[mythtv-commits] Ticket #12990: Playback jitter deinterlaced media

MythTV noreply at mythtv.org
Sat Oct 7 21:15:48 UTC 2017

#12990: Playback jitter deinterlaced media
 Reporter:  blm-ubunet@…                |          Owner:  pbennett
     Type:  Patch - Bug Fix             |         Status:  infoneeded
 Priority:  minor                       |      Milestone:  29.0
Component:  MythTV - Video Playback     |        Version:  Master Head
 Severity:  medium                      |     Resolution:
 Keywords:  jitter playback interlaced  |  Ticket locked:  0

Comment (by blm-ubunet@…):

 The biggest improvement is with frame-refresh rate mismatch.

 But that's not a likely playback problem any more except that right now
 mythtv video refresh rate selection with nvidia driver is broken.
 (Some kind soul has provided a patch for this.)

 Other thing patch tried to do was better frame/field repeat/slip for
 incorrect video modelines.
 The open source 'cvt' calculated 50Hz modelines for my needs caused frame
 error every 15mins.
 A quick spreadsheet analysis shows most modelines are (unnecessarily)

 There are better modelines for 4K digital displays (including RVB) that
 open source calculators do not generate but these are non-free.

 I submitted this patch about time when nvidia VDPAU advanced de-
 interlacing was broken for all 900 & 1000 series video cards (actually
 never worked).

 So not using 2x advanced DI may have made problem more obvious.
 Maybe can only see jitter problem with actual monitor & very fast video
 Plausible that modern TVs cover up (motion-flow) bad input.
 I eyeball the display with de-interlacing video test tracks or MotoGP.

 An unresolved issue with this patch is that the sync offset converges
 differently (better) after pause or rewind.

 In error, hidden in the patch was a better pause (& field swap for VDPAU).
 My intention was to get paused deinterlaced frame to be full resolution
 instead of half. But that's not possible without changing the output frame
 buffer & OSD overlay methods or breaking OSD!
 I wanted full resolution DI pause so could take photos of the VDPAU DI
 display corruption.

 MythTV pauses playback by racing to consume all decoded frames & then
 jiggles/shakes itself back to right frame when playback resumes. Looks
 Pause is actually re-rendering same field (or frame for prog. scan)
 repeatedly so the OSD overlays work.

 Thanks for looking & trying the patch.
 I'm still using it & always will.

Ticket URL: <https://code.mythtv.org/trac/ticket/12990#comment:5>
MythTV <http://www.mythtv.org>
MythTV Media Center

More information about the mythtv-commits mailing list