Screaming video

[bwh]

At Debconf we'll be having talks in the Parliamentary Tower and some other sessions in a room by the hacklab. In each of these rooms there will be one small quiet computer capturing video from the camera over Firewire, connected by Ethernet to a second computer (preferably outside the room) with more disk space and processor power, which will record, transcode and stream the video to the outside world.

On the first of these we just need to pipe dvgrab into netcat. On the second we need to netcat to a file and simultaneously feed that file into the transcoding and streaming software (ffmpeg2theora and oggfwd). Since our link to the Internet may not be reliable (and certainly isn't now) we expect that streaming may lag behind; that's where dvtail (which I mentioned previously) comes in.

Having identified the various pieces of the video puzzle, last night I actually wrote the scripts to do this. I didn't have a chance to test them properly, so they didn't actually work. Today I packaged them, fixed various silly bugs, and tried them on some of the computers we plan to use. This was stalled for a stupidly long time by the lack of Internet access, since Ganneff had planned to create users on an LDAP server elsewhere and then use a local LDAP cache, rather than create them entirely locally. Eventually we ended up with user accounts created on each machine. Next problem: we attached a camera to a Powerbook G4 and got nothing but errors from the Firewire driver and dvgrab. We tried changing cameras, cables, kernel versions, but with no success. Changing the kernel itself was a problem without access to backports. I was cursing the air blue and banging my head against the wall in frustration.

Finally we tried using different computers, and suddenly everything worked. I had missed one option to ffmpeg2theora, but once I added that we were able to stream across the LAN. Of course, that won't be of much use if we don't get the Internet connection working much better soon.