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diff --git a/project/templates/soundbinds.xhtml b/project/templates/soundbinds.xhtml new file mode 100644 index 0000000..4f0ff74 --- /dev/null +++ b/project/templates/soundbinds.xhtml @@ -0,0 +1,115 @@ + +{%- extends "base_plain.xhtml" -%} + + + +{%- block title -%}Ada Bindings for Libao, Libsndfile, PortAudio{%- endblock -%} + + + +{%- block footer -%}{{ plain_footer ("soundbinds.xhtml") }}{%- endblock -%} + + + +{%- block content %} +<h4>Ada Bindings for Libao, Libsndfile, PortAudio</h4> + +<p>Git repositories: +<a href="/cgi-bin/cgit.cgi/aao">aao</a>, +<a href="/cgi-bin/cgit.cgi/asndfile">asndfile</a>, +<a href="/cgi-bin/cgit.cgi/portadao">portadao</a></p> + +<h5>29/7/2023</h5> + +<p>Why am I making a single article about language bindings for three different libraries? +A few reasons. These three libraries are all quite small, they all cover similar and related +functionality, and all the bindings were written quickly one after the other. But ultimately I +just don't want to clutter the index up.</p> + +<p>The three libraries in question:</p> +<ul> + <li><i><a href="https://xiph.org/ao/" class="external">Libao</a>:</i> An extremely minimalist C + library for cross platform audio playback. It does the job, but the lack of options for buffer + data types and the lack of an asynchronous interface may make it not ideal for some uses.</li> + <li><i><a href="https://libsndfile.github.io/libsndfile/" class="external">Libsndfile</a>:</i> A + cross platform C library for reading and writing files containing sampled sound.</li> + <li><i><a href="http://portaudio.com/" class="external">PortAudio</a>:</i> A slightly more + elaborate C library for cross platform audio playback. Has the variety of buffer data types and + the asynchronous callback interface that libao lacks.</li> +</ul> + +<p>It is commonly thought that it is easy to bind a C library to another language. This is not the +case. Even for the thinnest of thin bindings and even when the other language is trying to make it +easy, there are problems. Enumerations, preprocessor macros, and callbacks are all awkward and they +are all involved here. Also, these are all thick bindings so things are even more fun. Nonetheless +it is all done. With the sole noteworthy exception of the RIFF chunk API in libsndfile, but we won't +talk about that.</p> + +<p>Error codes have been converted to exceptions, initialize/shutdown functions have been rendered +automatic, manual deallocations have been made obsolete, void pointers have been wrapped up, +callbacks have been made available, and dot notation for invoking subprograms has been used +extensively. Oh, and the rather odd command API for libsndfile has been tamed. Mostly. The array +types for all the sound samples have also been defined such that conversions between the types used +in each binding should be as painless as possible, without sacrificing the strong typing Ada is +known for.</p> + +<p>An excerpt of PortAudio code in C taken from an example program:</p> +<div class="precontain"> +<code> +err = Pa_Initialize(); +if( err != paNoError ) goto error; + +err = Pa_OpenDefaultStream( &stream, + 0, + 2, + paFloat32, + SAMPLE_RATE, + 256, + patestCallback, + &data ); +if( err != paNoError ) goto error; + +err = Pa_StartStream( stream ); +if( err != paNoError ) goto error; + +Pa_Sleep(NUM_SECONDS*1000); + +err = Pa_StopStream( stream ); +if( err != paNoError ) goto error; +err = Pa_CloseStream( stream ); +if( err != paNoError ) goto error; +Pa_Terminate(); +</code> +</div> + +<p>And the corresponding code snippet in Ada:</p> +<div class="precontain"> +<code> +Saw_Stream.Open_Default + (Input_Channels => 0, + Output_Channels => 2, + Format => Portaudio.Streams.Float_32_Format, + Sample_Rate => 44100.0, + Buffer_Frames => 256, + Callback => Saw_Callback'Unrestricted_Access); + +Saw_Stream.Start; + +delay 4.0; + +Saw_Stream.Stop; +Saw_Stream.Close; +</code> +</div> + +<p>More detailed and complete examples can be found in each of the binding repositories. +Alternatively, the documentation for each library can be consulted. Aside from doing away with +C-isms, the function names and behaviours have been more or less imported wholesale so the +information should mostly carry over.</p> + +<p>I'll admit, the only reason why I ended up creating the binding for libao is because I came +across that library first and it really is that minimalist. But I have specific purposes in mind +for the other two.</p> +{% endblock -%} + + |