[FFmpeg-user] G711 streaming

SCHILL Rolf ROLF.SCHILL at thalesgroup.com
Wed Dec 19 11:12:34 CET 2012

Thanks to the answer of Roger Pack I now understand a little bit more what happened.

The wav file was original an ogg codec audio stream converted with  sox to 8khz samplingrate in one channel.

Now I use a wav file converted direct (with abcde) from an audio-cd and play it with the following command:

ffmpeg -I input.wav -re -ar 8k -ac 1 -acodec pcm_alaw -f rtp rtp://ip-addr:port

the pkt_size option for rtp/udp I do not use for the moment, cause the mentioned command works.

so as a short resumee 
--> output depends on the input ;-)
--> for the pkt_size option I will check/read more to have an idea when it makes sense or not

Mit freundlichen Grüssen, With best regards

Thales Defence & Security Systems GmbH
Abt. PF/E664
Rolf Schill
Ostendstrasse 3,  75175 D-Pforzheim
Tel.: +49 7231 15 3190
Sekretariat: Frau Aberle, Tel. +49 7231 15 3111
mailto: Rolf.Schill at thalesgroup.com

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-----Ursprüngliche Nachricht-----
Von: ffmpeg-user-bounces at ffmpeg.org [mailto:ffmpeg-user-bounces at ffmpeg.org] Im Auftrag von SCHILL Rolf
Gesendet: Dienstag, 18. Dezember 2012 17:20
An: ffmpeg-user at ffmpeg.org
Betreff: [FFmpeg-user] G711 streaming

Hello (ffmpeg) world

I try to stream a wav file to an old fashioned voip device. It provides no rtcp or rstp support. It needs the packet with g711 codec content  in 20 ms  timing.

I try it with

ffmpeg -I nput.wav -re -acodec pcm_alaw -f rtp rtp://ip-addr:portnumber?pkt_size=172

This command streams well but all packets are send out in more or less a half second until the next packets come.

So the bitrate per second is ok, but not the timing.
See an csv export from the wireshark rtp tools

21,"356","370554515","0.01","13.58","374.73","31.92","","[ Ok ]","12/18/2012 17:08:52.517","204"

22,"357","370554665","0.01","13.91","393.47","33.44","","[ Ok ]","12/18/2012 17:08:52.517","204"

23,"358","370554815","0.01","14.21","412.21","34.96","","[ Ok ]","12/18/2012 17:08:52.517","204"

24,"359","370554965","0.01","14.49","430.95","36.48","","[ Ok ]","12/18/2012 17:08:52.517","204"

25,"360","370555115","0.01","14.76","449.69","38.00","","[ Ok ]","12/18/2012 17:08:52.517","204"

26,"361","370555265","0.02","15.00","468.42","39.52","","[ Ok ]","12/18/2012 17:08:52.517","204"

27,"362","370555415","0.01","15.24","487.15","41.04","","[ Ok ]","12/18/2012 17:08:52.517","204"

28,"363","370555565","0.02","15.46","505.89","41.73","","[ Ok ]","12/18/2012 17:08:52.517","100"

35,"364","370555611","511.57","46.10","0.07","43.25","","[ Ok ]","12/18/2012 17:08:53.028","204"

36,"365","370555761","0.02","44.39","18.80","44.77","","[ Ok ]","12/18/2012 17:08:53.028","204"

37,"366","370555911","0.00","42.79","37.54","46.29","","[ Ok ]","12/18/2012 17:08:53.028","204"

38,"367","370556061","0.00","41.29","56.29","47.81","","[ Ok ]","12/18/2012 17:08:53.028","204"

Does anyone has an idea how to solve the problem?

My google search and searching the doc gives me no answer, maybe I am to stupid or only a few people try to do such things ....

Mit freundlichen Grüssen, With best regards

Rolf Schill


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