18 Nov
2011
18 Nov
'11
8:22 p.m.
I ran into a similar issue and while searching for a solution, I found
a few threads describing the same problem but no solution.It turns out
that the sox command must have the proper arguments in order to
properly decode raw files.Feeding sox with an u-law stream and asking
to be decoded as an a-law stream will create garbled sound.
I posted a more descriptive procedure on how to extract audio from
rtpproxy pcap files
here:http://voipembedded.wordpress.com/extracting-audio-from-calls-recorded…
Regards,Ovidiu Sas
On Thu, Jan 14, 2010 at 5:37 PM, Vikram Ragukumar
<vragukumar(a)signalogic.com> wrote:
Hello,
I would also like to mention that the rtpproxy recorded .rtp files were
generated using the following command
rtpproxy -l listen_ip_address -s udp:127.0.0.1:7722 -a -P -F -r
record_directory_path -S spool_directory_path
where -P indicates that files would be recorded in the pcap format.
Thanks and Regards,
Vikram.
Vikram Ragukumar wrote:
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http://www.voipembedded.com
Carsten,
Thank you for your reply.
Carsten Bock wrote:
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Hi,
1)
Did you try to post your problem on the RTP-Proxy-Users' List?
http://lists.rtpproxy.org/mailman/listinfo/users
Probably, you might get more help there....
Yes i have posted on rtpproxy users list.
2)
Did you try to extract the Audio with Wireshark? If Wireshark can play
the Audio (and i assume it is correctly implemented), then the recorded
stream as such is correct. Then you can check, if the bug lies in rtpbreak
(or as a next step: sox). Just to limit the possible sources of the
problem...
I have not tried Wireshark to extract the audio. I have been using
rtpbreak to generate the .raw file. Subsequent to which i use sox to convert
the .raw to a .wav file. By importing the the .raw file into Hypersignal
software, we found that the .raw file doesnt entirely seem to be composed of
speech samples, so there could be a problem at the rtpbreak step.
This is the command i used to convert rtpproxy's capture file to .raw
format
rtpbreak -W -r capturefile.rtp
Am i missing something here ?
Thanks and Regards,
Vikram.
Carsten
2010/1/14 Vikram Ragukumar <vragukumar(a)signalogic.com
<mailto:vragukumar@signalogic.com>>
Hello,
An update,
I tried using sox to convert the two .raw files into 2 mono channel
wave files. The command line i used is below :
sox -r 8k -b -c 1 -u rtp.0.0.raw rtp0.wav
sox -r 8k -b -c 1 -u rtp.1.0.raw rtp1.wav
When i listen to the .wav files, i hear speech but it is buried in a
lot of noise. During blank periods (periods of no speech) there is a
constant volume high pitched noise. Also during periods of speech,
there seems to be bursts of noise in the background.
The other engineer i work with and i, think that it is possibly
because non-speech data is being interpreted as speech.
What switch options should i change while invoking sox from the
command line to get rid of the noise?
Thanks and Regards,
Vikram.
Vikram Ragukumar wrote:
Hello,
I used Kamailio+rtpproxy to record a session and rtpproxy
outputs the following files
long_file_name.a.rtp, long_file_name.a.rtcp,
long_file_name.o.rtp, long_file_name.o.rtcp
http://www.rtpproxy.org/wiki/RTPproxy/FAQ
From the Rtpproxy FAQ above, i tried to extract the audio using
rtpbreak and sox.
rtpbreak -W -r long_file_name.a.rtp
rtpbreak -W -r long_file_name.o.rtp
The above commands generate rtp.0.0.raw, rtp.1.0.raw.
Then when i run sox using
sox --combine merge -r 8k -A rtp.0.0.raw -r 8k -A rtp.1.0.raw -t
wavpcm -s out.wav i get the following errors :
sox: invalid option -- -
sox: -c must be given a number
Is there a switch/anything else that i am missing ?
Thanks in advance,
Regards,
Vikram.
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