/// <summary>
/// Reads the next mp3 frame
/// </summary>
/// <returns>Next mp3 frame, or null if EOF</returns>
private Mp3Frame ReadNextFrame(bool readData)
{
Mp3Frame frame = null;
try
{
frame = Mp3Frame.LoadFromStream(mp3Stream, readData);
if (frame != null)
{
tocIndex++;
}
}
catch (EndOfStreamException)
{
// suppress for now - it means we unexpectedly got to the end of the stream
// half way through
}
return(frame);
}
/// <summary>
/// Reads an MP3 frame from a stream
/// </summary>
/// <param name="input">input stream</param>
/// <returns>A valid MP3 frame, or null if none found</returns>
// Token: 0x060003A2 RID: 930 RVA: 0x0000CA43 File Offset: 0x0000AC43
public static Mp3Frame LoadFromStream(Stream input)
{
return(Mp3Frame.LoadFromStream(input, true));
}
/// <summary>
/// Opens MP3 from a stream rather than a file
/// Will not dispose of this stream itself
/// </summary>
/// <param name="inputStream">The incoming stream containing MP3 data</param>
/// <param name="frameDecompressorBuilder">Factory method to build a frame decompressor</param>
public Mp3FileReader(Stream inputStream, FrameDecompressorBuilder frameDecompressorBuilder)
{
if (inputStream == null)
{
throw new ArgumentNullException("inputStream");
}
try
{
mp3Stream = inputStream;
id3v2Tag = Id3v2Tag.ReadTag(mp3Stream);
dataStartPosition = mp3Stream.Position;
var firstFrame = Mp3Frame.LoadFromStream(mp3Stream);
if (firstFrame == null)
{
throw new InvalidDataException("Invalid MP3 file - no MP3 Frames Detected");
}
double bitRate = firstFrame.BitRate;
xingHeader = XingHeader.LoadXingHeader(firstFrame);
// If the header exists, we can skip over it when decoding the rest of the file
if (xingHeader != null)
{
dataStartPosition = mp3Stream.Position;
}
// workaround for a longstanding issue with some files failing to load
// because they report a spurious sample rate change
var secondFrame = Mp3Frame.LoadFromStream(mp3Stream);
if (secondFrame != null &&
(secondFrame.SampleRate != firstFrame.SampleRate ||
secondFrame.ChannelMode != firstFrame.ChannelMode))
{
// assume that the first frame was some kind of VBR/LAME header that we failed to recognise properly
dataStartPosition = secondFrame.FileOffset;
// forget about the first frame, the second one is the first one we really care about
firstFrame = secondFrame;
}
this.mp3DataLength = mp3Stream.Length - dataStartPosition;
// try for an ID3v1 tag as well
mp3Stream.Position = mp3Stream.Length - 128;
byte[] tag = new byte[128];
mp3Stream.Read(tag, 0, 128);
if (tag[0] == 'T' && tag[1] == 'A' && tag[2] == 'G')
{
id3v1Tag = tag;
this.mp3DataLength -= 128;
}
mp3Stream.Position = dataStartPosition;
// create a temporary MP3 format before we know the real bitrate
this.Mp3WaveFormat = new Mp3WaveFormat(firstFrame.SampleRate,
firstFrame.ChannelMode == ChannelMode.Mono ? 1 : 2, firstFrame.FrameLength, (int)bitRate);
CreateTableOfContents();
this.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.
// Calculated as a double to minimize rounding errors
bitRate = (mp3DataLength * 8.0 / TotalSeconds());
mp3Stream.Position = dataStartPosition;
// now we know the real bitrate we can create an accurate MP3 WaveFormat
this.Mp3WaveFormat = new Mp3WaveFormat(firstFrame.SampleRate,
firstFrame.ChannelMode == ChannelMode.Mono ? 1 : 2, firstFrame.FrameLength, (int)bitRate);
decompressor = frameDecompressorBuilder(Mp3WaveFormat);
this.waveFormat = decompressor.OutputFormat;
this.bytesPerSample = (decompressor.OutputFormat.BitsPerSample) / 8 * decompressor.OutputFormat.Channels;
// no MP3 frames have more than 1152 samples in them
this.bytesPerDecodedFrame = 1152 * bytesPerSample;
// some MP3s I seem to get double
this.decompressBuffer = new byte[this.bytesPerDecodedFrame * 2];
}
catch (Exception)
{
if (ownInputStream)
{
inputStream.Dispose();
}
throw;
}
}