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68 lines
2.5 KiB
C
68 lines
2.5 KiB
C
#include "coding.h"
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#include "../util.h"
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/* Nintendo GC Disc TracK streaming ADPCM (similar to CD-XA) */
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void decode_ngc_dtk(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do, int channel) {
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off_t frame_offset;
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int i, frames_in, sample_count = 0;
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size_t bytes_per_frame, samples_per_frame;
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uint8_t coef_index, shift_factor;
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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), stereo */
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bytes_per_frame = 0x20;
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samples_per_frame = 28;
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frames_in = first_sample / samples_per_frame;
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first_sample = first_sample % samples_per_frame;
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/* parse frame L/R header (repeated at 0x03/04) */
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frame_offset = stream->offset + bytes_per_frame*frames_in;
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coef_index = ((uint8_t)read_8bit(frame_offset+channel,stream->streamfile) >> 4) & 0xf;
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shift_factor = ((uint8_t)read_8bit(frame_offset+channel,stream->streamfile) >> 0) & 0xf;
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/* rare but happens, also repeated headers don't match (ex. Ikaruga (GC) SONG02.adp) */
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VGM_ASSERT_ONCE(coef_index > 4 || shift_factor > 12, "DTK: incorrect coefs/shift at %x\n", (uint32_t)frame_offset);
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/* decode nibbles */
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for (i = first_sample; i < first_sample+samples_to_do; i++) {
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int32_t hist = 0, new_sample;
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uint8_t nibbles = (uint8_t)read_8bit(frame_offset+0x04+i,stream->streamfile);
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/* apply XA filters << 6 */
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switch(coef_index) {
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case 0:
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hist = 0; // (hist1 * 0) - (hist2 * 0);
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break;
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case 1:
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hist = (hist1 * 60); // - (hist2 * 0);
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break;
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case 2:
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hist = (hist1 * 115) - (hist2 * 52);
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break;
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case 3:
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hist = (hist1 * 98) - (hist2 * 55);
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break;
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}
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hist = (hist + 32) >> 6;
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if (hist > 0x1fffff) hist = 0x1fffff;
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if (hist < -0x200000) hist = -0x200000;
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new_sample = (channel==0) ? /* L=low nibble first */
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get_low_nibble_signed(nibbles) :
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get_high_nibble_signed(nibbles);
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new_sample = (new_sample << 12) >> shift_factor;
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new_sample = (new_sample << 6) + hist;
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hist2 = hist1;
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hist1 = new_sample;
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outbuf[sample_count] = clamp16(new_sample >> 6);
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sample_count += channelspacing;
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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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