Simulate green areas of bad compression

[elmuz]

Hi all,
a friend of mine is doing a quite professional short movie. He wants to generate in a precise part of the video that annoyng green artifacts, due to bad compression. You can find them often in porn movies, emule-like...

I attach a sample...


He tried with After Effects but the results were too fake, even the sound wasn't perfect...

I think there are two ways...
1) Simulate by graphics, using After Effects... any idea or tutorial? Never heard about...
2) Generate it by wanted bad compression... possible?
2b) Doing it by the player, trying seek the video in a wrong position... suggestion?

I know it is a really strange question, he wants the audience to think there are technical problems in the cinema...

Thank you in advance...

[jagabo]

I've done it by writing garbage in the middle of a file with a hex editor.

[elmuz]

I've done it by writing garbage in the middle of a file with a hex editor.

Thank you!
Could you be more precise? If I find an HexEdit will I be able to upload a video directly? Let's say... export .avi MJEPG high quality would be ok?
Then... what do you mean by garbage? Random?
Will Premiere read that file or will I need any particular player/reader?

Thanks

[jagabo]

What you are doing is corrupting the video.Filling random sections with zeros usually gives green blocks like that. And it's difficult to get the junk exactly where you want it.

By the way, this is a nasty trick. Loading a corrupt video like this can crash the editor. I wouldn't use such a video directly in a production but rather recompress it so that the garbage is part of a new non-corrupt video. Or, if you have a corrupt video already, you could do the opposite of a green screen. Instead of making the green parts transparent make the rest transparent.

[elmuz]

It works! Great!
Even if it doesn't come out with green it produced an interesting result... I think it's just a matter of the amount of garbage inserted...
Thank you again!

[jagabo]

Glad it worked out for you. For a little more accuracy, you can use VirtualDub's hex editor along with its RIFF Chunk Tree viewer. It doesn't support copy/paste so I would use it as a guide to locating frames, then use your other hex editor to corrupt them.

And again, I wouldn't use the corrupt file in an project, but rather recompress it with VirtualDub so that the decoding errors are part of a new AVI without any errors. That way you don't risk crashing the editor after importing the video.