Speed up video

[jeremymc7]

Having an issue with speed up and out of sync video.

This happens which changing chapters or oddly enough changing audio tracks.

After changing the chapter or audio track the video is speed up about 2 times, while the audio is normal. Over about 2-3 seconds the video slows back down to normal and comes back in to sync with the audio.

Buffer issue?

• Mac Mini
• 2 GHz Intel Core 2 Duo
• 4GB Ram
• 10.5.2
• OSXBMC 0.50b1

[iordonez]

Log files?

[iordonez]

How does this look under .5b3?

[jeremymc7]

Yes, still exists in 0.5.0b5

No change.

[bmfrosty]

I've seen this. It usually only lasts a moment while the video speeds up to match the point in the audio track where where the switch happens.

Anything after this point is speculation.

I think this is because (I think) the cache only contains the streams which are being played back. The switch happens at the newest point in the buffer, and happens immediately instead of waiting until the previous audio stream catches up. The easiest fix would probably involve playing back the original audio stream until the audio stream you're switching to catches up with the current point in the buffer, and then making the switch. Another way would be to dump the buffer, and start over again with the new audio stream (lets say at the next keyframe). There are a lot of tradeoffs with this method, it may require a rebuffer and cause the video to pause if your network is too slow. Another way to address this would be to split buffer into a large network cache, and a smaller playback cache. The larger buffer contains the entire data stream, and the smaller contains the demuxed streams that are being played back - maybe just a frame or two worth. This would probably involve a major rewrite.

[bmfrosty]

Ok.....

This doesn't seem to be a cache problem. My assumption was wrong. The problem persists even when cache is turned completely off (unless that setting is false?). I'm going to see if I can catch what's happening in the log, but I suspect that it will end up being something that has to be looked at a in a different way.

[bmfrosty]

Here's a pastebin that shows switching audio streams. It will take someone with a better knowledge than I of the process to determine why this is happening.

http://pastebin.com/f43df1d2d

[iordonez]

Does the new mkv skipping patch fix it?

[jeremymc7]

If the patch is part of 0.5.0b8 then so it still persists.

[jeremymc7]

Testing in 0.5.0b9 this still happens but has gotten much better.

[jimmypop]

Is it possible that this change in b9 is responsible for ticket #288?