[Live-devel] Dynamic MPEG4 resolution streaming

[Shaswata Jash]

Instead of keeping the config data in the SDP (in that case, client may
utilize those out of band data to pre-allocate buffers for its decoder), you
may keep that data as part of RTP packets. However, if the client is
implemented such a way that it does not refresh necessary information (e.g.
size of buffers according to changed resolution) in accordance with the
successive changes in the resolution, in-band config data will not help in
anyway.

 

There can be another hack (essentially for those clients, which do not
refresh their internal data structures during change in resolution) - let
the server start streaming with certain resolution. If the network condition
drops off, the encoder in the server tries to reduce the effective
resolution. By the term effective resolution, I mean, server maintains the
original resolution but the effective viewing square is diminished and the
rest of the original square is blackened. Certainly, the blackened area will
take significantly less amount to pack its information in the MPEG4 video
bit stream and your purpose will still be solved. Again, once the network
condition is improved, you may increase the effective resolution. One
problem in this hack will be - you cannot increase the resolution beyond
your initial one (i.e. coming through the 'config').

 

With regards

Shaswata

 

  _____  

From: live-devel-bounces at ns.live555.com
[mailto:live-devel-bounces at ns.live555.com] On Behalf Of Ross Finlayson
Sent: Wednesday, October 03, 2007 3:07 PM
To: LIVE555 Streaming Media - development & use
Subject: Re: [Live-devel] Dynamic MPEG4 resolution streaming

 

I'm ultilizing live555 to implement a streaming server for streaming MPEG4
ES video from a MPEG4 hardware encoder.  Video is successfully send through
RTP protocol started by RTSP (with SDP).  I would like to ask if there is
any way I can dynamically change the video resolution from the server side
and announce to all live clients without starting a new session from
beginning? 

 

Why note just change the resolution (at the server end), and keep streaming,
as usual?  Is there not enough information in-band (in the MPEG-4 video
stream) for clients to detect this, and handle it properly?

-- 


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/

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