Hi,
Mahmoud M'HIRI wrote:
[...]
>>> didn't found something really particular to ACC..- correct me please).
>> rtp_aac.c implements the part of RFC 3640 which is used for AAC audio.
>> RFC 3640 can also be used for other kinds of MPEG4 audio or video ESs,
>> but I've never seen such features used in practice.
>
> I asked the question because it seemed for me to be very general, it's
> putting frames into packets and if the frame is larger than a packet, it's
> divided into multiple ones.. and I think that it's the same thing than AMR (
> http://tools.ietf.org/html/rfc3267#page-32)
Of course the code is putting more frames in a single packet, and is splitting
large frames. But the problem is how to assemble or split audio frames: the
precise syntax depends on the particular RFC, and the payload headers described
in RFC 3640 and RFC 3267 look quite different.
>> From a quick search, I found that AMR audio seems to be supported by
>> RFC 3267, for which I do not know the details (but at a first glance it
>> does not seem to be too similar to RFC 3640).
>
> Well, besides dispatching into packets and filling some header fields what
> should the packetizer do else?
Nothing else. The problem is to do this in a way that is compliant with the
standard. And this way is codec-specific (different payload headers, maybe
different ways of interleaving frames, etc...). Moreover, AMR seems to have
some scalability features, and the packetizer must be able to use them (at
least, this is the impression I got skimming RFC 3267).
> When I tried to test aac streaming, it's throwing to me: "AAC with no global
> headers is currently not supported" (c->extradata_size is returning false)..
> ?
You probably forgot to ask for global headers when encoding AAC audio. Adding
"-flags 0x00400000" should probably do the trick (there are probably better
ways,
but I do not remember right now). Or you can read the AAC audio from a mov (or
mp4)
container and use "-acodec copy".
Luca
Luca
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