Subject: Re: [linux-audio-dev] alsa sequencer filter client
From: Garett Shulman (shulmang_AT_colorado.edu)
Date: Tue Jan 27 2004 - 21:28:40 EET
Matthias Nagorni wrote:
>On Mon, 26 Jan 2004, Garett Shulman wrote:
>
>
>
>>Matthias Nagorni wrote:
>>
>>
>>
>>>On Sun, 25 Jan 2004, Garett Shulman wrote:
>>>
>>>
>>>
>>>
>>>>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
>>>>
>>>>
>>>>
>>>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
>>>
>>>
>>>
>>>
>>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
>
>
>
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
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