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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/>.
dabplussnoop.cpp
Extract MSC data and parse DAB+ frames from a ETI file
Authors:
Matthias P. Braendli <matthias@mpb.li>
*/
/* From the spec:
subchannel_index = MSC sub-channel size (kbps) / 8
audio_super_frame_size (bytes) = subchannel_index * 110
// Derived from
// au_start[n] = au_start[n - 1] + au_size[n - 1] + 2;
// 2 bytes for CRC
au_size[n] = au_start[n+1] - au_start[n] - 2;
he_aac_super_frame(subchannel_index)
{
he_aac_super_frame_header()
{
header_firecode 16
rfa 1
dac_rate 1
sbr_flag 1
aac_channel_mode 1
ps_flag 1
mpeg_surround_config 3
// end of audio parameters
if ((dac_rate == 0) && (sbr_flag == 1)) num_aus = 2;
// AAC core sampling rate 16 kHz
if ((dac_rate == 1) && (sbr_flag == 1)) num_aus = 3;
// AAC core sampling rate 24 kHz
if ((dac_rate == 0) && (sbr_flag == 0)) num_aus = 4;
// AAC core sampling rate 32 kHz
if ((dac_rate == 1) && (sbr_flag == 0)) num_aus = 6;
// AAC core sampling rate 48 kHz
for (n = 1; n < num_aus; n++) {
au_start[n]; 12
}
if !((dac_rate == 1) && (sbr_flag == 1))
alignment 4
}
for (n = 0; n < num_aus; n++) {
au[n] 8 * au_size[n]
au_crc[n] 16
}
}
*/
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <sstream>
#include <vector>
#include "faad_decoder.hpp"
#pragma once
// DabPlusSnoop is responsible for decoding DAB+ audio
class DabPlusSnoop {
public:
void set_subchannel_index(unsigned subchannel_index) {
m_subchannel_index = subchannel_index;
}
void enable_wav_file_output(bool enable) {
m_write_to_wav_file = enable;
}
void push(uint8_t* streamdata, size_t streamsize);
audio_statistics_t get_audio_statistics(void) const;
int subchid = -1;
private:
/* Data needed for FAAD */
FaadDecoder m_faad_decoder;
bool m_write_to_wav_file = false;
bool m_ps_flag = false;
bool m_aac_channel_mode = false;
bool m_dac_rate = false;
bool m_sbr_flag = false;
int m_mpeg_surround_config = false;
/* Functions */
bool seek_valid_firecode(void);
bool decode(void);
bool extract_au(std::vector<int> au_start);
bool analyse_au(std::vector<std::vector<uint8_t> >& aus);
unsigned m_subchannel_index = 0;
std::vector<uint8_t> m_data;
};
// StreamSnoop is responsible for saving msc data into files,
// and calling DabPlusSnoop's decode routine if it's a DAB+ subchannel
class StreamSnoop {
public:
StreamSnoop(int subchid, bool dump_to_file) :
dps(),
m_subchid(subchid),
m_raw_data_stream_fd(nullptr),
m_dump_to_file(dump_to_file) {
dps.subchid = subchid;
dps.enable_wav_file_output(dump_to_file);
}
~StreamSnoop();
StreamSnoop(StreamSnoop&& other);
StreamSnoop(const StreamSnoop& other) = delete;
StreamSnoop& operator=(const StreamSnoop& other) = delete;
void set_subchannel_index(unsigned subchannel_index)
{
dps.set_subchannel_index(subchannel_index);
}
void push(uint8_t* streamdata, size_t streamsize);
audio_statistics_t get_audio_statistics(void) const;
int stream_index = -1;
private:
DabPlusSnoop dps;
int m_subchid = -1;
FILE* m_raw_data_stream_fd;
bool m_dump_to_file;
};
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