10 Replies Latest reply on Aug 1, 2015 9:27 PM by Rick Gerard

    rotobrush doesn't work in certain frames

    Lisyaorancrazed

      I had previously asked this but forgot to add tags and wasn't getting any answers so here's a repost. I'm trying to mask a short video of a character into another piece of footage so I apply the mask over the character but every couple frames it doesn't let me edit the mask. In the frame by frame preview and the mask starts to include more than what I want it to so, I go to subtract or, in some cases, add but neither action changes the mask and I'm left with a mask that is nothing like I want it to be. The frames before and after the one frame that doesn't work are fine although this happens with multiple frames. I've read this is because rotobrush can't find the edge of what I want to mask. Is that correct? and is there a way to fix this?

        • 1. Re: rotobrush doesn't work in certain frames
          Mylenium Most Valuable Participant

          Screenshots, system info, exact version of AE. No point in describing an invisible elephant.

           

          Mylenium

          • 2. Re: rotobrush doesn't work in certain frames
            Lisyaorancrazed Level 1

            Sorry. Mackbook Pro, After effects CS6, Screen Shot 2015-07-28 at 10.49.42 PM.pngthis is from one of the working frames

             

            Screen Shot 2015-07-28 at 10.49.57 PM.pngthis is what it looks like after I add to the mask

             

            Screen Shot 2015-07-28 at 10.47.31 PM.png this is the next frame and thats what it looks like before and after I try to add or subtract. Also, as you can see in the image, it says I need to set the composition to 52.122 fps but I did and that error still comes up and it comes up every time I use rotobrush. Maybe they're related?

            • 3. Re: rotobrush doesn't work in certain frames
              Rick Gerard Adobe Community Professional & MVP

              Is this screen cap footage? It looks very odd. It also looks like there are frame rate issues. You MUST use rotobrush correctly to have any success. Please type rotobrush in the search help field at the top right corner of AE and follow at least the first two or three explanations of how to use the tool.

              • 4. Re: rotobrush doesn't work in certain frames
                Lisyaorancrazed Level 1

                Before I do that, I would like to know what part of it you are referring to when you say it looks odd. This is what it looks like in the layer panel. I know it says the frame rate is off but I set it to the right rate and it didn't fix that. In fact, I had said that below the last screen cap in my last reply and asked if the problems were related.

                • 5. Re: rotobrush doesn't work in certain frames
                  Dave LaRonde Level 6

                  May we assume that you realize that there's NOTHING intuitive about using Rotobrush, that you've done all the appropriate training, and that this falls into the realm of something other than operator error?

                  • 6. Re: rotobrush doesn't work in certain frames
                    Lisyaorancrazed Level 1

                    about nothing being intuitive, yes you may assume that much. In my original explanation I did mention how I read something saying that it's because rotobrush couldn't find the edge of what I wanted to mask even though it was working fine but, that was the only answer to the only question I could find with someone that had the same problem. I asked if that was right in my original explanation but you probably read that part. As for going through appropriate training, well, I'm not sure what you would call appropriate but I know how to add and subtract from the roto, I know how and when to freeze it, I know hitting space makes it play frame by frame, I know how to change the frame rate, I know that I have to edit the roto almost every frame, and I know that I have to drag that grey barScreen Shot 2015-07-29 at 11.24.02 AM.png (not sure if there's a specific name for it so I thought I should put a screen cap)to cover the amount of frames I want to be masked. I've watched several tutorials before I even attempted the rotobrush but perhaps there was something basic they left out? If there is something I have not listed or that I may have gotten wrong that would make this operator error, please let me know.

                    • 7. Re: rotobrush doesn't work in certain frames
                      Rick Gerard Adobe Community Professional & MVP

                      If the black area is part of the original footage then try selecting that. It's probably compression that is fowling up your Roto.

                      • 8. Re: rotobrush doesn't work in certain frames
                        Lisyaorancrazed Level 1

                        Sorry, can you explain compression to me so I can make more sense of your suggestion.

                        • 9. Re: rotobrush doesn't work in certain frames
                          Lisyaorancrazed Level 1

                          If you want me to just try selecting the black part in the frames that don't work, know that I did that and it didn't work. I can't select ANYTHING in those frames. If that's not quite what you mean, please elaborate.

                          • 10. Re: rotobrush doesn't work in certain frames
                            Rick Gerard Adobe Community Professional & MVP

                            Does that footage already have an alpha channel? Where did you get the footage? It looks very odd. Rotobrush needs to be applied to a layer in a comp that has matching frame rates and some edge detail. Those screenshots don't tell us much about the original footage except that it looks very odd. It looks like it may be game play screen capture. If that is the case you may not be able to use Rotobrush because of the way the footage was captured.

                             

                            Compression is what happens to images when the color and luminance channels are resampled and compressed. Anyone doing video should learn at least the basics of color space and compression so they know what to look for when they have problems. Your footage is blotchy which indicates compression artifacts or scaling or low bit depth. It isn't very sharp. The black background looks like it may be an alpha channel. Sorry I can't be of more help but I just don't know what could be wrong because you have not provided any details about the original footage or your workflow to this point.