91 lines
3.4 KiB
C++
91 lines
3.4 KiB
C++
#include "./mpegaudioframestream.h"
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#include "../exceptions.h"
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#include "../mediaformat.h"
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#include <sstream>
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using namespace std;
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using namespace CppUtilities;
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namespace TagParser {
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/*!
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* \class TagParser::MpegAudioFrameStream
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* \brief Implementation of TagParser::AbstractTrack MPEG audio streams.
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*/
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/*!
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* \brief Adds the information from the specified \a frame to the specified \a track.
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*/
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void MpegAudioFrameStream::addInfo(const MpegAudioFrame &frame, AbstractTrack &track)
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{
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track.m_version = frame.mpegVersion();
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track.m_format = MediaFormat(GeneralMediaFormat::Mpeg1Audio, static_cast<unsigned char>(frame.layer()));
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track.m_channelCount = frame.channelMode() == MpegChannelMode::SingleChannel ? 1 : 2;
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track.m_channelConfig = static_cast<std::uint8_t>(frame.channelMode());
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track.m_samplingFrequency = frame.samplingFrequency();
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}
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void MpegAudioFrameStream::internalParseHeader(Diagnostics &diag, AbortableProgressFeedback &progress)
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{
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CPP_UTILITIES_UNUSED(progress)
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static const string context("parsing MPEG audio frame header");
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if (!m_istream) {
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throw NoDataFoundException();
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}
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// get size
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m_istream->seekg(-128, ios_base::end);
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if (m_reader.readUInt24BE() == 0x544147) {
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m_size = static_cast<std::uint64_t>(m_istream->tellg()) - 3u - m_startOffset;
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} else {
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m_size = static_cast<std::uint64_t>(m_istream->tellg()) + 125u - m_startOffset;
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}
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m_istream->seekg(static_cast<streamoff>(m_startOffset), ios_base::beg);
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// parse frames until the first valid, non-empty frame is reached
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for (size_t invalidByteskipped = 0; m_frames.size() < 200 && invalidByteskipped <= 0x600u;) {
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MpegAudioFrame &frame = invalidByteskipped > 0 ? m_frames.back() : m_frames.emplace_back();
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try {
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frame.parseHeader(m_reader, diag);
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} catch (const InvalidDataException &e) {
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if (++invalidByteskipped > 1) {
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diag.pop_back();
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}
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m_istream->seekg(-3, ios_base::cur);
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continue;
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}
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if (invalidByteskipped > 1) {
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diag.emplace_back(DiagLevel::Critical, argsToString("The next ", invalidByteskipped, " bytes are junk as well."), context);
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}
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if (!frame.size()) {
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continue; // likely just junk, check further frames
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}
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invalidByteskipped = 0;
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if (frame.isProtectedByCrc()) {
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m_istream->seekg(2, ios_base::cur);
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}
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break;
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}
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if (!m_frames.back().isValid()) {
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return;
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}
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const MpegAudioFrame &frame = m_frames.back();
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addInfo(frame, *this);
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if (frame.isXingBytesfieldPresent()) {
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std::uint32_t xingSize = frame.xingBytesfield();
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if (m_size && xingSize != m_size) {
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diag.emplace_back(DiagLevel::Warning,
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"Real length of MPEG audio frames is not in accordance with value provided by Xing header. The Xing header value will be used.",
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context);
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m_size = xingSize;
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}
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}
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m_bitrate = frame.isXingFramefieldPresent() ? ((static_cast<double>(m_size) * 8.0)
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/ (static_cast<double>(frame.xingFrameCount() * frame.sampleCount()) / static_cast<double>(frame.samplingFrequency())) / 1024.0)
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: frame.bitrate();
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m_duration = TimeSpan::fromSeconds(static_cast<double>(m_size) / (m_bytesPerSecond = static_cast<std::uint32_t>(m_bitrate * 125)));
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}
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} // namespace TagParser
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