[FFmpeg-devel] Gain control not yet implemented
Tue Dec 4 17:27:19 CET 2007
On Nov 29, 2007 10:16 AM, Gabriel Teixeira <gabrieldiegoteixeira at gmail.com>
> I developed a application that uses the libavcodec, but only after
> some months of development and testing appeared a weird message that I
> never got before:
> [mpeg4aac @ 01290000]faac: frame decoding failed: Gain control not yet
> Since the audio was encoded with ffmpeg, I believed this frame
> wouldn't have gain control or any stuff that ffmpeg could not decode.
> This audio stream was sent over the web via multicast, so may be a
> fail in the information transported. Anyway, how to identify and
> correct this problem?
this is a bug in FAAC: scale factor differences must be in range [-60,
but faac can generate such big differences, and then writes
invalid huffman codes (cf huffman.c, WriteScalefactors()).
So you end up with invalid bitstreams.
This bug has been reported a long ago, a patch proposed, but wasn't
committed in cvs. Now, even the web page disappeared, so i can't
even find back the patch. I'll see if i can resurrect something on my
> Thanks in advance
> ffmpeg-devel mailing list
> ffmpeg-devel at mplayerhq.hu
More information about the ffmpeg-devel