Thanks all - very helpful I think the sound quality problem is definitely network related as it occurs in some locations and not in others, which is why my current strategy is to minimize bandwidth usage. On Wed, Nov 27, 2013 at 5:20 AM, Anthony Minessale < anthony.minessale@gmail.com> wrote:
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@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@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@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@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@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
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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 *MROffice - Meeting Market Research Needs*