descript-audio-codec VS opus

Hey HN,

My cofounder (four months ago, classmate) and I trained an AI music generation model and after a month of testing we're launching 1.0 today. Ours is interesting because it's a latent diffusion model instead of a language model, which makes it more controllable: https://sonauto.ai/

Others do music generation by training a Vector Quantized Variational Autoencoder like Descript Audio Codec (https://github.com/descriptinc/descript-audio-codec) to turn music into tokens, then training an LLM on those tokens. Instead, we ripped the tokenization part off and replaced it with a normal variational autoencoder bottleneck (along with some other important changes to enable insane compression ratios). This gave us a nice, normally distributed latent space on which to train a diffusion transformer (like Sora). Our diffusion model is also particularly interesting because it is the first audio diffusion model to generate coherent lyrics!

We like diffusion models for music generation because they have some interesting properties that make controlling them easier (so you can make your own music instead of just taking what the machine gives you). For example, we have a rhythm control mode where you can upload your own percussion line or set a BPM. Very soon you'll also be able to generate proper variations of an uploaded or previously generated song (e.g., you could even sing into Voice Memos for a minute and upload that!). @Musicians of HN, try uploading your songs and using Rhythm Control/let us know what you think! Our goal is to enable more of you, not replace you.

For example, we turned this drum line (https://sonauto.ai/songs/uoTKycBghUBv7wA2YfNz) into this full song (https://sonauto.ai/songs/KSK7WM1PJuz1euhq6lS7 skip to 1:05 if inpatient) or this other song I like better (https://sonauto.ai/songs/qkn3KYv0ICT9kjWTmins we accidentally compressed it with AAC instead of Opus which hurt quality, though)

We also like diffusion models because while they're expensive to train, they're cheap to serve. We built our own efficient inference infrastructure instead of using those expensive inference as a service startups that are all the rage. That's why we're making generations on our site FREE and UNLIMITED for as long as possible.

We'd love to answer your questions. Let us know what you think of our first model! https://sonauto.ai/

Another useful model to compare to would be DAC https://github.com/descriptinc/descript-audio-codec

This is the codec that TSAC extended, so it could be a nice comparison to see. I'd also echo Vocos (from sibling comment), it operates on the same Encodec tokens but generally has better reconstruction quality.

Opus doesn't support 44.1 kHz because compatibility and effort/benefit ratio:

https://github.com/xiph/opus/issues/43

The browser audio limitation is presumably a workaround to some bug or performance limitation that was relevant at some point in history (the site was created in 2014).

There is a pattern here (that also goes with the author's prior article on inverting gauss' sum formula): Generally if if you can make a formula that counts the combination of things you can convert that into a code to encode and decode those combinations into indexes.

So for example the opus audio codec needs to encode/decode vectors of dimension n whos absolute values sum to k. https://github.com/xiph/opus/blob/master/celt/cwrs.c#L74

Or this rolling cuckoo filter that optimally encode/decode four sorted numbers in a range 0..2N with the constraint that the they span a range of N. https://github.com/sipa/bitcoin/blob/202006_cuckoo_filter/sr...

If you're lucky there will be closed form expressions for the encoding and decoding equations. (There for both of the above, at least for some parameters, but in both those examples the implementations use small tables because for the ranges involved the tables end up being faster than sqrts).

Too bad 10Hz is a too slow to generate audio-rate bitops music.

(e.g. https://github.com/xiph/opus/blob/master/tests/test_opus_enc... )

Could anyone help me get a disk image files for older Global Underground CDs? I encoded my old CDs into subpar mp3 files, and I'd now like to have high-quality Opus encodings and experiment across various bitrates.

Presumably, OP is referring to the Opus audio codec versus Dolby's AC3 codec.

Indeed. https://opus-codec.org/

If there are multiple tags with the same name, Ffmpeg will only use the last tag. If you really need to have multiple tags with the same name in your OPUS files, use opusenc instead (https://opus-codec.org/). Beware that some playback software does not display multiple artists gracefully.

AFAIK ogg isn't really suitable for low latency audio streaming. Consider the Opus codec instead.

I have asked on GitHub also https://github.com/xiph/opus/issues/263 in anyone wants to respond there.