tagparser/mpegaudio/mpegaudioframe.cpp

#include "./mpegaudioframe.h"

#include "../exceptions.h"

#include <c++utilities/io/binaryreader.h>

using namespace std;
using namespace CppUtilities;

namespace TagParser {

/*!
 * \brief Returns the string representation for the specified \a channelMode.
 */
const char *mpegChannelModeString(MpegChannelMode channelMode)
{
    switch (channelMode) {
    case MpegChannelMode::Stereo:
        return "2 channels: stereo";
    case MpegChannelMode::JointStereo:
        return "2 channels: joint stereo";
    case MpegChannelMode::DualChannel:
        return "2 channels: dual channel";
    case MpegChannelMode::SingleChannel:
        return "1 channel: single channel";
    default:
        return nullptr;
    }
}

/*!
 * \class TagParser::MpegAudioFrame
 * \brief The MpegAudioFrame class is used to parse MPEG audio frames.
 */

const std::uint16_t MpegAudioFrame::s_bitrateTable[0x2][0x3][0xF] = { { { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448 },
                                                                          { 0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384 },
                                                                          { 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 } },
    { { 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256 }, { 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 },
        { 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 } } };

/*!
 * \brief Parses the header read using the specified \a reader.
 * \throws Throws InvalidDataException if the data read from the stream is
 *         no valid frame header.
 */
void MpegAudioFrame::parseHeader(BinaryReader &reader, Diagnostics &diag)
{
    m_header = reader.readUInt32BE();
    if (!isValid()) {
        diag.emplace_back(DiagLevel::Critical, "Header is invalid.", "parsing MPEG audio frame header");
        throw InvalidDataException();
    }
    reader.stream()->seekg(s_xingHeaderOffset - 4, ios_base::cur);
    m_xingHeader = reader.readUInt64BE();
    m_xingHeaderFlags = static_cast<XingHeaderFlags>(m_xingHeader & 0xffffffffuL);
    if (isXingHeaderAvailable()) {
        if (isXingFramefieldPresent()) {
            m_xingFramefield = reader.readUInt32BE();
        }
        if (isXingBytesfieldPresent()) {
            m_xingBytesfield = reader.readUInt32BE();
        }
        if (isXingTocFieldPresent()) {
            reader.stream()->seekg(64, ios_base::cur);
        }
        if (isXingQualityIndicatorFieldPresent()) {
            m_xingQualityIndicator = reader.readUInt32BE();
        }
    }
}

/*!
 * \brief Returns the MPEG version if known (1.0, 2.0 or 2.5); otherwise returns 0.
 */
double MpegAudioFrame::mpegVersion() const
{
    switch (m_header & 0x180000u) {
    case 0x180000u:
        return 1.0;
    case 0x100000u:
        return 2.0;
    case 0x0u:
        return 2.5;
    default:
        return 0.0;
    }
}

/*!
 * \brief Returns the MPEG layer if known (1, 2, or 3); otherwise returns 0.
 */
int MpegAudioFrame::layer() const
{
    switch (m_header & 0x60000u) {
    case 0x60000u:
        return 1;
    case 0x40000u:
        return 2;
    case 0x20000u:
        return 3;
    default:
        return 0;
    }
}

/*!
 * \brief Returns the sampeling frequency of the frame if known; otherwise returns 0.
 */
std::uint32_t MpegAudioFrame::samplingFrequency() const
{
    switch (m_header & 0xc00u) {
    case 0xc00u:
        return 0;
    case 0x800u:
        switch (m_header & 0x180000u) {
        case 0x180000u:
            return 32000;
        case 0x100000u:
            return 16000;
        case 0x0u:
            return 8000u;
        }
        break;
    case 0x400u:
        switch (m_header & 0x180000u) {
        case 0x180000u:
            return 48000;
        case 0x100000u:
            return 24000;
        case 0x0u:
            return 12000;
        }
        break;
    case 0x0u:
        switch (m_header & 0x180000u) {
        case 0x180000u:
            return 44100;
        case 0x100000:
            return 22050;
        case 0x0u:
            return 11025;
        }
        break;
    }
    return 0;
}

/*!
 * \brief Returns the channel mode if known; otherwise returns MpegChannelMode::Unspecifed.
 */
MpegChannelMode MpegAudioFrame::channelMode() const
{
    if (isValid()) {
        switch (m_header & 0xc0u) {
        case 0xc0u:
            return MpegChannelMode::SingleChannel;
        case 0x80u:
            return MpegChannelMode::DualChannel;
        case 0x40u:
            return MpegChannelMode::JointStereo;
        case 0x00:
            return MpegChannelMode::Stereo;
        default:;
        }
    }
    return MpegChannelMode::Unspecifed;
}

/*!
 * \brief Returns the sample count if known; otherwise returns 0.
 */
std::uint32_t MpegAudioFrame::sampleCount() const
{
    switch (m_header & 0x60000u) {
    case 0x60000u:
        return 384u;
    case 0x40000u:
        return 1152u;
    case 0x20000u:
        switch (m_header & 0x180000u) {
        case 0x180000u:
            return 1152u;
        case 0x100000u:
        case 0x0u:
            return 576u;
        }
    default:;
    }
    return 0;
}

/*!
 * \brief Returns the size if known; otherwise retruns 0.
 */
std::uint32_t MpegAudioFrame::size() const
{
    switch (m_header & 0x60000u) {
    case 0x60000u:
        return static_cast<std::uint32_t>(
            ((static_cast<double>(bitrate()) * 1024.0 / 8.0) / static_cast<double>(samplingFrequency())) * static_cast<double>(sampleCount())
            + static_cast<double>(paddingSize()));
    case 0x40000u:
    case 0x20000u:
        return static_cast<std::uint32_t>(
            ((static_cast<double>(bitrate()) * 1024.0 / 8.0) / static_cast<double>(samplingFrequency())) * static_cast<double>(sampleCount())
            + static_cast<double>(paddingSize()));
    default:
        return 0;
    }
}

} // namespace TagParser