106 lines
2.9 KiB
C
106 lines
2.9 KiB
C
/*
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* aac.c: Frontend Status Monitor plugin for the Video Disk Recorder
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*
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* See the README file for copyright information and how to reach the author.
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*
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*/
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#include "tools.h"
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#include "aac.h"
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#define IS_HEAAC_AUDIO(buf) (((buf)[0] == 0xFF) && (((buf)[1] & 0xF6) == 0xF0))
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int cFemonAAC::sampleRateS[16] =
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{
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96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 16000, 12000, 11025, 8000, -1, -1, -1, -1
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};
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cFemonAAC::cFemonAAC(cFemonAudioIf *audioHandlerP)
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: audioHandlerM(audioHandlerP)
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{
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}
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cFemonAAC::~cFemonAAC()
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{
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}
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bool cFemonAAC::processAudio(const uint8_t *bufP, int lenP)
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{
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cFemonBitStream bs(bufP, lenP * 8);
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if (!audioHandlerM)
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return false;
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/* ADTS Fixed Header:
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* syncword 12b always: '111111111111'
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* id 1b 0: MPEG-4, 1: MPEG-2
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* layer 2b always: '00'
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* protection_absent 1b
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* profile 2b 0: Main profile AAC MAIN 1: Low Complexity profile (LC) AAC LC 2: Scalable Sample Rate profile (SSR) AAC SSR 3: (reserved) AAC LTP
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* sampling_frequency_index 4b
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* private_bit 1b
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* channel_configuration 3b
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* original/copy 1b
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* home 1b
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* emphasis 2b only if ID == 0 (ie MPEG-4)
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*/
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// skip PES header
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if (!PesLongEnough(lenP))
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return false;
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bs.SkipBits(8 * PesPayloadOffset(bufP));
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// HE-AAC audio detection
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if (bs.GetBits(12) != 0xFFF) // syncword
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return false;
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bs.SkipBit(); // id
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// layer must be 0
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if (bs.GetBits(2)) // layer
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return false;
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bs.SkipBit(); // protection_absent
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bs.SkipBits(2); // profile
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int sampling_frequency_index = bs.GetBits(4); // sampling_frequency_index
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bs.SkipBit(); // private pid
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int channel_configuration = bs.GetBits(3); // channel_configuration
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audioHandlerM->SetAudioCodec(AUDIO_CODEC_HEAAC);
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audioHandlerM->SetAudioBitrate(AUDIO_BITRATE_RESERVED);
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switch (channel_configuration) {
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case 0:
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audioHandlerM->SetAudioChannel(AUDIO_CHANNEL_MODE_STEREO);
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break;
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case 1:
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audioHandlerM->SetAudioChannel(AUDIO_CHANNEL_MODE_JOINT_STEREO);
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break;
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case 2:
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audioHandlerM->SetAudioChannel(AUDIO_CHANNEL_MODE_DUAL);
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break;
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case 3:
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audioHandlerM->SetAudioChannel(AUDIO_CHANNEL_MODE_SINGLE);
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break;
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default:
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audioHandlerM->SetAudioChannel(AUDIO_CHANNEL_MODE_INVALID);
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break;
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}
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switch (sampling_frequency_index) {
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case 0xC ... 0xF:
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audioHandlerM->SetAudioSamplingFrequency(AUDIO_SAMPLING_FREQUENCY_RESERVED);
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break;
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default:
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audioHandlerM->SetAudioSamplingFrequency(sampleRateS[sampling_frequency_index]);
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break;
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}
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return true;
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}
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