116 lines
2.8 KiB
C
116 lines
2.8 KiB
C
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#include "ADTSHeader.h"
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#include "foundation/error.h"
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enum
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{
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ADTS_NOT_PROTECTED=1,
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ADTS_PROTECTED=0,
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ADTS_SYNC = 0xFFF,
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ADTS_MAIN = 0x00,
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ADTS_LC = 0x01,
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ADTS_SSR = 0x10,
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ADTS_LTP = 0x11,
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};
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int nsaac_adts_parse(nsaac_adts_header_t header, const uint8_t *buffer)
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{
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unsigned int syncword = (buffer[0] << 4) | (buffer[1] >> 4);
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unsigned int layer;
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unsigned int sample_rate_index;
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if (syncword != ADTS_SYNC)
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return NErr_LostSynchronization;
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header->syncword = syncword;
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header->id = (buffer[1] >> 3) & 1;
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layer = (buffer[1] >> 1) & 3;
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if (layer != 0)
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return NErr_WrongFormat;
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header->layer = layer;
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header->protection = (buffer[1]) & 1;
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header->profile = (buffer[2] >> 6) & 3;
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sample_rate_index = (buffer[2] >> 2) & 0xF;
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if (sample_rate_index == 15)
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return NErr_UnsupportedFormat; // might actually be OK if we can separately signal the sample rate
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if (sample_rate_index > 13)
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return NErr_Reserved;
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header->sample_rate_index = sample_rate_index;
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header->private_bit = (buffer[2] >> 1) & 1;
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header->channel_configuration = ((buffer[2] & 1) << 2) | ((buffer[3] >> 6) & 3);
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header->original = (buffer[3] >> 5) &1;
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header->home = (buffer[3] >> 4) &1;
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//copyright_identification_bit = (buffer[3] >> 3) & 1;
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//copyright_identification_start = (buffer[3] >> 2) & 1;
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header->frame_length = ((buffer[3] & 3) << 11) | (buffer[4]<<3) | ((buffer[5] >> 5) & 7);
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header->buffer_fullness = ((buffer[5] & 0x1F) << 6) | (buffer[6] >> 2);
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header->num_data_blocks = buffer[6] & 3;
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return NErr_Success;
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}
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static const unsigned int aac_sratetab[] =
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{
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96000,
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88200,
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64000,
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48000,
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44100,
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32000,
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24000,
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22050,
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16000,
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12000,
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11025,
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8000,
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7350,
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};
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unsigned int nsaac_adts_get_samplerate(nsaac_adts_header_t header)
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{
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return aac_sratetab[header->sample_rate_index];
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}
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int nsaac_adts_match(nsaac_adts_header_t header1, nsaac_adts_header_t header2)
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{
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if (header1->id != header2->id)
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return NErr_False;
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if (header1->profile != header2->profile)
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return NErr_False;
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if (header1->sample_rate_index != header2->sample_rate_index)
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return NErr_False;
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if (header1->channel_configuration != header2->channel_configuration)
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return NErr_False;
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return NErr_True;
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}
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int nsaac_adts_get_channel_count(nsaac_adts_header_t header)
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{
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switch(header->channel_configuration)
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{
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case 7:
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return 8;
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default:
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return header->channel_configuration;
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}
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}
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size_t nsaac_adts_get_header_size(nsaac_adts_header_t header)
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{
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if (header->protection == ADTS_PROTECTED)
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return 9;
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else
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return 7;
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}
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size_t nsaac_adts_get_frame_bitrate(nsaac_adts_header_t header)
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{
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uint64_t bitrate = nsaac_adts_get_samplerate(header) * header->frame_length * 8 / 1024;
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return (size_t)bitrate;
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}
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