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--></style><title>Re: [Live-devel] A General Doubt from 3GPP
Spec</title></head><body>
<div>This has nothing to do with '3GPP'. Your question is about
SDP - an IETF standard (which 3GPP - and many other organizations -
have adopted).</div>
<div><br></div>
<div><br></div>
<blockquote type="cite" cite><font face="Arial"
size="-1">Example,</font></blockquote>
<blockquote type="cite" cite><font face="Arial"
size="-1"> </font></blockquote>
<blockquote type="cite" cite><font face="Arial"
size="-1">Regular:</font></blockquote>
<blockquote type="cite" cite><font face="Arial" size="-1">a=rtpmap:97
MP4A-LATM/22050/2</font></blockquote>
<blockquote type="cite" cite><font face="Arial"
size="-1"> </font></blockquote>
<blockquote type="cite" cite><font face="Arial"
size="-1">Alternate:</font></blockquote>
<blockquote type="cite" cite><font face="Arial" size="-1">a=rtpmap:97
AMR/8000</font></blockquote>
<blockquote type="cite" cite><font face="Arial"
size="-1"> </font></blockquote>
<blockquote type="cite" cite><font face="Arial" size="-1">Is the above
alternate possible for any clip??</font></blockquote>
<div><br></div>
<div>No, this is not legal SDP. The dynamic RTP payload format
code (97 in this case) can be defined by only one "a=rtpmap:"
line.</div>
<div><br></div>
<div>What is legal, however, is to use two separate dynamic RTP
payload format codes within the same stream, and use one for MPEG-4
LATM audio, and the other for AMR audio - e.g.,</div>
<div><br></div>
<div><x-tab> </x-tab>m=audio
0 RTP/AVP 96 97</div>
<div>...</div>
<div><x-tab>
</x-tab>a=rtpmap:96 MP4A-LATM/22050/2</div>
<div><x-tab>
</x-tab>a=rtpmap:97 AMR/8000</div>
<div><br></div>
<div>However, our software currently does not support this (at either
the server or the client end).</div>
<div><br></div>
<div>(Note that this mailing list is for discussion of the
"LIVE555 Streaming Media" software, not for general
discussion of SDP etc.)</div>
<div><br></div>
<x-sigsep><pre>--
</pre></x-sigsep>
<div><br>
Ross Finlayson<br>
Live Networks, Inc.</div>
<div>http://www.live555.com/</div>
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