hi everyone i also experienced all of mochas problems like that one you experienced. Working with mocha, you have to know these steps in mind.
First you have to save as much as different versions of your mocha projects. save it every 10minutes, make it a habit and turn off the auto save in the preferences. Save manually by using save as command. auto save in mocha gets your life in hell if you save big roto projects.
Second, mocha is very unstable in windows xp. I am using 64bit vista and it is running smoothly. one issue of mocha is it’s non multicore capability. Think thrice before using the motion blur, rendering can take forever with this limitation, so unless mocha is multithreaded and 64bit capable then mocha is on top of the food chain.
Third, the GUI view of mocha is in fact very slow, so don’t get shocked when you move both the spline points so slow, this is really a mess that can make your roto job so slow, unless you are working with SD resolutions then speed it just optimal but still not fast. Until there is a new version of mocha that can solve these issues, just be aware.
Fourth, working with mocha is fun. the planar tracking is the only reason why mocha is useful, i don’t know why mocha is not capable of doing very simple tasks like other compositing apps. You can’t copy and paste keyframes, if there is then it is done on a hard way going on the curves editor, you also get errors when you are tracking and your memory is not enough. if you get errors do not save your project. instead kill the mocha process. because if you save it, i’m sure if you have 10 layers of complex roto only one layer can be retrieved. it is a mess for sure. that is why you have to save every second if you can and save different versions also.
Fifth the most important issue i see is i can’t see the actual motion blur in mocha, there is no preview when you apply blurs in your spline, and the worst like when i tested it on a 2k film with only 76frames on full motion blur on you are just wasting time. it takes forever rendering it with motion blur, after it is done rendering at last after 3 hours, the worst is when you playback the rendered clip.hehehe you can see your mattes turning on and off. This is really a mess when working with large resolution in mocha. My solution is to render just parts one by one with motion blur and composite that in fusion to get the full merged motion blurred matte. if you are in hurry better do your manual blurring of the matte in compositing, you can save time instead of waiting hours.
I am just saying these things based on experience after working a year and a half with mocha. Mocha is a nice roto and tracking app. only that it is still needs a lot of improvement to be an industry standard roto tool. It is very unstable. before you work in mocha you have to know mocha. What is the purpose of this powerful tool if it cant even render perfectly, it cant even save securely project files, and the worse, is it is slow on performance and cannot get the job done withoout encountering software bugs. I hope imagineers can address these issues on its next version, i am sure many are experiencing trouble with mocha. thanks. peace.