added parser for Opus identification header

opus/opusidentificationheader.cpp

@@ -0,0 +1,40 @@
+#include "./opusidentificationheader.h"
+
+#include "../ogg/oggiterator.h"
+
+#include "../exceptions.h"
+
+#include <c++utilities/conversion/binaryconversion.h>
+
+using namespace std;
+using namespace ConversionUtilities;
+
+namespace Media {
+
+/*!
+ * \class Media::OpusIdentificationHeader
+ * \brief The OpusIdentificationHeader class is an Opus identification header parser.
+ * \sa https://wiki.xiph.org/OggOpus
+ */
+
+/*!
+ * \brief Parses the Opus identification header which is read using the specified \a iterator.
+ * \remarks The header is assumed to start at the current position of \a iterator.
+ */
+void OpusIdentificationHeader::parseHeader(OggIterator &iterator)
+{
+    char buff[19 - 8];
+    iterator.read(buff, 8);
+    if(BE::toUInt64(buff) != 0x4F70757348656164u) {
+        throw InvalidDataException(); // not Opus identification header
+    }
+    iterator.read(buff, sizeof(buff));
+    m_version = static_cast<byte>(*(buff));
+    m_channels = static_cast<byte>(*(buff + 1));
+    m_preSkip = LE::toUInt16(buff + 2);
+    m_sampleRate = LE::toUInt32(buff + 4);
+    m_outputGain = LE::toUInt16(buff + 8);
+    m_channelMap = static_cast<byte>(*(buff + 10));
+}
+
+}

opus/opusidentificationheader.h

@@ -0,0 +1,110 @@
+#ifndef MEDIA_OPUSIDENTIFICATIONHEADER_H
+#define MEDIA_OPUSIDENTIFICATIONHEADER_H
+
+#include <c++utilities/application/global.h>
+#include <c++utilities/conversion/types.h>
+
+#include <istream>
+
+namespace Media {
+
+class OggIterator;
+
+class LIB_EXPORT OpusIdentificationHeader
+{
+public:
+    OpusIdentificationHeader();
+
+    void parseHeader(OggIterator &iterator);
+
+    byte version() const;
+    byte channels() const;
+    uint16 preSkip() const;
+    uint32 sampleRate() const;
+    uint16 outputGain() const;
+    byte channelMap() const;
+
+private:
+    byte m_version;
+    byte m_channels;
+    uint16 m_preSkip;
+    uint32 m_sampleRate;
+    uint16 m_outputGain;
+    byte m_channelMap;
+};
+
+/*!
+ * \brief Constructs a new vorbis identification header.
+ */
+inline OpusIdentificationHeader::OpusIdentificationHeader() :
+    m_version(0),
+    m_channels(0),
+    m_sampleRate(0),
+    m_outputGain(0),
+    m_channelMap(0)
+{}
+
+/*!
+ * \brief Returns the version (which should be 1 currently).
+ */
+inline byte OpusIdentificationHeader::version() const
+{
+    return m_version;
+}
+
+/*!
+ * \brief Returns the number of channels for the Opus stream.
+ */
+inline byte OpusIdentificationHeader::channels() const
+{
+    return m_channels;
+}
+
+/*!
+ * \brief Returns "pre-skip" value for the Opus stream.
+ *
+ * This is the number of samples (at 48 kHz) to discard from the decoder
+ * output when starting playback, and also the number to subtract from a
+ * page's granule position to calculate its PCM sample position.
+ */
+inline uint16 OpusIdentificationHeader::preSkip() const
+{
+    return m_preSkip;
+}
+
+/*!
+ * \brief Returns the INPUT sample rate.
+ * \remarks This is not the sample rate to use for playback of the encoded data.
+ * \sa https://wiki.xiph.org/OggOpus
+ */
+inline uint32 OpusIdentificationHeader::sampleRate() const
+{
+    return m_sampleRate;
+}
+
+/*!
+ * \brief Returns the output gain.
+ *
+ * This is a gain to be applied by the decoder. Virtually all players and media frameworks
+ * should apply it by default.
+ */
+inline uint16 OpusIdentificationHeader::outputGain() const
+{
+    return m_outputGain;
+}
+
+/*!
+ * \brief Returns the channel mapping family.
+ *
+ * The channel mapping family indicates the order and semantic meaning of the various channels
+ * encoded in each Opus packet.
+ * \sa https://wiki.xiph.org/OggOpus
+ */
+inline byte OpusIdentificationHeader::channelMap() const
+{
+    return m_channelMap;
+}
+
+}
+
+#endif // MEDIA_OPUSIDENTIFICATIONHEADER_H