This class reads information from a MP3 file.
- actual audio data in bytes
- position of first frame
- length (with VBR support, XING and VBRI)
- MPEG version and layer
- bitrate, approximated frame count
- samplerate, channels
- various flags (copyright,private,original,CRCs,emphasis)
The detection of the MP3's first frame is pretty safe,
ID3v2 will be skipped and the first frame needs to be followed
by a valid second frame.
