[Jack-Devel] Jack and thunderbolt

[Ralf Mardorf]

On Fri, 07 Dec 2018, liebrecht at grossmann-venter.com wrote:
>On 2018-12-07 00:54, Ralf Mardorf wrote:
>> However, hardware monitoring when using Class Compliant USB devices
>> usually can't be done by the audio device's internal routing, a
>> mixing console is needed for latency free monitoring, while cards
>> that need an individual ALSA driver, such as the HDSPe AIO might be
>> able to use the internal hardware routing (e.g. by hdspmixer).
>Thanks all for the insightful responses.
>
>The last part of your answer is something I dont see often.
>Do you have any point of departure where I can read up about which 
>devices can access the onboard DSP of audio interfaces such as those
>you mention eg 1818vsl or other. It is the first time I see hints of
>someone or programs able to access the onboard DSP for low latency
>monitoring. Didnt see this ever mentioned but it is desperately
>needed. After receiving your post I tried to find similar on the web,
>but it is all very unclear what is possible and for which devices.

Please reply to the mailing list and don't top-post.

That is probably a misunderstanding. The Presonus and the Focusrite 2nd
gen USB devices don't provide access to the device's internal routing
when using it with a Linux machine. They are class compliant and don't
need individual drivers. Sound devices that aren't class compliant need
an individual driver and there might be access to the device's internal
routing, as there is for some RME audio devices, when using the Linux's
hdspmixer wich is similar to RME's totalmix,
http://www.rme-audio.de/en/support/techinfo/hdsp_totalmix_software.php.

Monitoring without latency means, that you could route the input
channels, directly to the output channels. IOW if you connect a
microphone, you could listen to the unprocessed signal without latency,
it's not the signal processed by your Linux machine.