libopusfile provides a high-level API for decoding and seeking
within .opus files. It includes:
* Support for all files with at least one Opus stream (including
multichannel files or Ogg files where Opus is muxed with something else).
* Full support, including seeking, for chained files.
* A simple stereo downmixing API (allowing chained files to be
decoded with a single output format, even if the channel count changes).
* Support for reading from a file, memory buffer, or over HTTP(S)
(including seeking).
* Support for both random access and streaming data sources.