Quicktime Sound Glitch 2007-11-14 - By zmorris@(protected)
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Hi, we are having an mp3 playback glitch in Quicktime in 10.4.10. I
asked the Quicktime group and got no response, so I thought I'd try
here. Here is that email:
-- --
Hi All, we are having a problem with a looping mp3 stuttering at
certain points in our game. We think it's related to MoviesTask(),
but we are calling it 30 times per second. I have searched the
archives, but no luck. We load and start a movie with code similar
to the following:
////////////////////////////////////////
#define kMusicTaskTime 30
FSSpec fileSpec; // spec to your movie file
Movie movie;
TimeValue timeNow, duration;
Fixed playRate;
Media media;
QTCallBackUPP callbackUpp;
QTCallBack callback;
pascal void EndCallback( QTCallBack callback, long refCon )
{
GoToBeginningOfMovie( movie );
CallMeWhen( callback, callbackUpp, 0, triggerAtStop, 0, 0 );
StartMovie( movie );
}
pascal void MusicProcess( EventLoopTimerRef theTimer, void *userData )
{
MoviesTask( movie, nil );
}
EventLoopTimerUPP MusicProcessUPP = NewEventLoopTimerUPP
( MusicProcess );
EventLoopTimerRef MusicProcessRef;
/*TMTask musicTask;
pascal void MusicProcess( TMTask *myPtr )
{
MoviesTask( movie, nil );
PrimeTime( ( QElemPtr ) myPtr, kMusicTaskTime );
}*/
int main()
{
short refNum = 1;
// note: set up fileSpec here to point to your file
OpenMovieFile( &fileSpec, &refNum, fsRdPerm );
NewMovieFromFile( &movie, refNum, nil, nil, newMovieActive &
newMovieDontAskUnresolvedDataRefs, nil );
CloseMovieFile( refNum );
GoToBeginningOfMovie( movie );
// turn these hints off
SetMoviePlayHints( movie, 0, hintsUseSoundInterp | hintsHighQuality );
// set the loop hint to enhance performance
SetMoviePlayHints( movie, hintsLoop, hintsLoop );
timeNow = GetMovieTime( movie, nil );
duration = GetMovieDuration( movie );
playRate = GetMoviePreferredRate( movie );
media = GetTrackMedia( GetMovieIndTrack( movie, 1 ) );
//***LoadMovieIntoRam( movie, timeNow, duration, keepInRam );
//***LoadMediaIntoRam( media, timeNow, duration, keepInRam );
//***SetMediaPreferredChunkSize( media, 16384 );
//***FlattenMovie(...)
PrePrerollMovie( movie, timeNow, playRate, nil, nil );
PrerollMovie( movie, timeNow, playRate );
// turn on looping
{
TimeBase timebase = GetMovieTimeBase( movie );
callback = NewCallBack( timebase, callBackAtExtremes );
callbackUpp = NewQTCallBackUPP( EndCallback );
CallMeWhen( callback, callbackUpp, 0, triggerAtStop, 0, 0 );
}
StartMovie( movie );
InstallEventLoopTimer
(
GetCurrentEventLoop(),
kEventDurationNoWait,
kMusicTaskTime * kEventDurationMillisecond,
MusicProcessUPP,
nil,
&MusicProcessRef
);
/*musicTask.tmAddr = NewTimerUPP( MusicProcess );
musicTask.tmWakeUp = 0;
musicTask.tmReserved = 0;
InsTime( ( QElemPtr ) &musicTask );
PrimeTime( (QElemPtr ) &musicTask, kMusicTaskTime );*/
}
////////////////////////////////////////
We have also tried running MoviesTask() in a timer task, of course,
it makes no difference. Unfortunately the test machine is an iMac G4
1GHz across the country, so there is a day's turnaround time whenever
we send an update for them to try. We don't see the issue on our
G4. Specifically:
1. Will SetMediaPreferredChunkSize() really get QT to process the
sound in bigger chunks, or is there another call that is better?
2. Is there a way to raise the priority of the mp3 movie?
3. Is there a tool of some sort that can tell us whenever quicktime
stutters, and why?
We think the load on the machine is pretty low, so we can't figure
out why quicktime isn't getting enough time to process the song.
There is an outside chance they just have a corrupt OS install. Has
anyone seen this problem?
-- --
SetMediaPreferredChunkSize() didn't fix it. We have since tried it
on an iMac G3 400 and it plays fine. We are sure it's not a
performance issue. Does anyone know of a tool like Spotlight for OS
9, that we can use on OS X to make sure that the quicktime memory is
ok? Or is there a tool to test quicktime, like for audio units/core
audio or whatever?
We are really in a pinch here with the holidays coming and for the
life of us, can't solve this problem.
Thank you for your help,
--Zack
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