Subject: Re: [linux-audio-dev] Locking Midi to Audio
From: Tim Goetze (tim_AT_quitte.de)
Date: Sat Aug 17 2002 - 13:52:04 EEST
Erik de Castro Lopo wrote:
>Why not lock the Midi processing to the audio processing? If the buffer
>sizes for the audio are small, say 128 samples or less at 48kHz sampling
>rate then all Midi messages can be processed at that granularity without
>impacting the Midi timing too much. Midi can then be read and written via
>raw midi ports instead of /dev/sequencer style devices.
I'm not sure if it would allow one to process fewer frames/cycle; on
this box a 1 kHz rtc does not seem to have enough influence on audio
interrupt handling. The system is capable of 128 / 44.1, but not 64,
either with or without a rtc thread run behind audio. Haven't yet
tried running it before, but will post the results when I do.
If uid != 0, all I get is a fairly reliable 2048 / 44.1, that's much
worse than the 100 Hz scheduler, so MIDI timing would be screwed even
worse.
Essentially I'd love to drop the RTC thread completely and process
at 1 / 44.1. But probably the noise from the cooling system would
kill all musical ambition within 100 metres. :)
tim
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