[Ffmpeg-devel] Re: .mp4 demuxer broken?

bond b-o-n-d
Tue Mar 21 18:56:55 CET 2006

> Another problem spotted : many mp4 containing aac does not have a valid
> sample rate, is there a way to force decoding first frame to let faad
> init stream parameters ?

dont forget he-aac! he-aac means having an aac stream with lets say 22050hz,
and a sbr part which contains another "fake" 22050hz, making it together
44100. this is very useful for low bitrates
afaik the aac specs define that the aac decoder needs to be able to detect
he-aac without the container signalling it, and faad2 is able to do this

similarily there is parametric stereo, which is a mono aac stream containing
extra "fake" info about a second channel, making the stream stereo during

More information about the ffmpeg-devel mailing list