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-rw-r--r--src/dabplussnoop.cpp324
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diff --git a/src/dabplussnoop.cpp b/src/dabplussnoop.cpp
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+/*
+ Copyright (C) 2014, 2015 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
+ Parse DAB+ frames from a ETI file
+
+ Authors:
+ Matthias P. Braendli <matthias@mpb.li>
+ Mathias Coinchon <coinchon@yahoo.com>
+*/
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <string>
+#include <cassert>
+#include <sstream>
+#include <algorithm>
+#include <vector>
+#include "dabplussnoop.hpp"
+extern "C" {
+#include "firecode.h"
+#include "lib_crc.h"
+}
+#include "faad_decoder.hpp"
+#include "rsdecoder.hpp"
+
+#define DPS_INDENT "\t\t"
+#define DPS_PREFIX "DAB+ decode:"
+
+#define DPS_DEBUG 0
+
+using namespace std;
+
+void DabPlusSnoop::push(uint8_t* streamdata, size_t streamsize)
+{
+ // Try to decode audio
+ size_t original_size = m_data.size();
+ m_data.resize(original_size + streamsize);
+ memcpy(&m_data[original_size], streamdata, streamsize);
+
+ if (seek_valid_firecode()) {
+ // m_data now points to a valid header
+
+ if (decode()) {
+
+ // First dump to subchannel file (superframe+parity word)
+ if (m_raw_data_stream_fd == NULL) {
+ stringstream dump_filename;
+ dump_filename << "stream-" << m_index << ".msc";
+
+ m_raw_data_stream_fd = fopen(dump_filename.str().c_str(), "w");
+
+ if (m_raw_data_stream_fd == NULL) {
+ perror("File open failed");
+ }
+ }
+
+ fwrite(&m_data[0], m_subchannel_index, 120, m_raw_data_stream_fd);
+
+ // We have been able to decode the AUs, now flush vector
+ m_data.clear();
+ }
+ }
+}
+
+// Idea and some code taken from Xpadxpert
+bool DabPlusSnoop::seek_valid_firecode()
+{
+ if (m_data.size() < 10) {
+ // Not enough data
+ return false;
+ }
+
+ bool crc_ok = false;
+ size_t i;
+
+ for (i = 0; i < m_data.size() - 10; i++) {
+ uint8_t* b = &m_data[i];
+
+ // the three bytes after the firecode must not be zero
+ // (simple plausibility check to avoid sync in zero byte region)
+ if (b[3] != 0x00 || (b[4] & 0xF0) != 0x00) {
+ uint16_t header_firecode = (b[0] << 8) | b[1];
+ uint16_t calculated_firecode = firecode_crc(b+2, 9);
+
+ if (header_firecode == calculated_firecode) {
+ crc_ok = true;
+ break;
+ }
+ }
+ }
+
+ if (crc_ok) {
+#if DPS_DEBUG
+ printf(DPS_PREFIX " Found valid FireCode at %zu\n", i);
+#endif
+ //erase elements before the header
+ m_data.erase(m_data.begin(), m_data.begin() + i);
+ return true;
+ }
+ else {
+#if DPS_DEBUG
+ printf(DPS_PREFIX " No valid FireCode found\n");
+#endif
+
+ m_data.clear();
+ return false;
+ }
+}
+
+bool DabPlusSnoop::decode()
+{
+#if DPS_DEBUG
+ printf(DPS_PREFIX " We have %zu bytes of data\n", m_data.size());
+#endif
+
+ const size_t sf_len = m_subchannel_index * 120;
+ if (m_subchannel_index && m_data.size() >= sf_len) {
+ std::vector<uint8_t> b(sf_len);
+ std::copy(m_data.begin(), m_data.begin() + sf_len, b.begin());
+
+ RSDecoder rs_dec;
+ int rs_errors = rs_dec.DecodeSuperframe(b, m_subchannel_index);
+
+ if (rs_errors == -1) {
+ return false;
+ }
+
+ // -- Parse he_aac_super_frame
+ // ---- Parse he_aac_super_frame_header
+ // ------ Parse firecode and audio params
+ uint16_t header_firecode = (b[0] << 8) | b[1];
+ uint8_t audio_params = b[2];
+ int rfa = (audio_params & 0x80) ? true : false;
+ m_dac_rate = (audio_params & 0x40) ? true : false;
+ m_sbr_flag = (audio_params & 0x20) ? true : false;
+ m_aac_channel_mode = (audio_params & 0x10) ? true : false;
+ m_ps_flag = (audio_params & 0x08) ? true : false;
+ m_mpeg_surround_config = (audio_params & 0x07);
+
+ int num_aus;
+ if (!m_dac_rate && m_sbr_flag) num_aus = 2;
+ // AAC core sampling rate 16 kHz
+ else if (m_dac_rate && m_sbr_flag) num_aus = 3;
+ // AAC core sampling rate 24 kHz
+ else if (!m_dac_rate && !m_sbr_flag) num_aus = 4;
+ // AAC core sampling rate 32 kHz
+ else if (m_dac_rate && !m_sbr_flag) num_aus = 6;
+ // AAC core sampling rate 48 kHz
+
+#if DPS_DEBUG
+ printf( DPS_INDENT DPS_PREFIX "\n"
+ DPS_INDENT "\tfirecode 0x%x\n"
+ DPS_INDENT "\trfa %d\n"
+ DPS_INDENT "\tdac_rate %d\n"
+ DPS_INDENT "\tsbr_flag %d\n"
+ DPS_INDENT "\taac_channel_mode %d\n"
+ DPS_INDENT "\tps_flag %d\n"
+ DPS_INDENT "\tmpeg_surround_config %d\n"
+ DPS_INDENT "\tnum_aus %d\n",
+ header_firecode, rfa, m_dac_rate, m_sbr_flag,
+ m_aac_channel_mode, m_ps_flag, m_mpeg_surround_config,
+ num_aus);
+#else
+ // Avoid "unused variable" warning
+ (void)header_firecode;
+ (void)rfa;
+#endif
+
+
+ // ------ Parse au_start
+ auto au_starts = b.begin() + 3;
+
+ vector<uint8_t> au_start_nibbles(0);
+
+ /* Each AU_START is encoded in three nibbles.
+ * When we have n AUs, we have n-1 au_start values. */
+ for (int i = 0; i < (num_aus-1)*3; i++) {
+ if (i % 2 == 0) {
+ char nibble = au_starts[i/2] >> 4;
+
+ au_start_nibbles.push_back( nibble );
+ }
+ else {
+ char nibble = au_starts[i/2] & 0x0F;
+
+ au_start_nibbles.push_back( nibble );
+ }
+
+ }
+
+
+ vector<int> au_start(num_aus);
+
+ if (num_aus == 2)
+ au_start[0] = 5;
+ else if (num_aus == 3)
+ au_start[0] = 6;
+ else if (num_aus == 4)
+ au_start[0] = 8;
+ else if (num_aus == 6)
+ au_start[0] = 11;
+
+
+ int nib = 0;
+ for (int au = 1; au < num_aus; au++) {
+ au_start[au] = au_start_nibbles[nib] << 8 | \
+ au_start_nibbles[nib+1] << 4 | \
+ au_start_nibbles[nib+2];
+
+ nib += 3;
+ }
+
+#if DPS_DEBUG
+ printf(DPS_INDENT DPS_PREFIX " AU start\n");
+ for (int au = 0; au < num_aus; au++) {
+ printf(DPS_INDENT "\tAU[%d] %d 0x%x\n", au,
+ au_start[au],
+ au_start[au]);
+ }
+#endif
+
+ return extract_au(au_start);
+ }
+ else {
+ return false;
+ }
+}
+
+bool DabPlusSnoop::extract_au(vector<int> au_start)
+{
+ vector<vector<uint8_t> > aus(au_start.size());
+
+ // The last entry of au_start must the end of valid
+ // AU data. We stop at m_subchannel_index * 110 because
+ // what comes after is RS parity
+ au_start.push_back(m_subchannel_index * 110);
+
+ bool all_crc_ok = true;
+
+ for (size_t au = 0; au < aus.size(); au++)
+ {
+#if DPS_DEBUG
+ printf(DPS_PREFIX DPS_INDENT
+ "Copy au %zu of size %zu\n",
+ au,
+ au_start[au+1] - au_start[au]-2 );
+#endif
+
+ aus[au].resize(au_start[au+1] - au_start[au]-2);
+ std::copy(
+ m_data.begin() + au_start[au],
+ m_data.begin() + au_start[au+1]-2,
+ aus[au].begin() );
+
+ /* Check CRC */
+ uint16_t au_crc = m_data[au_start[au+1]-2] << 8 | \
+ m_data[au_start[au+1]-1];
+
+ uint16_t calc_crc = 0xFFFF;
+ for (vector<uint8_t>::iterator au_data = aus[au].begin();
+ au_data != aus[au].end();
+ ++au_data) {
+ calc_crc = update_crc_ccitt(calc_crc, *au_data);
+ }
+ calc_crc =~ calc_crc;
+
+ if (calc_crc != au_crc) {
+ printf(DPS_INDENT DPS_PREFIX
+ "Erroneous CRC for au %zu: 0x%04x vs 0x%04x\n",
+ au, calc_crc, au_crc);
+
+ all_crc_ok = false;
+ }
+ }
+
+ if (all_crc_ok) {
+ return analyse_au(aus);
+ }
+ else {
+ //discard faulty superframe (to be improved to correct/conceal)
+ m_data.clear();
+ return false;
+ }
+}
+
+bool DabPlusSnoop::analyse_au(vector<vector<uint8_t> >& aus)
+{
+ stringstream ss_filename;
+
+ ss_filename << "stream-" << m_index;
+
+ if (!m_faad_decoder.is_initialised()) {
+ m_faad_decoder.open(ss_filename.str(), m_ps_flag,
+ m_aac_channel_mode, m_dac_rate, m_sbr_flag,
+ m_mpeg_surround_config);
+ }
+
+ return m_faad_decoder.decode(aus);
+}
+
+void DabPlusSnoop::close()
+{
+ m_faad_decoder.close();
+
+ if (m_raw_data_stream_fd) {
+ fclose(m_raw_data_stream_fd);
+ }
+}
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