[Fix 11.3.1] Video Playback in 1.3 rc7 stalls audio playback

[Cheetah]

Hi!

I'm not sure if this is technically a bug ... I think it's more accurately described as a performance issue. Starting a video cue apparently stalls the main audio thread for long enough to cause running audio cues to stutter - unless I set my ASIO buffer size to obscenely large values. Setting the ASIO buffer to something > 4096 samples (at 44100 Hz) manages to skip over the delay most of the times, but that gives me a very huge latency - it feels like half a second. I usually run my card on buffer as small as 128 samples without glitches - it only happens when starting video cues. The chosen renderer makes a difference. Using VMR-7 seems to make video startup quicker.

The video files I'm playing are simple mp4 files (h264) in 1280x720 with low bitrate - so nothing particularly demanding. Video playback itself seems to be flawless, and there's no stuttering while the video plays back, only when new video cues start.

This is a fresh install of Windows 7 and recent drivers on a dual core AMD AM2 2,5Ghz with 3G ram and a Marian Marc8 soundcard (running on ASIO via BASS). Unfortunately I don't have a better system to see if throwing raw processing power at the problem would improve it - but I thought it was still interesting enough to report.

[Mike Daniell]

I don't think there's an issue directly related to using ASIO for audio file cues and also playing video cues. What I suspect is happening is that another video file is being pre-opened and buffered while the audio file is playing, and that may be causing the audio stutter. I'll send you details of a tracing version to run which should help me confirm that.

[Mike Daniell]

Fix ready for 11.3.1.