// Try to guess if the MPEG4 header contains the emphasis field (2 bits)
void
aac_reader_c::guess_adts_version() {
aac_header_t tmp_aacheader;
m_emphasis_present = false;
// Due to the checks we do have an ADTS header at 0.
find_aac_header(*m_chunk, INITCHUNKSIZE, &tmp_aacheader, m_emphasis_present);
if (tmp_aacheader.id != 0) // MPEG2
return;
// Now make some sanity checks on the size field.
if (tmp_aacheader.bytes > 8192) {
m_emphasis_present = true; // Looks like it's borked.
return;
}
// Looks ok so far. See if the next ADTS is right behind this packet.
int pos = find_aac_header(m_chunk->get_buffer() + tmp_aacheader.bytes, INITCHUNKSIZE - tmp_aacheader.bytes, &tmp_aacheader, m_emphasis_present);
if (0 != pos) // Not ok - what do we do now?
m_emphasis_present = true;
}
int
mpeg_ts_track_c::new_stream_a_aac() {
add_pes_payload_to_probe_data();
if (0 > find_aac_header(m_probe_data->get_buffer(), m_probe_data->get_size(), &m_aac_header, false))
return FILE_STATUS_MOREDATA;
mxdebug_if(reader.m_debug_aac, boost::format("first AAC header: %1%\n") % m_aac_header.to_string());
a_channels = m_aac_header.channels;
a_sample_rate = m_aac_header.sample_rate;
return 0;
}
void
aac_reader_c::read_headers() {
try {
int tag_size_start = skip_id3v2_tag(*m_in);
int tag_size_end = id3_tag_present_at_end(*m_in);
if (0 > tag_size_start)
tag_size_start = 0;
if (0 < tag_size_end)
m_size -= tag_size_end;
size_t init_read_len = std::min(m_size - tag_size_start, static_cast<uint64_t>(INITCHUNKSIZE));
if (m_in->read(m_chunk, init_read_len) != init_read_len)
throw mtx::input::header_parsing_x();
m_in->setFilePointer(tag_size_start, seek_beginning);
if (find_aac_header(*m_chunk, init_read_len, &m_aacheader, m_emphasis_present) < 0)
throw mtx::input::header_parsing_x();
guess_adts_version();
m_ti.m_id = 0; // ID for this track.
int detected_profile = m_aacheader.profile;
if (24000 >= m_aacheader.sample_rate)
m_aacheader.profile = AAC_PROFILE_SBR;
if ( (map_has_key(m_ti.m_all_aac_is_sbr, 0) && m_ti.m_all_aac_is_sbr[ 0])
|| (map_has_key(m_ti.m_all_aac_is_sbr, -1) && m_ti.m_all_aac_is_sbr[-1]))
m_aacheader.profile = AAC_PROFILE_SBR;
if ( (map_has_key(m_ti.m_all_aac_is_sbr, 0) && !m_ti.m_all_aac_is_sbr[ 0])
|| (map_has_key(m_ti.m_all_aac_is_sbr, -1) && !m_ti.m_all_aac_is_sbr[-1]))
m_aacheader.profile = detected_profile;
if ( map_has_key(m_ti.m_all_aac_is_sbr, 0)
|| map_has_key(m_ti.m_all_aac_is_sbr, -1))
m_sbr_status_set = true;
} catch (...) {
throw mtx::input::open_x();
}
show_demuxer_info();
}
