[CM] Fwd: Linux/Midi Test

[lieven moors]

I'm sorry to confuse you, but when I said that timing sounded rock solid,
I had forgotten that I had edited the juce_amalgamated.cpp file.
When I reverted to the original version, the timing sounded worse again.

I had edited the sendMessageNow funtion:

changed

    snd_seq_event_output_direct(seqHandle, &event);

into
    snd_seq_event_output (seqHandle, &event);
    snd_seq_drain_output (seqHandle);

Could somebody check this?


Kjetil S. Matheussen wrote:
>
> That's weird.
>
> Firstly, it's strange that you get bad timing when setting
> high priority (is that sched_fifo or sched_rr?).
>
> Secondly, das_watchdog should never kill any process. If
> the machine hangs, it just temporarily
> turns off realtime priority for most processes to see
> if that helps.
> And I should know this since I actually wrote das_watchdog. ;-)
>
>
>
> On Tue, 11 Aug 2009, lieven moors wrote:
>
>> And another thing, when selecting high priority,
>> I do hear sound initially, but it is totally fucked up (timingwise), 
>> and the process gets killed
>> finally by the watchdog.
>>
>> lieven moors wrote:
>>> I tried the test program with a suprising result.
>>> The timing sounds rock solid, with normal permissions, and with a 
>>> duration of 62.5 ms.
>>>
>>> P.S.
>>> When I selected realtime permission, the process was killed by 
>>> das_watchdog, and I heard nothing.
>>> (das_watchdog guards for realtime processes that block the system)
>>>
>>> William Andrew Burnson wrote:
>>>> Here is my test program to play back notes in a single JUCE thread 
>>>> to help detect jitter:
>>>> http://williamburnson.com/midi-test.tar.gz
>>>>
>>>> To use it, follow INSTRUCTIONS (basically, drop 
>>>> juce_amalgamated.cpp/h into the folder and type make)
>>>>
>>>> I tried using snd_seq_drain_output and I didn't notice any 
>>>> difference...
>>>>
>>>> ---- Original message ----
>>>>
>>>>> Date: Tue, 11 Aug 2009 15:43:31 +0200 (CEST)
>>>>> From: "Kjetil S. Matheussen" <k.s.matheussen at notam02.no>  Subject: 
>>>>> Re: [CM] Fwd: Linux/Midi Test  To: lieven moors 
>>>>> <lievenmoors at gmail.com>
>>>>> Cc: Heinrich Taube <taube at uiuc.edu>, cmdist at ccrma.Stanford.EDU, 
>>>>> Andrew Burnson <burnson2 at uiuc.edu>
>>>>>
>>>>>
>>>>>
>>>>> On Tue, 11 Aug 2009, lieven moors wrote:
>>>>>
>>>>>
>>>>>> I think I might know what the problem is with Juce. I had a look 
>>>>>> at the
>>>>>> Juce code myself,
>>>>>> and it looks like sendMessageNow() is not calling the
>>>>>> snd_seq_drain_output().
>>>>>>
>>>>> For what its worth, the one time I've written code which sends
>>>>> midi via alsa, the code calls snd_seq_drain_output as last
>>>>> operation. I don't remember what I did back then, but this
>>>>> could definitely be the problem. It sounds likely, at least.
>>>>>
>>>>>
>>>>> static void alsaseq_PutMidi(
>>>>>                 struct MidiLink *midilink,
>>>>>                 uint32_t msg
>>>>>                 )
>>>>> {
>>>>>   unsigned int d3=(msg>>8)&0xff;
>>>>>   unsigned int d2=(msg>>16)&0xff;
>>>>>   unsigned int d1=(msg>>24)&0xff;
>>>>>
>>>>>   unsigned char buffer[3]={d1,d2,d3};
>>>>>   snd_seq_event_t ev;
>>>>>   snd_midi_event_t *midi_ev;
>>>>>   snd_midi_event_new( 10, &midi_ev );
>>>>>
>>>>>   snd_seq_ev_clear( &ev );
>>>>>   snd_midi_event_encode(midi_ev,
>>>>>             buffer,
>>>>>             3,
>>>>>             &ev);
>>>>>   snd_midi_event_free( midi_ev );
>>>>>
>>>>>   snd_seq_ev_set_source(&ev,midilink->port);
>>>>>   snd_seq_ev_set_subs(&ev);
>>>>>
>>>>>   snd_seq_ev_schedule_tick( &ev, radium_queue, 1, 1);
>>>>>
>>>>>   snd_seq_event_output(radium_seq, &ev);
>>>>>
>>>>>   snd_seq_drain_output(radium_seq);
>>>>>
>>>>> }
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>