id	summary	reporter	owner	description	type	status	priority	milestone	component	version	severity	resolution	keywords	cc	mlocked
13532	Slow drift in a/v sync on non-nVidia system	jpilk	Mark Kendall	"In late 2019-render and now in master I get a slow drift, of order 2 seconds per hour, in a/v sync in a framed window display on a monitor.   The system uses ffmpeg decoding and deinterlace.  I don't see the drift on a system using nVidia graphics.  Mismatched use of frame display rates seems a possible root cause, but #13531 did not fix it.

{{{
At frontend startup on the NV box 
 
2019-12-05 14:16:59.461932 I  DisplayX11: Raw/unsorted XRANDR modes:
2019-12-05 14:16:59.461950 I  3600x1080 50.00
2019-12-05 14:16:59.461958 I  1680x1050 51.00
2019-12-05 14:16:59.461964 I  1440x900  52.00

2019-12-05 14:16:59.464301 I  DisplayX11: Updated/sorted XRANDR modes (interlaced modes may be removed):
2019-12-05 14:16:59.464319 I  1680x1050 59.95
2019-12-05 14:16:59.464328 I  1440x900  59.89
2019-12-05 14:16:59.464335 I  1280x1024 75.02   60.02

$ xrandr
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*+
   1440x900      59.89  
   1280x1024     75.02    60.02  

}}}

On the affected box only the raw/unsorted block is shown and the NV-CONTROL X extension is reported to be not available.

In both cases the 'raw' values have been rounded.  This seems strange.

Skipping backwards and forwards makes the effect worse.  

The -v playback log reports only small errors, and drops frames to keep them below  around 40 ms.
 "	Bug Report - General	closed	minor	31.0	MythTV - General	Master Head	medium	Fixed	a/v sync		0