Opened 7 years ago

Closed 7 years ago

#2342 closed defect (fixed)

ebur128 filter output seems to break format auto negotiation

Reported by: cus Owned by:
Priority: normal Component: avfilter
Version: git-master Keywords: ebur128
Cc: Blocked By:
Blocking: Reproduced by developer: yes
Analyzed by developer: no


Chaining the output of the ebur128 (audio) filter causes broken output.

How to reproduce:

ffmpeg -i stereo.mp3 -af ebur128,aformat=channel_layouts=mono dummy.wav

Clément Bœsch provided a patch, but it is not clear why it fixes the issue.

Change History (4)

comment:1 Changed 7 years ago by Cigaes

  • Reproduced by developer set
  • Status changed from new to open

The problem is that ebur128's query_formats() function sets the supported channel layouts (and formats) separately on its input and its audio output. That means lavfi is allowed to select them independently, and that ebur128 is expected to convert somehow. That is not what happens: ebur128 assumes that its input and audio output have the same format and channel layout; for that, it is supposed to set the supported formats and layouts together.

That is exactly what the fallback query_formats() code does, therefore just removing the code fixes the bug.

comment:2 Changed 7 years ago by ubitux

  • Resolution set to fixed
  • Status changed from open to closed

Fixed in 9efcfbed9dd64679145f5f39d9a812dfeea97172. Thanks Nicolas for the details, and sorry for the delay.

comment:3 Changed 7 years ago by ubitux

  • Resolution fixed deleted
  • Status changed from closed to reopened

This "fix" was nothing but wrong, shame on me. I thought I understood the issue, but it doesn't seem to be the case. I'll investigate, but something looks horribly broken, and I think multiple problems are surfacing here...

comment:4 Changed 7 years ago by ubitux

  • Resolution set to fixed
  • Status changed from reopened to closed
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