[SR-Users] [Kamailio-Users] Converting rtpproxy recorded .rtp file to .wav file

[Ovidiu Sas]

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-with-rtpproxy/
Regards,Ovidiu Sas
On Thu, Jan 14, 2010 at 5:37 PM, Vikram Ragukumar
<vragukumar at 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:
>>
>> Carsten,
>>
>> Thank you for your reply.
>>
>> Carsten Bock wrote:
>>>
>>> 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 at signalogic.com
>>> <mailto:vragukumar at 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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>>>
>>>
>>>
>>> --
>>> Carsten Bock
>>> Schomburgstr. 80
>>> 22767 Hamburg
>>> Germany
>>>
>>> Mobile +49 179 2021244
>>> Home +49 40 34927217
>>> Fax +49 40 34927218
>>> mailto:carsten at bock.info <mailto:carsten at bock.info>
>>>
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>>>  - "If God had wanted man to play soccer, he wouldn't have given us arms."
>>
>>
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