MKV H.264 video is choppy in 0.9.8a, but smooth in 0.8.6i

[gabriel.i.r]

Hello,

I recently upgraded VLC and found that some H.264 MKV videos that played without problems in 0.8.6i now have choppy picture in 0.9.8a.

I can produce this problem (correct playback in 0.8.6i but incorrect in 0.9.8a) on two different computers:
- 1.5 GHz Pentium M laptop running Windows XP SP2 (32-bit) with integrated graphics (circa 2005)
- 2.0 GHz 8-core Xeon desktop running Windows XP x64 with NVidia Quadro NVS 285 graphics (circa 2007)

On both computers and both VLC versions, CPU usage remains far below 100%.

I copied the first 5MB of two such problem videos to separate sample files, which reproduce the problem (plays fine in 0.8.6i, but picture is choppy in 0.9.8a).
I uploaded the samples here:
ftp://streams.videolan.org/incoming/smo ... 0.9.8a.mkv
ftp://streams.videolan.org/incoming/smo ... sample.mkv
[Edited to add this second, more obviously-choppy sample]

The original files were encoded from DVD source using Handbrake 0.9.2.

When playing this sample in 0.9.8a, the Messages window doesn’t report any errors besides “cannot load some cues/chapters/tags etc. (broken seekhead or file)” which I presume is because the file is only the first 5MB of a larger MKV file.

I also tried to find the earliest version after 0.8.6i which gave choppy playback on the sample. I didn’t see Win32 binaries on the FTP site for 0.9.0 or 0.9.1, but 0.9.2 does have the choppiness. So if this issue is a “bug” then I guess it was introduced somewhere between 0.8.6i and 0.9.2

Has this issue been addressed somewhere already? If so, I’d appreciate a pointer to the discussion.

If not, I’d be happy to provide any more information or help to people who can fix this issue.

Thanks for your time,

Gabriel Rosenhouse
gabriel.i.r@gmail.com

EDIT: As requested by j-b below, I filed a bug report, here: http://trac.videolan.org/vlc/ticket/2562

[Jean-Baptiste Kempf]

Is your CPU peaking?

[gabriel.i.r]

No, as I stated in the original post, on both computers CPU usage is mild when playing samples in either VLC version. (On the laptop, it's around 60%, on the desktop it's less than 3%).

[Jean-Baptiste Kempf]

Can you test the 1.0.0-dev test version?

[gabriel.i.r]

I tried the Win32 build at http://people.videolan.org/~jb/build/vl ... -win32.exe (dated 23 Feb 2009) and had the same problem.

Is there a different build I should try?

[Jean-Baptiste Kempf]

No, fill a bug report.

[random]

Any other players other then vlc you can find will play this file correctly?
Looks like playback frame rate issue

[random]

Try and encode the same clip again with frame rate of 30 or 25 fps or with megui this clearly looks like an encoder issue.