x264 zones parameter

Is the "zones" parameter ever working? I've tried to do an encode with both vbv-enabled (for bluray, so maxrate 39 Mbps and bufsize 30 Mbps) and without vbv. In both cases the encoder seems to ignore the values. Just as a test, I've tried Code:

Zones can't change ratecontrol modes in the middle of an encode; you're using bitrate mode, so you can't switch to CRF for a section of the encode. You can apply a bitrate weight though, I think (I don't remember the syntax for this though).

I've tried "Q" and "B" too (which sets respectively a constant quantizer or a bitrate multiplier). for example --zones 307,376,b=0.1 In all cases, the result is almost the same. It seems that my attempt to force the bitrate/quantizer is ignored during the encode process.

Did you have the zones specified in the 1st pass? I did some quick (non BD) 1pass CRF tests and it works ok

Yes, I've setup the zone (the same, copy/pasted) on both passes. Edit: I'm investigating, because sometimes it appears to abide the forced quantizer. Edit2: Ok, it seems to work. VBV take precedence over quantizer/bitrate override so it doesn't lower q/b at adjacent GOPs (to conform to both VBV and override) but it simply ignore it. Also (and this was my mistake) when using seek+frames parameters (to start the encoder at a different place) the frames specified in the zone doesn't correspond anymore (at least it seems to me). Is this confirmed?

I did some more tests with VBV and BD parameters 2pass and it seems to work ok But I didn't test the results of --seek or --frames . But wouldn't it make sense that the frame reference numbers change? Effectively it becomes a different video as if you had cut it with something else (e.g. Trim() in avisynth) , so shouldn't the zone numbers change ?

I've tried to change QP of frames 377/378 due to high distorted output (QP>25, it starts a new scene so it's very visible). Changing only those 2 frames produces no visible alteration (probably due to the fact that the previous scene is indeed very hard so probably the bitrate was maximized to vbv). Lowering 353 to 376 (previous GOP) with b=0.7 and forcing 377/378 with QP=9 worked as expected. Regarding the seek/frames and zones... I think it should work (imho) in a small different way. Let me explain: if I want to trim (and nothing more) I can do that via AviSynth or other ways around (for example a different export). Seek+frames should also be very useful for debug purposes. For example to test zones very far from the beginning of a movie. If I want to "zone" frame 100.000 and see the results, I simply can't encode the whole film (hours+hours of encode and for more tests the hours increase even more) so it can be very useful to start at frame 98.000 and then encode 3.000 frames to see the results. This allows to keep the zones/qpfile intact (as a reference, it's the whole film). Basically the encoder should consider that the starting frame is not 0 but 98.000 and then should apply the zones/qpfile accordingly... at least I think this would be more useful. In this way it can be simply used in both ways (simple trim and debug).

I wrote a tool to help with seek and zones/qpfile:

Uh, thanks cretindesalpes! I'll put a look at it! Thanks also to all the contributors of this thread