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[sangean]

On 12/07/2016 09:33 PM, BugMaster wrote:
> On Wed, 07 Dec 2016 20:08:36 +0000, Eymen Kurdoglu wrote:
>> Thanks for your quick reply. I've been told that what I've referred
>> to as QS might be the qscale in x264.
>> Essentially I'm interested in the quantity given by 4+6*log2( QP ).
> I am dunno where you have taken this formula but if you need
> linearized quantizer (not logarithmic as QP) than yes qscale is what
> you need. It is calculated as:
>
> /* Terminology:
>   * qp = h.264's quantizer
>   * qscale = linearized quantizer = Lagrange multiplier
>   */
> static inline float qp2qscale( float qp )
> {
>      return 0.85f * powf( 2.0f, ( qp - (12.0f + QP_BD_OFFSET) ) / 6.0f );
> }
>
> where QP_BD_OFFSET is 0 for 8-bit and 12 for 10-bit encoding.
>
>> If getting this quantity for each MB is not possible/difficult, it
>> would also help me to just record the mean QP used in each MB of each frame.
> As you feature request is of very limited benefit (if any) to others
> libx264 users I doubt it would be added (at least I am not going to
> add it). I even don't understand what for you needed it and what
> benefit you get. So if this for some research project and not
> production need than you have better chance to patch libx264 yourself
> and change API to whatever you need.
>
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