VLC, video stuttering with ALSA sound output
Hi!
Starting somewhere around VLC 2.x, I experience "video stuttering"
problems on some files, mostly >= 720P, MKV/H.264+AC3, but not only on
such files - for example I also experience it on some of MPEG2 files (mpeg
container, mpeg2 video and audio codecs). HW acceleration is disabled, the
problem always reproduces at least on 2 different Debian machines (laptop
and PC, both 32-bit and both with snd-hda-intel kernel module), and on
both debian-multimedia and normal VLC/libav* packages. The same files play
without problem in mplayer/mplayer2/mpv.
vlc -vvv output shows many "ES_OUT_SET_(GROUP_)PCR is called too late"
errors; on each error the video playback temporarily stops ("stutters").
...
[0x87a0a30] main audio output warning: playback way too early (-563272):
playing silence
[0x87a0a30] main audio output debug: inserting 27037 zeroes
[0xf4c11150] main input error: ES_OUT_SET_(GROUP_)PCR is called too late
(pts_delay increased to 300 ms)
[0xf4c11150] main input error: ES_OUT_RESET_PCR called
[0xf4c11150] main input debug: Buffering 0%
...
[0xf0c45bc0] main decoder debug: End of audio preroll
...
[0xf4c11150] main input debug: Stream buffering done (334 ms in 3 ms)
[0xf4c11150] main input debug: Decoder buffering done in 0 ms
[0x87a0a30] main audio output debug: inserting 9553 zeroes
[0xebc00c58] main vout display debug: auto hiding mouse cursor
[0xf0c36aa8] main decoder debug: End of video preroll
[0xf4c11150] main input error: ES_OUT_SET_(GROUP_)PCR is called too late
(pts_delay increased to 320 ms)
[0xf4c11150] main input error: ES_OUT_RESET_PCR called
...
The key point is, first I thought it's some video decoder problems, but I
was wrong!
I've tried different setups and discovered that the problem is in _direct_
ALSA sound output - i.e. it works without any problem with PulseAudio!
Also it works with sound disabled or if the "discard all samples" audio
device is selected (so it's not an audio decoder problem).
I don't want to install PulseAudio, just because for me it's an useless
ALSA wrapper (everything always worked fine without it) and because I
don't like Lennart's creations. :-)
In any case I think it's a bug if ALSA output doesn't work in VLC...
Does anyone know something about this problem? Any upstream bugs or
possible ideas of fixing? Or should I just report it to debian
(-multimedia?) or even directly to upstream and wait for the solution?
--
With best regards,
Vitaliy Filippov
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