/// <summary>
/// Gets the <see cref="XingHeader"/> of a <see cref="Mp3Frame"/>. If the <paramref name="frame"/> does not has an <see cref="XingHeader"/> the return value will be null.
/// </summary>
/// <param name="frame"><see cref="Mp3Frame"/> which should get checked whether it contains a <see cref="XingHeader"/>.</param>
/// <returns><see cref="XingHeader"/> of the specified <paramref name="frame"/> or null.</returns>
public static XingHeader FromFrame(Mp3Frame frame)
{
XingHeader header = new XingHeader();
int offset = CalcOffset(frame);
if (offset == -1)
return null;
if (CheckForValidXingHeader(frame, offset))
{
header._startIndex = offset;
offset = offset + 4;
}
else
{
return null;
}
header.HeaderFlags = (XingHeaderFlags)ReadHeaderFlags(frame, offset);
offset = offset + 4;
if ((header.HeaderFlags & XingHeaderFlags.Frames) != 0)
{
header._framesOffset = offset;
offset += 4;
}
if ((header.HeaderFlags & XingHeaderFlags.Bytes) != 0)
{
header._bytesOffset = offset;
offset += 4;
}
if ((header.HeaderFlags & XingHeaderFlags.Toc) != 0)
{
header._tocOffset = offset;
offset += 100;
}
if ((header.HeaderFlags & XingHeaderFlags.QualityIndicator) != 0)
{
header._qualityIndicator = ReadHeaderFlags(frame, offset);
offset += 4;
}
header._endIndex = offset;
return header;
}
private static int CalcOffset(Mp3Frame frame)
{
int offset = 0;
if (frame.MPEGVersion == MpegVersion.Version1)
{
if (frame.ChannelMode != Mp3ChannelMode.Mono)
offset = 32 + 4;
else
offset = 17 + 4;
}
else if (frame.MPEGVersion == MpegVersion.Version2)
{
if (frame.ChannelMode != Mp3ChannelMode.Mono)
offset = 17 + 4;
else
offset = 9 + 4;
}
else
{
return -1;
}
return offset;
}
private static int ReadHeaderFlags(Mp3Frame frame, int offset)
{
byte[] data = null;
if (frame.ReadData(ref data, 0) < 4)
throw new System.IO.EndOfStreamException();
int i = 0;
for (int j = 0; j <= 3; j++)
{
i = data[offset + j];
i <<= 8;
}
return i;
}
private static bool CheckForValidXingHeader(Mp3Frame frame, int offset)
{
byte[] data = null;
if (frame.ReadData(ref data, 0) < 4)
return false;
if (data[offset + 0] == 'X' && data[offset + 1] == 'i' && data[offset + 2] == 'n' && data[offset + 3] == 'g')
{
return true;
}
else
return false;
}
/// <summary>
/// Creates a new instance of the <see cref="Mp3Frame"/> class based on a <see cref="Stream"/>.
/// </summary>
/// <param name="stream"><see cref="Stream"/> which provides MP3 data.</param>
/// <returns>A new instance of the <see cref="Mp3Frame"/> class based on the specified <paramref name="stream"/>.</returns>
public static Mp3Frame FromStream(Stream stream)
{
Mp3Frame frame = new Mp3Frame(stream);
return(frame.FindFrame(stream, true) ? frame : null);
}
private int ReadRawDataFromFrame(ref byte[] buffer, out Mp3Frame frame)
{
bool success = false;
frame = null;
do
{
try
{
frame = GetNextFrame(_stream, ref buffer);
success = true;
}
catch (IOException)
{
}
catch (WebException)
{
}
if (!success)
{
do
{
CloseResponse();
InitializeConnection();
if (_stream == null)
Thread.Sleep(100);
} while (_stream == null);
}
} while (!success);
if (frame == null)
{
buffer = new byte[0];
return 0;
}
if (buffer.Length > frame.FrameLength)
Array.Clear(buffer, frame.FrameLength, buffer.Length - frame.FrameLength);
return frame.FrameLength;
}
/// <summary>
/// Creates a new instance of the <see cref="Mp3Frame"/> class based on a <see cref="Stream"/>.
/// </summary>
/// <param name="stream"><see cref="Stream"/> which provides MP3 data.</param>
/// <param name="data">Byte array which recieves the content of the <see cref="Mp3Frame"/>.</param>
/// <returns>A new instance of the <see cref="Mp3Frame"/> class based on the specified <paramref name="stream"/>.</returns>
public static Mp3Frame FromStream(Stream stream, ref byte[] data)
{
Mp3Frame frame = new Mp3Frame(stream);
if (frame.FindFrame(stream, false))
{
data = data.CheckBuffer(frame.FrameLength);
Array.Copy(frame._headerBuffer, 0, data, 0, 4);
int read = stream.Read(data, 4, frame.FrameLength - 4);
if (read != frame.FrameLength - 4)
return null;
return frame;
}
return null;
}
/// <summary>
/// Creates a new instance of the <see cref="Mp3Frame"/> class based on a <see cref="Stream"/>.
/// </summary>
/// <param name="stream"><see cref="Stream"/> which provides MP3 data.</param>
/// <returns>A new instance of the <see cref="Mp3Frame"/> class based on the specified <paramref name="stream"/>.</returns>
public static Mp3Frame FromStream(Stream stream)
{
Mp3Frame frame = new Mp3Frame(stream);
return frame.FindFrame(stream, stream.CanSeek) ? frame : null;
}
