A gentle warning when using GSM codecs Every codec compress voice at the cost of quality. And some codecs like GSM and G.729 are not a nice combination. If you use GSM to save disk space and play it back using G.729 the resulting voice might contain some added noise due to algorithmic incompatibility. jan _____ From: freeswitch-users-bounces@lists.freeswitch.org [mailto:freeswitch-users-bounces@lists.freeswitch.org] On Behalf Of David Ponzone Sent: 24. juni 2011 23:42 To: FreeSWITCH Users Help Subject: Re: [Freeswitch-users] .wav vs .gsm file sizes for recording calls. Wes, it's because you are confusing 2 things. GSM is a codec, so it's a sound format. WAVE is a kind of container (like MKV) that can contain various codecs. In your case, you probably did a mistake using sox (it's not an easy tool), so you ended up with a wav which is still GSM audio inside. You have to tell sox which exact output format you want. AFAIR, you have to use the -s option (for signed linear). David Ponzone Direction Technique email: david.ponzone@ipeva.fr tel: 01 74 03 18 97 gsm: 06 66 98 76 34 Service Client IPeva tel: 0811 46 26 26 www.ipeva.fr <BLOCKED::http://www.ipeva.fr/> - www.ipeva-studio.com <BLOCKED::http://www.ipeva-studio.com/> Ce message et toutes les pièces jointes sont confidentiels et établis à l'intention exclusive de ses destinataires. Toute utilisation ou diffusion non autorisée est interdite. Tout message électronique est susceptible d'altération. IPeva décline toute responsabilité au titre de ce message s'il a été altéré, déformé ou falsifié. Si vous n'êtes pas destinataire de ce message, merci de le détruire immédiatement et d'avertir l'expéditeur. Le 24/06/2011 à 23:26, Wes a écrit : In my tests, if I record a call in .wav format, a 10 second file is about 177,000 bytes, while a 10 second .gsm file is 17,000 bytes. I then used sox to convert the .gsm file to a .wav file, and it stayed at around 17,000 bytes. So, is the default recording format for .wav using a higher sample rate? vs the default conversion format for the sox tool? checking the file type using "file" I see that the larger one is: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, mono 8000 Hz and the wav created by sox via the default conversion from .gsm is: RIFF (little-endian) data, WAVE audio, GSM 6.10, mono 8000 Hz So apparently the larger wav file is 16 bit... how are these recording parameters controlled? Can I set it to record directly into the smaller wav format? Or will I have to run sox on every file... _______________________________________________ Join us at ClueCon 2011, Aug 9-11, Chicago http://www.cluecon.com 877-7-4ACLUE FreeSWITCH-users mailing list FreeSWITCH-users@lists.freeswitch.org http://lists.freeswitch.org/mailman/listinfo/freeswitch-users UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users http://www.freeswitch.org