[vlc]

[chris.2.dobbs at bt.com]

Ok, this one is driving me buts now so I would like to throw it to the
floor if I may.

To re-cap, I am trying to use VLC to playback an RTP/H263 video stream
(RTP/H263 payload using RFC2429). I am giving VLC the following SDP
manually as a file (which was created after several prods in the right
direction by Ross Finlayson)

v=0
o=- 7776 3 IN IP4 10.215.130.112
s=Test H263 stream
i=Parameters for the session streamed by "ChipsAhoyH263"
t=0 0
m=video 7776 RTP/AVP 98
a=rtpmap:98 H263-1998/90000
a=fmtp:98 profile=0; level=40
b=TIAS:2048000 

I start the remote stream on my server which starts blasting UDP/RTP
packets at port 7776 on my client machine.

On the client I start vlc up like this:

vlc -vvv file://c:\testH263.sdp

VLC comes up and after about 10 seconds(not sure why the delay is so
high) it starts to playback the stream. However after about 3-4 seconds,
the playback freezes and the following messages appear on the debug
screen:

 ffmpeg warning: illegal ac vlc code at 2x8
 (h263 at 00B1E370)
ffmpeg warning: Error at MB: 98
 (h263 at 00B1E370)
ffmpeg debug: concealing 65 DC, 65 AC, 65 MV errors
 (h263 at 00B1E370)
live555 debug: lost 2048 bytes
live555 debug: increasing buffer size to 524288

The playback then resumes for similar period and then freezes again -
this continues for a about 5 mins and then VLC blows up.


I have created the source H263 file (which I am streaming) using the
Telenor h263 encoder and have verified it's validity by playing it back
using ffplay (in the ffmpeg package). I am however not too sure I have
got the RTP payload correct as the RFC is not exactly helpful. I simple
tag on the RFC2429 2 byte header and set the P bit to 1 everytime.
Also, I noticed that the results are quite different on linux - the
live555 module in VLC simply states that there is no data to playback
and gives up...very odd I thought as the windows build seems to at least
read in the packets.

Any help would be very much appreciated as I really want to use VLC for
this as we want to use the transcoding facilites which look great.

Many regards,
-Chris Dobbs



PS/
My packet sizes are around 2500 bytes so I increased the VLC MTU setting
to 3000.

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