[CELT-dev] Issue with signals with lots of bass

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Fri Dec 12 20:33:06 PST 2008


I've now enabled by default the fix for the low-frequency problems and
so far it seems to be an improvement in terms of CPU too. Please try it
out and report and success/failure.



Jean-Marc Valin a écrit :
> Hi,
> We've just found an issue when encoding signals that have very powerful
> bass (e.g. a loud 40 Hz tone). Turns out that was a combination of the
> MDCT leakage with some inefficiency in the VQ search. There's a
> tentative fix for that in git, which I'm encouraging everyone to test.
> To enable the fix, look for these lines in alg_quant() (vq.c):
> #if 0
>    if (K > (N>>1))
> Just replace with #if 1 and the fix will be enabled. I'm not yet 100%
> sure it's safe, so please report and problem (or success). The good
> thing is that this should not only solve the original, but it should
> also reduce the CPU usage.
> Cheers,
> 	Jean-Marc
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