75 lines
3.9 KiB
Markdown
75 lines
3.9 KiB
Markdown
PortAudio.jl
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============
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PortAudio.jl is a wrapper for [libportaudio](http://www.portaudio.com/), which gives cross-platform access to audio devices. It is compatible with the types defined in [SampledSignals.jl](https://github.com/JuliaAudio/SampledSignals.jl). It provides a `PortAudioStream` type, which can be read from and written to.
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#### NOTE: This package currently requires the master branch of the `Compat`, `SampledSignals` and `RingBuffers` packages. Use `Pkg.checkout` to checkout the master.
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## Opening a stream
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The easiest way to open a source or sink is with the default `PortAudioStream()` constructor, which will open a 2-in, 2-out stream to your system's default device(s). The constructor can also take the input and output channel counts as positional arguments, or a variety of other keyword arguments.
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```julia
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PortAudioStream(inchans=2, outchans=2; eltype=Float32, samplerate=48000Hz, blocksize=4096, synced=false)
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```
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You can open a specific device by adding it as the first argument, either as a `PortAudioDevice` instance or by name. You can also give separate names or devices if you want different input and output devices
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```julia
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PortAudioStream(device::PortAudioDevice, args...; kwargs...)
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PortAudioStream(devname::AbstractString, args...; kwargs...)
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```
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You can get a list of your system's devices with the `PortAudio.devices()` function:
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```julia
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julia> PortAudio.devices()
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6-element Array{PortAudio.PortAudioDevice,1}:
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PortAudio.PortAudioDevice("AirPlay","Core Audio",0,2,0)
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PortAudio.PortAudioDevice("Built-in Microph","Core Audio",2,0,1)
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PortAudio.PortAudioDevice("Built-in Output","Core Audio",0,2,2)
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PortAudio.PortAudioDevice("JackRouter","Core Audio",2,2,3)
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PortAudio.PortAudioDevice("After Effects 13.5","Core Audio",0,0,4)
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PortAudio.PortAudioDevice("Built-In Aggregate","Core Audio",2,2,5)
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```
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## Reading and Writing
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The `PortAudioStream` type has `source` and `sink` fields which are of type `PortAudioSource <: SampleSource` and `PortAudioSink <: SampleSink`, respectively. are subtypes of `SampleSource` and `SampleSink`, respectively (from [SampledSignals.jl](https://github.com/JuliaAudio/SampledSignals.jl)). This means they support all the stream and buffer features defined there. For example, if you load SampledSignals with `using SampledSignals` you can read 5 seconds to a buffer with `buf = read(stream.source, 5s)`, regardless of the sample rate of the device.
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PortAudio.jl also provides convenience wrappers around the `PortAudioStream` type so you can read and write to it directly, e.g. `write(stream, stream)` will set up a loopback that will read from the input and play it back on the output.
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## Examples
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### Set up an audio pass-through from microphone to speaker
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```julia
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stream = PortAudioStream(2, 2)
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write(stream, stream)
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```
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### Open your built-in microphone and speaker by name
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```julia
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stream = PortAudioStream("Built-in Microph", "Built-in Output")
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write(stream, stream)
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```
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### Record 10 seconds of audio and save to an ogg file
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```julia
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julia> using PortAudio, SampledSignals, LibSndFile
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julia> stream = PortAudioStream("Built-in Microph", 2, 0)
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PortAudio.PortAudioStream{Float32,SIUnits.SIQuantity{Int64,0,0,-1,0,0,0,0,0,0}}
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Samplerate: 48000 s⁻¹
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Buffer Size: 4096 frames
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2 channel source: "Built-in Microph"
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julia> buf = read(stream, 10s)
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480000-frame, 2-channel SampleBuf{Float32, 2, SIUnits.SIQuantity{Int64,0,0,-1,0,0,0,0,0,0}}
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10.0 s at 48000 s⁻¹
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▁▄▂▃▅▃▂▄▃▂▂▁▁▂▂▁▁▄▃▁▁▄▂▁▁▁▄▃▁▁▃▃▁▁▁▁▁▁▁▁▄▄▄▄▄▂▂▂▁▃▃▁▃▄▂▁▁▁▁▃▃▂▁▁▁▁▁▁▃▃▂▂▁▃▃▃▁▁▁▁
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▁▄▂▃▅▃▂▄▃▂▂▁▁▂▂▁▁▄▃▁▁▄▂▁▁▁▄▃▁▁▃▃▁▁▁▁▁▁▁▁▄▄▄▄▄▂▂▂▁▃▃▁▃▄▂▁▁▁▁▃▃▂▁▁▁▁▁▁▃▃▂▂▁▃▃▃▁▁▁▁
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julia> save(joinpath(homedir(), "Desktop", "myvoice.ogg"), buf)
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```
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