[Mp4-tech] H.264: about the caculation of mvCLX
Alan Thomson
A.Thomson indigovision.com
Tue Jun 28 16:29:56 EDT 2005
Hi -
The equations are correct; the text is misleading.
Delete "multiplying", insert "dividing" and it makes more sense.
For example a luma component of 3 (quarter-luma-samples)
yields a chroma component of 3 (eighth-chroma-samples).
BR,
Alan
> -----Original Message-----
> From: AngelZhang innosis.com.cn [mailto:AngelZhang innosis.com.cn]
> Sent: 28 June 2023 02:47
> To: mp4-tech lists.mpegif.org
> Subject: [Mp4-tech] H.264: about the caculation of mvCLX
>
>
> hi experts,
> In the part 8.4.1.4 of H264 standard,the description of mvCLX's
> derivation is written as following:
> "if the current macroblock is a frame macroblock,the horizontal and
> vertical components of the chroma motion vector mvCLX are derived by
> multiplying the corresponding components of luma motion
> vector mvLX by 2,
> through mapping one-quarter sample mvLX units to one-eighth
> sample mvCLX
> units"
> but the formular :
> mvCLX[0]=mvLX[0]
> mvCLX[1]=mvLX[1]
> havn't implement what the standard has said to multiply 2.
>
> i am confused about it very much.please give me your idea.
>
> thanks
> angel
>
>
>
>
>
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