[CELT-dev] Bad artifacts at 32kbps
bsder at allcaps.org
Thu Apr 14 11:09:07 PDT 2011
On 4/14/11 10:19 AM, Benjamin M. Schwartz wrote:
> OK. Many audio chips only do a fixed samplerate (like 48 KHz), but if
> yours can really do 24 KHz then that's perfectly reasonable.
Yeah, my sample rates are quite flexible.
> The issue I was alluding to is that CELT is tuned for 48 KHz operation,
> and other samplerates (i.e. the "custom modes") have received much less
> attention, which is part of the reason they're disabled by default.
Ah, then I'll make sure to stay with multiples of 48KHz. I was
scratching my head how I was going to deal with 44.1KHz, but now I don't
have to. That's a bonus.
> Unfortunately Option 3 is not exposed by the celtenc tool ... but it _is_
> exposed by the opusenc tool, as -bandwidth SWB. See
> for details. (Opus includes CELT, and is expected to replace it.)
Should I be using a different repository than I currently am? I'd hate
to make patches/changes on a dead repository.
I pulled with:
git clone git://git.xiph.org/celt.git
>> Bandwidth isn't really my limitation. Local RAM and processor MIPS are.
>> Consequently, I'm trying to twist the knobs in ways that cross the
>> power-of-2 boundaries that will allow me to tighten resource usage.
> OK. If you're that crazy then you can do things like choose a power-of-2
> framesize (e.g. 512 samples at 24 KHz -> 21.33 ms), substitute your own
> platform-optimized FFT lib ... or find some optimizations (C or assembly)
> and send us patches.
Yeah, I'm that crazy. :)
First up is figuring out how to preallocate all of the RAM I will need.
After that, I need to put a profiler on this and see where time is
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