Fix Audio desync missing in latest version

[jack-cole]

After updating the latest version, The Fix Audio Desync option is missing. Now my videos have out of sync audio when I convert them.

[argorar]

That was a work around to fix some cases, was not 100% accurate, all of the ones I have registered work with last update. Upload a test file.

[jack-cole]

Here is the full video that plays fine in MPV. https://drive.google.com/file/d/1y0PpC8G3bwBquwu7MHmDmomfhxmlHu5H/view?usp=sharing This file is created by Nvidia Shadowplay. I do not have any control over its output, other than framerate and bitrate.

When I use WebMConverter to trim the last part where I am in the car and get shot, the audio is desynced by a few seconds. https://drive.google.com/file/d/1URJisQmSuGffpXPyK3R4Na_e6SV6Tx1b/view?usp=sharing

[argorar]

You updated shadowplay recently?
I have a test file made with shadowplay that syncs well. Your video doesn't work with previous webm versions without weird artefacts.

[jack-cole]

Shadowplay uses variable framerate, so when a game's framerate dips so does the recorded video, which causes issues with syncing the audio. I don't know how MPV and other video applications are able to sync it. I have it set to record at 30FPS, but you can see in the first screenshot it's less than that for the video I sent, while the second screenshot is one without dips.

[argorar]

With second file at 30FPS sync right?

[jack-cole]

These are the settings I use. It chooses 29 fps for that video that has frame dips.

[jack-cole]

#17

[argorar]

Your file has different values of tbr:

Video recorded with shadowplay, correct tbr:

[argorar]

#17

The video provided in that issue sync correctly in latest version.

[jack-cole]

I set my FPS to 30 to save filesize, so the TBR is 30. My recordings can drop below 30 fps due to lag, which is why the TBR doesn't match the FPS.

[argorar]

That mess internal calculations to determine exact times. If posible use another configuration like 24 fps and test again.

[jack-cole]

I used another application called Handbrake and it was able to sync the audio fine when trimmed to those last ten seconds. I prefer WebMConverter over that since it has a better UI and features. Is it possible to make this work in WebMConverter?

[argorar]

It will not in short term. The dependencies with third party libraries make much harder to fix issues related to codecs because the development is dead.

Support in this matter will be dropped from now.

Maybe, one day, these dependencies will be erased to use instead just ffmpeg.