/// <summary>
/// Initializes a new instance of the <see cref="VbriHeader"/> class.
/// </summary>
/// <param name="firstFrame">The first frame.</param>
/// <param name="firstFrameBuffer">The first frame buffer.</param>
/// <param name="offset">The offset.</param>
public VbriHeader(MpaFrame firstFrame, StreamBuffer firstFrameBuffer, long offset)
: base(firstFrame, firstFrameBuffer, offset, VbrHeaderType.Vbri)
{
/*
FhG VBRI Header
size description
4 'VBRI' (ID)
2 version
2 delay
2 quality
4 # bytes
4 # frames
2 table size (for TOC)
2 table scale (for TOC)
2 size of a table entry (max. size = 4 byte (must be stored in an integer))
2 frames per table entry
?? dynamic table consisting out of frames with size 1-4 whole length in table size! (for TOC)
*/
// name
Name = firstFrameBuffer.ReadString(4);
// version
Version = (short)firstFrameBuffer.ReadBigEndianInt16();
// delay
_delay = firstFrameBuffer.ReadBigEndianInt16();
// quality
Quality = firstFrameBuffer.ReadBigEndianInt16();
// size of the file, in bytes, of all the data
FileSize = firstFrameBuffer.ReadBigEndianInt32();
// amount of frames
FrameCount = firstFrameBuffer.ReadBigEndianInt32();
// number of entries in the table (for TOC)
TableEntries = (short)firstFrameBuffer.ReadBigEndianInt16();
// table scale (for TOC)
TableScale = (short)firstFrameBuffer.ReadBigEndianInt16();
// size of a table entry (in bytes)
TableEntrySize = (short)firstFrameBuffer.ReadBigEndianInt16();
// frames per table entry
FramesPerTableEntry = (short)firstFrameBuffer.ReadBigEndianInt16();
// dynamic table consisting out of frames
TableLength = TableEntries * TableEntrySize;
Toc = new int[TableEntries + 1];
for (int i = 0; i <= TableEntries; i++)
{
int value = firstFrameBuffer.ReadBigEndianInt(TableEntrySize);
Toc[i] = value * TableScale;
}
_totalLengthMilliseconds = firstFrame.AudioLength * FrameCount;
}
////------------------------------------------------------------------------------------------------------------------------------
private bool ReadFrame(StreamBuffer sb)
{
if (sb == null)
throw new ArgumentNullException("sb");
StartOffset = sb.Position;
if (!ReadHeader(sb))
return false;
for (int channel = 0; channel < Channels; channel++)
{
FlacSubFrame subFrame = FlacSubFrame.ReadFrame(sb, channel, this);
_subFrames.Add(subFrame);
}
_crc16 = sb.ReadBigEndianInt16();
int crc16 = Crc16.Calculate(new byte[0]);
if (_crc16 != crc16)
throw new InvalidDataException("Corrupt CRC16.");
EndOffset = sb.Position;
return true;
}
////------------------------------------------------------------------------------------------------------------------------------
/// <summary>
/// Reads the specified stream buffer.
/// </summary>
/// <param name="sb">The stream buffer.</param>
/// <param name="sampeSize">Size of the sample.</param>
/// <param name="blockSize">Size of the block.</param>
protected override void Read(StreamBuffer sb, int sampeSize, int blockSize)
{
UnencodedWarmUpSamples = new int[Order];
for (int i = 0; i < Order; i++)
UnencodedWarmUpSamples[i] = sb.ReadBigEndianInt32();
int other = sb.ReadBigEndianInt16();
QuantizedCoefficientsPrecision = (other & 0xF) + 1;
QuantizedCoefficientShift = (other >> 4) & 0x1F;
UnencodedPredictorCoefficients = new int[Order];
for (int i = 0; i < Order; i++)
UnencodedPredictorCoefficients[i] = sb.ReadBigEndianInt32();
Residual = FlacResidual.Read(sb, blockSize, Order);
}
/// <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;
}
/// <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;
}
public void ReadBigEndianInt16Test()
{
const short Value = 0x5678;
const short Expected = 0x7856;
StreamBuffer target = new StreamBuffer(BitConverter.GetBytes(Value)) { Position = 0 };
long actual = target.ReadBigEndianInt16();
Assert.AreEqual(Expected, actual);
}
////------------------------------------------------------------------------------------------------------------------------------
/// <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();
}
}