////------------------------------------------------------------------------------------------------------------------------------
public static FlacResidual Read(StreamBuffer sb, int blockSize, int order)
{
FlacResidual residual = new FlacResidual { _values = sb.ReadByte() };
int partitions = 1 << residual.PartitionOrder;
residual.RicePartitions = new FlacRicePartition[partitions];
for (int i = 0; i < partitions; i++)
residual.RicePartitions[i] = FlacRicePartition.Read(sb, i, residual.PartitionOrder, order, blockSize, residual.CodingMethod);
return residual;
}
/// <summary>
/// Initializes a new instance of the <see cref="XingHeader"/> class.
/// </summary>
/// <param name="firstFrame">The first frame.</param>
/// <param name="firstFrameBuffer">The first frame buffer.</param>
/// <param name="offset">The offset.</param>
public XingHeader(MpaFrame firstFrame, StreamBuffer firstFrameBuffer, long offset)
: base(firstFrame, firstFrameBuffer, offset, VbrHeaderType.Xing)
{
/*
XING VBR-Header
size description
4 'Xing' or 'Info'
4 flags (indicates which fields are used)
4 frames (optional)
4 bytes (optional)
100 toc (optional)
4 a VBR quality indicator: 0=best 100=worst (optional)
--------- +
120 bytes
*
* NOTE: the frames (frameCount) in the XING header does not include its own frame.
* So the total frames is actually XING framecount + 1
*/
// name of the tag as found in the file
Name = firstFrameBuffer.ReadString(4);
// The flags indicate which fields are used in the XING header
Flags = firstFrameBuffer.ReadBigEndianInt32();
// Extract total frames in the file (XING header excludes it's own frame)
if ((Flags & XingHeaderFlags.FrameCountFlag) != 0)
FrameCount = firstFrameBuffer.ReadBigEndianInt32();
// Extract size of the file, in bytes
if ((Flags & XingHeaderFlags.FileSizeFlag) != 0)
FileSize = firstFrameBuffer.ReadBigEndianInt32();
// Extract TOC (Table of Contents) for more accurate seeking
if ((Flags & XingHeaderFlags.TocFlag) != 0)
{
Toc = new int[100];
for (int i = 0; i < 100; i++)
Toc[i] = firstFrameBuffer.ReadByte();
}
if ((Flags & XingHeaderFlags.VbrScaleFlag) != 0)
Quality = firstFrameBuffer.ReadBigEndianInt32();
// The LAME tag is always 120 bytes after the XING header - regardless of which fields are used
LameTag = LameTag.FindTag(firstFrameBuffer, offset + 120);
}
private static ApeHeader ReadHeader(StreamBuffer stream, long startHeaderPosition, long endHeaderPosition)
{
if (stream == null)
throw new ArgumentNullException("stream");
stream.Position = startHeaderPosition;
while (startHeaderPosition < endHeaderPosition)
{
int y = 0;
while (stream.ReadByte() == TagIdentifierBytes[y++])
{
startHeaderPosition++;
if (y != TagIdentifierBytes.Length)
continue;
ApeHeader hdr = new ApeHeader
{
Position = stream.Position - TagIdentifierBytes.Length,
Version = (ApeVersion)(stream.ReadLittleEndianInt32() / 1000),
Size = stream.ReadLittleEndianInt32(),
FrameCount = stream.ReadLittleEndianInt32(),
Flags = stream.ReadLittleEndianInt32(),
ReservedBytes = new byte[8]
};
stream.Read(hdr.ReservedBytes, 8);
if (IsValidTag(hdr))
return hdr;
startHeaderPosition -= ApeTag.HeaderSize;
stream.Position = startHeaderPosition + 1;
break;
}
startHeaderPosition++;
}
return null;
}
/// <summary>
/// Reads the header.
/// </summary>
/// <param name="sb">The <see cref="StreamBuffer"/>.</param>
/// <returns>
/// true if the header is read and valid; otherwise, false.
/// </returns>
/// <exception cref="System.ArgumentNullException">Thrown if <paramref name="sb"/> is null.</exception>
private bool ReadHeader(StreamBuffer sb)
{
if (sb == null)
throw new ArgumentNullException("sb");
long startPosition = sb.Position;
// Sync code '11111111111110'
_header = sb.ReadBigEndianInt32();
if (((_header >> 18) & FrameSync) != FrameSync)
return false;
/*
Blocking strategy:
•0 : fixed-block size stream; frame header encodes the frame number
•1 : variable-block size stream; frame header encodes the sample number
*/
long num = ReadBigEndianUtf8Int64(sb, out _sampleFrameNumberBytes);
switch (BlockingStrategy)
{
case FlacBlockingStrategy.FixedBlocksize:
Samples = num;
FrameNumber = num
*
(FlacStream.StreamInfoMetadataBlocks.Any()
? FlacStream.StreamInfoMetadataBlocks.First().MinimumBlockSize
: 1);
break;
case FlacBlockingStrategy.VariableBlocksize:
Samples = num;
FrameNumber = -1;
break;
}
/*
Block size in inter-channel samples:
•0000 : reserved
•0001 : 192 samples
•0010-0101 : 576 * (2 ^ (n - 2)) samples, i.e. 576/1152/2304/4608
•0110 : get 8 bit (block size - 1) from end of header
•0111 : get 16 bit (block size - 1) from end of header
•1000-1111 : 256 * (2 ^ (n - 8)) samples, i.e. 256/512/1024/2048/4096/8192/16384/3276
*/
int blockSize = (_header >> 12) & 0xF;
switch (blockSize)
{
case 0x01:
BlockSize = 192;
break;
case 0x02:
case 0x03:
case 0x04:
case 0x05:
BlockSize = 576 << (blockSize - 2);
break;
case 0x06:
BlockSize = sb.ReadByte() + 1;
break;
case 0x07:
BlockSize = sb.ReadBigEndianInt16() + 1;
break;
default:
BlockSize = 256 << (blockSize - 8);
break;
}
/*
Sample rate:
•0000 : get from STREAMINFO metadata block
•0001 : 88.2kHz
•0010 : 176.4kHz
•0011 : 192kHz
•0100 : 8kHz
•0101 : 16kHz
•0110 : 22.05kHz
•0111 : 24kHz
•1000 : 32kHz
•1001 : 44.1kHz
•1010 : 48kHz
•1011 : 96kHz
•1100 : get 8 bit sample rate (in kHz) from end of header
•1101 : get 16 bit sample rate (in Hz) from end of header
•1110 : get 16 bit sample rate (in tens of Hz) from end of header
•1111 : invalid, to prevent sync-fooling string of 1s
*/
int samplingRate = (_header >> 8) & 0xF;
if (samplingRate == 0x00)
{
SamplingRate = FlacStream.StreamInfoMetadataBlocks.Any()
? FlacStream.StreamInfoMetadataBlocks.First().SampleRate
: 0;
}
else if (samplingRate <= 0x0B)
{
SamplingRate = SampleRates[samplingRate];
}
else
{
switch (samplingRate)
{
case 0x0C:
// Sample rate in kHz
SamplingRate = sb.ReadByte() * 1000;
break;
case 0x0D:
// Sample rate in Hz
SamplingRate = sb.ReadBigEndianInt16();
break;
case 0x0E:
// Sample rate in 10s of Hz
SamplingRate = sb.ReadBigEndianInt16() * 10;
break;
}
}
/*
Channel assignment
•0000-0111 : (number of independent channels)-1. Where defined, the channel order follows SMPTE/ITU-R recommendations.
The assignments are as follows:
◦1 channel: mono
◦2 channels: left, right
◦3 channels: left, right, center
◦4 channels: front left, front right, back left, back right
◦5 channels: front left, front right, front center, back/surround left, back/surround right
◦6 channels: front left, front right, front center, LFE, back/surround left, back/surround right
◦7 channels: front left, front right, front center, LFE, back center, side left, side right
◦8 channels: front left, front right, front center, LFE, back left, back right, side left, side right
•1000 : left/side stereo: channel 0 is the left channel, channel 1 is the side(difference) channel
•1001 : right/side stereo: channel 0 is the side(difference) channel, channel 1 is the right channel
•1010 : mid/side stereo: channel 0 is the mid(average) channel, channel 1 is the side(difference) channel
•1011-1111 : reserved
*/
int channelAssignment = (_header >> 4) & 0xF;
if (channelAssignment < 0x08)
{
ChannelAssignment = FlacChannelAssignment.Independent;
Channels = channelAssignment + 1;
}
else
{
Channels = 2;
switch (channelAssignment)
{
case 0x08:
ChannelAssignment = FlacChannelAssignment.LeftSide;
break;
case 0x09:
ChannelAssignment = FlacChannelAssignment.RightSide;
break;
case 0x0A:
ChannelAssignment = FlacChannelAssignment.MidSide;
break;
}
}
/*
Sample size in bits:
•000 : get from STREAMINFO metadata block
•001 : 8 bits per sample
•010 : 12 bits per sample
•011 : reserved
•100 : 16 bits per sample
•101 : 20 bits per sample
•110 : 24 bits per sample
•111 : reserved
*/
int sampleSize = (_header >> 0x01) & 0x07;
SampleSize = (sampleSize == 0x00)
? (FlacStream.StreamInfoMetadataBlocks.Any()
? FlacStream.StreamInfoMetadataBlocks.First().BitsPerSample
: 0)
: SampleSizes[sampleSize];
_crc8 = sb.ReadByte();
long endPosition = sb.Position;
long length = endPosition - startPosition;
byte[] crcBytes = new byte[length];
sb.Position -= length;
sb.Read(crcBytes, (int)length);
byte crc8 = Crc8.Calculate(crcBytes);
if (_crc8 != crc8)
throw new InvalidDataException("Corrupt CRC8.");
return true;
}
////------------------------------------------------------------------------------------------------------------------------------
private static long ReadBigEndianUtf8Int64(StreamBuffer sb, out byte[] utf8Bytes)
{
//// Decoded long range Coded value
//// 0000 0000 ・00 0000 007F 0xxxxxxx
//// 0000 0080 ・00 0000 07FF 110xxxxx 10xxxxxx
//// 0000 0800 ・00 0000 FFFF 1110xxxx 10xxxxxx 10xxxxxx
//// 0001 0000 ・00 001F FFFF 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
//// 0020 0000 ・00 03FF FFFF 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
//// 0400 0000 ・00 7FFF FFFF 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
//// 8000 0000 ・0F FFFF FFFF 11111110 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
// Where xxx represent the bits in the uncoded value, in the same order.
const int ByteCountMask = 0x80; // 10000000
const int ByteMask = 0x3F; // 00111111
int byteCount = 1;
long value = sb.ReadByte();
if (value > ByteCountMask)
{
int bytes = 0;
while (((value << bytes) & ByteCountMask) == ByteCountMask)
bytes++;
value &= ByteMask >> (bytes - 1);
for (int i = bytes - 1; i > 0; i--)
value = (value << (6 * i)) | ((long)sb.ReadByte() & ByteMask);
byteCount += bytes - 1;
}
sb.Position -= byteCount;
utf8Bytes = new byte[byteCount];
sb.Read(utf8Bytes, byteCount);
return value;
}
private static MusicMatchHeader ReadHeaderFooter(StreamBuffer stream, long startHeaderPosition, long endHeaderPosition, IList<byte> identifierBytes, TagOrigin tagOrigin)
{
if (stream == null)
throw new ArgumentNullException("stream");
stream.Position = startHeaderPosition;
while (startHeaderPosition < endHeaderPosition)
{
int y = 0;
while (stream.ReadByte() == identifierBytes[y++])
{
startHeaderPosition++;
if (y != identifierBytes.Count)
continue;
if (tagOrigin == TagOrigin.Start)
{
MusicMatchHeader header = new MusicMatchHeader
{
Position = stream.Position - identifierBytes.Count,
Padding1 = new byte[2],
Padding2 = new byte[2],
Padding3 = new byte[2],
SpacePadding2 = new byte[226]
};
// 0x00 0x00 Padding
stream.Read(header.Padding1, header.Padding1.Length);
// <8-byte numerical ASCII string>
header.XingEncoderVersion = stream.ReadString(8);
// 0x00 0x00 Padding
stream.Read(header.Padding2, header.Padding2.Length);
// Xing encoder version <8-byte numerical ASCII string>
header.MusicMatchVersion = stream.ReadString(8);
// 0x00 0x00 Padding
stream.Read(header.Padding3, header.Padding3.Length);
// Space padding <226 * 0x20 >
stream.Read(header.SpacePadding2, header.SpacePadding2.Length);
ValidateHeader(header, null);
return header;
}
if (tagOrigin == TagOrigin.End)
{
MusicMatchHeader footer = new MusicMatchHeader
{
Position = stream.Position - identifierBytes.Count,
SpacePadding1 = new byte[13],
SpacePadding2 = new byte[12]
};
// Space padding <13 * 0x20>
stream.Read(footer.SpacePadding1, 13);
// version <4-byte numerical ASCII string> e.g. 3.05
footer.MusicMatchVersion = stream.ReadString(4);
// Space padding <12 * 0x20>
stream.Read(footer.SpacePadding2, 12);
ValidateHeader(null, footer);
return footer;
}
}
startHeaderPosition++;
}
return null;
}
/// <summary>
/// Reads the extended header.
/// </summary>
/// <param name="streamBuffer">The stream buffer.</param>
/// <param name="tag">The tag.</param>
/// <param name="crcData">The CRC data.</param>
/// <returns>
/// The extended header if used; otherwise, null.
/// </returns>
/// <exception cref="System.IO.InvalidDataException">Thrown if the extended header size does not match the amount of bytes read for the extended header.</exception>
private static Id3v2ExtendedHeader ReadExtendedHeader(StreamBuffer streamBuffer, Id3v2Tag tag, out int crcData)
{
crcData = 0;
if (!tag.UseExtendedHeader)
return null;
// The extended header contains information that can provide further insight in the structure of the tag,
// but is not vital to the correct parsing of the tag information; hence the extended header is optional.
int extendedHeaderSize = 0;
long startPosition = streamBuffer.Position;
Id3v2ExtendedHeader extendedHeader = null;
if ((tag.Version >= Id3v2Version.Id3v230) && (tag.Version < Id3v2Version.Id3v240))
{
// Where the 'Extended header size', currently 6 or 10 bytes, excludes itself.
extendedHeaderSize = streamBuffer.ReadBigEndianInt32() + 4;
int extendedFlags = streamBuffer.ReadBigEndianInt16();
extendedHeader = Id3v2ExtendedHeader.InitExtendedHeader(tag.Version, extendedFlags);
extendedHeader.PaddingSize = streamBuffer.ReadBigEndianInt32();
if (extendedHeader.CrcDataPresent)
crcData = streamBuffer.ReadBigEndianInt32();
}
else if (tag.Version >= Id3v2Version.Id3v240)
{
// Where the 'Extended header size' is the size of the whole extended header, stored as a 32 bit synchsafe integer.
// An extended header can thus never have a size of fewer than six bytes.
extendedHeaderSize = streamBuffer.ReadBigEndianInt32();
extendedHeaderSize = Id3v2Tag.GetUnsynchedValue(extendedHeaderSize);
int extendedFlagsFieldLength = streamBuffer.ReadByte();
// The extended flags field, with its size described by 'number of flag bytes', is defined as: %0bcd0000
int extendedFlags = streamBuffer.ReadInt(extendedFlagsFieldLength);
extendedHeader = Id3v2ExtendedHeader.InitExtendedHeader(tag.Version, extendedFlags);
extendedHeader.SetExtendedFlagsFieldLength(extendedFlagsFieldLength);
// Each flag that is set in the extended header has data attached,
// which comes in the order in which the flags are encountered (i.e. the data for flag 'b' comes before the data for flag 'c').
// Unset flags cannot have any attached data. All unknown flags MUST be unset and their corresponding data removed when a tag is modified.
//
// Every set flag's data starts with a length byte, which contains a value between 0 and 127 ($00 - $7f),
// followed by data that has the field length indicated by the length byte.
// If a flag has no attached data, the value $00 is used as length byte.
// If this flag is set, the present tag is an update of a tag found earlier in the present file or stream.
// If frames defined as unique are found in the present tag, they are to override any corresponding ones found in the earlier tag.
// This flag has no corresponding data.
if (extendedHeader.TagIsUpdate)
{
// If a flag has no attached data, the value $00 is used as length byte.
streamBuffer.ReadByte();
}
// If this flag is set, a CRC-32 [ISO-3309] data is included in the extended header.
// The CRC is calculated on all the data between the header and footer as indicated by the header's tag length field, minus the extended header.
// Note that this includes the padding (if there is any), but excludes the footer.
// The CRC-32 is stored as an 35 bit synchsafe integer, leaving the upper four bits always zeroed.
if (extendedHeader.CrcDataPresent)
{
long crcBytes = streamBuffer.ReadBigEndianInt64(5);
crcData = (int)Id3v2Tag.GetUnsynchedValue(crcBytes, 5);
}
// For some applications it might be desired to restrict a tag in more ways than imposed by the ID3v2 specification.
// Note that the presence of these restrictions does not affect how the tag is decoded, merely how it was restricted before encoding.
// If this flag is set the tag is restricted as follows:
if (extendedHeader.TagIsRestricted)
{
// Restrictions: %ppqrrstt
byte tagRestrictions = (byte)streamBuffer.ReadByte();
extendedHeader.TagRestrictions = new Id3v2TagRestrictions
{
// p - Tag size restrictions
TagSizeRestriction = (Id3v2TagSizeRestriction)(tagRestrictions & Id3v2TagRestrictions.TagSizeRestrictionFlags),
// q - Text encoding restrictions
TextEncodingRestriction = (Id3v2TextEncodingRestriction)(tagRestrictions & Id3v2TagRestrictions.TextEncodingRestrictionFlags),
// r - Text fields size restrictions
TextFieldsSizeRestriction = (Id3v2TextFieldsSizeRestriction)(tagRestrictions & Id3v2TagRestrictions.TextFieldsSizeRestrictionFlags),
// s - Image encoding restrictions
ImageEncodingRestriction = (Id3v2ImageEncodingRestriction)(tagRestrictions & Id3v2TagRestrictions.ImageEncodingRestrictionFlags),
// t - Image size restrictions
ImageSizeRestriction = (Id3v2ImageSizeRestriction)(tagRestrictions & Id3v2TagRestrictions.ImageSizeRestrictionFlags)
};
}
}
if ((streamBuffer.Position - startPosition) != extendedHeaderSize)
{
throw new InvalidDataException(
string.Format(
"ExtendedHeaderSize does not match amount of bytes read: expected {0} but got {1} bytes.",
extendedHeaderSize,
streamBuffer.Position - startPosition));
}
return extendedHeader;
}
private static Id3v2Header ReadHeader(StreamBuffer stream, long startHeaderPosition, long endHeaderPosition, byte[] identifierBytes)
{
if (stream == null)
throw new ArgumentNullException("stream");
stream.Position = startHeaderPosition;
// Look for a header/footer between the start position and end position.
while (startHeaderPosition < endHeaderPosition)
{
int y = 0;
// identifierBytes is the HeaderIdentifier or the FooterIdentifier encoded.
while (stream.ReadByte() == identifierBytes[y++])
{
startHeaderPosition++;
if (y != identifierBytes.Length)
continue;
// The first byte of ID3 version is it's major version, while the second byte is its revision number.
// All revisions are backwards compatible while major versions are not.
// If software with ID3v2 and below support should encounter version three or higher it should simply ignore the whole tag.
// Version and revision will never be $FF.
int majorRevision = stream.ReadByte();
int revisionNumber = stream.ReadByte();
if ((majorRevision >= 0x10) || (revisionNumber >= 0x10))
{
stream.Position -= 2;
break;
}
// Return header/footer found.
return new Id3v2Header
{
Position = stream.Position - identifierBytes.Length - 2,
Identifier = Encoding.ASCII.GetString(identifierBytes),
Version = (Id3v2Version)((majorRevision * 10) + revisionNumber),
// One byte of flags.
// ID3v2.2.0: %xx000000
Flags = (byte)stream.ReadByte(),
// The ID3 tag size is encoded with four bytes where the first bit (bit 7) is set to zero in every byte, making a total of 28 bits.
// The zeroed bits are ignored, so a 257 bytes long tag is represented as $00 00 02 01.
// ID3v2.2.0: The ID3 tag size is the size of the complete tag after unsychronisation, including padding, excluding the header (total tag size - 10).
Size = Id3v2Tag.GetUnsynchedValue(stream.ReadBigEndianInt32())
};
}
startHeaderPosition++;
}
return null;
}
////------------------------------------------------------------------------------------------------------------------------------
private static ApeItem ReadItem(ApeVersion version, StreamBuffer sb, long maximumItemSize)
{
if (sb == null)
throw new ArgumentNullException("sb");
// Find the item.
long startPosition = sb.Position;
long bytesToSkip = GetBytesUntilNextItem(version, sb, maximumItemSize);
// Not found; return null.
if (bytesToSkip == -1)
return null;
// Move the stream position to the start of the frame.
sb.Position = startPosition + bytesToSkip;
int valueSize = sb.ReadLittleEndianInt32();
if ((valueSize <= 0) || (valueSize > ApeTag.MaxAllowedSize))
return null;
int flags = sb.ReadLittleEndianInt32();
maximumItemSize -= 8;
int itemKeyLengthBytes = 0;
long maximumBytesToRead = maximumItemSize;
if (maximumBytesToRead > 0)
{
for (int y = 0; y < maximumBytesToRead; y++)
{
int character = sb.ReadByte();
if (character == 0x00) // 0x00 byte - string terminator.
break;
itemKeyLengthBytes++;
}
}
// Name
sb.Seek(-(itemKeyLengthBytes + 1), SeekOrigin.Current);
string key = sb.ReadString(itemKeyLengthBytes, Encoding.UTF8);
if ((key.Length < MinKeyLengthCharacters) || (itemKeyLengthBytes > MaxKeyLengthBytes))
return null;
// Skip Item key terminator (0x00 byte)
int keyTerminator = sb.ReadByte();
if (keyTerminator != 0x00)
return null;
ApeItem item = GetItem(version, key, flags);
return item.ReadItem(version, valueSize, sb, maximumItemSize) ? item : null;
}
////------------------------------------------------------------------------------------------------------------------------------
private static FlacMetadataBlock ReadBlock(StreamBuffer stream)
{
int flags = stream.ReadByte();
// Length
int length = stream.ReadBigEndianInt(3);
if (length >= stream.Length)
return null;
byte[] data = new byte[length];
stream.Read(data, length);
FlacMetadataBlock metadataBlock;
FlacMetadataBlockType blockType = (FlacMetadataBlockType)(flags & HeaderFlags.BlockType);
switch (blockType)
{
case FlacMetadataBlockType.Padding:
metadataBlock = new FlacPaddingMetadataBlock();
break;
case FlacMetadataBlockType.Application:
metadataBlock = new FlacApplicationMetadataBlock();
break;
case FlacMetadataBlockType.StreamInfo:
metadataBlock = new FlacStreamInfoMetadataBlock();
break;
case FlacMetadataBlockType.SeekTable:
metadataBlock = new FlacSeekTableMetadataBlock();
break;
case FlacMetadataBlockType.VorbisComment:
metadataBlock = new FlacVorbisCommentsMetadataBlock();
break;
case FlacMetadataBlockType.CueSheet:
metadataBlock = new FlacCueSheetMetadataBlock();
break;
case FlacMetadataBlockType.Picture:
metadataBlock = new FlacPictureMetadataBlock();
break;
default:
metadataBlock = new FlacMetadataBlock();
break;
}
metadataBlock.Flags = flags;
metadataBlock.Data = data;
return metadataBlock;
}
/// <summary>
/// Reads the <see cref="Id3v2FrameEncodingType"/> from the stream.
/// </summary>
/// <param name="streamBuffer">The stream buffer.</param>
/// <returns>
/// The <see cref="Id3v2FrameEncodingType"/>.
/// </returns>
/// <remarks>
/// Since the encoding type is first read from the stream, the position should be set to the byte containing the encoding type.
/// If the encoding type is <see cref="Id3v2FrameEncodingType.UTF16LittleEndian"/>,
/// it will try to read the byte order marker from the stream
/// to see if the encoding type is <see cref="Id3v2FrameEncodingType.UTF16BigEndian"/>.
/// If no byte order marker is found or if the byte order marker is not recognized,
/// it will return <see cref="Id3v2FrameEncodingType.UTF16LittleEndian"/> as default encoding.
/// <para />
/// The position of the stream will not be modified.
/// </remarks>
public static Id3v2FrameEncodingType ReadEncodingTypeFromStream(StreamBuffer streamBuffer)
{
int encodingByte = streamBuffer.ReadByte();
if ((encodingByte == -1) || !IsValidEncodingType(encodingByte))
return Id3v2FrameEncodingType.Default;
if (encodingByte > (byte)Id3v2FrameEncodingType.UTF16LittleEndian)
encodingByte += 1;
// Cast the encoding type.
Id3v2FrameEncodingType encodingType = (Id3v2FrameEncodingType)encodingByte;
// If it's not little endian, then we don't need to figure out if it's little or big; return here.
if (encodingType != Id3v2FrameEncodingType.UTF16LittleEndian)
return encodingType;
// See which byte order the frame encoding is.
byte[] byteOrderMarker = new byte[2];
// Not enough bytes available; probably little endian then.
if (streamBuffer.Read(byteOrderMarker, 2, false) < 2)
return Id3v2FrameEncodingType.UTF16LittleEndian;
// Little endian byte order marker?
if (((byteOrderMarker[0] == 0xFF) && (byteOrderMarker[1] == 0xFE))
|| ((byteOrderMarker[0] == 0x00) && (byteOrderMarker[1] == 0x00)))
return Id3v2FrameEncodingType.UTF16LittleEndian;
// Big endian byte order marker?
if ((byteOrderMarker[0] == 0xFE) && (byteOrderMarker[1] == 0xFF))
return Id3v2FrameEncodingType.UTF16BigEndian;
// Default to little endian.
return Id3v2FrameEncodingType.UTF16LittleEndian;
}
public void ReadByteTestMovePositionFalse()
{
const byte Value = 0xEF;
const byte Expected = 0xEF;
StreamBuffer target = new StreamBuffer(BitConverter.GetBytes(Value)) { Position = 0 };
int actual = target.ReadByte(false);
Assert.AreEqual(Expected, actual);
Assert.IsTrue(target.Position == 0);
}
////------------------------------------------------------------------------------------------------------------------------------
/// <summary>
/// Initializes a new instance of the <see cref="LameTag"/> class.
/// </summary>
/// <param name="firstFrameBuffer">The first frame buffer containing a <see cref="LameTag"/>.</param>
public LameTag(StreamBuffer firstFrameBuffer)
{
// string lameTag = "LAME"
firstFrameBuffer.ReadString(4);
float ver;
float.TryParse(firstFrameBuffer.ReadString(4), out ver);
Version = ver;
firstFrameBuffer.Seek(-8, SeekOrigin.Current);
if (Version < 3.90f)
{
// Initial LAME info, 20 bytes for LAME tag. for example, "LAME3.12 (beta 6)"
// LAME prior to 3.90 writes only a 20 byte encoder string.
EncoderVersion = firstFrameBuffer.ReadString(20);
}
else
{
EncoderVersion = firstFrameBuffer.ReadString(9);
// Revision Information Tag + VBR Info
int infoAndVbr = firstFrameBuffer.ReadByte();
// Revision information in 4 MSB
InfoTagRevision = infoAndVbr >> 4;
if (InfoTagRevision == Formats.InfoTagRevision.Reserved)
throw new ArgumentException("InfoTagRevision bit is set to reserved (0xF)");
// VBR info in 4 LSB
VbrMethod = infoAndVbr & 0x0F;
// lowpass information, multiply by 100 to get hz
LowpassFilterValue = firstFrameBuffer.ReadByte() * 100;
// Radio replay gain fields
// Peak signal amplitude
PeakSignalAmplitude = firstFrameBuffer.ReadFloat();
// Radio Replay Gain
RadioReplayGain = firstFrameBuffer.ReadInt16();
// Audiophile Replay Gain
AudiophileReplayGain = firstFrameBuffer.ReadInt16();
// Encoding Flags + ATH type
int encodingFlagsAndAthType = firstFrameBuffer.ReadByte();
// Encoding Flags in 4 MSB
EncodingFlags = encodingFlagsAndAthType >> 4;
// LAME ATH Type in 4 LSB
AthType = encodingFlagsAndAthType & 0x0F;
// If ABR, this will be the specified bitrate
// Otherwise (CBR/VBR), the minimal bitrate (255 means 255 or bigger)
BitRate = firstFrameBuffer.ReadByte();
// the 12 bit values (0-4095) of how many samples were added at start (encoder delay)
// in X and how many 0-samples were padded at the end in Y to complete the last frame.
EncoderDelays = firstFrameBuffer.ReadInt(3);
EncoderDelaySamples = EncoderDelays & 0xFFF;
EncoderDelayPaddingSamples = EncoderDelays >> 12;
////int numberSamplesInOriginalWav = frameCount
Misc = firstFrameBuffer.ReadByte();
// Any mp3 can be amplified by a factor 2 ^ ( x * 0.25) in a lossless manner by a tool like eg. mp3gain
// if done so, this 8-bit field can be used to log such transformation happened so that any given time it can be undone.
Mp3Gain = firstFrameBuffer.ReadByte();
// Preset and surround info
PresetSurroundInfo = firstFrameBuffer.ReadInt16();
// 32 bit integer filed containing the exact length in bytes of the mp3 file originally made by LAME excluded ID3 tag info at the end.
MusicLength = firstFrameBuffer.ReadBigEndianInt32();
// Contains a CRC-16 of the complete mp3 music data as made originally by LAME.
_musicCrc = (short)firstFrameBuffer.ReadBigEndianInt16();
// contains a CRC-16 of the first 190 bytes (0x00 - 0xBD) of the Info header frame.
// This field is calculated at the end, once all other fields are completed.
_infoTagCrc = (short)firstFrameBuffer.ReadBigEndianInt16();
}
}
