[x264-devel] Default value for the --scenecut option causes heavy undesirable flood of I slices in active scenes

[Vladimir Chernyshov]

You can download the sample from 
http://koti.welho.com/vchernys/raw-d2.1.y4m.bz2 (~94MB)

Decompress it with bzip2 before feeding to x.264 (bzip2 -d xxx.bz2).

The drop in the bitrate is most drastic in the CQP mode (qcomp=1). In 
this mode, x.264 causes most B and P frames to be exchanged for I 
frames, and because I frames by default are quantized with much lower QP 
than the configured crf value, this causes the average quality to be 
greatly higher than requested and the corresponding waste of bits.

regards,
Vladimir


Marc Schulz wrote:
> Could you provide samples of your source?
> 
> I'm interested to see the quality difference between the two with such a 
> drastic drop in the bitrate at the given crf value. I would imagine the 
> quality drop to be substantial.
> 
>