[0] https://opus-codec.org/docs/opus-tools/opusenc.html [1] > Set encoding computational complexity (0–10, default: 10). Zero gives the fastest encodes but lower quality, while 10 gives the highest quality but slower encoding.
Complexity 0 is about twice as fast as 10. Which isn't bad, but if you want to go really fast it still leaves something to be desired.
I ask because I know Opus is used quite commonly in real-time applications (e.g. voip), and I remember when researching in the past that it is actually capable of lower inherent latency because of support for smaller frame sizes than some of its competition.
I haven't looked into how expensive it is to encode in terms of CPU time, so I assume maybe you're taking about a bottleneck in terms of the number of simultaneous streams you can support on a single CPU?
> I haven't looked into how expensive it is to encode in terms of CPU time, so I assume maybe you're taking about a bottleneck in terms of the number of simultaneous streams you can support on a single CPU?
Yup! I work on https://vircadia.com/ -- we have to compress audio in real time and every user gets their own mix since it depends on their location in 3D space. It turns out to add up pretty fast, and you can't fit that many people into a cheap VPS.
That's why I'm working on FLAC support for it. If bandwidth is plentiful but CPU resources are lacking it's a good alternative to have.
This code originally came from the High Fidelity company, which made their own codec. It's some piece of black magic that cuts down audio by exactly 1/4th and is amazingly fast. But it's closed source.
It's a lossy codec that's for some reason fixed rate, and shrinks audio by exactly 1/4th. The resulting quality is very good (works perfectly fine for music), and it's much faster than Opus. It retains stereo and high frequencies and sounds just fine. I'm sure there's a tradeoff somewhere, but it's certainly good enough to hold music events without people complaining.
I think it might be possibly related to codecs like AptX.
So far I've not found anything competitive that we could use -- stuff is either closed, or far more CPU intensive.
Usually a fixed compression ratio is a terrible tradeoff, but for streaming it kind-of makes sense.
This means codec costs add up fast. You can't just encode once and stream the same thing to a dozen people.
Interesting use-case, got my brain racing off to find silly solutions.
A weakness in the open source landscape I found is that there's a lack of fast codecs. If you want to encode in real time (eg, streaming speech or an artist playing in the moment), and encode per client for positional audio in a 3D world, then Opus becomes a bottleneck.
FLAC according to some preliminary tests helps by being faster than Opus to encode.