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<DIV dir=ltr align=left><SPAN class=630293118-05022008><FONT face=Arial
color=#0000ff size=2>Thanks Ross for the answers. They are very helpful. I
believe I have found the cause of my synchronization problems. I switched that
thread to the live555 email list.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=630293118-05022008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=630293118-05022008><FONT face=Arial
color=#0000ff size=2>Guy Bonneau</FONT></SPAN></DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> vlc-devel-bounces@videolan.org
[mailto:vlc-devel-bounces@videolan.org] <B>On Behalf Of </B>Ross
Finlayson<BR><B>Sent:</B> Tuesday, February 05, 2008 11:08 AM<BR><B>To:</B>
Mailing list for VLC media player developers<BR><B>Subject:</B> Re:
[vlc-devel] demux/live555.cpp Elementary Stream
Synchronization.<BR></FONT><BR></DIV>
<DIV></DIV>
<BLOCKQUOTE cite="" type="cite"><FONT face=Arial size=-1>I'm trying to play
with VLC Media Player 2 elementary streams that are sent in 2 RTP subsession
with the live555 library in a testing application. One subsession is an
Mpeg2 Video Elementary Stream and the other subsession is a 2
channels audio PCM sampled at 48000 KHz. Both elementary stream are in
sync and genlocked at the source. I have much trouble getting VLC Media
player plays the 2 streams synchronized.</FONT></BLOCKQUOTE>
<DIV><BR></DIV>
<DIV>First, to get a/v synchronization at the client, you *must* be using
RTCP, as well as RTP.</DIV>
<DIV><BR></DIV>
<DIV>Second, your presentation times - at the sender - must be aligned with
'wall clock' time - i.e., the times you would get if you were to call
"gettimeofday()".</DIV>
<DIV><BR></DIV>
<DIV>If your audio and video streams have correct presentation times which are
aligned with 'wall clock' time, and you are using RTCP, then - at the receiver
(VLC) end - these same presentation times *will* be delivered to the decoding
software, and the decoding software *will* do a/v synchronization
correctly.</DIV>
<DIV><BR></DIV>
<BLOCKQUOTE cite="" type="cite"><FONT face=Arial size=-1>I have looked at
the code of live555.cpp in the VLC Media Player project. It seems to me
that the code is designed such that it is not possible to receive 2
streams that doesn't have the same sample rate. In this case 90 KHz for the
video and 48KHz for the audio.</FONT></BLOCKQUOTE>
<DIV><BR></DIV>
<DIV>No, that's not correct. (BTW, instead of "sample rate", you mean
"RTP timestamp frequency".) The code handles different RTP timestamp
frequencies (for different streams) just fine.</DIV><X-SIGSEP><PRE>--
</PRE></X-SIGSEP>
<DIV><BR>Ross Finlayson<BR>Live Networks,
Inc.<BR>http://www.live555.com/</DIV></BLOCKQUOTE></BODY></HTML>