On Mar 22, 2012, at 7:24 PM, Panks wrote: > > I went through iv code today, as it already uses qtimer for 'slide show', so > if I implement the opengl part and use of double PBO, then giving iv a > playback capability won't be a big deal. We can add play, pause and forward > button easily later on. :)
Of course, the trick is that we can't read images from disk at 24 fps at that resolution (I really don't think -- my intuition is that read speed is probably 1-2 Hz), so a big part of this task is going to be to intelligently buffer the images so that playback can happen at frame rate. And we need to deal with detecting and handling gracefully what happens when somebody wants to play back a stack of frames whose sum is greater than the amount of GPU texture memory available, which happens pretty fast -- a 2048x1536 x 3 channel x "half" (2 byte) = 18 MB per frame, you will fill GPU memory with only several seconds of footage. Hey, how does that work? Has anybody here written a good playback app before? (I haven't.) The one I use at work, for example, seems to be able to play back essentially infinite amounts of video (I've certainly made it play tens of seconds, maybe minutes), and it doesn't appear to be showing me a lossy of lower precision image than when I view the stills, nor do I ever notice it pausing to refill a buffer (other than when it first starts up). So do apps like this work, particularly when the full image stack would exceed RAM? Anyway, doing this well is certainly a good sized summer project, don't fool yourself into thinking it's going to be a simple modification of the current timer and adding a couple buttons. -- Larry Gritz [email protected] _______________________________________________ Oiio-dev mailing list [email protected] http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
