[Ffmpeg-devel] Re: AMR bitrate

[gravsten at yahoo.com]

> > I have a question regarding encoding and decoding of AMR using
> > ffmpeg. To me it seems that the bitrate mode is fixed after
> > avcodec_open(). Is that correct (the bitrate mode cannot be changed
> > on the fly)?
> 
> No the bitrate can't be changed on the fly and user questions
> to the user list.

Actually, the standard let one negotiation a set of AMR bit rates beforehand,
and the transmitter may arbitrarily change bitrate within the agreed set on an
AMR frame boundary (20ms).

I am unsure whether ffmpeg let you change the bitrate on-the-fly (i.e. without
close/open codec), but if not, you should be able to fix this by merely making
the AMR codec access a bitrate value in the avctx structure directly (ffmpeg
only serves as a proxy to an external AMR library originally from the ITU).




 
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