Originally Posted by poisondeathray View Post
Yes, intra wouldn't rely on info from other frames

The problem is , even adding 1 frame , can alter the frametype distribution and bitrate distribution . (It will depend on content) . So your patch size can balloon up. On some content that end frame might be coded as a P-frame, but that can effect small changes to say frames 5-6 previous. And, x264 is more complex than that, it uses prediction on macroblock basis, not just frames. This will be unpredictable
This is exactly what i have been seeing!, sometimes its really good saving, sometimes its awful, and when i modify smal changes with the bitrate it seems to dramatically change whether its good or awful with no predictable results.

Small changes to 5-6 may be ok, as long as they are small! the bit for bit differencing will cope with that at a cost of describing those frames which have changed is small (if its large, then its competing with jpg compression again).

It sounds like whatever i do with this, it wont be scientific. There is an added disaster that the sequence of images at the start could be just 1 image or many hundreds of images long over time, which would make the bitrate calculation difficult (maybe impossible - ive not solved it yet), as a default bitrate would need to be defined and not changed from patch to patch.

Originally Posted by poisondeathray View Post
I'll give it some more thought, but I think the best way to go is still Intra only, and you're right the bitrate savings will be miniscule for 1 frame anyways (not worth it). However, the bitrate savings for a sequence is huge when using x264 vs. jpeg still images
Thanks, i appreciate your help, and your clarifications, alot of what you have described, im seeing and now i understand a bit better why.

I'll try the intra suggestion and post my findings.