51 lines
2.2 KiB
ReStructuredText
51 lines
2.2 KiB
ReStructuredText
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How libmidi1 works
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~~~~~~~~~~~~~~~~~~
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Midi1 is implemented on top of midi2, which means that libmidi.so
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depends on libmidi2.so to do the real work. BeOS versions earlier than
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R5 did not include a midi_server, because midi1 itself did not need it.
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(A server is only really useful if data must be shared between teams,
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something that midi1 did not allow.)
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Midi2 is backwards compatible with midi1: The old libmidi.so still
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exists so that applications using the old API will run (providing binary
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compatibility). The old ``BMidiPort`` object is now a wrapper that uses
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the new ``BMidiRoster`` to allow connections to any published MIDI
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producer or consumer. Published MIDI objects are presented to the old
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MIDI apps as if they were physical MIDI ports.
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Here is a very nice picture of how ``BMidiPort`` works:
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|image0|
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The softsynth
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~~~~~~~~~~~~~
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The General MIDI synthesizer is implemented in ``BSoftSynth``. This is a
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private class (not usable outside the API). It is not a real
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``BMidiEndpoint``, so you will not see it appear on Patchbay. I did this
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for simplicity's sake, for backwards compatibility (this is how the R5
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synth worked too), and because we will have to give the Midi Kit a
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complete makeover for R2 anyway.
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The ``BMidiSynth`` and ``BSynth`` classes delegate most of the work to
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``BSoftSynth``. Not all of their methods are implemented, since some of
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them are very obscure. It would be a lot of work to figure out what they
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do, while it is likely that no applications use them anyway. However,
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``BMidiSynth`` and ``BSynth`` should perform most common tasks without
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problems.
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``BSamples`` doesn't do anything; its functions are mostly empty. In
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other words, with the OpenBeOS Midi Kit you cannot push waveform data
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into the output of the softsynth.
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For simplicity's sake, ``BMidiSynthFile`` is implemented using
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``BMidiStore``, since the latter already knows how to parse Standard
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MIDI Files. Duplicating that functionality elsewhere would be pointless.
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However, this makes the behavior of our ``BMidiSynthFile`` a little
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different from what the BeBook says — as long as your applications are
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written properly, you shouldn't notice any differences.
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.. |image0| image:: midiport.png
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