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Topic: Encoding CELT-only Opus streams (Read 5774 times) previous topic - next topic
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Encoding CELT-only Opus streams

Hello. I don't like the sound color of opus I get in some bitrate-samplerate combinations and I think that's the sound color of SILK, so I want to encode a CELT-only Opus stream. How can I encode a CELT-only Opus stream?

Re: Encoding CELT-only Opus streams

Reply #1 –
I'm not sure if you can force that with the official encoder, although since silk is only used at very low bitrates, you can probably avoid it just by slightly increasing bitrate to the point where the encoder thinks it can encode using CELT for all frames.

Re: Encoding CELT-only Opus streams

Reply #2 –
Is there an unofficial encoder that supports SILK-only and CELT-only modes?
 

Re: Encoding CELT-only Opus streams

Reply #4 –
Quote from: Klymins on
Hello. I don't like the sound color of opus I get in some bitrate-samplerate combinations and I think that's the sound color of SILK, so I want to encode a CELT-only Opus stream. How can I encode a CELT-only Opus stream?
::)
...

Quote from: C.R.Helmrich on
Doesn't the --music option of the official encoder do what you're looking for? See also https://opus-codec.org/docs/opus-tools/opusenc.html.
Yes, but below some point it just uses hybrid/silk even with that option (depends on bandwidth). Around 12 kbps CBR, though VBR let you go down around 10kbps. Then below 6kbps CBR, Opus decides to use CELT again, just because SILK doesn't work anymore (except for do VBR between 6 and 3 kbps). CELT quality is quite bad, but maybe is more acceptable than SILK noisy and choppy sounds (only at the horizon of ~5 kbps, when SILK/CELT comparison is interesting, below that point anything is crap). CELT minimum limit is 1.2 kbps (just wavelets or something with quite poor definition, it will blow your ears if you try to hear it).

Quote from: Klymins on
Is there an unofficial encoder that supports SILK-only and CELT-only modes?
AFAIK, no. Only the "official" last encoders/decoders of SILK and CELT from 2011. You wouldn't use them, as support is nonexistent, and quality... (SILK actually no idea, but CELT before merging was [at least] slightly worse than modern Opus, leaving aside an higher delay)


So, use --music option and bitrate above 13 kbps. (I advice that there is no real stereo at these bitrates, it appears around 20 kbps and it's quite noticeable how Opus struggles to give anything decent).

As a side note, there's not simple way to get "pure" SILK audio stream.