[FFmpeg-devel] LATM BitStreamFilter

Paul Kendall paul
Fri May 1 07:09:07 CEST 2009


On Friday 01 May 2009 12:31:31 pm Robert Swain wrote:
> Michael Niedermayer wrote:
> > On Wed, Apr 29, 2009 at 08:21:06PM +1200, Paul Kendall wrote:
> >> Can I ask why LATM is preferred as a bit stream filter rather than
> >> as a decoder, or built into the AAC decoder, as ADTS is?
> >
> > A simple use case
> > you have a demuxer that outputs AAC in LATM, and a muxer that doesnt
> > allow LATM.
> > Only a bitstream filter can fix this up in the current architecture
> > unless you want to change it to allow multiple demuxers to be chained, in
> > which case you could implement it as a demuxer too.
>
> This may be an idea.
>
> I think Paul was asking if the bitstream filters could only be inserted
> after encoding/before multiplexing and not after demultiplexing/before
> decoding which is where it is needed.

Yes this is what is need ed for this case.

>
> > Now if LATM supports multiple AAC streams and this would be actually used
> > in practice then implementing it as a demuxer would be needed as a
> > bitstream filter cannot have more than 1 stream as output.
>
> It seems all instances in the wild at the moment use only one AAC stream
> per LATM stream. Is that right Paul?

Correct.

[...]

>
> Regards,
> Rob

Cheers,
Paul



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