50 lines
1.3 KiB
C
50 lines
1.3 KiB
C
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#include "adts.h"
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const uint32_t freq_table[16] = {96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050,
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16000, 12000, 11025, 8000, 7350, 0, 0, 0};
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const short channel_table[8] = {0, 1, 2, 3, 4, 5, 6, 8};
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uint32_t parse_adts(char* buffer, struct ADTSData* out) {
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uint32_t tmp = 0;
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// sync word 0xfff
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tmp = (buffer[0] << 8) | (buffer[1] & 0xf0);
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if ((tmp & 0xffff) != 0xfff0)
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return 0;
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out->MPEG2 = (buffer[1] >> 3) & 0x1;
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// bit 17 to 18
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out->profile = (buffer[2] >> 6) + 1;
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// bit 19 to 22
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tmp = (buffer[2] >> 2) & 0xf;
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out->samplerate_idx = tmp;
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out->samplerate = (tmp > 15) ? 0 : freq_table[tmp];
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// bit 24 to 26
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tmp = ((buffer[2] & 0x1) << 2) | ((buffer[3] >> 6) & 0x3);
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out->channel_idx = tmp;
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out->channels = (tmp > 7) ? 0 : channel_table[tmp];
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// bit 55 to 56
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out->framecount = (buffer[6] & 0x3) + 1;
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// bit 31 to 43
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tmp = (buffer[3] & 0x3) << 11;
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tmp |= (buffer[4] << 3) & 0x7f8;
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tmp |= (buffer[5] >> 5) & 0x7;
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out->length = tmp;
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return tmp;
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}
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// last two bytes of MF AAC decoder user data
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uint16_t mf_get_aac_tag(struct ADTSData input) {
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uint16_t tag = 0;
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tag |= input.profile << 11;
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tag |= input.samplerate_idx << 7;
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tag |= input.channel_idx << 3;
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return tag;
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}
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