john@pslam.demon.co.uk
2003-Mar-19 17:14 UTC
[vorbis-dev] specbis, vorbis decoder from scratch
As promised a few weeks back, here's my implementation of the Vorbis 1.0 specification. This is all from scratch using the specification only (well, a bit of double checking vs libvorbis where it had typos), and runs integer-only after codec setup. There's a long list of things which are incomplete and very non-compliant (some listed in the README file). Mostly, I've settled for non-compliant where I strongly disagree with the requirements of the spec. I'll need to think about these some more (hopefully thinking up some solutions) before I start arguments. I basically have a strong dislike for the unbounded (or 2^256, which is near enough) magnitude floating point residue vectors and the many problems that creates for integer decoders. In the end I didn't bother and just used integers, which turns out not to be a problem for anything generated by oggenc 1.0 (but would break with anything else). There's a lot of really sucky algorithms in my implementation which need removing because of their performance, memory usage, or accuracy - but completeness and correctness is my priority to start with. It's running real time at about 100MHz of Athlon, and that's good enough to start with. I'd like to cram it into something a lot smaller like 50MHz of ARM eventually, but that'll involve way more than just brute force optimisation. Anyway, it's GPL (for now) and it can be found at: http://www.pslam.demon.co.uk/specbis-2003-03-20.tar.bz2 Enjoy - any comments are very welcome. Yes, the name sucks. -- John Ripley http://www.pslam.demon.co.uk --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'vorbis-dev-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.
Seemingly Similar Threads
- Ogg vorbis decoder - Independent implementation questions
- Building a new decoder - some questions on the spec (residue decode)
- Why is Vorbis development slow?
- Vorbis decoding from scratch and the old MP3->.OGG story (new thread, was: Please confirm your message)
- Low-bitrate-compatible vorbis decoder/player?