RE: [AVT] RFC3558 header-free packet format question

With frame sizes of 16, 40, 80 and 171 bits it would not be
possible to distinguish one 80 bit frame from two 40 bit frames. 

In a general case, e.g. were one wants to send multiple frames
in one packet, I believe the header-free format should not be
the one used.

Rgds,
/L-E

> -----Original Message-----
> From: Qiaobing Xie [mailto:Qiaobing.Xie@motorola.com]
> Sent: den 17 september 2004 12:39
> To: Lars-Erik Jonsson (LU/EAB)
> Cc: AVT List; adamli@icsl.ucla.edu
> Subject: Re: [AVT] RFC3558 header-free packet format question
> 
> 
> Hi, Lars-Erik/Magnus,
> 
> Thank you both for the explanation. Yes, it makes sense now. 
> Does the intended 
> ROHC-LLA/CDMA2000 operation (as described by both of you) 
> must require the 
> one-frame-per-packet limitation on the header-free format? 
> This is not obvious to me at least.
> 
> regards,
> -Qiaobing
> 
> Lars-Erik Jonsson (LU/EAB) wrote:
> 
> > Qiaobing,
> > 
> > The header-free format was included to make no-overhead-over-the-air
> > possible, then obviously assuming IP/UDP/RTP header compression on
> > the wireless link. By using RFC 3242, the header overhead can be
> > totally eliminated under certain conditions, thus one frame per RTP
> > packet can make much sense.
> > 
> > Cheers,
> > /L-E
> > 
> > 
> > 
> >>-----Original Message-----
> >>From: avt-bounces@ietf.org [mailto:avt-bounces@ietf.org]On Behalf Of
> >>Qiaobing Xie
> >>Sent: den 17 september 2004 05:51
> >>To: AVT List
> >>Cc: adamli@icsl.ucla.edu
> >>Subject: [AVT] RFC3558 header-free packet format question
> >>
> >>
> >>Hi, Adam,
> >>
> >>The text in section 4.2 of RFC3558 **seems** to indicate that 
> >>only ONE speech frame is 
> >>allowed per RTP packet when header-free format is used. This 
> >>seems to be overly limiting and 
> >>may severely hinder the usage of this payload format (e.g., I 
> >>don't think any over-the-air 
> >>link can afford to use one frame per RTP packet arrangement, 
> >>and if over-the-air link can 
> >>not use header-free format, what would be its purpose?). One 
> >>would think that as long as the 
> >>same codec rate (hence the layout and size) is in use, more 
> >>than one frame should be able to 
> >>be unambiguously carried in a header-free RTP packet.
> >>
> >>Maybe I missed something.
> >>
> >>regards,
> >>-Qiaobing
> >>
> >>
> >>_______________________________________________
> >>Audio/Video Transport Working Group
> >>avt@ietf.org
> >>https://www1.ietf.org/mailman/listinfo/avt
> >>
> > 
> > 
> 

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