[Freeswitch-users] Recording G729

Tue Nov 26 19:20:35 MSK 2013

If you are recording a call that is also transcoding, it will record the
audio at the point between the 2 codecs where it decodes the inbound audio
and before it re-encodes it.  In your scenario, for example, in the process
when it decodes the gsm and before it re-encodes to pcmu, that is what will
be saved into the recording.

If you are not transcoding, if both sides of the call were pcmu, it would
still decode it in order to record because it muxes it.

You should try doing only pcmu on the call to compare quality and then you
can tell if its related to the GSM or the network conditions.

If you are worried about quality, g729 is more efficient and uses less
bandwidth but is not going to help much on quality.

On Tue, Nov 26, 2013 at 3:10 AM, Steven Ayre <steveayre at gmail.com> wrote:

> Also, unless the call is already using the same codec you're still going
> to have to have to transcode from whatever the file is encoded in.
>
> You'll probably only get a CPU benefit when the file is recorded in the
> same codec as the call *and* you're using mod_native_file.
>
>
> On 26 November 2013 09:07, Steven Ayre <steveayre at gmail.com> wrote:
>
>> Also: even if you record to wav, and both legs are something else (eg
>>> g729, iLBC, whatever), would the recording transcoding not undo the
>>> potential benefit of not having to transcode between a- and b-leg?
>>
>>
>> You require extra CPU (and with mod_com_g729 more licenses) but can get
>> better quality as a result. It's a trade-off.
>>
>> Depending on what you're doing you could look at mod_native_file,
>> which'll play a file pre-recorded in the codec in use and fallback to WAV
>> if it isn't found. For example if it's something like IVR options.
>>
>> It probably isn't worth it for things like voicemail though.
>>
>> -Steve
>>
>>
>>
>> On 26 November 2013 04:07, Kees Varekamp <kees at mroffice.org> wrote:
>>
>>> OK I'll try and check if that helps - although CPU really doesnt seem an
>>> issue. Another thought: if you run lame on the same server wouldn't it get
>>> a comparable cpu load anyway? Or even worse since it is batch wise?
>>>
>>> Also: even if you record to wav, and both legs are something else (eg
>>> g729, iLBC, whatever), would the recording transcoding not undo the
>>> potential benefit of not having to transcode between a- and b-leg?
>>>
>>> Thanks,
>>>
>>> Kees
>>>
>>>
>>> On Tue, Nov 26, 2013 at 4:09 PM, Yuri Ritvin <yuri.ritvin at gmail.com>wrote:
>>>
>>>> You'll better record in a standard WAV format and will convert it into
>>>> MP3 with lame (you need to install lame, of course, onto your server) thus
>>>> off-loading some burden from the freeswitch processing. Say you record WAV
>>>> files into a folder /opt/freeswitch/sounds/recorded and wanna have MP3
>>>> files in a folder /opt/freeswitch/sounds/recorded/mp3, then you create the
>>>> following script and run it via crontab every 15 minutes (or any desired
>>>> time interval):
>>>>
>>>> #!/bin/bash
>>>> cd /opt/freeswitch/sounds/recorded
>>>> for i in `find . -name "*.wav" -cnewer mp3|cut -d/ -f2|cut -d. -f1`
>>>> do
>>>> lame -S -h --resample 16 -b 24 $i.wav mp3/$i.mp3
>>>> done
>>>>
>>>>
>>>>
>>>> On Mon, Nov 25, 2013 at 9:39 PM, Kees Varekamp <kees at mroffice.org>wrote:
>>>>
>>>>> Hi all,
>>>>>
>>>>> I'm suffering from poor sound quality on my setup, using GSM on the
>>>>> a-leg and PCMU on the b-leg. I'm thinking it's mostly bandwidth/network
>>>>> related, so I'm considering switching to G729 on both legs, as that is the
>>>>> only compressed codec that the b-leg supports (it's a sip gateway).
>>>>>
>>>>> But a complicating factor is that the calls need to be recorded in mp3.
>>>>>
>>>>> So I have some questions that I hope someone here can answer:
>>>>>
>>>>>
>>>>>    - Does transcoding (for example GSM<>PCMU) negatively affect the
>>>>>    sound quality, even when the CPU seems to be ok with it?
>>>>>    - If yes, does recording 2 legs using the same codec (say G729) to
>>>>>    a different sound format (say mp3) have the same (negative) effect?
>>>>>    - When you use G729 on both legs (using mod_com_g729), it is even
>>>>>    possible to record to mp3?
>>>>>
>>>>>
>>>>> Thank you,
>>>>>
>>>>> Kees
>>>>>
>>>>>
>>>>>
>>>>> _________________________________________________________________________
>>>>> Professional FreeSWITCH Consulting Services:
>>>>> consulting at freeswitch.org
>>>>> http://www.freeswitchsolutions.com
>>>>>
>>>>> 
>>>>> 
>>>>>
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>>>>>
>>>>
>>>>
>>>> _________________________________________________________________________
>>>> Professional FreeSWITCH Consulting Services:
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>>>> http://www.freeswitchsolutions.com
>>>>
>>>> 
>>>> 
>>>>
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>>>
>>>
>>> --
>>> Kees Varekamp
>>> *MROffice Director*
>>> 44 Castleford street, 0604, Auckland, New Zealand
>>> Phone: +6492821656
>>> Skype: kees.mroffice
>>> Web: mro <http://mro-global.com>ffice.org
>>>
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>>>
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>>>
>>> 
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>>
>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
>
> 
> 
>
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-- 
Anthony Minessale II

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