[mythtv] Call for testing branch devel/ffmpeg-resync (ffmpeg-cleanup)

[Scott Theisen]

On 7/4/22 12:42, Piotr Oniszczuk wrote:
>
>> Wiadomość napisana przez Scott Theisen<scott.the.elm at gmail.com>  w dniu 04.07.2022, o godz. 03:38:
>>
>> I have rebased onto the master branch my ffmpeg-cleanuphttps://github.com/MythTV/mythtv/pull/416  pull request and Peter Bennett has pulled it into the devel/ffmpeg-resync branch for ease of testing.
>>
>> Peter and I have tested it, but we would appreciate more testing before merging it into master.
>>
>> Thanks,
>>
>> Scott Theisen
> Scott,
>
> I gave very brief testing of hw assisted decode on various hw in my testbed:
>    
> stateless v4l2_request API; h6 & rpi4; mpeg2/h264/hevc/vp8/vp9: OK
> stateful v4l_m2m API; rpi4; h264: OK
> vdpau API; ION2; h264: NOK; see (1)
> vaapi API; intel n3450; mpeg2/hevc/vp8/vp9: OK; h264 NOK; see (2)
>
>
> (1): i'm observing issue with LiveTV staring in approx 2..3 per 5 starts with ffmpeg decode. Also some h264 test videos are failing do decode: hxxp://warped.inet2.org/h264-Sat_1080i_25fps.mkv
> I'm not observing this with current master - so it looks like issue happens on ffmpeg-resync branch.
> https://pastebin.com/fq6iSH7J  is log from 2 LiveTV starts: 1st with expected vdpau and second where it goes with ffmpeg (probably as fallback from failed vdpau attempt).
>
> (2):  issue seems similar to (1)
>
> Let me know if I can do anything extra to chelp...

Piotr,

Since the issue is only with LiveTV, try the attached patch.  (The 
commit hash is against my ffmpeg-cleanup branch but that doesn't really 
matter.)

 From your log:
```
2022-07-04 17:13:03.806788 W [mpegts @ 00007f229cb19780] Could not find 
codec parameters for stream 0 (Video: h264, none): unspecified size
Consider increasing the value for the \'analyzeduration\' (60000000) and 
\'probesize\' (5000000) options
2022-07-04 17:13:03.807066 I AFD: Stream #0: ID: 0x281 Codec ID: h264 
Type: Video(0x0) Bitrate: 0
...
2022-07-04 17:13:03.808502 I VDPAUDec: VDPAU does not support decoding 
\'h264 0x0\'
2022-07-04 17:13:03.808542 I AFD: Unavailable decoders: vdpau
...
2022-07-04 17:13:03.850283 I Duration: 00:00:02.52, start: 92891.733922, 
bitrate: 1979 kb/s
```

It appears the stream was too short to properly initialize the hardware 
decoder.  Comments in avformatdecoder.cpp mention it could be up to 5 
seconds between keyframes.  That obviously depends on the encoder and 
the settings the broadcaster uses.  (If I remember correctly, ATSC in 
the US requires a keyframe every second so a picture can be displayed 
quickly.)

Restoring the checks for a fully initialized video codec parser for 
LiveTV should fix that by waiting 250ms at a time for more recorded 
stream to decode.


Regarding your mkv sample, I can play it fine with ffmpeg decoding with 
it in my Videos directory.  So I would need a log from master and a log 
of it not working to try to determine what went wrong.  I would prefer 
logs where `--logpath=SOME_PATH` is in the command line so I can see the 
file and line numbers.

Thanks for testing,

Scott
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