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Diffstat (limited to 'media/libtheora/lib/idct.c')
| -rw-r--r-- | media/libtheora/lib/idct.c | 330 |
1 files changed, 330 insertions, 0 deletions
diff --git a/media/libtheora/lib/idct.c b/media/libtheora/lib/idct.c new file mode 100644 index 0000000000..838e3ad8ca --- /dev/null +++ b/media/libtheora/lib/idct.c @@ -0,0 +1,330 @@ +/******************************************************************** + * * + * 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); +} |