Emulating Line Shuffling Encryption

[Spuff]

Hello all,

Very strange request, for a video I'm working on I need to make a model of an old British(ish) video encryption standard used by the BBC, that being Videocrypt-S. For clarity this is not vanilla Videocrypt which there is home-brew software to emulate but it's a totally different beast using a line cut & rotate.

That's not especially interesting, but in essence what I need to do is to be able to shuffle videolines.

The standard should be a field split in to blocks of 6x47 lines (no idea about the remaining 6, in my experiments I've just tagged them on to the bottom, it's not vitally important, this is just for a demonstration - it's not explained the BBC Whitepaper either).

The lines within the blocks of 47 should be randomly shuffled on one field, the other field can be left clear. Source file is 720x576.

Can you do randomised line manipulation in AVISynth as I'm tying myself up in knots here and getting nowhere or it is futile?

Pointers welcome, otherwise I'll come up with a solution using AE.

Thank you all

[johnmeyer]

Look over in doom9.org for a guy named StainlessS. He developed an AVISynth package called RT_stats. It includes a random number generator called RT_RandInt. Click here:

RT_stats RT_RandInt

AVISynth does, of course, have a built-in random number generator, Rand, but it will give you the same random numbers each time it is run. RandInt is supposed to give you different numbers each time.

[Spuff]

Ah @johnmeyer that's brilliant, I'll take a look!

Thanks!