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/*
Copyright (C) 2017 Matthias P. Braendli (http://www.opendigitalradio.org)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
faad_decoder.cpp
Use libfaad to decode the AAC content of the DAB+ subchannel
Authors:
Matthias P. Braendli <matthias@mpb.li>
*/
#include "faad_decoder.hpp"
extern "C" {
#include "wavfile.h"
}
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <cassert>
#include <string>
#include <sstream>
#include <vector>
using namespace std;
FaadDecoder::FaadDecoder() :
m_data_len(0),
m_fd(nullptr),
m_initialised(false)
{
}
void FaadDecoder::open(string filename, bool ps_flag, bool aac_channel_mode,
bool dac_rate, bool sbr_flag, int mpeg_surround_config)
{
m_filename = filename;
m_ps_flag = ps_flag;
m_aac_channel_mode = aac_channel_mode;
m_dac_rate = dac_rate;
m_sbr_flag = sbr_flag;
m_mpeg_surround_config = mpeg_surround_config;
}
bool FaadDecoder::decode(vector<vector<uint8_t> > aus)
{
for (size_t au_ix = 0; au_ix < aus.size(); au_ix++) {
vector<uint8_t>& au = aus[au_ix];
NeAACDecFrameInfo hInfo;
int16_t* outBuffer;
if (!m_initialised) {
/* AudioSpecificConfig structure (the only way to select 960 transform here!)
*
* 00010 = AudioObjectType 2 (AAC LC)
* xxxx = (core) sample rate index
* xxxx = (core) channel config
* 100 = GASpecificConfig with 960 transform
*
* SBR: implicit signaling sufficient - libfaad2 automatically assumes SBR on sample rates <= 24 kHz
* => explicit signaling works, too, but is not necessary here
*
* PS: implicit signaling sufficient - libfaad2 therefore always uses stereo output (if PS support was enabled)
* => explicit signaling not possible, as libfaad2 does not support AudioObjectType 29 (PS)
*/
int core_sr_index = m_dac_rate ? (m_sbr_flag ? 6 : 3) : (m_sbr_flag ? 8 : 5); // 24/48/16/32 kHz
int core_ch_config = get_aac_channel_configuration();
if(core_ch_config == -1) {
printf("Unrecognized mpeg surround config (ignored): %d\n", m_mpeg_surround_config);
return false;
}
uint8_t asc[2];
asc[0] = 0b00010 << 3 | core_sr_index >> 1;
asc[1] = (core_sr_index & 0x01) << 7 | core_ch_config << 3 | 0b100;
long unsigned samplerate;
unsigned char channels;
long int init_result = NeAACDecInit2(m_faad_handle.decoder, asc, sizeof(asc), &samplerate, &channels);
if(init_result != 0) {
/* If some error initializing occured, skip the file */
printf("Error initializing decoder library: %s\n", NeAACDecGetErrorMessage(-init_result));
NeAACDecClose(m_faad_handle.decoder);
return false;
}
m_initialised = true;
}
outBuffer = (int16_t *)NeAACDecDecode(m_faad_handle.decoder, &hInfo, &au[0], au.size());
assert(outBuffer != nullptr);
m_sample_rate = hInfo.samplerate;
m_channels = hInfo.channels;
size_t samples = hInfo.samples;
#if 0
printf("bytes consumed %d\n", (int)(hInfo.bytesconsumed));
printf("samplerate = %d, samples = %zu, channels = %d,"
" error = %d, sbr = %d\n", m_sample_rate, samples,
m_channels, hInfo.error, hInfo.sbr);
printf("header = %d\n", hInfo.header_type);
#endif
if (hInfo.error != 0) {
printf("FAAD Warning: %s\n",
faacDecGetErrorMessage(hInfo.error));
return false;
}
if (m_fd == nullptr) {
stringstream ss;
ss << m_filename << ".wav";
m_fd = wavfile_open(ss.str().c_str(), m_sample_rate);
}
if (samples) {
if (m_channels == 1) {
int16_t *buffer = (int16_t *)alloca (2 * samples);
size_t i;
for (i = 0; i < samples; i ++) {
buffer [2 * i] = ((int16_t *)outBuffer) [i];
buffer [2 * i + 1] = buffer [2 * i];
}
wavfile_write(m_fd, buffer, 2*samples);
}
else if (m_channels == 2) {
wavfile_write(m_fd, outBuffer, samples);
}
else {
printf("Cannot handle %d channels\n", m_channels);
}
}
}
return true;
}
void FaadDecoder::close()
{
if (m_fd) {
wavfile_close(m_fd);
}
}
int FaadDecoder::get_aac_channel_configuration()
{
switch(m_mpeg_surround_config) {
case 0: // no surround
return m_aac_channel_mode ? 2 : 1;
case 1: // 5.1
return 6;
case 2: // 7.1
return 7;
default:
return -1;
}
}
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