[vlc-devel] vlc and trickplay

Thomas Wentzel tw at 2m.dk
Wed Sep 14 20:09:10 CEST 2005

Hi all

I am using vlc to stream ts and ps mpeg-files to multicast addresses.
This is all good and well.
I am looking to extend this to also stream to unicast addresses.
On the server side vlc is simply run as
vlc --intf rc --rc-fake-tty --rc-host localhost:<rcport> --sout 
udp://<ip>:<port> --ttl 5

The idea is that when streaming to unicast then it should be possible to 
control the playback with respect to (fast)forward/rewind/pause etc (aka 
trickplay) through the rc interface.
I have tried to alter vlc to allow this. And allthough I managed to get 
a crude forward and backward functionality (simply by forcing the 
DEMUX_SET_POSITION to appropriate values) this wasn't satisfactory. So I 
  abandoned this approach and focused on fast forwarding (or even slow 
forwarding) using the RateCallback function.
This however seems to be a dead end. When streaming I get a warning 
saying that the rate can't be altered. When using file:// instead of 
udp:// as --sout the rate is changed, but there is no visible change to 
the output file :(.
I guess my understanding of how the basics of vlc works is flawed. I 
want vlc to stream my input with whatever changes I enforce on it - but 
it seems that vlc streams my input in parallel so that whatever I do to 
the input streams isn't manifested in the output stream!? Is this correct?
Could anybody give me a pointer as to how I would go about implementing 
the desired functionality?
Another thing: I came across a thread on this list from nov. 20 2004 
titled, "Kasenna pause and trickplay patch".
Allthough the patch is really for vlc as a client it is still kind of 
interesting. Can anybody tell me why this patch didn't make it into vlc?
Judging from the feed back to the intial mail it seemed as if the patch 
was generally considered sound.

Best Regards

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