Audio over OSC is aimed to be a message based audio system using Open Sound Control OSC as a syntax format.
A first implementation a library with externals for PureData (Pd).
More on message based audio system see docu/lac2014_aoo.pdf
- each endpoint can have multiple sources/sinks (each with their own ID)
- AoO sources can send audio to any sink at any time; if the sink ID is a wildcard, it will send to all sinks on the endpoint.
- AoO sinks can listen to several sources at the same time
- AoO sinks and sources can operate at different blocksizes and samplerates
- AoO sources can dynamically change the channel onset
- timing differences (e.g. because of clock drifts) are adjusted via a time DLL filter + dynamic resampling
- the stream format can be set dynamically
- plugin API to register codecs; currently only PCM (uncompressed) and Opus (compressed) are implemented
- aoo_source and aoo_sink C++ classes have a lock-free ringbuffer, so that audio processing and network IO can run on different threads. In the case of aoo_sink, the buffer also helps to deal with network jitter, packet reordering and packet loss at the cost of latency. The size can be adjusted dynamically.
- aoo_sink can ask the source(s) to resend dropped packets, the settings are free adjustable.
- settable UDP packet size for audio data (to optimize for local networks or the internet)
- [aoo_pack~] takes audio signals and outputs OSC messages (also accepts /request messages from sinks)
- [aoo_unpack~] takes OSC messages from several sources and turns them into audio signals
- [aoo_route] takes OSC messages and routes them based on the ID
- [aoo_send~] send an AoO stream (with threaded network IO)
- [aoo_receive~] receive one or more AoO streams (with threaded network IO)
- message to notify sinks about format changes: /AoO/<sink>/format [i]<src> [i]<salt> [i]<nchannels> [i]<samplerate> [i]<blocksize> [s]<codec> [b]<options>
- message to deliver audio data, large blocks are split across several frames: /AoO/<sink>/data [i]<src> [i]<salt> [i]<seq> [d]<sr> [i]<channel_onset> [i]<totalsize> [i]<nframes> [i]<frame> [b]<data>
- message from sink to source to request the format (e.g. the salt has changed) /AoO/<src>/request [i]<sink>
- message from sink to source to request dropped packets. The arguments are pairs of sequence + frame (-1 = whole block) /AoO/<src>/resend [i]<sink> [i]<salt> [ [i]<seq> [i]<frame> ... ]
- multichannel opus codec
- fade in/fade out
- unit tests!
main git repository at git.iem.at:
git clone https://git.iem.at/cm/aoo
docu -- documentation, papers
pd -- Pd library for OSC, first implementation for experiments lib -- C++ library with a C interface, create and manage AoO sources/sinks
- New project page on Feb.2014 - winfried ritsch
- checked in in sourceforge repo (see above)
- added aao_lib
- New test implementation Feb. 2020 - christof ressi
| authors: | Winfried Ritsch, Christof Ressi |
|---|---|
| date: | march 2014 - february 2020 |
| version: | 0.1 |