[Mp4-tech] How to convert 4X4 interger transform to equivalent
dct transform
乾
luckyking gmail.com
Thu Aug 11 15:42:58 ESTEDT 2005
X is the original 4 * 4 martrix,
Y is the DCT coefficient matrix
Y = AXA' and X = A'YA
a a a a
A = b c -c b ;
a -a -a a
c -b b -c
a=1/2 ; b=sqrt(1/2)cos(PI/8) ; c = sqrt(1/2)cos(3*PI/8)
is can be equivalent as below:
Y = ( CXC')#E
# means that to the result matrix's coefficient is to mutiply the two
coefficient at the response position.
Here,
1 1 1 1
C = 1 d -d -1 ;d = c/b =0.414,
1 -1 -1 1
d -d 1 -d
for simplification and maintain orthogonality, made d = 0.5 and b = sqrt(2/5);
make the second line and forth line of C multiple with 2, so as the
second colomn and forth conomn. Named it as Cf
also make E corresponding Ef
to make Y = (CfXCf')#Ef
we get Cf and Ef:
1 1 1 1
Cf= 2 1 -1 -2
1 -1 -1 1
1 -2 2 -1
And:
a*a a*b/2 a*a a*b/2
Ef= a*b/2 b*b/4 a*b/2 b*b/4
a*a a*b/2 a*a a*b/2
a*b/2 b*b/4 a*b/2 b*b/4
H.264 make #Ef in quantification Process.
On 8/11/05, mp4-tech-request lists.mpegif.org
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> 1. How to convert 4X4 interger transform to equivalent dct
> transform (tummala kalyani)
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Wed, 10 Aug 2023 17:28:46 +0530
> From: tummala kalyani <tummalakalyani gmail.com>
> Subject: [Mp4-tech] How to convert 4X4 interger transform to
> equivalent dct transform
> To: mp4-tech lists.mpegif.org
> Message-ID: <13936ad5050810045829078b11 mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> can any one explain me to how to convert 4 X 4 integer transform used
> in H.264 to normal 4X4 dct transform matrix.
>
> --
> Kalyani Tummala
> M.Tech CSE II year
> MBM Hall of Residence- #B2
> IIT Kharagpur - 721302
> mobile: 919932736720
>
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