113 lines
2.9 KiB
C
113 lines
2.9 KiB
C
/*
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* latm.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 "latm.h"
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int cFemonLATM::bitrateS[3][16] =
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{
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{0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, -1}, // MPEG-2 Layer I
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{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, -1}, // MPEG-2 Layer II/III
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{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, -1} // MPEG-2 Layer II/III
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};
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int cFemonLATM::sampleRateS[4] =
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{
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22050, 24000, 16000, -1
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};
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cFemonLATM::cFemonLATM(cFemonAudioIf *audioHandlerP)
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: audioHandlerM(audioHandlerP)
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{
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}
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cFemonLATM::~cFemonLATM()
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{
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}
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bool cFemonLATM::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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// 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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// MPEG audio detection
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if (bs.GetBits(12) != 0x56E) // syncword
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return false;
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audioHandlerM->SetAudioCodec(AUDIO_CODEC_LATM);
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if (bs.GetBit() == 0) // id: MPEG-1=1, extension to lower sampling frequencies=0
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return true; // @todo: lower sampling frequencies support
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int layer = 3 - bs.GetBits(2); // layer: I=11, II=10, III=01
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bs.SkipBit(); // protection bit
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int bit_rate_index = bs.GetBits(4); // bitrate index
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int sampling_frequency = bs.GetBits(2); // sampling frequency
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bs.SkipBit(); // padding bit
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bs.SkipBit(); // private pid
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int mode = bs.GetBits(2); // mode
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switch (mode) {
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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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if (layer == 3) {
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audioHandlerM->SetAudioBitrate(AUDIO_BITRATE_FREE);
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}
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else {
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switch (bit_rate_index) {
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case 0:
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audioHandlerM->SetAudioBitrate(AUDIO_BITRATE_FREE);
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break;
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case 0xF:
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audioHandlerM->SetAudioBitrate(AUDIO_BITRATE_RESERVED);
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break;
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default:
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audioHandlerM->SetAudioBitrate(1000 * bitrateS[layer][bit_rate_index]);
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break;
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}
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}
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switch (sampling_frequency) {
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case 3:
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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]);
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break;
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}
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return true;
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}
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