Rotoscoping long sequences
by Matthew Beall
on
Oct 26, 2009 at 8:49:38 pm
I have a very long sequence of HDV footage, about 12,000 frames.. I need to blacken out the actors face.. I usually do this in combustion. I am evaluating mocha for this, as the demo videos make planar tracking look very fast an useful. However, I find interactivity to be very slow. The HDV footage is a TGA sequence. Should I turn cache off? Playback is slow, and tracking is extremely slow.. Is there another file format that would give me better speed?
Re: Rotoscoping long sequences by John-Paul Smith on Oct 26, 2009 at 10:59:00 pm
Hi Matthew,
TGA should be a good format to use, although if you have the material in a compressed format such as an HDV-encoded QuickTime movie that will probably be faster. In any case, if your footage resides on a fast disc, you should definitely turn off caching. Make sure you turn it off in preferences (Output Settings | Cache Original Clip) and you should get the best performance. Caching is only useful when your footage is on a slow network drive and you have pointed your cache folder in preferences to be a fast local drive.
Make sure the Texture RAM to reserve setting in mocha preferences is at a good value. 75% of the RAM on your graphics card would be a safe bet. More texture RAM means a longer section can be scrubbed at full speed, but setting this value too high will slow things down and make the software unstable.
What kind of hardware are you using?
Tracking speed is highly dependent on the size of the area you're tracking and the amount of motion. If you're tracking an area with lots of texture, you could get away with reducing the Min % Pixels Used on the Track tab, which will speed things up. On my laptop, I experimented tracking an area about 200x100 on a long HDV TGA sequence and got about 2fps. I'd expect a desktop machine to be faster, maybe 4fps, but this would be in the normal performance range for mocha. The tracker is doing a lot more work than a point tracker, giving much more robust results, but the trade off is that it will be slower.
Re: Rotoscoping long sequences by Matthew Beall on Oct 27, 2009 at 3:32:16 pm
What kind of hardware are you using?
I tried it on both a dual-core 3ghz notebook, and a 2.5ghz quad-core notebook.. Both were about what your tests were, 2 or 3 frames a sec..
I also can't seem to cache out very many frames for real-time scrubbing, which would be essential for checking the rotoscope spline.. I think I could get maybe 40 or 50 frames.. Most of my clips are around 900-1000 frames, I would like to cache out at least half of those so I can play or scrub at realtime..
I hope I can figure it out, I'd really like to use mocha.. I have lots of other scenes in this project where I could use planar tracking..
