[linux-audio-dev] alsa sequencer filter client

[Garett Shulman]

Matthias Nagorni wrote:

>On Mon, 26 Jan 2004, Garett Shulman wrote:
>
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>>Matthias Nagorni wrote:
>>
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>>>On Sun, 25 Jan 2004, Garett Shulman wrote:
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>>>>Hello, I am trying to create a very simple midi filter client for the alsa
>>>>sequencer based on aseqview-0.1.4. I have alsa 0.9.8. This code shows the
>>>>   
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>>>>
>>>Maybe you can base it on my MIDI router example in
>>>http://www.suse.de/~mana/alsa090_howto.html
>>>
>>>A QT MIDI router which you could take as example code is located at
>>>ftp://ftp.suse.com/pub/people/mana/qmidiroute-0.0.2.tar.bz2
>>>
>>>Matthias
>>>
>>> 
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>>Matthias, Thank you for the suggestion. Your howto is exactly the information
>>I need. Very nice. The code I was working with before is callback based. Do
>>you have any opinion about callback vs. polling in regards to the alsa
>>sequender? Do you think I will get less overhead if I use bits of the code in
>>your howto in the callback framework? Thanks. -Garett
>>    
>>
>
>Discussed this briefly with Takashi (author of ALSA sequencer). Currently 
>there is no wrapper library implemented, so the polling method I use in my 
>MIDI examples is the only way to handle the asynchronous MIDI events.
>If you want, you can regard the "midi_route" function as callback 
>function. You could even write a wrapper function yourself which has a 
>function pointer as argument, the while(1) { poll (... } as body and will 
>call its argument function whenever poll returns, indicating that a new 
>MIDI event is available for read. 
>
>Matthias
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The code I was using before was the portlib.c and portlib.h files that 
are included with aseqview. I beleive that this is code that Takashi 
created. Maybe this code works in a manner similar to what you are 
describing. I will have to take a closer look at the internals of this 
code. Thanks for the info. -Garett