[LAU] Video card for audio (silent, low latency etc)

[Len Ovens]

On Mon, 30 Mar 2020, David W. Jones wrote:

> On March 30, 2020 6:48:25 AM HST, Jannis Achstetter <jannis_achstetter at web.de> wrote:
>>
>> Currently, Intel doesn't provide any standalone video cards, to no HD
>> 630 or similar as PCIe add-in. They will soon launch those products,
>> though:
>> https://en.wikipedia.org/wiki/Intel_Xe
>> Looking at their power requirements, I doubt that they will be
>> passively cooled.
>
> That's why I thought it might require a motherboard replacement:
>
> https://www.techcenturion.com/intel-hd-graphics-630

Yup. That is the way of it. From the wiki above, the Intel Xe will 
"compete" with Nvidia and AMD, which one would expect would require 
cooling. But it is still futureware anyway and so not much help. In truth 
"competitive with" could mean with lowend units but that is unlikely.

There are two things to consider, most people use a "lowlatency" kernel 
rather than a hard real time kernel any more. I have personally found that 
if care is taken selecting the motherboard, cpu and periferals and care is 
taken setting the system up and care is taken with running the system, it 
is possible to have clean and stable audio down to 1ms (jack time 16/2) 
with a PCI audio card. USB audio is constrained by the USB arcitecture to 
probably twice that at least anyway. The lowlatency kernels will work fine 
with most proprietary graphics drivers and the last time I worked with 
Nouveau I found it to use more CPU, run hotter and have other issues. I 
don't know if that has changed as I got myself an i5 with on chip GPU and 
have modest graphic requirements anyway. I chose the i5 for an equal 
core/thread count over an i7 where I would want to turn hyperthreading off 
anyway (no multithreading cores eases cooling concerns as well).

The second consideration is cooling. Cooling and performance go hand in 
hand. If you have gotten to the GPU already, I would expect you have 
already worked through getting a fanless powersupply and a fanless method 
of cooling the CPU. It is also assumed you are working with a desktop 
system that has some room in the case. It is unforunate that most mother 
boards put the highest throughput PCIe slot closest to the CPU, but it may 
be possible to move it farther away and replace the stock fan/heatsink 
with something closer to some of the silent CPU cooling options. Yes that 
means modifying the GPU. Computers are not made for audio or sound studio 
use, that requires extra work. Low latency to a computer engineer is 30ms 
not 5ms (read enough of Intel's docs and you will see this).

USB audio devices and the USB system: (ok this is not related to cooling) 
Most modern mother boards have a USB setup that does internal routing and 
somehow all the USB port on the mother board end up being on the same USB 
bus. This means that your mouse and your USB audio device end up sharing 
the same USB bus and the same IRQ ... and so a mouse movement can cause 
xruns at low latencies. If you have a desktop system... do yourself a 
favour and install a PCIe USB card for use with your USB audio device (and 
nothing else). Boost the priority of that card above other things (not 
just USB) for a better low latency experience.

Finally, low latency is not required for a lot of studio uses. External 
monitoring works very well for most things with a higher latency. Most 
recording can use 30ms latency or higher just fine. The exceptions are the 
use of the system as a guitar effects rack or as a soft synth. So 
recording a keyboard that uses a plugin in the DAW as it's sound source 
does require lower latency. An external General midi sound generator may 
be an option for some people. I would also suggest recording with few or 
no plugins if lower latency is needed and then mixing with higher latency 
when plugins for effects are needed... all this is common sense.

--
Len Ovens
www.ovenwerks.net