78 lines
2.4 KiB
C++
78 lines
2.4 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 IoUtilities;
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using namespace ConversionUtilities;
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using namespace ChronoUtilities;
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namespace Media {
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/*!
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* \class Media::MpegAudioFrameStream
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* \brief Implementation of Media::AbstractTrack for a stream of
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* MPEG audio frames (run-of-the-mill MP3 file).
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*/
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/*!
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* \brief Constructs a new track for the \a stream at the specified \a startOffset.
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*/
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MpegAudioFrameStream::MpegAudioFrameStream(iostream &stream, uint64 startOffset) :
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AbstractTrack(stream, startOffset)
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{
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m_mediaType = MediaType::Audio;
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}
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/*!
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* \brief Destroys the track.
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*/
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MpegAudioFrameStream::~MpegAudioFrameStream()
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{}
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TrackType MpegAudioFrameStream::type() const
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{
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return TrackType::MpegAudioFrameStream;
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}
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void MpegAudioFrameStream::internalParseHeader()
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{
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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<uint64>(m_istream->tellg()) - 3u - m_startOffset;
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} else {
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m_size = static_cast<uint64>(m_istream->tellg()) + 125u - m_startOffset;
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}
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m_istream->seekg(m_startOffset, ios_base::beg);
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// parse frame header
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MpegAudioFrame frame;
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frame.parseHeader(*m_istream);
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m_version = frame.mpegVersion();
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m_format = MediaFormat(GeneralMediaFormat::Mpeg1Audio, frame.layer());
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m_channelCount = frame.channelMode() == MpegChannelMode::SingleChannel ? 1 : 2;
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m_samplesPerSecond = frame.samperate();
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if(frame.isXingBytesfieldPresent()) {
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uint32 xingSize = frame.xingBytesfield();
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if(xingSize != m_size) {
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addNotification(NotificationType::Warning, "Real length MPEG of audio frames is not equal with value provided by Xing header. The Xing header value will be used.", context);
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m_size = xingSize;
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}
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}
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m_bitrate = frame.isXingFramefieldPresent()
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? ((static_cast<double>(m_size) * 8.0) / (static_cast<double>(frame.xingFrameCount() * frame.sampleCount()) / static_cast<double>(frame.samperate())) / 1024.0)
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: frame.bitrate();
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m_bytesPerSecond = m_bitrate * 125;
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m_duration = TimeSpan::fromSeconds(static_cast<double>(m_size) / (m_bitrate * 128.0));
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m_frames.push_back(frame);
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}
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}
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