[Asterisk-video] H324M AMR audio working!!!

[Sergio Garcia Murillo]

From: "matteo brancaleoni" <mbrancaleoni at espia.it>
Sent: Thursday, March 01, 2007 2:39 PM
> Hi,
> btw... the audio is a bit "broken", I mean that
> has some interruptions in it.
> But maybe is the encoding... I'll check.
>
You can check it using the if2amr test program with the out media dump file
and see if
it also has the interruptions, it probably won't so the problem is mor
probable to be with
the video problem

> When switching between 2 videos, the audio always
> arrives immediately and the video a bit later.
> But maybe this 3G related :)

No, the problem is a bandwith one, and related with ffmpeg (and it's also
proably affecting
audio also)
The main problem using ffmpeg is that it's a vbr encoding, and althought you
can adjust
adjust a lot of parameters I still have not been able to find the way of
make it behave
correctly.
The problem is the length of the I-Frames, that is to long ( you can check
it encoding with -vstat).
It can returns frames of 10Kb long , and the rest of P-Frames is just a few
bytes. With a file
playing in a computer there is not much problem or even streaming it using
som buffer.
But we are sending it through an isdn channel so it's going to take a few
seconds just to
send the first I frame (you can calculate it) and that's probably the delay
you're seeing in
the video..
The audio could be affected as well because in the meanwhile all those
frames are been queued
in the stack and rigth now i don't priorize them, so its probably that the
amr channel is starved
and the audio frames are not sent with the correct timing...

> really good work.
> Now we need only an amr codec and we can bridge sip :)

Thanxs, It won't be too diffciult using the libavocodec from ffpmeg..

Greetings
Sergio Garcia
http://sip.fontventa.com/