The audio part of the MPEG standard specifies three layers, whereat each
layer specifies its own file format. All three layers are using similar
audio coding techniques, but they vary in efficiency and complexity.
Layer I needs the fewest calculation time for en-/decoding a stream, layer III
the most. But a layer I MPEG audio stream is bigger than a layer III stream
at the same quality. This program is able to decode and play only layer I
and II streams, layer III is not supported (yet?!?).

The maplay decodes layer I and layer II MPEG audio streams and plays them
using a CD-quality audio device or sends the to stdout normally as 16 bit
signed PCM values, interleaved for stereo streams.

This player supports all modes, which are single channel, stereo,
joint stereo and dual channel, and all bitrates except free mode.
The missing free mode support should not be a problem for now,
because I haven't seen such a stream yet.
