Development plans for DVswitch

Ben Hutchings ben at
Mon Nov 29 04:00:05 UTC 2010

Over this past week I had hoped to do some serious development on
DVswitch.  I have not made as much progress as I hoped, but I have
implemented an important piece.

We now have an firewire source that runs as an RTP/RTSP server and does
not depend on dvgrab.  Since this runs as a server, it can be started at
any time - no need to script it.  It's not complete as we don't yet have
a way to control tally lights over RTSP.  Also you can't set the
listening port, but that's trivial to fix.  This is currently built as

Our other two important sources are dvsource-file and dvsource-alsa.  I
believe the former can be replaced by an RTP/RTSP file server such as
live555MediaServer.  The latter is still to be done.  We should also
replace dvsource-v4l-dv, but I'm not sure anyone's actually using that.

Since the Alioth (FusionForge) tracker is a pain to use, I'll briefly
summarise what I think are the immediate tasks to be done:

1. Implement an audio buffer in the mixer, independent of video frames.
2. Support audio-only sources in the connector and mixer (depends on 1).
3. Add a per-source delay value in the mixer.
4. Reimplement dvsource-alsa as an RTP/RTSP server (depends on 2 and 3).
5. Complete the source configuration UI.
6. Implement persistence of source configuration (i.e. load and save).
7. Define and implement tally light control within RTSP.
8. Drop the old source protocol and clients (depends on 4-7).

If anyone would like to take on some of these tasks, please speak up.  I
can provide some guidance, but you must be prepared to work a lot of it
out yourself.

Of course I really want to sort out sinks as well.  I'm a bit nervous of
recording over UDP, and there is no implementation of the RECORD command
in RTSP!  So perhaps we should do it this way:

- Make the mixer an RTP/RTSP server.
- Reimplement dvsink-command based on openRTSP (this is a utility
included in the liveMedia package).
- Implement file sinks within the mixer.  Anyone who wants to record
remotely can use a network file system or network storage protocol.

Does that sound like a workable plan?


Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.
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