[Linuxsampler-devel] multiple MIDI input ports per sampler channel

[Christian S. <sch...@li...>]

Hi everybody!

I just added support for multiple MIDI input ports per sampler channel.

	SVN revision: 2500
	LinuxSampler version: 1.0.0.svn25
	LSCP version: 1.6 (new)

Until now one could only use exactly one MIDI input port per sampler channel.
Under certain conditions it makes sense however to be able to connect more
than MIDI input port on the same sampler channel (without being forced to
create new sampler channels just for that). Here is the full SVN diff:

	http://svn.linuxsampler.org/cgi-bin/viewvc.cgi?view=revision&revision=2500

Since this is a design change, I had to modify major parts of the sampler. New
C++ API methods were added, old ones marked as being deprecated. However full
API and behavior backward compatibility *should* be provided. So your
graphical frontend(s) and/or LSCP scripts *should* still work as usual. If
something is not working anymore, then please tell me!

I added the following new LSCP commands (LSCP v1.6):

	ADD CHANNEL MIDI_INPUT <sampler-channel> <midi-device-id> [<midi-input-port>]
	http://www.linuxsampler.org/api/draft-linuxsampler-protocol.html#ADD%20CHANNEL%20MIDI_INPUT

	REMOVE CHANNEL MIDI_INPUT <sampler-channel> [<midi-device-id> [<midi-input-port>]]
	http://www.linuxsampler.org/api/draft-linuxsampler-protocol.html#REMOVE%20CHANNEL%20MIDI_INPUT

	LIST CHANNEL MIDI_INPUT <sampler-channel>
	http://www.linuxsampler.org/api/draft-linuxsampler-protocol.html#LIST%20CHANNEL%20MIDI_INPUTS

As with the C++ API changes, the old LSCP commands (and old response fields of
"GET CHANNEL INFO") are marked as deprecated, but still there and should
provide full behavior backward compatibility. If not, then it is a bug and
please tell me!

I also thought about making the MIDI channel setting individual for each MIDI
port connected. However I found that its use case would be too exotic and
would introduce a usability nightmare for users. So I decided to leave only
one single MIDI channel setting for all MIDI input ports connected to one
sampler channel.

Implementation detail: if more than one MIDI input port is connected to one
SamplerChannel/EngineChannel, then a mutex.lock() is used for each MIDI event
coming in to protect the input MIDI RingBuffer against concurrent input. If
there is only one MIDI input port, then no mutex.lock() is used. The Mutex
lock is a bit undesired, it could be avoided by changing the design a bit
more. But for now it should probably be OK.

CU
Christian