/// <summary>
/// construct object to wrap the audio
/// passing in audio size and id3 length tag (if any) to help with bitrate calculations
/// </summary>
/// <param name="firstFrame"></param>
/// <param name="id3DurationTag">length from ID3v2, if any</param>
public Audio(AudioFrame firstFrame, TimeSpan? id3DurationTag)
{
if (firstFrame == null)
{
throw new InvalidAudioFrameException("MPEG Audio Frame not found");
}
_firstFrame = firstFrame;
_id3DurationTag = id3DurationTag;
/*_hasInconsistencies = false;*/
}
/// <summary>
/// seek and create derived type of AudioFrame from stream
/// </summary>
/// <param name="stream">source stream, advanced by length of the frame on read</param>
/// <param name="remainingBytes">number of bytes in audio block, as reported by the caller</param>
/// <returns>wrapper for derived type of AudioFrame</returns>
static public AudioFrame CreateFrame( Stream stream, uint remainingBytes )
{
// find and parse frame header, then rewind stream back to start.
// if reach the end of the file, return null
// if any other error, throw
long firstFrameStart = stream.Position;
AudioFrameHeader header = CreateHeader( stream, remainingBytes );
if( header == null )
return null;
uint frameFullSize;
// if free rate file, find the start of the next frame and use the difference as the frame size.
// NB. This won't be very efficient!
if( header.IsFreeBitRate )
{
uint firstFrameHdrSize = (uint)(stream.Position - firstFrameStart);
frameFullSize = firstFrameHdrSize + GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
//GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
//GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
//GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
//GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
//GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
//GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
//GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
//GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
//GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
//GetNextFrameOffset(stream, remainingBytes - (uint)(stream.Position - firstFrameStart));
}
else
{
uint? frameLengthInBytes = header.FrameLengthInBytes;
Trace.Assert(frameLengthInBytes != null);
frameFullSize = (uint)header.FrameLengthInBytes;
}
// rewind the stream to the start of the frame, so we can read it all in one chunk
stream.Position = firstFrameStart;
AudioFrame firstTry = new AudioFrame(stream, header, frameFullSize, remainingBytes);
return CreateSpecialisedHeaderFrame( firstTry );
}
/// <summary>
/// copy construct AudioFrame for derived classes
/// </summary>
/// <param name="other"></param>
protected AudioFrame(AudioFrame other)
{
_frameBuffer = other._frameBuffer;
_header = other._header;
_headerBytes = other._headerBytes;
}
/// <summary>
/// construct XingHeader frame from a pre-existing raw frame; "downcast".
/// </summary>
/// <param name="baseclass"></param>
public AudioFrameXingHeader(AudioFrame baseclass)
: base(baseclass)
{
}
/// <summary>
/// construct XingHeader frame from a pre-existing raw frame; "downcast".
/// </summary>
/// <param name="baseclass"></param>
public AudioFrameVbriHeader(AudioFrame baseclass)
: base(baseclass)
{
}
private static AudioFrame CreateSpecialisedHeaderFrame( AudioFrame firstTry )
{
//string wholeHeader = ASCIIEncoding.ASCII.GetString(_frameBuffer, 0, _frameBuffer.Length);
if( firstTry.IsXingHeader )
{
//if (firstTry.IsLameHeader)
// return new AudioFrameLameHeader(firstTry);
//else
return new AudioFrameXingHeader( firstTry );
}
else if( firstTry.IsVbriHeader )
return new AudioFrameVbriHeader( firstTry );
else
return firstTry;
}
/// <summary>
/// create derived type of AudioFrame from buffer, or throw
/// </summary>
/// <param name="sourceBuffer"></param>
/// <returns>wrapper for derived type of AudioFrame</returns>
static public AudioFrame CreateFrame( byte[] sourceBuffer )
{
AudioFrame firstTry = new AudioFrame( sourceBuffer );
return CreateSpecialisedHeaderFrame( firstTry );
}
