[vlc-devel] The quantization parameter QP in x264.c

Ilkka Ollakka ileoo at videolan.org
Wed Jul 25 10:52:09 CEST 2012

On Tue, Jul 24, 2012 at 03:53:51PM +0100, Moad Toutou wrote:
> Hello,


> I just installed the codec vlc compilation mode. I documented the
> process of video compression and I found that video compression goes
> through several stages. The step of quantization step is the most
> impotent because this is when we decide the rate of compression. The
> quantization step manipulates a parameter called: The quantization
> parameter. I want to extract and learn which part of the code is
> implemented ?

You should check x264 sourcecode, which actually implements the
encoding, vlc side is just code to utilize libx264 inside vlc.

> For a given video, I would like to display (fprintf("Qp=%d",qp)) the
> corresponding value of qp.  I looked at the file x264.c, I do not see
> where is calculated the  quantization paramaitre QP

> I would be grateful to give me ideas on this problem.

> Thank you in advance.
Ilkka Ollakka
If life is a stage, I want some better lighting.
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