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The net needs a free way to combine video and slides for showing talks

These days it is getting very common to make videos of presentations, and even to do live streams of them. And most of these presentations have slides in Powerpoint or Keynote or whatever. But this always sucks, because the camera operator -- if there is one -- never moves between the speaker and the slide the way I want. You can't please everybody of course.

In the proprietary "web meeting" space there are several tools that will let people do a video presentation and sync it with slides, ideally by pre-transmitting the slide deck so it is rendered in full resolution at the other end, along with the video. In this industry there are also some video players where you can seek along in the video and it automatically seeks within the slides. This can be a bit complex if the slides try to do funny animations but it can be done.

Obviously it would be nice to see a flash player that understands it is playing a video and also playing slides (even video of slides, though it would be better to do it in higher quality since it isn't usually full motion video.) Sites like youtube could support it. However, getting the synchronization requires that you have a program on the presenting computer, which you may not readily control.

One simple idea would be a button the camera operator could push to say "Copy this frame to the slide window." Then the camera would, when there is a new slide, move or switch over there, and the button would be pushed, and the camera could go immediately back to the speaker. Usually though the camera crew has access to the projector feed and would not need to actually point a camera, in fact some systems "switch" to the slides by just changing the video feed. A program which sends the projector feed with huge compresion (in other words, an I frame for any slide change and nothing after) would also work well. No need to send all the fancy transitions.

But it would be good to send the slides not as mpeg, but as PNG style, to be sharper if you can't get access to the slides themselves. I want a free tool, so I can't ask for the world, yet, but even something as basic as this would make my watching of remote presentations and talks much better. And it would make people watching my talks have a better time too -- a dozen or so of them are out on the web.

I'm in O'Hare waiting to fly to Munich for DLD. More details to come.


You're aware of, right? They do exactly what you're talking about for prerecorded academic lectures.


No, I haven't seen these guys but I am glad they are doing it. My question is, why haven't I seen them? I see tons of video streams of lectures with slides on the net, but I never saw one with this. I guess this link may help get the word out.

I would think HD resolution (16x9) would permit division into two frames, one for the slide and one for the speaker. That would permit the slides to advance at the speaker's pace.

I have also thought about this on and off over the years; I think the pieces exist but haven't been put together. For playback, SMIL can sync still images with video; the supporters of SMIL (QuickTime and Real) have fallen out of fashion but I suspect you could implement a SMIL runtime in HTML5. For recording, there are cheap USB VGA capture devices, but nobody knows they exist and I don't think they have Linux or Mac drivers. also does many of its talks this way. It would be nice to know what software they use so it can be more widely done.

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