-metadata has no effect for .ogg file containing opus audio

[derkades]

System info
ffmpeg: git master 20220910
os: ubuntu 22.04

How to reproduce:
./ffmpeg -i opus_with_title.ogg -codec copy -metadata title=somethingelse out.ogg

The output file will still have the original title.

I have attached a short sample file, but I can reproduce the issue with any ogg file containing opus audio.

Apparently this bug(?) has existed for a while, see this StackOverflow post from 2018: ​https://stackoverflow.com/questions/50522753/ffmpeg-add-metadata-to-oggopus-and-embed-image

[mkver]

Your command only sets the format (i.e. whole file) metadata title, but this seems to be ignored by the muxer. Instead the muxer writes per-stream metadata and that is also what the demuxer reports. To set it, you need to set stream metadata: -metadata:s title=somethingelse (see the documentation for how to set it for specific streams only). Not sure if this is a bug; probably not.

[derkades]

I see now, thanks. For ogg files I indeed need to set metadata for the stream instead of the container. I don't know enough about file formats to say if ogg supports metadata or not (if it does, the ffmpeg muxer should probably support it?).