How can I eliminate latency in quicktime streamed video

I'm prototyping a client that displays streaming video from a HaiVision Barracuda through a quicktime client. I've been unable to reduce the buffer size below 3.0 seconds... for this application, we need as low a latency as the network allows, and prefer video dropouts to delay. I'm doing the following:

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {

    NSString *path = [[NSBundle mainBundle] pathForResource:@"haivision" ofType:@"sdp"];

    NSError *error = nil;
    QTMovie *qtmovie = [QTMovie movieWithFile:path error:&error];
    if( error != nil ) {
        NSLog(@"error: %@", [error localizedDescription]);
    }

    Movie movie = [qtmovie quickTimeMovie];
    long trackCount = GetMovieTrackCount(movie);
    Track theTrack = GetMovieTrack(movie,1);
    Media theMedia = GetTrackMedia(theTrack);
    MediaHandler theMediaHandler = GetMediaHandler(theMedia);
    QTSMediaPresentationParams myPres;

    ComponentResult c = QTSMediaGetIndStreamInfo(theMediaHandler, 1,kQTSMediaPresentationInfo,
                             &myPres);
    Fixed shortdelay = 1<<15;
    OSErr theErr = QTSPresSetInfo (myPres.presentationID,
                               kQTSAllStreams,
                               kQTSTargetBufferDurati开发者_开发问答onInfo,
                                &shortdelay );
    NSLog(@"OSErr %d", theErr);

    [movieView setMovie:qtmovie];
    [movieView play:self];
}

I seem to be getting valid objects/structures all the way down to the QTSPres, though the ComponentResult and OSErr are both returning -50. The streaming video plays fine, but the buffer is still 3.0seconds. Any help/insight appreciated.

J

Lower the video quality. This will result in less data to send allowing the 3s buffer to be sent faster.