RE: [AVT] Determining the desired transmitted resolution and frame rate when using H.264

Hi,

H.264 does not have the definition of fixed frame sizes. The level gives
some maximum values which enable you to estimate the maximum size of the
frame and the frame rate.

Using max-mbps, max-fs you can override the level parameters. Still this
does not allow you to request a specific resolution or number of macro
b;ocks per second.

There is currently work done at the ITU on defining additional
parameters to H.241 in order to allow such functionality and after it is
done there I assume we will try to update RFC 3984 with this
functionality.

BTW: there are some new parameters now in
draft-ietf-avt-rtp-h264-params-00 and you should look at it.

Roni Even

________________________________

From: Shahaf Rozanski [mailto:Shahaf.Rozanski@audiocodes.com] 
Sent: Tuesday, July 03, 2007 11:17 AM
To: avt@ietf.org
Cc: Yuval Nissan; Keren Malachi
Subject: [AVT] Determining the desired transmitted resolution and frame
rate when using H.264 

Hi,

In the SDP negotiation each agent declares it supported receive
capabilities. For H.264 it can be done using the profile-level-id
mechanism suggested in RFC 3984.

Let's assume that the offerer declared baseline profile level 1.1. As a
result he is willing to receive different configuration e.g. up to CIF
resolution with 7.5 FPS or up to QCIF with 30 FPS.

Is there a method for the offerer to hint the answerer that he would
like to receive in a specific configuration (e.g. QCIF 30FPS)?

This can be useful if the offerer is a UE that is best suited for QCIF
resolutions. 

Thanks,

Shahaf