Codec 101 - need help with the basics
Hi I need some assistance in understanding the codec minefield. When a stream of audio is sent to FreeSWITCH (FS) using a particular codec, does FS just pass it on or is there some level of translation occurring? I guess my question relates to a situation where an FXO gateway (GXW410x) uses the G723 codec and the receiing phone does not have a matching codec (the phone has G.722, G.711 a law, G.711 u law, G.726 and G.729 as options). How is this managed by the phone, FreeSWITCH and the FXO device? Should I be setting something in FS to handle this issue? I have 2 cordless Siemens C610 IP phones an I am having sound quality issues (incoming sound is soft) and I was wondering how big a part the codec plays in this equation. I have desk phones that are from the same manufacturer as the FXO gateway (Grandstream) and they have very good sound quality. Calling internally between all the phones has crystal clear sound. Thanks in advance O
On Thu, Jun 21, 2012 at 3:09 AM, ocset <ocset@the800group.com> wrote:
Hi
I need some assistance in understanding the codec minefield.
When a stream of audio is sent to FreeSWITCH (FS) using a particular codec, does FS just pass it on or is there some level of translation occurring?
In some situations audio may be just passed thru, but most real life scenarios will involve some level of translation (transcoding).
I guess my question relates to a situation where an FXO gateway (GXW410x) uses the G723 codec and the receiing phone does not have a matching codec (the phone has G.722, G.711 a law, G.711 u law, G.726 and G.729 as options). How is this managed by the phone, FreeSWITCH and the FXO device? Should I be setting something in FS to handle this issue?
Whenever FreeSWITCH detects format mismatch between the parties it will perform transcoding (translation of one audio format to another). You have several configuration options to force a given list of codecs to be offered. Now, in some shameless self-promotion, I suggest you to read or watch my presentation on FreeSWITCH media handling from here: http://www.moythreads.com/congresos/cluecon2011/media-handling-freeswitch-fi... http://www.youtube.com/watch?v=508jpSQk8qE That should make things a bit clearer for you.
I have 2 cordless Siemens C610 IP phones an I am having sound quality issues (incoming sound is soft) and I was wondering how big a part the codec plays in this equation. I have desk phones that are from the same manufacturer as the FXO gateway (Grandstream) and they have very good sound quality.
I don't think the codec has a role in your issue, if the audio is soft or quiet it has more to do with the gain control. If you place calls to those Siemens phones without using the gateway (ie, calling in to play a file) is the audio still low? *Moises Silva **Manager, Software Engineering*** msilva@sangoma.com Sangoma Technologies 100 Renfrew Drive, Suite 100, Markham, ON L3R 9R6 Canada t. +1 800 388 2475 (N. America) t. +1 905 474 1990 x128 f. +1 905 474 9223 **<http://www.sangoma.com/contact?utm_source=signature&utm_medium=email&utm_campaign=email+signatures> Products<http://sangoma.com/products?utm_source=signature&utm_medium=email&utm_campaign=email%2Bsignatures> | Solutions<http://sangoma.com/solutions?utm_source=signature&utm_medium=email&utm_campaign=email%2Bsignatures> | Events<http://sangoma.com/about_us/events?utm_source=signature&utm_medium=email&utm_campaign=email%2Bsignatures> | Contact<http://www.sangoma.com/contact?utm_source=signature&utm_medium=email&utm_campaign=email%2Bsignatures> | Wiki<http://wiki.sangoma.com/?utm_source=signature&utm_medium=email&utm_campaign=email%2Bsignatures> | Facebook<http://www.facebook.com/pages/Sangoma-VoIP-Cards/43578453335?utm_source=signature&utm_medium=email&utm_campaign=email%2Bsignatures> | Twitter<http://www.twitter.com/sangoma?utm_source=signature&utm_medium=email&utm_campaign=email%2Bsignatures>`| | YouTube<http://www.youtube.com/sangomatechnologies?utm_source=signature&utm_medium=email&utm_campaign=email%2Bsignatures>
try using greedy instead of generous :) it will work --- On Sun, 6/24/12, Moises Silva <moises.silva@gmail.com> wrote: From: Moises Silva <moises.silva@gmail.com> Subject: Re: [Freeswitch-users] Codec 101 - need help with the basics To: "FreeSWITCH Users Help" <freeswitch-users@lists.freeswitch.org> Date: Sunday, June 24, 2012, 6:47 AM On Thu, Jun 21, 2012 at 3:09 AM, ocset <ocset@the800group.com> wrote: Hi I need some assistance in understanding the codec minefield. When a stream of audio is sent to FreeSWITCH (FS) using a particular codec, does FS just pass it on or is there some level of translation occurring? In some situations audio may be just passed thru, but most real life scenarios will involve some level of translation (transcoding). I guess my question relates to a situation where an FXO gateway (GXW410x) uses the G723 codec and the receiing phone does not have a matching codec (the phone has G.722, G.711 a law, G.711 u law, G.726 and G.729 as options). How is this managed by the phone, FreeSWITCH and the FXO device? Should I be setting something in FS to handle this issue? Whenever FreeSWITCH detects format mismatch between the parties it will perform transcoding (translation of one audio format to another). You have several configuration options to force a given list of codecs to be offered. Now, in some shameless self-promotion, I suggest you to read or watch my presentation on FreeSWITCH media handling from here: http://www.moythreads.com/congresos/cluecon2011/media-handling-freeswitch-fi... http://www.youtube.com/watch?v=508jpSQk8qE That should make things a bit clearer for you. I have 2 cordless Siemens C610 IP phones an I am having sound quality issues (incoming sound is soft) and I was wondering how big a part the codec plays in this equation. I have desk phones that are from the same manufacturer as the FXO gateway (Grandstream) and they have very good sound quality. I don't think the codec has a role in your issue, if the audio is soft or quiet it has more to do with the gain control. If you place calls to those Siemens phones without using the gateway (ie, calling in to play a file) is the audio still low? Moises Silva Manager, Software Engineering msilva@sangoma.com Sangoma Technologies100 Renfrew Drive, Suite 100, Markham, ON L3R 9R6 Canada t. +1 800 388 2475 (N. America)t. +1 905 474 1990 x128 f. +1 905 474 9223 Products | Solutions | Events | Contact | Wiki | Facebook | Twitter`| | YouTube -----Inline Attachment Follows----- _________________________________________________________________________ Professional FreeSWITCH Consulting Services: consulting@freeswitch.org http://www.freeswitchsolutions.com FreeSWITCH-powered IP PBX: The CudaTel Communication Server http://www.cudatel.com Official FreeSWITCH Sites http://www.freeswitch.org http://wiki.freeswitch.org http://www.cluecon.com Join Us At ClueCon - Aug 7-9, 2012 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
participants (3)
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Moises Silva
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ocset
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Sherif Omran