<html><head><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"><base href="x-msg://1839/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><blockquote type="cite"><div lang="FR" link="blue" vlink="purple" style="font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div class="Section1" style="page: Section1; "><div style="margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); ">I guess this could be interesting to carry information inside the stream independandly of codec used.</span></div></div></div></blockquote><div><br></div><div>That might be "interesting", but not necessarily appropriate. It depends on what sort of 'information' this is. The use of a RTP header extension is appropriate ***only if*** the information is directly related to the RTP packets (not just the stream as a whole). For example, one can imagine some RTP packets carrying an extra timestamp (e.g., a 'decoding timestamp'), in addition to the usual RTP timestamp (from which a 'presentation timestamp' is derived). </div><div><br></div>If the 'information' is static, and unchanging, then it could be put in the stream's SDP description (e.g., the 'info' or 'description' SDP lines). There are (optional) parameters to "ServerMediaSession::createNew()" to provide this information, and also - at the receiving end - member functions of "MediaSession" to get this information:</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>sessionName();</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>sessionDescription();</div><div><br></div><div>Another way to get information that's static (or doesn't change much) is to use the RTSP "GET_PARAMETER" command, as you've done.</div><div><br></div><div>For information that is time-based - i.e., changes over time - but is not directly related to an existing media stream (i.e., the audio or video stream) - then the information could itself be its own RTP media stream - e.g., using the "text" media type. Note, for example, that we support time-varying T.140 text streams over RTP, using the class "T140TextRTPSink". (That's used for transmitting text over RTP; for receiving such streams, we just use "SimpleRTPSource".) We use such streams to transmit the 'subtitle' tracks from Matroska files (and VLC, when used as a RTP receiver, will also display these as subtitles).</div><br><br><div apple-content-edited="true">
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">Ross Finlayson<br>Live Networks, Inc.<br><a href="http://www.live555.com/">http://www.live555.com/</a></span></span>
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