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accurate MTAF decoding

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git-svn-id: https://vgmstream.svn.sourceforge.net/svnroot/vgmstream@948 51a99a44-fe44-0410-b1ba-c3e57ba2b86b
This commit is contained in:
halleyscometsw 2011-05-14 08:00:40 +00:00
parent cf60da0f24
commit d321549532
1 changed files with 71 additions and 36 deletions
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107
src/coding/mtaf_decoder.c
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@ -4,36 +4,80 @@
#include "../util.h"
// A hybrid of IMA and Yamaha ADPCM found in Metal Gear Solid 3
// Currently this is all guesswork
int index_table[16] = {
-1, -1, -1, -1, 2, 4, 6, 8,
-1, -1, -1, -1, 2, 4, 6, 8
};
// This table is estimated by least-squares errors in the stored predictors
// .8 fixed point
int step_table[32] = {
455,558,651,779,940,1131,1354,1613,1937,2300,2734,3277,3882,4652,5553,6607,7855,9357,11153,13312,15871,18862,22477,26796,31915,38030,45309,53931,64264,76554,91181,108629,
// thanks to Sergey T. for pointing me to the step size table
static int16_t step_size[32][16] = {
{ 1, 5, 9, 13, 16, 20, 24, 28,
-1, -5, -9, -13, -16, -20, -24, -28, },
{ 2, 6, 11, 15, 20, 24, 29, 33,
-2, -6, -11, -15, -20, -24, -29, -33, },
{ 2, 7, 13, 18, 23, 28, 34, 39,
-2, -7, -13, -18, -23, -28, -34, -39, },
{ 3, 9, 15, 21, 28, 34, 40, 46,
-3, -9, -15, -21, -28, -34, -40, -46, },
{ 3, 11, 18, 26, 33, 41, 48, 56,
-3, -11, -18, -26, -33, -41, -48, -56, },
{ 4, 13, 22, 31, 40, 49, 58, 67,
-4, -13, -22, -31, -40, -49, -58, -67, },
{ 5, 16, 26, 37, 48, 59, 69, 80,
-5, -16, -26, -37, -48, -59, -69, -80, },
{ 6, 19, 31, 44, 57, 70, 82, 95,
-6, -19, -31, -44, -57, -70, -82, -95, },
{ 7, 22, 38, 53, 68, 83, 99, 114,
-7, -22, -38, -53, -68, -83, -99, -114, },
{ 9, 27, 45, 63, 81, 99, 117, 135,
-9, -27, -45, -63, -81, -99, -117, -135, },
{ 10, 32, 53, 75, 96, 118, 139, 161,
-10, -32, -53, -75, -96, -118, -139, -161, },
{ 12, 38, 64, 90, 115, 141, 167, 193,
-12, -38, -64, -90, -115, -141, -167, -193, },
{ 15, 45, 76, 106, 137, 167, 198, 228,
-15, -45, -76, -106, -137, -167, -198, -228, },
{ 18, 54, 91, 127, 164, 200, 237, 273,
-18, -54, -91, -127, -164, -200, -237, -273, },
{ 21, 65, 108, 152, 195, 239, 282, 326,
-21, -65, -108, -152, -195, -239, -282, -326, },
{ 25, 77, 129, 181, 232, 284, 336, 388,
-25, -77, -129, -181, -232, -284, -336, -388, },
{ 30, 92, 153, 215, 276, 338, 399, 461,
-30, -92, -153, -215, -276, -338, -399, -461, },
{ 36, 109, 183, 256, 329, 402, 476, 549,
-36, -109, -183, -256, -329, -402, -476, -549, },
{ 43, 130, 218, 305, 392, 479, 567, 654,
-43, -130, -218, -305, -392, -479, -567, -654, },
{ 52, 156, 260, 364, 468, 572, 676, 780,
-52, -156, -260, -364, -468, -572, -676, -780, },
{ 62, 186, 310, 434, 558, 682, 806, 930,
-62, -186, -310, -434, -558, -682, -806, -930, },
{ 73, 221, 368, 516, 663, 811, 958, 1106,
-73, -221, -368, -516, -663, -811, -958, -1106, },
{ 87, 263, 439, 615, 790, 966, 1142, 1318,
-87, -263, -439, -615, -790, -966, -1142, -1318, },
{ 104, 314, 523, 733, 942, 1152, 1361, 1571,
-104, -314, -523, -733, -942, -1152, -1361, -1571, },
{ 124, 374, 623, 873, 1122, 1372, 1621, 1871,
-124, -374, -623, -873, -1122, -1372, -1621, -1871, },
{ 148, 445, 743, 1040, 1337, 1634, 1932, 2229,
-148, -445, -743, -1040, -1337, -1634, -1932, -2229, },
{ 177, 531, 885, 1239, 1593, 1947, 2301, 2655,
-177, -531, -885, -1239, -1593, -1947, -2301, -2655, },
{ 210, 632, 1053, 1475, 1896, 2318, 2739, 3161,
-210, -632, -1053, -1475, -1896, -2318, -2739, -3161, },
{ 251, 753, 1255, 1757, 2260, 2762, 3264, 3766,
-251, -753, -1255, -1757, -2260, -2762, -3264, -3766, },
{ 299, 897, 1495, 2093, 2692, 3290, 3888, 4486,
-299, -897, -1495, -2093, -2692, -3290, -3888, -4486, },
{ 356, 1068, 1781, 2493, 3206, 3918, 4631, 5343,
-356, -1068, -1781, -2493, -3206, -3918, -4631, -5343, },
{ 424, 1273, 2121, 2970, 3819, 4668, 5516, 6365,
-424, -1273, -2121, -2970, -3819, -4668, -5516, -6365, },
};
int delta_table[16] = {
1, 3, 5, 7, 9, 11, 13, 15,
-1, -3, -5, -7, -9,-11,-13,-15
};
// convert from .8 fixed to nearest int
static int16_t roundy(long v)
{
if (v > 0)
{
return (v+0x80)/0x100;
}
else
{
return -(((-v)+0x80)/0x100);
}
}
void decode_mtaf(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do, int channel, int channels) {
int32_t sample_count;
@ -43,7 +87,7 @@ void decode_mtaf(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing,
int c = channel%2;
int16_t init_idx = read_16bitLE(cur_off+4+c*2, stream->streamfile);
int16_t init_hist = read_16bitLE(cur_off+8+c*4, stream->streamfile);
int32_t hist = stream->adpcm_history1_32;
int32_t hist = stream->adpcm_history1_16;
int step_idx = stream->adpcm_step_index;
//printf("channel %d: first_sample = %d, stream->offset = 0x%lx, cur_off = 0x%lx init_idx = %d\n", channel, first_sample, (unsigned long)stream->offset, cur_off, init_idx);
@ -62,7 +106,7 @@ void decode_mtaf(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing,
first_sample = first_sample%0x100;
if (first_sample%0x100 == 0) {
hist = init_hist*0x100;
hist = init_hist;
#if 0
if (step_idx != init_idx) {
@ -88,18 +132,9 @@ void decode_mtaf(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing,
nibble = byte >> 4;
}
hist += delta_table[nibble] * step_table[step_idx];
hist = clamp16(hist+step_size[step_idx][nibble]);
if (hist > INT16_MAX*0x100L)
{
hist = INT16_MAX*0x100L;
}
if (hist < INT16_MIN*0x100L)
{
hist = INT16_MIN*0x100L;
}
outbuf[sample_count] = roundy(hist);
outbuf[sample_count] = hist;
step_idx += index_table[nibble];
if (step_idx < 0)
@ -114,6 +149,6 @@ void decode_mtaf(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing,
// update state
stream->adpcm_step_index = step_idx;
stream->adpcm_history1_32 = hist;
stream->adpcm_history1_16 = hist;
}