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<title>Re: [Live-devel] Dynamic MPEG4 resolution streaming</title>
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>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.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>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’).<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>With regards<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Shaswata<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
live-devel-bounces@ns.live555.com [mailto:live-devel-bounces@ns.live555.com] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Ross Finlayson<br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, October 03, 2007
3:07 PM<br>
<b><span style='font-weight:bold'>To:</span></b> LIVE555 Streaming Media -
development & use<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Live-devel] Dynamic
MPEG4 resolution streaming</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'>
<p class=MsoNormal><font size=2 face="Times New Roman"><span style='font-size:
10.0pt'>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? </span></font><o:p></o:p></p>
</blockquote>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>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?<o:p></o:p></span></font></p>
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<pre><font size=2 face="Courier New"><span style='font-size:10.0pt'><x-sigsep>-- <o:p></o:p></span></font></pre>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
</x-sigsep>Ross Finlayson<br>
Live Networks, Inc.<br>
http://www.live555.com/<o:p></o:p></span></font></p>
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