[LAD] ALSA MIDI latency test results are far away from reality

Robin Gareus robin at gareus.org
Wed Jul 14 15:40:43 UTC 2010


On 07/14/2010 05:27 PM, Ralf Mardorf wrote:
> On Wed, 2010-07-14 at 17:24 +0200, Ralf Mardorf wrote:
>> On Wed, 2010-07-14 at 17:21 +0200, Ralf Mardorf wrote:
>>> On Wed, 2010-07-14 at 10:53 -0400, Paul Davis wrote:
>>>> On Wed, Jul 14, 2010 at 9:52 AM, Clemens Ladisch <clemens at ladisch.de> wrote:
>>>>> Is this connection through JACK or through ALSA, i.e., does it show up
>>>>> in the output of "aconnect -l"?  From what I understand, JACK's sample-
>>>>> synchronous timing always adds latency, and might add period-related
>>>>> jitter depending on the implementation.
>>>>
>>>> the good stuff adds 1 JACK period of latency to whatever the ALSA
> 
> PPS:
> 
> A misunderstanding by me?
> 
>>>> sequencer's direct delivery + the driver does, and zero jitter.
> 
> Is there JACK MIDI for hw MIDI too, but only for virtual synth?

No, JACK-MIDI is a protocol in software.

There are bridges to hardware which go connect either via ALSA-sequencer
or raw-ALSA interface to the MIDI hardware.

JACKd itself includes those bridges (-Xseq, -Rraw) and there are also
stand-alone apps (fi a2jmidi_bridge, a2jmidid,..) which can do the same.

> - Ralf
> 
> *Offline now*
> 
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