how to edit i-frames without re-encoding of h264 ?

[ChristianUndCo]

I have HD material from restored films. But the recording service has its channel logo in it.

The logo is completely in the black border and as I strongly suspect, the logo is only saved in the I-frames. (no motion vectors are affected)

Now I have done the following manually:

I deleted the first I-frame from the h264 elementary stream using a hex editor.

I encoded an I-frame with a covered logo in the same settings (!) as the original stream.

I used the hex editor to copy the new I-frame into the place of the old one.

And what can I say: it works! The logo is gone and the stream is intact. Every player (even the very critical ones) does not display a logo until the next I-frame.

So it works manually!

The only flaw is that I have completely re-encoded the I-frame. This should also be lossless. So patch the I-frame at the position and patch the position, where the logo is, to black.

Is there a tool of Bento4 that can help me with that? At first find macroblocks (only in I-frames) of the logo and paint them black?