[Ffmpeg-devel] FAAC rate control broken?

Luca Abeni lucabe72
Wed Dec 21 12:09:20 CET 2005

On Tue, 2005-12-20 at 16:49 +0100, Luca Abeni wrote:
> Reducing the faac_cfg->bandWidth value a lot (something like
> avctx->sample_rate / 8) does work...
> Any suggestion about a proper value for "bandWidth"?
Ok, after some investigation it looks like the safest thing to do is to
se "bandWidth" to 0 (leaving to libfaac the responsibility to decide a
correct value).
With the attached patch, ffmpeg is able to encode in AAC 64kbps stereo
audio at 44100Hz...

It cannot go under 60kbps because libfaac thinks that it is impossible
to encode audio at 44100Hz at less than 29500bps per channel :(
(libfaac contains a bitrate <--> bandwidth table that needs to be fixed,
but this is another story... A possible workaround would be to include a
similar table in libavcodec/faac.c and to set bandWidth to a proper

Anyway, does the simples thing by leaving the "bandWidth" decision to
libfaac... Can it be applied?

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