Is Vorbis supported?

[wesleywerner]

Hello,

I sort of assumed that reading vorbis encoded audio was supported, and was a little surprised when my project balked when I tried to process an ogg file.

I can see there are source code files in Mediabunny to handle the vorbis file format, yet when I try to convert from vorbis to Opus I get "EncodingError: The given encoding is not supported".

You can recreate the problem by uploading a vorbis encoded audio file on the examples/file-compression example page.

Just wondering if this is on my side only or if this is a known issue? Any hints or feedback welcomed, work-arounds or solutions would be even more appreciated :)

Testing in Firefox 141.0.2 (Linux 64-bit).

$ ffprobe "Ac Dc - Dirty Deeds Done Dirt Cheap.ogg" 
ffprobe version 5.1.6-0+deb12u1 Copyright (c) 2007-2024 the FFmpeg developers
  built with gcc 12 (Debian 12.2.0-14)
Input #0, ogg, from 'Ac Dc - Dirty Deeds Done Dirt Cheap.ogg':
  Duration: 00:03:49.68, start: 0.000000, bitrate: 136 kb/s
  Stream #0:0: Audio: vorbis, 44100 Hz, stereo, fltp, 128 kb/s

[Vanilagy]

2025-08-10.13-51-25.mp4

Answer: yes.

[Vanilagy]

Oh yeah what the heck, when trying to play a Vorbis Ogg in Firefox, I get a super strange issue as well:

Instead of "decode is not supported" or something like that. Strange. Need to see what's going on here. Any "internal error" in Mediabunny are a red flag to me, they shouldn't happen. Perhaps this is related to the "probably supported" thing you mentioned.

A solution here would be to create a custom Vorbis decoder extension for Mediabunny.

I found this! https://www.npmjs.com/package/@wasm-audio-decoders/ogg-vorbis

Seems like quite a cool and established library as well (150k weekly downloads!). Feel free to try and hook it up to a custom decoder, it shouldn't be too hard.

[Vanilagy]

Edit: It may not be too easy. This is an Ogg Vorbis decoder, not a Vorbis decoder. Mediabunny already decodes Ogg by itself, so only the raw, isolated codec data is left over in the end. Not sure if the library supports that. Feel free to look into this more.

[Vanilagy]

The real move might be a direct WASM compile of https://github.com/xiph/vorbis

Similar to what I did with @mediabunny/mp3-encoder. Again, if you have the time, see if you can play with this.

[Vanilagy]

Sorry for the spam. I actually got it to work in Firefox!

2025-08-12.08-48-24.mp4

Vorbis has this weird thing where the first packet doesn't actually contain any audio data but instead "seeds" the decoder with the correct state. Chromium doesn't emit any AudioData for that (which I believe is the correct behavior), but Firefox does, so I simply needed to skip the zero-length AudioData by Firefox and voila, it works.

[wesleywerner]

Ah that is excellent, I tested and it indeed works. Thanks @Vanilagy!
Also thanks for the wasm decoder alternative, this is good to keep in the back pocket. :)