[mythtv-commits] Ticket #13532: Slow drift in a/v sync on non-nVidia system

MythTV noreply at mythtv.org
Thu Dec 5 15:10:15 UTC 2019


#13532: Slow drift in a/v sync on non-nVidia system
--------------------------------------+--------------------------
     Reporter:  jpilk                 |      Owner:  (none)
         Type:  Bug Report - General  |     Status:  new
     Priority:  minor                 |  Milestone:  needs_triage
    Component:  MythTV - General      |    Version:  Master Head
     Severity:  medium                |   Keywords:  a/v sync
Ticket locked:  0                     |
--------------------------------------+--------------------------
 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.

-- 
Ticket URL: <https://code.mythtv.org/trac/ticket/13532>
MythTV <http://www.mythtv.org>
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