[mythtv] AVSync in master, Normal decoding, vga monitor and built-in audio analog stereo

John Pilkington johnpilk222 at gmail.com
Wed Dec 11 09:14:44 UTC 2019

On 10/12/2019 16:15, John Pilkington wrote:

> I have that ( bd4822a ) running in Fedora 30, using for comparison a 
> Normal profile with OpenGL YV12 and HQ deinterlacers, and see/hear no 
> sign of drift in a BBC1 SD recording.  The reported AVSync is usually 1 
> or 2 ms with occasional single values around 45 ms.
> The OSD shows MPEG-2 ffmpeg, Deint 2x CPU bwdif, and two CPUs at around 30%

I have a build from the same commit on el7 now, and have settings with 
which I don't see drift.  There's still some jitter in the sync values 
reported, the StdDevs are comparable with the larger AVSync2 increment 
that seems to be needed, and the CPUs are busier than in F30.  Perhaps 
that's just progress.

In a post on 8 Dec Peter said:

> The audio time is taken from the audio sent to the sound card and adjusted for the amount of audio in the sound card buffer, as supplied by the operating system. Depending on the audio setup, this can be inaccurate and the figure obtained can jump around the correct value. I suspect that your playback problems may be caused by this, resulting in video playback slowing down and speeding up inconsistently. When this is the case, setting the audio adjustment to the smallest value is the best solution.

Is that buffering lag within the new loop, and is there a similarly 
accessible lag on the video side?  Just asking...

  > John

More information about the mythtv-dev mailing list