109 lines
3.3 KiB
Markdown
109 lines
3.3 KiB
Markdown
# jacket
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A [Nim] wrapper for the [JACK] client side [C API] aka *libjack*.
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## Project status
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This software is in *beta status*.
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The majority of JACK client APIs have been wrapped and are functional (see
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[examples]), but some APIs (e.g. threading) still need wrapping. Others, like
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the server control or the deprecated session API, will probably not be covered
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by these bindings. While this project is in beta stage, symbol names may still
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be changed and things moved around before the first stable release.
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## Installation
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* Clone this repository.
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* Change into the `jacket` directory.
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* Run [`nimble install`] (or `nimble develop`).
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* Run the [examples] with `nim compile --run examples/<example>.nim`.
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(Some examples need `--threads:on` with Nim < 2.0).
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## Usage
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Here is a very minimal JACK client application, which just passes audio through
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from its single input port to its output port.
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Any error checking and handling has been omitted for brevity's sake. See the
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files in the [examples] directory for more robust example code.
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```nim
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import std/os
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import system/ansi_c
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import jacket
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var
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jackClient: ClientP
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status: cint
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exitSignalled: bool = false
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inpPort, outPort: PortP
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type JackBufferP = ptr UncheckedArray[DefaultAudioSample]
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proc signalCb(sig: cint) {.noconv.} =
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exitSignalled = true
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proc shutdownCb(arg: pointer = nil) {.cdecl.} =
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exitSignalled = true
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proc processCb(nFrames: NFrames, arg: pointer): cint {.cdecl.} =
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var inpbuf = cast[JackBufferP](portGetBuffer(inpPort, nFrames))
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var outbuf = cast[JackBufferP](portGetBuffer(outPort, nFrames))
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# copy samples from input to output buffer
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for i in 0 ..< nFrames:
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outbuf[i] = inpbuf[i]
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# Create JACK Client ptr
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jackClient = clientOpen("passthru", NullOption.ord, status.addr)
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# Register audio input and output ports
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inpPort = jackClient.portRegister("in_1", JACK_DEFAULT_AUDIO_TYPE, PortIsInput.ord, 0)
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outPort = jackClient.portRegister("out_1", JACK_DEFAULT_AUDIO_TYPE, PortIsOutput.ord, 0)
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# Set JACK callbacks
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jackClient.onShutdown(shutdownCb)
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discard jackClient.setProcessCallback(processCb, nil)
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# Handle POSIX signals
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c_signal(SIGINT, signalCb)
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c_signal(SIGTERM, signalCb)
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# Activate JACK client ...
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discard jackClient.activate()
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while not exitSignalled:
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sleep(50)
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discard jackClient.clientClose()
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```
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## License
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This software is released under the *MIT License*. See the file
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[LICENSE.md](./LICENSE.md) for more information.
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Please note that the JACK client library (libjack), which this project wraps,
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is licensed under the [LGPL-2.1]. This wrapper does not statically or
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dynamically link to libjack, but only loads it via the dynamic linker at
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run-time.
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Software using this wrapper is, in the opinion of its author, not considered a
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derivative work of libjack and not required to be released under the LGPL, but
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no guarantees are made in this regard and users are advised to employ
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professional legal counsel when in doubt.
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## Author
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*jacket* is written by [Christopher Arndt].
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[C API]: https://jackaudio.org/api/
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[Christopher Arndt]: mailto:info@chrisarndt.de
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[examples]: ./examples
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[JACK]: https://jackaudio.org/
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[LGPL-2.1]: https://spdx.org/licenses/LGPL-2.1-or-later.html
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[`nimble install`]: https://github.com/nim-lang/nimble#nimble-usage
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[Nim]: https://nim-lang.org/
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