[Ffmpeg-devel] Raw aac

Måns Rullgård mru
Wed Feb 8 16:09:09 CET 2006

Erik Slagter said:
> On Wed, 2006-02-08 at 14:54 +0000, M?ns Rullg?rd wrote:
>> >> > IIRC gpac does understand ADTS, but as ffmpeg doesn't, that is not an
>> >> > option for me for the moment.
>> >>
>> >> Now it does.
>> >
>> > Quick test: encoding works
>> Yes, I tested that much before committing ;-)
>> > Extracting AAC from mp4 to ADTS from a file encoded by ffmpeg-cvs from
>> > about four months ago, gives invalid data, "file" says "data" and gpac
>> > reports the sampling rate and other metadata wrong. Gpac extracts the
>> > track from the mp4 itself fine, though.
>> It figures.  The mp4 file contains raw aac, so the adts headers would have
>> to be created.  I guess the aac outputformat could do this.
>> > I'll have to check if this also happens with files encoded/muxed by a
>> > recent ffmpeg cvs version.
>> Don't waste your time on that.  It won't work.  Patches welcome, as always.
> Okay, so you're basically saying: "raw" encoding works and demuxing
> doesn't, right? It would be nice to have, but gpac can do it too, it's
> not that a big deal. The encoding stuff is also very nice to have
> already.

The aac data found in mp4 files needs the extradata to be useful.  The aac
"muxer" I added yesterday ignores the extradata and happily writes the raw
aac data to the output file.  Making sense of such a file is impossible.

What exactly is it you want to be able to do?

M?ns Rullg?rd
mru at inprovide.com

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