 6 interface? ° d ONLN dæ å < ò N * ___ ° d ONLN d¬ § < ∞ › * Here is some information on the ° d ONLN d‚ § › ∞˛ )°8alias and FSSpec system services that QuickTime supplies ° d ONLN d ∞ < º â ( ÿ Zunder System 6: ° d ONLN d+ » < ‘ *-1. QuickTime support for aliases on System 6: ° d ONLN dY ‡ < Ït *BMost of the Alias Manager is available, with these few exceptions: ° d ONLN dú ¯ < @ *• ° d ONLN dû ¯ E∂ ) QNewAlias will accept a fromFile parameter, but it never creates a relative alias. ° d ONLN d < @ (, Z• ° d ONLN dÚ E* ) -NewAliasMinimalFromFullPath is not available. ° d ONLN d < @ (8 Z• ° d ONLN d" E o ) AResolveAlias will accept a fromFile parameter, but it ignores it. ° d ONLN dd <( @ (D Z• ° d ONLN df E( € ) ResolveAliasFile is not present. ° d ONLN dá( <4 @ (P Z• ° d ONLN dâ( E4x ) 2MatchAlias may be called, but the kARMSearchMore, ° d ONLN dª(x4˛ (PñkARMSearchRelFirst, and ° d ONLN d”4 <@ø (\ ZQkARMMultVols flags are not available. If you pass them in, they will be ignored. ° d ONLN d$4ø@˛ (\› Furthermore, ° d ONLN d1@ <L( (h Z4if you pass in a matchProc, it will never be called. ° d ONLN dfL <X @ * • ° d ONLN dhL EXb ) =UpdateAlias will accept a fromFile parameter, but ignores it. ° d ONLN d¶X <d @ (Ä Z• ° d ONLN d®X Edn ) :The System 6 Alias Manager will not mount network volumes. ° d ONLN d„p <|b (ò Z7So to summarize, on System 6 the Alias Manager doesn’t ° d ONLN dpb|˛ (òÄ!handle relative aliases, multiple ° d ONLN d<| <àè (§ ZBvolume searches, searchMore searches, and network volume mounting. ° d ONLN dî <† Í *'On the good side, nearly all calls are ° d ONLN d¶î ͆˛ )Æ8present. Aliases created on System 6 are compatible with ° d ONLN dfl† <¨î (» ZESystem 7 aliases. And aliases made on System 7 will work on System 6. ° d ONLN d%∏ <ƒˆ *\Unfortunately, QuickTime does not currently install an Alias Manager Gestalt selector as it ° d ONLN dÅ∏ˆƒ˛ (‡is ° d ONLN dу <–Ô (Ï Z^only a partial implementation. You can check for the Alias Manager using Gestalt and if it is ° d ONLN d‚ƒÔ–˛ (Ï
not ° d ONLN dÊ– <‹ (¯ Z,present, look for QuickTime (using Gestalt) ° d ONLN d–‹˛ )“/and if QuickTime is present, assume you have an ° d ONLN dB‹ <Ë ( Z0Alias Manager, subject to the limitations above. ° d ONLN dsÙ < Ó *%2. FSp file system calls and System 6 ° d ONLN dô < â *QuickTime also ° d ONLN d® Ⲡ)MKmakes extensive use of the FSSpec data structure introduced in the System 7 ° d ONLN dÙ <$ ˜ (@ Z$File Manager. Nearly all the FSSpec ° d ONLN d ˜$˛ )ª1calls are available on System 6 when QuickTime is ° d ONLN dJ$ <0G (L Z:installed. The following calls are available on System 6, ° d ONLN dÑ$G0˛ (Le#and should behave as documented for ° d ONLN d®0 << k (X Z System 7: ° d ONLN d≤H <T ï * FSMakeFSSpec ° d ONLN d√T <` Ñ *
FSpOpenDF ° d ONLN d—` <l Ñ *
FSpOpenRF ° d ONLN dfll <x z *
FSpCreate ° d ONLN dÌx <Ñ â * FSpDirCreate ° d ONLN d˛Ñ <ê y *
FSpDelete ° d ONLN d ê <ú à * FSpGetFInfo ° d ONLN d ú <® Ü * FSpSetFInfo ◊ X◊
° d ONLN d ) f * FSpSetFLock ° d ONLN d ) 5 g * FSpRstFLock ° d ONLN d 5 A ^ *
FSpRename ° d ONLN d . A M c * FSpCatMove ° d ONLN d = M Y u * FSpOpenResFile ° d ONLN d P Y e z * FSpCreateResFile ° d ONLN d e e q m * FSpGetCatInfo ° d ONLN d w } â fi *)The following call is not available when ° d ONLN d † } fi â⁄ )Δ/using the QuickTime System 6 version of the FSp ° d ONLN d – â ï 0 ( ± 6calls: ° d ONLN d ◊ ° ≠ } * FSpExchangeFiles ° d ONLN d Ï π ≈ ≠ * Again, the Gestalt selector for ° d ONLN d π ≠ ≈⁄ )ï<the FSp calls is not installed when QuickTime is there. This ° d ONLN dI ≈ — ( Ì 66means that the gestaltFSAttr Gestalt selector may not ° d ONLN d ≈ —⁄ ( Ì9%be present, and gestaltHasFSSpecCalls ° d ONLN d• — › ¯ ( ˘ 61may not be set, even if gestaltFSAttr is present.
° d ONLN d◊ ı Õ *'?'pnot' resource format for QuickTime-like preview in dialog box
° d ONLN d > * Written: ° d ONLN d! ] * Last reviewed: ° d ONLN d1( 4≥ *UI would like to implement the preview/thumbnail feature in the Standard File dialog, ° d ONLN dÜ(≥4⁄ (P— just like ° d ONLN dê4 @ª (\ 6Wthe extension included with QuickTime. Is that code available separate from QuickTime? ° d ONLN dÁ4ª@⁄ (\ŸIf not, ° d ONLN dÔ@ L< (h 6?could I at least get information on how the preview is created? ° d ONLN d/L X * * ___ ° d ONLN d3d p ç *To implement your own ° d ONLN dId çp⁄ )uEpreview/thumbnail feature, simply duplicate the Standard File dialog, ° d ONLN dèp | (ò 62add the necessary 'DITL' resources, and install a ° d ONLN d¡p|⁄ )Í,custom filter procedure for handling preview ° d ONLN dÓ| à t (§ 6commands. On the ° d ONLN dˇ| tà⁄ )\ESystem 7 CD there’s an example, StdFileSample, that shows exactly how ° d ONLN dEà îL (∞ 6=to create a custom file dialog. The Macintosh Technical Note ° d ONLN dÇàLî⁄ (∞j“Customizing Standard File” ° d ONLN dûî †g (º 6D(formerly #47) describes how to do this as well. For generating and ° d ONLN d‚îg†⁄ (ºÖdisplaying the preview, ° d ONLN d˙† ¨ Ñ (» 6you can use the ° d ONLN d
† Ѩ⁄ )l8following PreviewResourceRecord, found at the end of the ° d ONLN dC¨ ∏ ì (‘ 6ImageCompression.h file: ,
Courier
° d ONLN d\ƒ œ Æ * struct PreviewResourceRecord { ° d ONLN d{Œ Ÿ Ω *
! unsigned long modDate; ° d ONLN dùÿ „ — *
% short version; ° d ONLN d√‚ Ì ¬ *
" OSType resType; ° d ONLN dÊÏ ˜ « *
# short resID; ° d ONLN d
ˆ " *
};
° d ONLN d
K *;typedef struct PreviewResourceRecord PreviewResourceRecord; ° d ONLN dI $Ü * Etypedef PreviewResourceRecord *PreviewResourcePtr, **PreviewResource; ° d ONLN dè0 <Ä *NThis is the format for the 'pnot' resource, which defines the preview for the ° d ONLN d›0Ä<⁄ (Xûmovie file, usually ° d ONLN dÒ< H C (d 6 pointing ° d ONLN d˙< CH⁄ )+Pto a 'PICT' resource. It’s all you need to generate QuickTime-compatible preview ° d ONLN dKH T î (p 6without using QuickTime. ◊ 4◊˘
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° d ONLN d ) < 8ä ( T Z0MCSetClip and clipping with the movie controller
° d ONLN d 1 8 < D b * Written: ° d ONLN d ; D < P Å * Last reviewed: ° d ONLN d K \ < h *-I use SetMovieDisplayClipRgn to set my movie ° d ONLN d x \ h˛ )‰-clip, but the movie doesn’t obey my clipping. ° d ONLN d ¶ h < tO ( ê Z9Does the movie controller component ignore this clipping? ° d ONLN d ‡ t < Ä N * ___ ° d ONLN d ‰ å < ò S *You ° d ONLN d Ë å S ò˛ )Zprobably are directly modifying a movie that is attached to a controller without notifying ° d ONLN dC ò < §é ( ¿ ZLthe controller of the changes. The controller uses the display clip for its ° d ONLN dè òé §˛ ( ¿¨own purposes, such as ° d ONLN d• § < ∞ r ( à Z for badges. ° d ONLN d± º < » Ü *If you want to ° d ONLN d¿ º Ü »˛ )JGdo clipping with the movie controller you must use MCSetClip. MCSetClip ° d ONLN d » < ‘ l ( Z
takes two ° d ONLN d » l ‘˛ )0Uregions. The first clips both the movie and the controller. The second clips just the ° d ONLN dh ‘ < ‡ ( ¸ Z.movie, and is equivalent to the movie display ° d ONLN dñ ‘ ‡˛ )ÿ4clip. If both clips are set, the controller does the ° d ONLN dÀ ‡ < Ïb ( Z>right thing and merges them as appropriate. If you don’t want ° d ONLN d ‡b Ï˛ (Ä"one or the other of the clips, set ° d ONLN d, Ï < ¯ z ( Z
them to zero. ° d ONLN d: <ó *LIn general, if you are going to do something to a movie that is attached to ° d ONLN dÜó˛ (,µa controller you must ° d ONLN dú < ô (8 Zeither do it through ° d ONLN d± ô ˛ )]Hthe controller, using the action calls, or you must call MCMovieChanged. ° d ONLN d˙ <(ù (D ZIOtherwise, the controller would need to constantly poll the movie to see ° d ONLN dC ù(˛ (Dªif its state changed. ° d ONLN dY( <4 Î (P Z$Clearly this would be Evil and Slow.
° d ONLN d~L <[` *'*Problem with disabling a movie video track
° d ONLN dfl <Óã *'1Determining whether a movie is set to loop or not
° d ONLN d"Ó <˙ b * Written: ° d ONLN d+Ó à˙ ¨ )L8/11/92 ° d ONLN d3˙ < Å (" ZLast reviewed: ° d ONLN dB˙ à ¨ )L9/15/92 ° d ONLN dJ < (: Z+How does Simple Player determine whether a ° d ONLN du ˛ )€1movie is set to loop or not? Movie files that are ° d ONLN dß <*¿ (F ZOset to loop seem to have a string of 'LOOP' at the end of the 'moov' resource. ° d ONLN dˆ ¿*˛ (Ffi Does Simple ° d ONLN d* <6 ¶ (R ZPlayer check 'LOOP'? ° d ONLN d6 <B N * ___ ° d ONLN dN <Z ÿ *!Simple Player identifies whether ° d ONLN d<N ÿZ˛ )ú<movies are set to loop by looking within the user data atoms ° d ONLN dyZ <fû (Ç ZGfor the 'LOOP' atom, as you’ve noticed. It’s a 4-byte Boolean in which ° d ONLN d¿Zûf˛ (Ǻa value of 1 means ° d ONLN d”f <r{ (é ZAstandard looping and a value of 0 means palindrome looping. Your ° d ONLN df{r˛ (éôapplications should add the ° d ONLN d0r <~ ∏ (ö Zuser data 'LOOP' atom to ° d ONLN dIr ∏~˛ )|>the end of the movie when a user chooses to loop. We recommend ° d ONLN dà~ <ä x (¶ Z this method ° d ONLN dî~ xä˛ )<Mas a standard mechanism for determining the looping status of a movie. If the ° d ONLN d‚ä <ñ (≤ Z 'LOOP' atom ° d ONLN dÓä ñ˛ )CPdoesn’t exist, there’s no looping. The calls you need to access this information ◊ X◊
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° d ONLN d )Ã *Rare GetMovieUserData, GetUserData, AddUserData, and RemoveUserData, as defined in ° d ONLN d R Ã )⁄ ( EÍthe ° d ONLN d V ) 5' ( Q 65Movie Toolbox chapter of the QuickTime documentation.
° d ONLN d å M \_ *'-Determining QuickDraw video media pixel depth
° d ONLN d ∫ \ h > * Written: ° d ONLN d √ \ d h à )L8/18/92 ° d ONLN d À h t ] ( ê 6Last reviewed: ° d ONLN d ⁄ h d t é )L10/11/92 ° d ONLN d „ Ä å| ( ® 6JHow do I get the pixel depth of a QuickTime video media for a given track? ° d ONLN d. å ò * * ___ ° d ONLN d2 § ∞ › *)The following sample code does the trick: ,
Courier
° d ONLN d\ º « Ü *#include <QuickDraw.h> ° d ONLN ds Δ — w *
Media coolMedia=nil; ° d ONLN d“fi È& *6coolMedia = GetFirstVideoMedia(coolMovie,&trackIndex); ° d ONLN d Ë Û: *
:if (!trackIndex || !coolMedia) return -1; // we need both ° d ONLN dDÚ ˝? *
;GetMediaSampleDescription(coolMedia,trackIndex,imageDescH); ° d ONLN dÄ *4return (*(ImageDescriptionHandle)imageDescH)->depth; ° d ONLN dµ *
} ◊ 4◊˘
*µ12 )
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° d ONLN d ) < 8ø ( T Z6QuickTime 1.0 GetMoviePict grayscale images -157 error
° d ONLN d 7 8 < D b * Written: ° d ONLN d @ 8 à D ¨ )L8/27/92 ° d ONLN d H D < P Å ( l ZLast reviewed: ° d ONLN d W D à P ≤ )L10/11/92 ° d ONLN d ` \ < h¥ ( Ñ ZLTrying to read any single frame (except the first) from a grayscale (4, 16, ° d ONLN d ¨ \¥ h˛ ( Ñ“or 256 grays), ° d ONLN d ª h < t Ó ( ê Z QuickTime movie gives a -157 ° d ONLN d ÿ h Ó t˛ )≤0error (invalid pixel depth). I do “framehandle = ° d ONLN d t < Äo ( ú ZAGetMoviePict(damovie,daunitnum)” and test if it’s 0. If so, then ° d ONLN dJ to IJ ( úç I do “io = GetMoviesError()” ° d ONLN dg Ä < å Q ( ® Zand ° d ONLN dk Ä Q å˛ )Vit gives me the -157 error. GetMoviePict is working fine for all color and black/white ° d ONLN d¬ å < ò≠ ( ¥ ZLmovies. It just doesn’t work on “Animation” grayscale and “Video” grayscale ° d ONLN d å≠ ò˛ ( ¥Àmovies. Is this a ° d ONLN d ò < § S ( ¿ Zbug? ° d ONLN d% § < ∞ N * ___ ° d ONLN d) º < »Í *[It is true that grayscale images will cause a -157 error with GetMoviePict using QuickTime ° d ONLN dÑ ºÍ »˛ ( ‰1.0. ° d ONLN dâ » < ‘: ( Z4QuickTime 1.5 will fix this problem. Some grayscale ° d ONLN dΩ »: ‘˛ )˛(images may work, if the color tables are ° d ONLN dÊ ‘ < ‡ a ( ¸ Zcustom ° d ONLN dÌ ‘ a ‡˛ )%Umade. To check for this situation, you can look at the clutID of the ImageDescription ° d ONLN dC ‡ < ϧ ( ZLstructure. If the clutId is 0, then there is a custom color table attached. ° d ONLN dè ‡§ Ï˛ (¬For these images, ° d ONLN d° Ï < ¯ ¥ ( ZGetMoviePict may work. ◊ X◊
(Ï ZMovie Toolbox Q&As (Ï˙13 )
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IR . ° d ONLN d z < çX ( ß Z Movies ‘LOOP’ Atom and Friends
° d ONLN d å < õ Ö * QuickTime ° d ONLN d ) åz õ˛ ( ∑òM.QT.MoviesLOOP
° d ONLN d 9 ß < ≥ q ( œ Z Written by: ° d ONLN d E ß Ñ ≥ ∫ )H John Wang ° d ONLN d O ß± ≥˛ ( œœ
November 1992 ° d ONLN d ] ø < Àh ( Á Z>This Technical Note discusses entertaining uses for QuickTime ° d ONLN d õ øh À˛ ( ÁÜ user data atoms, Apple defined ° d ONLN d ∫ À < ◊ Ç ( Û Zand otherwise. ° d ONLN d … „ < Ô b *Topics ° d ONLN d – Ô W ˚ ≠ + • User Data Types ° d ONLN d ‚ ˚ W ù *
• Sample Code ° d ONLN d W € * • Inside the User Data Atom > X>
° d ONLN d 8 <G è (c Z Introduction
° d ONLN dS <_˘ *^It is often desirable for an application to preserve the window position and looping state of ° d ONLN dwS˘_˛ ({a ° d ONLN dy_ <k Ù (á Z&movie. This Technical Note describes ° d ONLN dü_ Ùk˛ )∏6the “Apple Sanctified” method of doing this using user ° d ONLN d÷k <w r (ì Z data atoms. ° d ONLN d‰É <èµ *LUser data atoms allow applications to store custom information which can be ° d ONLN d0Éµè˛ (´”easily accessed ° d ONLN d@è <õº (∑ ZMusing QuickTime Movie Toolbox calls. These user data atoms are text or data ° d ONLN dçèºõ˛ (∑⁄ which can be ° d ONLN döõ <ß5 (√ Z5associated and stored in any movie, track, or media. ° d ONLN dœõ5߲ )˘+ A reference to the list of user data atoms ° d ONLN d˚ß <≥ e (œ Z for each ° d ONLN dß e≥˛ ))Sof these locations can be accessed with the following routines: GetMovieUserData(), ° d ONLN dX≥ <øô (€ ZHGetTrackUserData(), and GetMediaUserData(). Once a reference to a list ° d ONLN d†≥ôø˛ (€∑of user data atoms is ° d ONLN d∂ø <Àj (Á Z?obtained, an application can store, retrieve, and manage items ° d ONLN dıøjÀ˛ (Áà in the list using the following ° d ONLN dÀ <◊b (Û Z7routines: GetNextUserDataType(), CountUserDataType(), ° d ONLN dLÀb◊˛ (ÛÄ AddUserData(), GetUserData(), ° d ONLN dj◊ <„ (ˇ ZPRemoveUserData(), AddUserDataText(), GetUserDataText, and RemoveUserDataText(). ° d ONLN d∫◊„˛ (ˇ A ° d ONLN dΩ„ <Ô j ( Z complete ° d ONLN dΔ„ jÔ˛ ).Pdescription of these routines can be found in Inside Macintosh: QuickTime in the ° d ONLN dÔ <˚@ ( Z4“Working With Movie User Data” section of chapter 2.
° d ONLN dL <" ™ *'User Data Types
° d ONLN d\. <:á *KEvery user data atom carries a type identifier. This identifier is stored ° d ONLN dß.á:˛ (V•in a long integer, similar ° d ONLN d¬: <Fá (b Z>to a Resource Manager type. Apple has reserved all lowercase ° d ONLN d :áF˛ (b•user data types values. ° d ONLN dF <R¥ (n ZSApplications are free to use types values containing at least one uppercase letter. ° d ONLN dm^ <j I *In ° d ONLN dp^ Ij˛ )
>⁄ )r atom exists in the movie's user ° d ONLN d' Ã% ˝ (A Í data list, ° d ONLN d2 ˝%⁄ )1*then looping is performed according to its ° d ONLN d]% Ã1⁄ (M Í8value: 0 for normal looping and 1 for palindrome looping ° d ONLN dó1 <= f (Y Z'WLOC' ° d ONLN dû1 Ã=¶ )ê(Handle to a point record indicating the ° d ONLN dΔ1¶=⁄ )⁄
, if ((** (long **) theLoop) == 1) ° d ONLN d§ Ø k *
loopInfo = 2; *
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*2 ) of 3 (Ïm Movies ‘LOOP’ Atom and Friends ˇ Ç ◊# ˇ ˇˇˇˇ # ◊
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December 1992 / X /
° d ONLN d ) < 5’ ( Q ZTThe following example demonstrates how to add a looping atom to a movie to indicate ° d ONLN d T )’ 5˛ ( QÛ that user ° d ONLN d ^ 5 < A û ( ] Zhas selected looping:
° d ONLN d t M < X è * Handle theLoop; ° d ONLN d é W < b ï *
6 theCount = CountUserDataType(theUserData, 'LOOP'); ° d ONLN dé ß < ≤ ä *
while (theCount--) ° d ONLN d• ± < º Ì *
/ RemoveUserData(theUserData, 'LOOP', 1); ° d ONLN d’ ª < Δ Ô *
. AddUserData(theUserData, theLoop, 'LOOP');
° d ONLN d — < › Ç *The following ° d ONLN d — Ç ›˛ )FJexample demonstrates how to remove a looping atom from a movie to indicate ° d ONLN d] › < È º ( Z that looping is not selected:
° d ONLN d| ı < ï * Movie theMovie; ° d ONLN dó ˇ <
° *
UserData theUserData; ° d ONLN dµ < é *
short theCount; ° d ONLN d– <( Ò *- theUserData = GetMovieUserData(theMovie); ° d ONLN d˛' <2 *
° d ONLN düÇ <é *OThose of you who parse user data atoms directly by accessing the 'moov' handle ° d ONLN dÓÇ é˛ (™Ë rather than ° d ONLN d˙é <ö e (∂ Z with the ° d ONLN dé eö˛ ))Yappropriate movie toolbox calls, will notice a trailing long integer of value 0 after all ° d ONLN d]ö <¶& (¬ Z3user data atoms in the list. This is required for ° d ONLN dêö&¶˛ )Í)backward compatibility with QuickTime 1.0 ° d ONLN d∫¶ <≤ (Œ Z0which has a bug that requires the trailer. The ° d ONLN dͶ ≤˛ )‚/size of the 'udta' atom does reflect this extra ° d ONLN d≤ <æŒ (⁄ ZTtrailing long integer. QuickTime 1.0 and future versions will automatically handle ° d ONLN dn≤Œæ˛ (⁄Ï this when ° d ONLN dxæ < Q (Ê Z:manipulating user data atoms with the movie toolbox calls. ° d ONLN d¥Ó <˙ ¶ *0Further Reference: X ° d ONLN d«˚ N R +
• ° d ONLN d…˚ ` Î )Inside Macintosh: QuickTime ° d ONLN d‰˚ Îm )ã, Movie Toolbox Reference ◊ X◊
