I have tried to decode an audio conversation from me and a collegue of mine done with MSN messenger audio connection. Starting from pcap, i removed all the headers to have only the RTP payload. I would like to decode this file. From SIP messagging, it results that the RTP Payload Type is 111 (rtpmap: 111 SIREN/16000). I have tried to use the vivog723.acm codec but it doesn’t work.
Someone can help me?
hey! i am facing the same problem... i have voice conversation through MSN in rtpDump... I tried using JMStudio... but in vain...
if someone can assist me with some suggestions... can email me on firstname.lastname@example.org
thnx in advance...
RED stands for “Redundant Audio Data”. It is used to send the actual and some former frames (timeslices) in one RTP packet. If packet loss is high, the encoder can send older frames as well, possibly with lower bitrate codec. Inside a RED packet, any codec can appear which is in the rtpmap.
RED is specified in RFC 2198:
It is quite easy to decode these packages.
I don’t think you will be able to decode these media stream.
They are encoded in Microsoft proprietary algorithms.
I don’t say it’s impossible.
I just say it’s not something you can decipher
using any lambda decoder.