mirror of
https://github.com/vgmstream/vgmstream.git
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86 lines
3.0 KiB
C
86 lines
3.0 KiB
C
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#include "coding.h"
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#include "../util.h"
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/* FADPCM table */
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static const int8_t fadpcm_coefs[8][2] = {
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{ 0 , 0 },
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{ 60 , 0 },
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{ 122 , 60 },
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{ 115 , 52 },
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{ 98 , 55 },
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{ 0 , 0 },
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{ 0 , 0 },
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{ 0 , 0 },
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};
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/* FMOD's FADPCM, basically XA/PSX ADPCM with a fancy header layout.
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* Code/layout could be simplified but tries to emulate FMOD's code.
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* Algorithm and tables debugged from their PC DLLs. */
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void decode_fadpcm(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do) {
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off_t frame_offset;
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int i, j, k;
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int block_samples, num_frame, samples_done = 0, sample_count = 0;
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int coef_index[8], shift_factor[8];
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int32_t hist1; //= stream->adpcm_history1_32;
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int32_t hist2; //= stream->adpcm_history2_32;
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/* external interleave (fixed size), mono */
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block_samples = (0x8c - 0xc) * 2;
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num_frame = first_sample / block_samples;
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first_sample = first_sample % block_samples;
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frame_offset = stream->offset + 0x8c*num_frame;
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/* parse 0xc header */
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{
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uint32_t coefs, shifts;
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coefs = read_32bitLE(frame_offset + 0x00, stream->streamfile);
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shifts = read_32bitLE(frame_offset + 0x04, stream->streamfile);
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hist1 = read_16bitLE(frame_offset + 0x08, stream->streamfile);
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hist2 = read_16bitLE(frame_offset + 0x0a, stream->streamfile);
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for (i = 0; i < 8; i++) {
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coef_index[i] = (coefs >> i*4) & 0x0f;
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shift_factor[i] = (shifts >> i*4) & 0x0f;
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}
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/* header samples are not written to outbuf */
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}
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/* decode nibbles, grouped in 0x10 * 0x04 * 2 */
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for (i = 0; i < 8; i++) {
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off_t group_offset = frame_offset + 0x0c + 0x10*i;
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int32_t coef1 = fadpcm_coefs[(coef_index[i] % 0x07)][0]; /* indexes > 7 are repeats (ex. 0x9 is 0x2) */
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int32_t coef2 = fadpcm_coefs[(coef_index[i] % 0x07)][1];
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int32_t shift = 0x16 - shift_factor[i];
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for (j = 0; j < 4; j++) {
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uint32_t nibbles = read_32bitLE(group_offset + 0x04*j, stream->streamfile);
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for (k = 0; k < 8; k++) {
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int32_t new_sample;
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new_sample = (nibbles >> k*4) & 0x0f;
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new_sample = (new_sample << 28) >> shift; /* sign extend + scale */
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new_sample = (new_sample - hist2*coef2 + hist1*coef1);
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new_sample = new_sample >> 6; /* (new_sample / 64) has minor rounding differences */
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new_sample = clamp16(new_sample);
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if (sample_count >= first_sample && samples_done < samples_to_do) {
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outbuf[samples_done * channelspacing] = new_sample;
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samples_done++;
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}
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sample_count++;
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hist2 = hist1;
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hist1 = new_sample;
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}
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}
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}
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//stream->adpcm_history1_32 = hist1;
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//stream->adpcm_history2_32 = hist2;
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}
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