[mythtv-users] Playback issue with certain video

[Shawn King]

On 10/22/2012 03:56 AM, Martin Moores wrote:
> 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
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i think this is also related to tickets #10706 
<http://code.mythtv.org/trac/ticket/10706> and #10942 
<http://code.mythtv.org/trac/ticket/10942> all 3 samples use  
FF_BUFFER_TYPE_INTERNAL buffers. commenting out the if 
(!decode.contains(*it)) in the function 
VideoBuffers::DoneDisplayingFrame(VideoFrame *frame) makes the videos 
for ticket #10706 and this video to play correctly.  all 3 videos show 
that there's mostly finished(displayed but still in decode queue) frames 
so i think the issue is mythtv isnt removing these frames from the 
decode list and after a while it just runs out of frames and has to drop 
all frames to continue playback.
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