[mythtv-users] Playback issue with certain video

[Martin Moores]

On 21 October 2012 14:41, Mark Greenwood <fatgerman at gmail.com> wrote:
>
> On 21 Oct 2012, at 11:40, Martin Moores wrote:
>
>> On 20 October 2012 22:37, Jean-Yves Avenard <jean-yves at avenard.org> wrote:
>>>
>>>
>>> On Sunday, 21 October 2012, Mark Greenwood wrote:
>>>>
>>>>
>>>> I haven't tried playing it on my myth box, but I can tell you it's MJPEG,
>>>> not MPEG2, which might be why your myth box is having trouble with it. File
>>>> seems OK for an MJPEG file though, it's 30fps at 640x480 resolution. The
>>>> audio is 8-bit PCM, mono, 8KHz, which is unusual and could also be the
>>>> source of the problem.
>>>>
>>>>
>>> The format of the audio is irrelevant, myth will perform any conversion on
>>> the fly as required and is able to play 8, 16, 24, 32 bits integer and float
>>> audio
>>>
>>
>> Thanks for the replies both.  If Myth doesn't know what it is and
>> guesses wrong, then I guess that could be the issue.  I have no idea
>> how to tell though.
>>
>> Hopefully someone will get chance to take a look
>
> OK I've tried it on my myth box (0.25) and I get similar playback errors to you - it plays but it stutters.
>
> Mine does recognise it as MJPG :
>
> 2012-10-21 14:26:53.641 AFD: Opened codec 0xa3092d10, id(MJPEG) type(Video)
> 2012-10-21 14:26:53.641 AFD: codec PCM_U8 has 1 channels
> 2012-10-21 14:26:53.641 AFD: codec PCM_U8 has 1 channels
> 2012-10-21 14:26:53.641 AFD: Opened codec 0xa3093580, id(PCM_U8) type(Audio)
> 2012-10-21 14:26:53.923 AO: Resampling from 8 kHz to 32 kHz with quality medium
> 2012-10-21 14:26:53.951 AO: Opening audio device 'hdmi:CARD=NVidia,DEV=0' ch 2(1) sr 32000 sf signed 32 bit reenc 0
> 2012-10-21 14:26:53.962 AudioPlayer: Enabling Audio
>
>  After that I get loads of
>
> 2012-10-21 14:26:59.551 Player(3): Waited 100ms for video buffers ffffffffffffffffffffffAf
> 2012-10-21 14:26:59.551 Player(3): Timed out waiting for frames, and
>                         there are not enough free frames. Discarding buffered frames.
> 2012-10-21 14:26:59.560 Player(3): Waited 100ms for video buffers AAAAAAAAAAAAAAAAAAAAAAAA
> 2012-10-21 14:27:00.096 ALSA, Error: WriteAudio: buffer underrun
> 2012-10-21 14:27:00.823 Player(3): Waited 100ms for video buffers fffffffffffffffffffffAff
>
> etc etc.
>
> As an experiment I bunged it into avidemux and tried two variants:
>
> Copy the video stream but convert the audio to MP3 - same playback problem.
> Convert the video to x264 but keep the audio stream the same - plays perfectly.
>
> So it's either something dodgy with your file (avidemux thinks it's fine) or myth has issues with MJPG.
>
> Mark
>
> Mark

Mark,

Much appreciated you giving it a go, thanks, now I know it is not my
system as such, but a possibly bad video file.

Devs, what's the best thing to do about this?  If it is the video that
is bad, then no further action of course, as it is not a myth issue.
But I guess it is possible it's a myth/linux issue?  Is it the ffmpeg
guys that need to look at this, wasn't sure if it needed reporting
there.

Cheers

Martin