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Opened 2 years ago

Last modified 4 months ago

#1164 assigned enhancement

av-sync finer tuning

Reported by: Antoine Martin Owned by: Antoine Martin
Priority: major Milestone: 3.1
Component: sound Version: trunk
Keywords: Cc:

Description

Follow up from #835.

Things that we want to quantify because they may need to be taken into account when calculating the video sync delay:

  • operating system / driver output buffering: how long it takes from the moment we send bytes to the soundcard until they actually come out of the speakers
  • gstreamer internal buffering its sink element, different on each OS
  • application specific internal processing delay (which we should probably ignore - the application should submit sound and video in sync to the server OS)
  • picture decoding time: this is small, but should have been substracted from the total already
  • opengl double-buffering vs single-buffering and framerate (we do have a value for vsync we export) - also needs to be substracted from the total
  • any other display specific delay: 4k vs 1080p should not make any difference, at least I can't think of how it would - maybe related to #981

From what I've heard, the audio is a bit late, especially on non-Linux platforms.
If that's the case, we can quite easily add per-OS tweaks.

Change History (7)

comment:1 Changed 2 years ago by Antoine Martin

Milestone: 0.170.18

too late for 0.17

comment:2 Changed 2 years ago by Antoine Martin

Edit: ignore comment, reverted in r12870.

See also #1261 for multiple b-frames support, r12868 takes delayed frames into account when calculating the delay.

Last edited 2 years ago by Antoine Martin (previous) (diff)

comment:3 Changed 2 years ago by Antoine Martin

Milestone: 0.181.0

Milestone renamed

comment:4 Changed 2 years ago by Antoine Martin

There may also be differences between codecs, see ticket:1075#comment:10 : Mp3, on the other hand, seemed to be about 6-8 frames audio late.

comment:5 Changed 22 months ago by Antoine Martin

Milestone: 1.03.0

Not going to happen for this release. Re-scheduling.

comment:6 Changed 9 months ago by Antoine Martin

Owner: changed from alas to Antoine Martin
Status: newassigned

As of r17223, uses can tune the av-sync from the system tray.

comment:7 Changed 4 months ago by Antoine Martin

Milestone: 3.03.1
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