[mythtv] 2019-devel: lipsync drift

[John Pilkington]

On 23/11/2019 12:31, John Pilkington wrote:
> On 18/11/2019 11:58, Mark Kendall wrote:
>> On Mon, 18 Nov 2019 at 11:47, John Pilkington <johnpilk222 at gmail.com> 
>> wrote:
>>> I'm still getting loss of a/v sync in my el7 box, more noticeable in
>>> some recordings than others, but the fedora 30 system built at the same
>>> commit has not yet done the same, using either NVdec or ffmpeg decoding.
>>
>> I'm assuming el7 is enterprise linux 7?
>>
>> What decoder/playback settings is that box using?
>>
>> Thanks, Mark
> 
> My original reply to this revealed many opportunities for system 
> misalignments that might be causing this drift, and I won't repeat them.
> 
> But here are lines from frontend startup and closedown that look as if 
> they are system specific and could perhaps underlie a slow drift if all 
> the digits are significant and the usage isn't quite right.
> 
> {{{
> 
> 2019-11-23 11:35:57.867339 I  DispResX: Created
> 2019-11-23 11:35:57.867956 N  DispRes: Desktop video mode: 1440x900 
> 74.984 Hz
> 
> 2019-11-23 11:49:27.987070 I  DispRes: Changing to 1440x900 75.000 Hz
> 2019-11-23 11:49:28.013150 I  DispRes: SwitchToGUI: Switched to 1440x900 
> 75.000 Hz
> 
> }}}
> 
> xrandr offers 59.89 +  74.98* at that (full) resolution of the only 
> attached screen; I'm using a 1024x576 window
> 
> The Std.Devs shown here look (unfeasibly?) large, and sync was very bad 
> while getting them.  The CPUs look busy.  BBC Four SD.  Playback is fine 
> apart from the sync issue, and via DLNA on the TV it's excellent.
> 
> {{{
> 2019-11-23 12:11:19.873565 I  Player(0): FPS:   25.88 Mean: 38642 
> Std.Dev: 28904 CPUs: 101% 101%
> 2019-11-23 12:11:20.890110 I  Player(0): FPS:   24.60 Mean: 40647 
> Std.Dev: 25888 CPUs: 98% 97%
> 2019-11-23 12:11:21.903609 I  Player(0): FPS:   24.67 Mean: 40528 
> Std.Dev: 26322 CPUs: 104% 97%
> 2019-11-23 12:11:22.894285 I  Player(0): FPS:   25.24 Mean: 39615 
> Std.Dev: 25965 CPUs: 103% 102%
> 
> }}}

Here, FWIW, are the corresponding lines for the F30 box, which has an 
nVidia card driving a VGA monitor and an HDMI TV, using a single image 
surface; again, on the monitor mythTV is using a 1024x576 window.

{{{
2019-11-24 14:37:47.305471 I  DispResX: Created
2019-11-24 14:37:47.306061 N  DispRes: Desktop video mode: 3600x1080 
50.000 Hz
============
2019-11-24 14:38:13.380206 I  DispRes: Changing to 3600x1080 nan Hz
2019-11-24 14:38:13.380213 E  DispResX: Desired resolution and frame 
rate not found.
2019-11-24 14:38:13.380223 E  DispRes: SwitchToGUI: xrandr failed for 
3600x1080 50.000  Hz
2019-11-24 14:38:13.380234 I  DispResX: Deleted

Screen 0: minimum 8 x 8, current 3600 x 1080, maximum 16384 x 16384
VGA-0 connected primary 1680x1050+0+0 (normal left inverted right x axis 
y axis) 433mm x 271mm
    1680x1050     59.95*+

HDMI-0 connected 1920x1080+1680+0 (normal left inverted right x axis y 
axis) 698mm x 392mm
    1920x1080     50.00*+  60.00    59.94    23.98    60.05    60.00 
50.04

}}}

I haven't noticed drift on either of those F30 screens, but won't say it 
definitely isn't there.  After a 1-hour uninterrupted playback in el7, I 
got normal sync with a 3200 ms applied offset.  Right ballpark...

Both running c794391ad

 >
 > Cheers,
 >
 > John