<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; ">Hi Ross,<DIV><BR class="khtml-block-placeholder"></DIV><DIV>I was browsing trough my archives and stumbled upon this one. Do you think that such a patch is a good idea?</DIV><DIV>It actually sounds quite logical to me, since the whole idea is to base PCR on "servertime"</DIV><DIV>However perhaps it can have unexpected effects. I know too little of SR RTCP to really know for sure.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>DJ<BR><DIV><BR><DIV>Begin forwarded message:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><B>From: </B></FONT><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica">Luca Abeni <<A href="mailto:lucabe72@email.it">lucabe72@email.it</A>></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><B>Date: </B></FONT><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica">24 oktober 2005 11:00:08 GMT+02:00</FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><B>To: </B></FONT><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica"><A href="mailto:vlc-devel@videolan.org">vlc-devel@videolan.org</A></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><B>Subject: </B></FONT><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica"><B>[vlc-devel] Problem in livedotcom.cpp</B></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><B>Reply-To: </B></FONT><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica"><A href="mailto:vlc-devel@videolan.org">vlc-devel@videolan.org</A></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV> <DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Hello,</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I am testing vlc to receive RTP streams. In some experiments, I saw that</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">vlc has a lot of problems if there is a big jitter in the video frames'</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">arrival times.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">For example, in an experiment I introduced a random delay, up to 3</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">seconds, on the video packets, and I saw that the video plays "almost</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">ok", but the audio is often interrupted - of course, I am pre-buffering</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">3 seconds of stream: the command line I use is</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">vlc --rt-priority -vvv --file-caching 3000 stream:test.sdp</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">(mp4ip player and QT player both correctly receive and play the stream,</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">without problems in the audio or in the video).</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I tried to analyse the problem, and it seems to me that it is caused by</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">the way used to update the reference clock in</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">modules/demux/livedotcom.cpp: if I understand well, the i_pcr value used</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">in</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">es_out_Control( p_demux->out, ES_OUT_SET_PCR, i_pcr )</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">(in the Demux() function) is computed based on the presentation time of</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">the last received frame. This is ok if the jitter in the frame arrival</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">time is small, but seems to completely screw the reference clock if</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">frames can arrive up to 3 seconds late as in my test.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I do not know the vlc internals and the live.com code too much</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">(basically, I started to study vlc code to fix this problem), so maybe I</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">am asking a stupid question... But why is a PTS used to compute the PCR?</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I tried to modify the code to update the reference clock based on the</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">NTP time contained in the last received SR RTCP packet, and this seems</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">to fix the problem I am seeing. I attach a patch that hopefully shows</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">what I mean (with this patch applied, vlc can succesfully play the</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">stream with delayed video packets).</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Can someone comment on this patch: is it acceptable? Or am I</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">misunderstanding something?</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>Thanks,</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>Luca</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">--<SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_____________________________________________________________________________</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Copy this in your signature, if you think it is important:</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-converted-space"> </SPAN>N O<SPAN class="Apple-converted-space"> </SPAN>W A R ! ! !</DIV></BLOCKQUOTE></DIV></DIV></BODY></HTML>