Q: Is it possible to mask frames in h264 w/o reencoding?

[Andy_Scull]

I usually use VDubMod to do that, but it doesn't work with new mkvs. The only option is avs but quality drops a lot :(. Anyone knows if there's a way to process h264 video stream masking the frames I want, and directly put it to another file? Even at keyframes would be fine.
I do it for all tv series, to mask op/end and still have the same video timecode(for ext subs/audio/compatibility etc). Before that I was cutting the videos but now I like it this way.

[Andy_Scull]

I managed to do that. If anyone's interested - here are the steps i took -
1. split original mkv using mkvtoolnix (mmg.exe, split at timecodes)
2. open one of resulting files in vdmod (errors because of vfr, no picture at all)
3. select everything but first and last frame
4. mask and save.
5. merge everything back into one file.
And here it it - same times, no openings/closings, size is -50mb compared to orig.