Hi Mahmoud,
Mahmoud M'HIRI wrote:
> I'm trying to live transcode input (mp2/mpeg2video) to
> libamr_nb/ffh263(Supported formats in mobile devices), the problem is
> that when launching
> ffmpeg:
>
> ffmpeg -i rtp://0.0.0.0?localport=2020 -acodec libamr_nb -ar 8000 -ac 1 -ab
> 12.2k -f rtp rtp://192.168.50.147:8082 -an -vcodec h263p -flags aic -r 14 -b
> 20k -s 176*144 -f rtp rtp://192.168.50.147:8080
There are some problems here:
1) I suspect "-i rtp://0.0.0.0?localport=2020" could be wrong
2) AMR and H.263 packetizations are not currently supported by the RTP
muxer, and by the SDP generator. I am not sure if H263+ requires a
dynamic payload type, or if payload type 34 can be used. In any case,
the SDP generator should be extended to support H263.
3) When there are two streams with dynamic payload types, libavformat
ends up giving the same PT to both the two streams. I suspect this is
not wrong, but having the same PT for two different codecs confuses some
players.
[...]
> I have this very poor SDP:
>
> v=0
> o=- 0 0 IN IPV4 127.0.0.1
> t=0 0
> s=No Name
> a=tool:libavformat
> m=audio 8082 RTP/AVP 96
> c=IN IP4 192.168.50.42
> m=video 8080 RTP/AVP 96
> c=IN IP4 192.168.50.42
This happens because H263 and AMR in RTP are not supported (yet).
[...]
> I attached the SDP file I'm using. Realplayer is buffering until 100% but
> not displaying video, and the audio is very fast as if the sampling
> frequency is incorrect.
Since the RTP muxer does not support H263 and AMR, the packetization is
probably wrong. Also, I do not know where you got the config values
from, but they might be wrong.
Luca
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