This is very cool. I've been meaning to try out some audio programming in Julia but now I really must..
On Sun, Mar 20, 2016 at 5:31 AM, Spencer Russell <[email protected]> wrote: > Hey there, Julians. > > So AudioIO has been languishing for some time now, and I’ve been busily > working away at the next generation. One of the issues with AudioIO is that > it was a lot to swallow if you just wanted to play or record some audio. > I’ve been focusing on getting the fundamental APIs right, so that the fancy > stuff can be built on top. > > There’s a new JuliaAudio <https://github.com/JuliaAudio> organization and > 5 shiny new packages. They’re still pretty young, but most of them have > good test coverage. I’m planning on registering to METADATA soon, but I > wanted to solicit some feedback first. > > SampleTypes.jl <https://github.com/JuliaAudio/SampleTypes.jl> is the most > important as it defines the architecture that glues together the rest of > the packages. It defines a set of stream and buffer types that should make > it easy to move sampled data around. It’s called SampleTypes instead of > AudioTypes because it should be useful for any sort of regularly-sampled, > multi-channel data (e.g. complex samples from an SDR, multi-channel EEG, > etc.). The types are sample-rate aware, and the samplerate can be stored in > real units using SIUnits.jl. That allows cool features like reading in data > using seconds instead of samples. > > Part of the idea with SampleTypes is to make it really easy to plug in a > streaming audio backend, for instance SampleTypes handles conversion > between formats, channel counts, and sample rates (currently just linear > interpolation), so the underlying device libraries don’t have to. SampleBuf > (the buffer type) is an AbstractArray, and it should be pretty drop-in > replaceable to normal Arrays, but with extra goodies. If there are cases > where it doesn’t act like an Array please file an Issue. > > LibSndFile.jl <https://github.com/JuliaAudio/LibSndFile.jl> and > PortAudio.jl <https://github.com/JuliaAudio/PortAudio.jl> used to be part > of AudioIO, but are now separate packages. They wrap well-established > cross-platform C libraries for interacting with files and real-time audio > devices, respectively. > > LibSndFile has been designed to work with FileIO, so loading a file is as > easy at `load(“myfile.wav”)` and it will figure out the format from the > extension and magic bytes in the file header. > > PortAudio.jl has been massively simplified from what was in AudioIO. Test > coverage is at 95%, but because PortAudio doesn’t provide a way to simulate > input the tests aren’t very strong. They also don’t run on Travis. > > JACKAudio.jl <https://github.com/JuliaAudio/JACKAudio.jl> is a wrapper > for libjack, a great audio routing tool designed for low-latency, pro audio > applications. Unfortunately we’re not yet at the point where we can get > super low latency from Julia, but it’s working pretty well now and I think > there’s still room to tune it for better performance. > > RingBuffers.jl <https://github.com/JuliaAudio/RingBuffers.jl> is a small > utility package that provides the RingBuffer type. It’s a fixed-size > multi-channel circular ringbuffer with configurable overflow/underflow > behavior. It uses normal Arrays and is not specific to this architecture, > except that is assumes each channel of data is a column of a 2D Array. > > Here’s a screenshot from the PortAudio README that gives a good flavor for > the sort of things these packages can do together: > > > Please kick the tires and let me know what doesn’t work or is confusing. > Also, if you maintain an audio-related package and want to plug into this > architecture, I’d be happy to start growing the JuliaAudio organization > both in maintainers and packages. > > -s >
