VSE: Audio and Video doesn't sync in playback #79231

New Issue

Hjalti Hjálmarsson · 2020-07-24T13:46:29+02:00

2020-07-24 13:46:29 +02:00

System Information
Operating system: Linux-5.4.0-7624-generic-x86_64-with-debian-bullseye-sid 64 Bits
Graphics card: Radeon Vega Frontier Edition (VEGA10, DRM 3.35.0, 5.4.0-7624-generic, LLVM 9.0.1) X.Org 4.6 (Core Profile) Mesa 20.0.4

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-07-24 10:15, hash: b53c46d760
Worked: (newest version of Blender that worked as expected)

Short description of error
When playing the Video Sequencing Editor, the audio and video doesn't sync

Exact steps for others to reproduce the error
New file
Go to the VSE
Insert a video file with audio (something like a basic AV-sync-test video)
Set playback to AV-Sync
Hit play
The audio is lagging behind by around 2 frames
...if you export the video, the problem does not occur in the exported video

Here is an example with .blend and .mov: #79231-av-sync-vse.zip

**System Information** Operating system: Linux-5.4.0-7624-generic-x86_64-with-debian-bullseye-sid 64 Bits Graphics card: Radeon Vega Frontier Edition (VEGA10, DRM 3.35.0, 5.4.0-7624-generic, LLVM 9.0.1) X.Org 4.6 (Core Profile) Mesa 20.0.4 **Blender Version** Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-07-24 10:15, hash: `b53c46d760` Worked: (newest version of Blender that worked as expected) **Short description of error** When playing the Video Sequencing Editor, the audio and video doesn't sync **Exact steps for others to reproduce the error** New file Go to the VSE Insert a video file with audio (something like a basic AV-sync-test video) Set playback to AV-Sync Hit play The audio is lagging behind by around 2 frames ...if you export the video, the problem does not occur in the exported video Here is an example with `.blend` and `.mov`: [#79231-av-sync-vse.zip](https://archive.blender.org/developer/F8722968/T79231-av-sync-vse.zip)

Hjalti Hjálmarsson commented

2020-07-24 13:46:29 +02:00

Added subscriber: @Hjalti

Dalai Felinto commented

2020-07-27 11:35:53 +02:00

Added subscriber: @dfelinto

Dalai Felinto commented

2020-07-27 11:35:53 +02:00

The test file he was using to test it:
av_sync_24fps.mov

The test file he was using to test it: [av_sync_24fps.mov](https://archive.blender.org/developer/F8722910/av_sync_24fps.mov)

Sybren A. Stüvel self-assigned this 2020-07-27 11:39:08 +02:00

Sybren A. Stüvel commented

2020-07-27 11:45:22 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Sybren A. Stüvel commented

2020-07-27 11:45:22 +02:00

I can confirm.

...if you export the video, the problem does not occur in the exported video

When audio-scrubbing there are no sync issues either.

I can confirm. > ...if you export the video, the problem does not occur in the exported video When audio-scrubbing there are no sync issues either.

Sybren A. Stüvel commented

2020-07-27 12:22:06 +02:00

I have updated the task description with a ZIP containing an example blend file + the above video file. This is what happens on my computer when I play it back:

#79231-av-sync-vse-master-bfeb94ecccbf9222e.mp4

I have updated the task description with a ZIP containing an example blend file + the above video file. This is what happens on my computer when I play it back: [#79231-av-sync-vse-master-bfeb94ecccbf9222e.mp4](https://archive.blender.org/developer/F8722971/T79231-av-sync-vse-master-bfeb94ecccbf9222e.mp4)

Sybren A. Stüvel commented

2020-07-27 12:23:17 +02:00

Added subscriber: @ZedDB

Sybren A. Stüvel commented

2020-07-27 13:13:12 +02:00

@Hjalti Could you give these sound settings a try?

On my machine this seems to fix the issue.

@Hjalti Could you give these sound settings a try? ![image.png](https://archive.blender.org/developer/F8723018/image.png) On my machine this seems to fix the issue.

Sebastian Parborg commented

2020-07-27 16:28:27 +02:00

Just a general update, we tried and it seems like we got good sync if we switched to SDL with a mixing buffer of <=512.

OpenAL is locked to a minimum of 1024 under the hood.

Just a general update, we tried and it seems like we got good sync if we switched to SDL with a mixing buffer of <=512. OpenAL is locked to a minimum of 1024 under the hood.

Sybren A. Stüvel commented

2020-07-28 16:31:01 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Sybren A. Stüvel closed this issue

2020-07-28 16:31:01 +02:00

Sybren A. Stüvel commented

2020-07-28 17:13:04 +02:00

The issue was resolved by switching to better performing audio settings (see #79231#986004).

@ZedDB also did a test with the JACK backend, and that performed perfectly as well. These kind of sync issues is exactly what JACK was meant to resolve, so it's a good thing to keep supporting it.

The issue was resolved by switching to better performing audio settings (see #79231#986004). @ZedDB also did a test with the JACK backend, and that performed perfectly as well. These kind of sync issues is exactly what JACK was meant to resolve, so it's a good thing to keep supporting it.

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

VSE: Audio and Video doesn't sync in playback #79231