330 lines
11 KiB
C
330 lines
11 KiB
C
/********************************************************************
|
|
* *
|
|
* THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE. *
|
|
* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
|
|
* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
|
|
* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
|
|
* *
|
|
* THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2009 *
|
|
* by the Xiph.Org Foundation and contributors http://www.xiph.org/ *
|
|
* *
|
|
********************************************************************
|
|
|
|
function:
|
|
last mod: $Id$
|
|
|
|
********************************************************************/
|
|
|
|
#include <string.h>
|
|
#include "internal.h"
|
|
#include "dct.h"
|
|
|
|
/*Performs an inverse 8 point Type-II DCT transform.
|
|
The output is scaled by a factor of 2 relative to the orthonormal version of
|
|
the transform.
|
|
_y: The buffer to store the result in.
|
|
Data will be placed in every 8th entry (e.g., in a column of an 8x8
|
|
block).
|
|
_x: The input coefficients.
|
|
The first 8 entries are used (e.g., from a row of an 8x8 block).*/
|
|
static void idct8(ogg_int16_t *_y,const ogg_int16_t _x[8]){
|
|
ogg_int32_t t[8];
|
|
ogg_int32_t r;
|
|
/*Stage 1:*/
|
|
/*0-1 butterfly.*/
|
|
t[0]=OC_C4S4*(ogg_int16_t)(_x[0]+_x[4])>>16;
|
|
t[1]=OC_C4S4*(ogg_int16_t)(_x[0]-_x[4])>>16;
|
|
/*2-3 rotation by 6pi/16.*/
|
|
t[2]=(OC_C6S2*_x[2]>>16)-(OC_C2S6*_x[6]>>16);
|
|
t[3]=(OC_C2S6*_x[2]>>16)+(OC_C6S2*_x[6]>>16);
|
|
/*4-7 rotation by 7pi/16.*/
|
|
t[4]=(OC_C7S1*_x[1]>>16)-(OC_C1S7*_x[7]>>16);
|
|
/*5-6 rotation by 3pi/16.*/
|
|
t[5]=(OC_C3S5*_x[5]>>16)-(OC_C5S3*_x[3]>>16);
|
|
t[6]=(OC_C5S3*_x[5]>>16)+(OC_C3S5*_x[3]>>16);
|
|
t[7]=(OC_C1S7*_x[1]>>16)+(OC_C7S1*_x[7]>>16);
|
|
/*Stage 2:*/
|
|
/*4-5 butterfly.*/
|
|
r=t[4]+t[5];
|
|
t[5]=OC_C4S4*(ogg_int16_t)(t[4]-t[5])>>16;
|
|
t[4]=r;
|
|
/*7-6 butterfly.*/
|
|
r=t[7]+t[6];
|
|
t[6]=OC_C4S4*(ogg_int16_t)(t[7]-t[6])>>16;
|
|
t[7]=r;
|
|
/*Stage 3:*/
|
|
/*0-3 butterfly.*/
|
|
r=t[0]+t[3];
|
|
t[3]=t[0]-t[3];
|
|
t[0]=r;
|
|
/*1-2 butterfly.*/
|
|
r=t[1]+t[2];
|
|
t[2]=t[1]-t[2];
|
|
t[1]=r;
|
|
/*6-5 butterfly.*/
|
|
r=t[6]+t[5];
|
|
t[5]=t[6]-t[5];
|
|
t[6]=r;
|
|
/*Stage 4:*/
|
|
/*0-7 butterfly.*/
|
|
_y[0<<3]=(ogg_int16_t)(t[0]+t[7]);
|
|
/*1-6 butterfly.*/
|
|
_y[1<<3]=(ogg_int16_t)(t[1]+t[6]);
|
|
/*2-5 butterfly.*/
|
|
_y[2<<3]=(ogg_int16_t)(t[2]+t[5]);
|
|
/*3-4 butterfly.*/
|
|
_y[3<<3]=(ogg_int16_t)(t[3]+t[4]);
|
|
_y[4<<3]=(ogg_int16_t)(t[3]-t[4]);
|
|
_y[5<<3]=(ogg_int16_t)(t[2]-t[5]);
|
|
_y[6<<3]=(ogg_int16_t)(t[1]-t[6]);
|
|
_y[7<<3]=(ogg_int16_t)(t[0]-t[7]);
|
|
}
|
|
|
|
/*Performs an inverse 8 point Type-II DCT transform.
|
|
The output is scaled by a factor of 2 relative to the orthonormal version of
|
|
the transform.
|
|
_y: The buffer to store the result in.
|
|
Data will be placed in every 8th entry (e.g., in a column of an 8x8
|
|
block).
|
|
_x: The input coefficients.
|
|
Only the first 4 entries are used.
|
|
The other 4 are assumed to be 0.*/
|
|
static void idct8_4(ogg_int16_t *_y,const ogg_int16_t _x[8]){
|
|
ogg_int32_t t[8];
|
|
ogg_int32_t r;
|
|
/*Stage 1:*/
|
|
t[0]=OC_C4S4*_x[0]>>16;
|
|
t[2]=OC_C6S2*_x[2]>>16;
|
|
t[3]=OC_C2S6*_x[2]>>16;
|
|
t[4]=OC_C7S1*_x[1]>>16;
|
|
t[5]=-(OC_C5S3*_x[3]>>16);
|
|
t[6]=OC_C3S5*_x[3]>>16;
|
|
t[7]=OC_C1S7*_x[1]>>16;
|
|
/*Stage 2:*/
|
|
r=t[4]+t[5];
|
|
t[5]=OC_C4S4*(ogg_int16_t)(t[4]-t[5])>>16;
|
|
t[4]=r;
|
|
r=t[7]+t[6];
|
|
t[6]=OC_C4S4*(ogg_int16_t)(t[7]-t[6])>>16;
|
|
t[7]=r;
|
|
/*Stage 3:*/
|
|
t[1]=t[0]+t[2];
|
|
t[2]=t[0]-t[2];
|
|
r=t[0]+t[3];
|
|
t[3]=t[0]-t[3];
|
|
t[0]=r;
|
|
r=t[6]+t[5];
|
|
t[5]=t[6]-t[5];
|
|
t[6]=r;
|
|
/*Stage 4:*/
|
|
_y[0<<3]=(ogg_int16_t)(t[0]+t[7]);
|
|
_y[1<<3]=(ogg_int16_t)(t[1]+t[6]);
|
|
_y[2<<3]=(ogg_int16_t)(t[2]+t[5]);
|
|
_y[3<<3]=(ogg_int16_t)(t[3]+t[4]);
|
|
_y[4<<3]=(ogg_int16_t)(t[3]-t[4]);
|
|
_y[5<<3]=(ogg_int16_t)(t[2]-t[5]);
|
|
_y[6<<3]=(ogg_int16_t)(t[1]-t[6]);
|
|
_y[7<<3]=(ogg_int16_t)(t[0]-t[7]);
|
|
}
|
|
|
|
/*Performs an inverse 8 point Type-II DCT transform.
|
|
The output is scaled by a factor of 2 relative to the orthonormal version of
|
|
the transform.
|
|
_y: The buffer to store the result in.
|
|
Data will be placed in every 8th entry (e.g., in a column of an 8x8
|
|
block).
|
|
_x: The input coefficients.
|
|
Only the first 3 entries are used.
|
|
The other 5 are assumed to be 0.*/
|
|
static void idct8_3(ogg_int16_t *_y,const ogg_int16_t _x[8]){
|
|
ogg_int32_t t[8];
|
|
ogg_int32_t r;
|
|
/*Stage 1:*/
|
|
t[0]=OC_C4S4*_x[0]>>16;
|
|
t[2]=OC_C6S2*_x[2]>>16;
|
|
t[3]=OC_C2S6*_x[2]>>16;
|
|
t[4]=OC_C7S1*_x[1]>>16;
|
|
t[7]=OC_C1S7*_x[1]>>16;
|
|
/*Stage 2:*/
|
|
t[5]=OC_C4S4*t[4]>>16;
|
|
t[6]=OC_C4S4*t[7]>>16;
|
|
/*Stage 3:*/
|
|
t[1]=t[0]+t[2];
|
|
t[2]=t[0]-t[2];
|
|
r=t[0]+t[3];
|
|
t[3]=t[0]-t[3];
|
|
t[0]=r;
|
|
r=t[6]+t[5];
|
|
t[5]=t[6]-t[5];
|
|
t[6]=r;
|
|
/*Stage 4:*/
|
|
_y[0<<3]=(ogg_int16_t)(t[0]+t[7]);
|
|
_y[1<<3]=(ogg_int16_t)(t[1]+t[6]);
|
|
_y[2<<3]=(ogg_int16_t)(t[2]+t[5]);
|
|
_y[3<<3]=(ogg_int16_t)(t[3]+t[4]);
|
|
_y[4<<3]=(ogg_int16_t)(t[3]-t[4]);
|
|
_y[5<<3]=(ogg_int16_t)(t[2]-t[5]);
|
|
_y[6<<3]=(ogg_int16_t)(t[1]-t[6]);
|
|
_y[7<<3]=(ogg_int16_t)(t[0]-t[7]);
|
|
}
|
|
|
|
/*Performs an inverse 8 point Type-II DCT transform.
|
|
The output is scaled by a factor of 2 relative to the orthonormal version of
|
|
the transform.
|
|
_y: The buffer to store the result in.
|
|
Data will be placed in every 8th entry (e.g., in a column of an 8x8
|
|
block).
|
|
_x: The input coefficients.
|
|
Only the first 2 entries are used.
|
|
The other 6 are assumed to be 0.*/
|
|
static void idct8_2(ogg_int16_t *_y,const ogg_int16_t _x[8]){
|
|
ogg_int32_t t[8];
|
|
ogg_int32_t r;
|
|
/*Stage 1:*/
|
|
t[0]=OC_C4S4*_x[0]>>16;
|
|
t[4]=OC_C7S1*_x[1]>>16;
|
|
t[7]=OC_C1S7*_x[1]>>16;
|
|
/*Stage 2:*/
|
|
t[5]=OC_C4S4*t[4]>>16;
|
|
t[6]=OC_C4S4*t[7]>>16;
|
|
/*Stage 3:*/
|
|
r=t[6]+t[5];
|
|
t[5]=t[6]-t[5];
|
|
t[6]=r;
|
|
/*Stage 4:*/
|
|
_y[0<<3]=(ogg_int16_t)(t[0]+t[7]);
|
|
_y[1<<3]=(ogg_int16_t)(t[0]+t[6]);
|
|
_y[2<<3]=(ogg_int16_t)(t[0]+t[5]);
|
|
_y[3<<3]=(ogg_int16_t)(t[0]+t[4]);
|
|
_y[4<<3]=(ogg_int16_t)(t[0]-t[4]);
|
|
_y[5<<3]=(ogg_int16_t)(t[0]-t[5]);
|
|
_y[6<<3]=(ogg_int16_t)(t[0]-t[6]);
|
|
_y[7<<3]=(ogg_int16_t)(t[0]-t[7]);
|
|
}
|
|
|
|
/*Performs an inverse 8 point Type-II DCT transform.
|
|
The output is scaled by a factor of 2 relative to the orthonormal version of
|
|
the transform.
|
|
_y: The buffer to store the result in.
|
|
Data will be placed in every 8th entry (e.g., in a column of an 8x8
|
|
block).
|
|
_x: The input coefficients.
|
|
Only the first entry is used.
|
|
The other 7 are assumed to be 0.*/
|
|
static void idct8_1(ogg_int16_t *_y,const ogg_int16_t _x[1]){
|
|
_y[0<<3]=_y[1<<3]=_y[2<<3]=_y[3<<3]=
|
|
_y[4<<3]=_y[5<<3]=_y[6<<3]=_y[7<<3]=(ogg_int16_t)(OC_C4S4*_x[0]>>16);
|
|
}
|
|
|
|
/*Performs an inverse 8x8 Type-II DCT transform.
|
|
The input is assumed to be scaled by a factor of 4 relative to orthonormal
|
|
version of the transform.
|
|
All coefficients but the first 3 in zig-zag scan order are assumed to be 0:
|
|
x x 0 0 0 0 0 0
|
|
x 0 0 0 0 0 0 0
|
|
0 0 0 0 0 0 0 0
|
|
0 0 0 0 0 0 0 0
|
|
0 0 0 0 0 0 0 0
|
|
0 0 0 0 0 0 0 0
|
|
0 0 0 0 0 0 0 0
|
|
0 0 0 0 0 0 0 0
|
|
_y: The buffer to store the result in.
|
|
This may be the same as _x.
|
|
_x: The input coefficients.*/
|
|
static void oc_idct8x8_3(ogg_int16_t _y[64],ogg_int16_t _x[64]){
|
|
ogg_int16_t w[64];
|
|
int i;
|
|
/*Transform rows of x into columns of w.*/
|
|
idct8_2(w,_x);
|
|
idct8_1(w+1,_x+8);
|
|
/*Transform rows of w into columns of y.*/
|
|
for(i=0;i<8;i++)idct8_2(_y+i,w+i*8);
|
|
/*Adjust for the scale factor.*/
|
|
for(i=0;i<64;i++)_y[i]=(ogg_int16_t)(_y[i]+8>>4);
|
|
/*Clear input data for next block.*/
|
|
_x[0]=_x[1]=_x[8]=0;
|
|
}
|
|
|
|
/*Performs an inverse 8x8 Type-II DCT transform.
|
|
The input is assumed to be scaled by a factor of 4 relative to orthonormal
|
|
version of the transform.
|
|
All coefficients but the first 10 in zig-zag scan order are assumed to be 0:
|
|
x x x x 0 0 0 0
|
|
x x x 0 0 0 0 0
|
|
x x 0 0 0 0 0 0
|
|
x 0 0 0 0 0 0 0
|
|
0 0 0 0 0 0 0 0
|
|
0 0 0 0 0 0 0 0
|
|
0 0 0 0 0 0 0 0
|
|
0 0 0 0 0 0 0 0
|
|
_y: The buffer to store the result in.
|
|
This may be the same as _x.
|
|
_x: The input coefficients.*/
|
|
static void oc_idct8x8_10(ogg_int16_t _y[64],ogg_int16_t _x[64]){
|
|
ogg_int16_t w[64];
|
|
int i;
|
|
/*Transform rows of x into columns of w.*/
|
|
idct8_4(w,_x);
|
|
idct8_3(w+1,_x+8);
|
|
idct8_2(w+2,_x+16);
|
|
idct8_1(w+3,_x+24);
|
|
/*Transform rows of w into columns of y.*/
|
|
for(i=0;i<8;i++)idct8_4(_y+i,w+i*8);
|
|
/*Adjust for the scale factor.*/
|
|
for(i=0;i<64;i++)_y[i]=(ogg_int16_t)(_y[i]+8>>4);
|
|
/*Clear input data for next block.*/
|
|
_x[0]=_x[1]=_x[2]=_x[3]=_x[8]=_x[9]=_x[10]=_x[16]=_x[17]=_x[24]=0;
|
|
}
|
|
|
|
/*Performs an inverse 8x8 Type-II DCT transform.
|
|
The input is assumed to be scaled by a factor of 4 relative to orthonormal
|
|
version of the transform.
|
|
_y: The buffer to store the result in.
|
|
This may be the same as _x.
|
|
_x: The input coefficients.*/
|
|
static void oc_idct8x8_slow(ogg_int16_t _y[64],ogg_int16_t _x[64]){
|
|
ogg_int16_t w[64];
|
|
int i;
|
|
/*Transform rows of x into columns of w.*/
|
|
for(i=0;i<8;i++)idct8(w+i,_x+i*8);
|
|
/*Transform rows of w into columns of y.*/
|
|
for(i=0;i<8;i++)idct8(_y+i,w+i*8);
|
|
/*Adjust for the scale factor.*/
|
|
for(i=0;i<64;i++)_y[i]=(ogg_int16_t)(_y[i]+8>>4);
|
|
/*Clear input data for next block.*/
|
|
for(i=0;i<64;i++)_x[i]=0;
|
|
}
|
|
|
|
/*Performs an inverse 8x8 Type-II DCT transform.
|
|
The input is assumed to be scaled by a factor of 4 relative to orthonormal
|
|
version of the transform.*/
|
|
void oc_idct8x8_c(ogg_int16_t _y[64],ogg_int16_t _x[64],int _last_zzi){
|
|
/*_last_zzi is subtly different from an actual count of the number of
|
|
coefficients we decoded for this block.
|
|
It contains the value of zzi BEFORE the final token in the block was
|
|
decoded.
|
|
In most cases this is an EOB token (the continuation of an EOB run from a
|
|
previous block counts), and so this is the same as the coefficient count.
|
|
However, in the case that the last token was NOT an EOB token, but filled
|
|
the block up with exactly 64 coefficients, _last_zzi will be less than 64.
|
|
Provided the last token was not a pure zero run, the minimum value it can
|
|
be is 46, and so that doesn't affect any of the cases in this routine.
|
|
However, if the last token WAS a pure zero run of length 63, then _last_zzi
|
|
will be 1 while the number of coefficients decoded is 64.
|
|
Thus, we will trigger the following special case, where the real
|
|
coefficient count would not.
|
|
Note also that a zero run of length 64 will give _last_zzi a value of 0,
|
|
but we still process the DC coefficient, which might have a non-zero value
|
|
due to DC prediction.
|
|
Although convoluted, this is arguably the correct behavior: it allows us to
|
|
use a smaller transform when the block ends with a long zero run instead
|
|
of a normal EOB token.
|
|
It could be smarter... multiple separate zero runs at the end of a block
|
|
will fool it, but an encoder that generates these really deserves what it
|
|
gets.
|
|
Needless to say we inherited this approach from VP3.*/
|
|
/*Then perform the iDCT.*/
|
|
if(_last_zzi<=3)oc_idct8x8_3(_y,_x);
|
|
else if(_last_zzi<=10)oc_idct8x8_10(_y,_x);
|
|
else oc_idct8x8_slow(_y,_x);
|
|
}
|