[x264-devel] Encoder questions

[vpstranger at tutanota.com]

Hello!
I've recently started using x264 and I have a couple of questions.

The default deadzone size (21 for inter blocks,11 for intra) seems large to me. If the 21 interval is centered at zero, then all the frequency coefficients less than 10.5 will turn to zero with this deadzone. As I understand, there are quite many of them which are lower than this value and the compression literature that I read mentioned much less deadzone. So why is it so big?

When I see the encode stats for each frame, I see that for all B frames there is the amount of P blocks listed and no B blocks. I assume it is a program error, isn't it?

When I tried to calculate SSIM for each frame, I got a warning in the log that with adaptive quantization turned off SSIM calculation will be incorrect. I don't understand how these two are related. Adaptive quantization modifies quantization parameter values for different blocks in a frame, so why is it not possible to calculate the metric correctly if it is turned off?
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