/// <summary>
/// Opens MP3 from a stream rather than a file
/// Will not dispose of this stream itself
/// </summary>
/// <param name="inputStream"></param>
public Mp3FileReader(Stream inputStream)
{
// Calculated as a double to minimize rounding errors
double bitRate;
mp3Stream = inputStream;
id3v2Tag = Id3v2Tag.ReadTag(mp3Stream);
dataStartPosition = mp3Stream.Position;
var mp3Frame = new Mp3Frame(mp3Stream);
sampleRate = mp3Frame.SampleRate;
frameLengthInBytes = mp3Frame.FrameLength;
bitRate = mp3Frame.BitRate;
xingHeader = XingHeader.LoadXingHeader(mp3Frame);
// If the header exists, we can skip over it when decoding the rest of the file
if (xingHeader != null) dataStartPosition = mp3Stream.Position;
mp3DataLength = mp3Stream.Length - dataStartPosition;
// try for an ID3v1 tag as well
mp3Stream.Position = mp3Stream.Length - 128;
var tag = new byte[128];
mp3Stream.Read(tag, 0, 3);
if (tag[0] == 'T' && tag[1] == 'A' && tag[2] == 'G')
{
id3v1Tag = tag;
mp3DataLength -= 128;
}
mp3Stream.Position = dataStartPosition;
CreateTableOfContents();
tocIndex = 0;
// [Bit rate in Kilobits/sec] = [Length in kbits] / [time in seconds]
// = [Length in bits ] / [time in milliseconds]
// Note: in audio, 1 kilobit = 1000 bits.
bitRate = (mp3DataLength*8.0/TotalSeconds());
mp3Stream.Position = dataStartPosition;
Mp3WaveFormat = new Mp3WaveFormat(sampleRate, mp3Frame.ChannelMode == ChannelMode.Mono ? 1 : 2, frameLengthInBytes,
(int) bitRate);
decompressor = new AcmMp3FrameDecompressor(Mp3WaveFormat); // new DmoMp3FrameDecompressor(this.Mp3WaveFormat);
waveFormat = decompressor.OutputFormat;
bytesPerSample = (decompressor.OutputFormat.BitsPerSample)/8*decompressor.OutputFormat.Channels;
// no MP3 frames have more than 1152 samples in them
// some MP3s I seem to get double
decompressBuffer = new byte[1152*bytesPerSample*2];
}
/// <summary>
/// Load Xing Header
/// </summary>
/// <param name="frame">Frame</param>
/// <returns>Xing Header</returns>
public static XingHeader LoadXingHeader(Mp3Frame frame)
{
var xingHeader = new XingHeader();
xingHeader.frame = frame;
int offset = 0;
if (frame.MpegVersion == MpegVersion.Version1)
{
if (frame.ChannelMode != ChannelMode.Mono)
{
offset = 32 + 4;
}
else
{
offset = 17 + 4;
}
}
else if (frame.MpegVersion == MpegVersion.Version2)
{
if (frame.ChannelMode != ChannelMode.Mono)
{
offset = 17 + 4;
}
else
{
offset = 9 + 4;
}
}
else
{
return(null);
// throw new FormatException("Unsupported MPEG Version");
}
if ((frame.RawData[offset + 0] == 'X') &&
(frame.RawData[offset + 1] == 'i') &&
(frame.RawData[offset + 2] == 'n') &&
(frame.RawData[offset + 3] == 'g'))
{
xingHeader.startOffset = offset;
offset += 4;
}
else
{
return(null);
}
var flags = (XingHeaderOptions)ReadBigEndian(frame.RawData, offset);
offset += 4;
if ((flags & XingHeaderOptions.Frames) != 0)
{
xingHeader.framesOffset = offset;
offset += 4;
}
if ((flags & XingHeaderOptions.Bytes) != 0)
{
xingHeader.bytesOffset = offset;
offset += 4;
}
if ((flags & XingHeaderOptions.Toc) != 0)
{
xingHeader.tocOffset = offset;
offset += 100;
}
if ((flags & XingHeaderOptions.VbrScale) != 0)
{
xingHeader.vbrScale = ReadBigEndian(frame.RawData, offset);
offset += 4;
}
xingHeader.endOffset = offset;
return(xingHeader);
}
/// <summary>
/// Load Xing Header
/// </summary>
/// <param name="frame">Frame</param>
/// <returns>Xing Header</returns>
public static XingHeader LoadXingHeader(Mp3Frame frame)
{
var xingHeader = new XingHeader();
xingHeader.frame = frame;
int offset = 0;
if (frame.MpegVersion == MpegVersion.Version1)
{
if (frame.ChannelMode != ChannelMode.Mono)
offset = 32 + 4;
else
offset = 17 + 4;
}
else if (frame.MpegVersion == MpegVersion.Version2)
{
if (frame.ChannelMode != ChannelMode.Mono)
offset = 17 + 4;
else
offset = 9 + 4;
}
else
{
return null;
// throw new FormatException("Unsupported MPEG Version");
}
if ((frame.RawData[offset + 0] == 'X') &&
(frame.RawData[offset + 1] == 'i') &&
(frame.RawData[offset + 2] == 'n') &&
(frame.RawData[offset + 3] == 'g'))
{
xingHeader.startOffset = offset;
offset += 4;
}
else
{
return null;
}
var flags = (XingHeaderOptions) ReadBigEndian(frame.RawData, offset);
offset += 4;
if ((flags & XingHeaderOptions.Frames) != 0)
{
xingHeader.framesOffset = offset;
offset += 4;
}
if ((flags & XingHeaderOptions.Bytes) != 0)
{
xingHeader.bytesOffset = offset;
offset += 4;
}
if ((flags & XingHeaderOptions.Toc) != 0)
{
xingHeader.tocOffset = offset;
offset += 100;
}
if ((flags & XingHeaderOptions.VbrScale) != 0)
{
xingHeader.vbrScale = ReadBigEndian(frame.RawData, offset);
offset += 4;
}
xingHeader.endOffset = offset;
return xingHeader;
}