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70 lines
2.3 KiB
C
70 lines
2.3 KiB
C
#include "meta.h"
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#include "../coding/coding.h"
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#include "../util.h"
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#ifdef VGM_USE_MPEG
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/* AHX is a CRI format which contains an MPEG-2 Layer 2 audio stream.
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* Although the MPEG frame headers are incorrect... */
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VGMSTREAM * init_vgmstream_ahx(STREAMFILE *streamFile) {
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VGMSTREAM * vgmstream = NULL;
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off_t start_offset;
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int channel_count = 1;
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int loop_flag = 0;
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/* check extension, case insensitive */
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if ( !check_extensions(streamFile, "ahx") ) goto fail;
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/* check first 2 bytes */
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if ((uint16_t)read_16bitBE(0,streamFile)!=0x8000) goto fail;
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/* get stream offset, check for CRI signature just before */
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start_offset = (uint16_t)read_16bitBE(2,streamFile) + 4;
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if ((uint16_t)read_16bitBE(start_offset-6,streamFile)!=0x2863 ||/* "(c" */
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(uint32_t)read_32bitBE(start_offset-4,streamFile)!=0x29435249 /* ")CRI" */
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) goto fail;
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/* check for encoding type */
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/* 2 is for some unknown fixed filter, 3 is standard ADX, 4 is
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* ADX with exponential scale, 0x11 is AHX */
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/* Sappharad reports that old AHXs (Sonic Adventure 2) don't have this flag.
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* When I see one perhaps I can add an exception for those. */
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if (read_8bit(4,streamFile) != 0x11) goto fail;
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/* check for frame size (0 for AHX) */
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if (read_8bit(5,streamFile) != 0) goto fail;
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/* check for bits per sample? (0 for AHX) */
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if (read_8bit(6,streamFile) != 0) goto fail;
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/* check channel count (only mono AHXs are known) */
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if (read_8bit(7,streamFile) != 1) goto fail;
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/* At this point we almost certainly have an AHX file,
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* so let's build the VGMSTREAM. */
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vgmstream = allocate_vgmstream(channel_count,loop_flag);
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if (!vgmstream) goto fail;
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/* fill in the vital statistics */
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vgmstream->num_samples = read_32bitBE(0xc,streamFile);
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/* This is the One True Samplerate, the MPEG headers lie. */
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vgmstream->sample_rate = read_32bitBE(8,streamFile);
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vgmstream->coding_type = coding_MPEG_custom;
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vgmstream->layout_type = layout_none;
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vgmstream->meta_type = meta_AHX;
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vgmstream->codec_data = init_mpeg_codec_data_ahx(streamFile, start_offset, channel_count);
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if ( !vgmstream_open_stream(vgmstream, streamFile, start_offset) )
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goto fail;
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return vgmstream;
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fail:
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close_vgmstream(vgmstream);
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return NULL;
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}
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#endif
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