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

John Pilkington johnpilk222 at gmail.com
Fri Dec 13 12:05:50 UTC 2019

Re-sending to list.

On 13/12/2019 08:21, Mark Kendall wrote:
> On Wed, 11 Dec 2019 at 09:15, John Pilkington <johnpilk222 at gmail.com> wrote:
>> 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.
> John
> There is one potential 'gotcha' that probably applies to your systems
> (as you are using predominantly software decoding).
> With the conversion to use FFmpeg for deinterlacing, you may see
> higher load with the medium and high quality deinterlacers. While I
> would expect the low quality (onefield/bob) to be comparable to the
> old mythtv equivalent filter, the medium uses yadif and the high
> quality bwdif. The equivalent medium to high versions previously would
> have been something like linearblend and yadif. This is because
> FFmpeg/libavfilter doesn't offer anything that fits into the 'medium'
> quality bracket - so I had to make do.
> Regards
> Mark

Thanks Mark:  The el7 system is now on 4fddad7097e, and sync seems to be 
subjectively ok on the SD material that I have played on it.  -v 
playback AV Sync is usually around 25 ms, either ahead or behind, and 
frames are still being dropped. It may be that the opposite isn't 
logged.  MPEG-2 ffmpeg, 2x CPU onefield.  CPU around 2x 90% with the OSD 
active, slightly lower without.

I now have a 4-core Fedora 30 box with nVidia GT_710 at 440.36 and an 
hdmi connection and will try to find out what that can do.   What has 
puzzled me with nVidia in the past has been the slight loss of picture 
rigidity during slow pans, and that's a different topic.


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