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vdr-plugin-femon/femonlatm.c

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/*
* Frontend Status Monitor plugin for the Video Disk Recorder
*
* See the README file for copyright information and how to reach the author.
*
*/
#include "femontools.h"
#include "femonlatm.h"
unsigned int cFemonLATM::s_Bitrates[3][16] =
{
{0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, -1}, // MPEG-2 Layer I
{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, -1}, // MPEG-2 Layer II/III
{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, -1} // MPEG-2 Layer II/III
};
unsigned int cFemonLATM::s_Samplerates[4] =
{
22050, 24000, 16000, -1
};
cFemonLATM::cFemonLATM(cFemonAudioIf *audiohandler)
: m_AudioHandler(audiohandler)
{
}
cFemonLATM::~cFemonLATM()
{
}
bool cFemonLATM::processAudio(const uint8_t *buf, int len)
{
cBitStream bs(buf, len * 8);
if (!m_AudioHandler)
return false;
// skip PES header
if (!PesLongEnough(len))
return false;
bs.skipBits(8 * PesPayloadOffset(buf));
// MPEG audio detection
if (bs.getBits(12) != 0x56E) // syncword
return false;
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m_AudioHandler->SetAudioCodec(AUDIO_CODEC_LATM);
if (bs.getBit() == 0) // id: MPEG-1=1, extension to lower sampling frequencies=0
return true; // @todo: lower sampling frequencies support
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int layer = 3 - bs.getBits(2); // layer: I=11, II=10, III=01
bs.skipBit(); // protection bit
int bit_rate_index = bs.getBits(4); // bitrate index
int sampling_frequency = bs.getBits(2); // sampling frequency
bs.skipBit(); // padding bit
bs.skipBit(); // private pid
int mode = bs.getBits(2); // mode
switch (mode) {
case 0:
m_AudioHandler->SetAudioChannel(AUDIO_CHANNEL_MODE_STEREO);
break;
case 1:
m_AudioHandler->SetAudioChannel(AUDIO_CHANNEL_MODE_JOINT_STEREO);
break;
case 2:
m_AudioHandler->SetAudioChannel(AUDIO_CHANNEL_MODE_DUAL);
break;
case 3:
m_AudioHandler->SetAudioChannel(AUDIO_CHANNEL_MODE_SINGLE);
break;
default:
m_AudioHandler->SetAudioChannel(AUDIO_CHANNEL_MODE_INVALID);
break;
}
if (layer == 3) {
m_AudioHandler->SetAudioBitrate(AUDIO_BITRATE_FREE);
}
else {
switch (bit_rate_index) {
case 0:
m_AudioHandler->SetAudioBitrate(AUDIO_BITRATE_FREE);
break;
case 0xF:
m_AudioHandler->SetAudioBitrate(AUDIO_BITRATE_RESERVED);
break;
default:
m_AudioHandler->SetAudioBitrate(1000 * s_Bitrates[layer][bit_rate_index]);
break;
}
}
switch (sampling_frequency) {
case 3:
m_AudioHandler->SetAudioSamplingFrequency(AUDIO_SAMPLING_FREQUENCY_RESERVED);
break;
default:
m_AudioHandler->SetAudioSamplingFrequency(s_Samplerates[sampling_frequency]);
break;
}
return true;
}