MovieRender crash when finishing video with audio

Development Rendering
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1

I used Movie Render Queue for a while with my project now, it was working 100% after setting up with ffmpeg. But recently we added ambience audio to the project, and at the same time MRQ simply crashed every time we rendered something. It always happened at the end, even after ffmpeg finished rendering the video correctly the engine would simply crash.

After some tinkering I found out that ffmpeg is working correctly(as it works when manually used) and a strange crash log pointing to the last error the engine suffered.

[2024.01.20-00.45.00:401][218]LogAudioMixer: Error: Command Queue has grown to 1198kb, containing 7961 cmds, last complete pump was 8.96168 seconds ago.
[2024.01.20-00.45.00:401][218]LogAudioMixer: Warning: Stall in AudioRenderThread Phase: ‘Finished’
[2024.01.20-00.45.00:401][218]LogAudioMixer: Warning: Inflight Task: SW_LowBirds4, 8.96 secs, Procedural=0
[2024.01.20-00.45.00:401][218]LogAudioMixer: Warning: Inflight Task: SW_LowBirds5, 9.02 secs, Procedural=0
[2024.01.20-00.45.00:401][218]LogAudioMixer: Warning: Inflight Task: SW_HeavyFire2, 9.18 secs, Procedural=0
[2024.01.20-00.45.00:401][218]LogAudioMixer: Warning: Inflight Task: SW_LoudBirds1, 8.96 secs, Procedural=0
[2024.01.20-00.45.00:401][218]LogAudioMixer: Warning: Inflight Task: SW_HeavyFire2, 9.07 secs, Procedural=0
[2024.01.20-00.45.00:401][218]LogAudioMixer: Warning: Inflight Task: SW_HeavyFire3, 8.96 secs, Procedural=0

What it seems, this might be the error causing the crash, I have no clue as to how the audio mixer got 7961 cmds, if it’s refering to actual CMD consoles.

I’ll keep going and see if I can fix the issue on my own, and hope this might help someone in the future.

2

I removed the audio from the project manually and the rendering started working again…

It seems I was right, maybe the audio mixer gets overwhelmed and ends up crashing Unreal when the system is stalled rendering, still no clue on how to fix this for now.

[After hours I gave up, it’s clear that Movie Render Queue keeps simulating the project while it’s rendering through ffmpeg, and that’s very likely the cause of the problem]