[x264-devel] Getting the quantization stepsize (not QP)

[BugMaster]

On Wed, 07 Dec 2016 17:31:48 +0000, Eymen Kurdoglu wrote:
> Hi all,

> Is there a way to get the mean value of the quantization stepsize
> (QS) used in a frame, instead of the mean value of the QP used
> (which is the one that the debug log outputs)? Due to the non-linear
> mapping between the quantization stepsize and the QP, finding the QS
> equivalent of the mean QP is not equal to the actual mean value of the QS. 

> I would appreciate it if someone can direct me to the part of the code that might change this. 

> Here are the specific settings I'm using in my app.
> High profile, veryfast, zerolatency, single thread, no scene-cuts,
> no weighted prediction and the RC parameters are:
> param.rc.i_rc_method = X264_RC_ABR;
> param.rc.i_bitrate = i_target;
> param.rc.i_vbv_max_bitrate = param.rc.i_bitrate;
> param.rc.i_vbv_buffer_size = param.rc.i_bitrate/10; 

> Thanks a lot, and have a nice day!

> Eymen

Hi. What do you mean exactly by quantization stepsize (QS)? This is
the first time I see this term used especially with H.264 encoding.