Piper Vamp C++

Supporting code in C++ for the Piper audio feature extractor protocol, primarily for making Vamp plugins work with the Piper protocol.

Includes:

• code to adapt Piper messages to the classes used in the Vamp Plugin SDK
• a command-line converter between Piper serialisations
• a server that makes Vamp plugins available via Piper binary messages with Cap'n Proto serialisation