M. Gagnon wrote:
> This is interesting, Pieter, however my app already has the knowledge of
> notes and events, the only reason i had midi bytes was because i converted
> the events into bytes because then i could make them play using a single
> function on mac.
>
> Apparently on Linux/Alsa it's not this way, so i should probably learn how
> to put a serie of events in a sequence and then play it. The most recent
> sample of this i found was dated '2002' and didn't work, and my own attempts
> with the documentation didn't either.
>
> I am already able to send events directly. Where can i find recent
> infomation on how to schedule them in a queue and play them after?
I found the doxygen docs that come with alsa-devel sufficient.
What you have to do is convert your own 'events' into ALSA seq events,
and then use the snd_seq_event_output function. Things as timestamps
etc... are properties of ALSA seq events, and can be set using
snd_seq_event_* functions.
Pieter
PS: One tricky thing if you use multiple ports is that the port an event
should be sent to is also a property of the event.
>
> thanks
>
>
>> From: Pieter Palmers <pieterp@xxxxxxx>
>> To: "M. Gagnon" <fire_void@xxxxxxxxxxx>
>> CC: alsa-devel@xxxxxxxxxxxxxxxxxxxxx
>> Subject: Re: Development Question
>> Date: Sat, 17 Mar 2007 22:36:31 +0100
>>
>> M. Gagnon wrote:
>>> Hi, i am now trying to port an application to linux using Alsa. At some
>>> point, i have midi bytes as char* and i have to play them. This is exactly
>>> the same data you'd find in a file, expect that it's in memory instead.
>>> How is that possible?
>>>
>>> If this is not possible, i could always take any help on playing midi
>>> using sequencers I looked at the docs, i found a few samples, but they
>>> seemed to be outdated and the one that could interest me segfaulted. After
>>> i debugged it and fixed the segfault, it played nothing... (and i'm sure
>>> my midi is configured correctly BTW, pmidi works and i also succeeded in
>>> getting single notes to play)
>> This is how I do playback in the freebob backend for jack:
>>
>> for (s=0;s<samples_read;s++) {
>> signed int *byte=(buff+s);
>> snd_seq_event_t ev;
>> if ((snd_midi_event_encode_byte(
>> port->parser,(*byte) & 0xFF, &ev)
>> ) > 0) {
>> // a midi message is complete, send it out to ALSA
>> snd_seq_ev_set_subs(&ev);
>> snd_seq_ev_set_direct(&ev);
>> snd_seq_ev_set_source(&ev, port->seq_port_nr);
>> snd_seq_event_output_direct(port->seq_handle, &ev); }
>> }
>>
>> you can check the freebob_driver_midi_* functions in the freebob jack
>> backend for more detail.
>>
>> Pieter
>>
>
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