AFAIK, there is no standard which tells that the 5ms samples per frame, need to be used for G.711 codec.
Since G.711 codec involves just sampling and quantization, its more implementation specific. Certain implementations of G.711 codec operate on sample intervals of 5ms. Hence, encoding of 5ms of G.711 samples in one frame. Here, ptime can be multiples of 5ms. Some implementations operate on sample intervals of 10ms. Hence, encoding of 10ms of G.711 samples in one frame. Here, ptime would be multiples of 10ms. Thanks, Jagan On Mon, Sep 22, 2008 at 9:18 PM, Schwarz Albrecht < [EMAIL PROTECTED]> wrote: > I know that 125 µs relates to the sample period, which is however identical > to the frame size in case of G.711 IMHO. > Could you provide your reference concerning the 5 ms definition? > > Thanks, Albrecht > > > > ________________________________ > > From: Aneesh Naik [mailto:[EMAIL PROTECTED] > Sent: Montag, 22. September 2008 14:45 > To: Schwarz Albrecht > Cc: Sachin Rastogi; [email protected] > Subject: Re: [Sip-implementors] Should 'ptime' value be multiple > of 5 or 10 > > > 125 µs is not the frame size of G.711. It is the time sampling > rate. > > 8000 samples in 1 sec. > 1 sample in 125 µs. > > Number of such samples are combined to form a frame of data. > This frame size for G.711 is 5ms. > > Hope this clears your understanding. > > Thanks, > Aneesh > > > On Mon, Sep 22, 2008 at 5:43 PM, Schwarz Albrecht < > [EMAIL PROTECTED]> wrote: > > > > > The frame size for g.711 is 5ms > > > G.711 has a frame size of 125 µs in my understanding. > See ITU-T G.711. > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] > On > > Behalf Of Sachin Rastogi > > Sent: Montag, 22. September 2008 13:45 > > To: Aneesh Naik > > Cc: [email protected] > > Subject: Re: [Sip-implementors] Should 'ptime' value be > > multiple of 5 or 10 > > > > Thanks Aneesh,Alex for quick reply. > > > > > > Sachin > > > > On Mon, Sep 22, 2008 at 3:03 PM, Aneesh Naik > > <[EMAIL PROTECTED]> wrote: > > > > > Yes, as explained by alex the ptime depend on the frame > size... > > > The frame size for g.711 is 5ms, for g.729 is 10ms and > for > > g.723 it is > > > 30 ms. > > > So the ptime for 711 and 729 can be 10, 20, 30... and > for > > 723 it can > > > be 30,60.... > > > > > > -Aneesh > > > > > > On Mon, Sep 22, 2008 at 1:50 PM, Alex Balashov > > > <[EMAIL PROTECTED] > > > >wrote: > > > > > > > There are no drafts or recommendations mandating that > ptime be a > > > > particular value because the desired packetisation > duration is > > > > closely related to the frame size and other > > characteristics of particular codecs. > > > > > > > > However, almost no media gateway equipment out there > will support > > > > anything other than the usual 10-30 ms for the usual > suspects - > > > > G.711u/A, G.729A, etc. > > > > > > > > There are certain recommendations or mandates for > ptime > > values based > > > > on particular codecs. For instance, 20 ms is > recommended > > when using > > > > Speex > > > > ( > http://www.speex.org/docs/manual/speex-manual/node14.html): > > > > > > > > --- > > > > > > > > 4.1.1. Registration of media type audio/speex > > > > > > > > Media type name: audio > > > > > > > > Media subtype name: speex > > > > > > > > Required parameters: > > > > > > > > None > > > > > > > > Optional parameters: > > > > > > > > ptime: see RFC 4566. SHOULD be a multiple of 20 > msec. > > > > > > > > maxptime: see RFC 4566. SHOULD be a multiple of > 20 msec. > > > > > > > > > > > > > > > > Sachin Rastogi wrote: > > > > > > > > > Hi All, > > > > > Is there any rfc/draft or recommendation which > suggests > > that 'ptime' > > > > > value should multiple of 5 or 10? Can I use 'ptime' > > value as 11 or > > > > > 12 > > > or > > > > 18 > > > > > or 19? > > > > > > > > > > > > > > > > > > > > Thanks > > > > > Sachin Rastogi > > > > > _______________________________________________ > > > > > Sip-implementors mailing list > > > > > [email protected] > > > > > > > > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > > > > > > > > > > > -- > > > > Alex Balashov > > > > Evariste Systems > > > > Web : http://www.evaristesys.com/ > > > > Tel : (+1) (678) 954-0670 > > > > Direct : (+1) (678) 954-0671 > > > > Mobile : (+1) (706) 338-8599 > > > > _______________________________________________ > > > > Sip-implementors mailing list > > > > [email protected] > > > > > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > > > > > > > > > > > > > > > -- > > > Aneesh > > > _______________________________________________ > > > Sip-implementors mailing list > > > [email protected] > > > > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > > > > _______________________________________________ > > Sip-implementors mailing list > > [email protected] > > > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > > > > > > > -- > Aneesh > > > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
