[vlc-devel] Bug-Report

[Winfried Wacker]

Hello VLC developers,

I would like to report what appears to be a reproducible issue with AV1 
playback.

**Environment**

* VLC version: 3.0.23 Vetinari (64-bit)
* Operating System: Windows 11 Home
* GPU: NVIDIA GeForce GTX 1050 Ti (Pascal, no AV1 hardware decoding)
* Monitor: Standard SDR display

**Issue**
When opening any AV1-encoded video, the entire video output flashes 
black exactly three times before playback starts.

The flashing only occurs at the beginning of playback. After the third 
flash, the video plays normally without any further issues.

**Expected behavior**
Playback should begin immediately without any black flashes.

**Observed behavior**
The whole video output briefly turns black three times in rapid 
succession immediately before the first frame is displayed.

**Additional observations**

* The issue occurs with every AV1 file I have tested.
* H.264 and H.265 videos do not show this behavior.
* Enabling or disabling hardware-accelerated decoding makes no difference.
* Trying different VLC video output modules also makes no difference.
* The same AV1 files play normally in mpv on the same computer without 
any flashing.

Because mpv does not exhibit this behavior with the same files and 
hardware, I suspect this may be related to VLC's AV1 playback path or 
video renderer initialization.

If required, I can provide sample files or additional debug logs.

Thank you for your work on VLC.

-- 
Gruß Winfried