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Elk OS – Audio Operating System

elk.audio

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Re: Elk OS – Audio Operating System

#71

Post by PaulDavisThe1st »

viraptor wrote: post #65
PaulDavisThe1st wrote: post #19

Earlier quoted context omitted.

Almost all of the original PREEMPT_RT patchset are mainlined now, but the features are not (all) enabled by default. Low latency will always present a tradeoff with bandwidth, and Linux is used for so many different purposes that one is not clearly more important than the other. For more than 10 years, Linux with the PREEMPT_RT patch has been capable of more-or-less hard real time, with latencies in the 10's of usecs…

If anyone wants to try the as-much-rt-as-possible build in a nice ready package, there's the Xanmod project https://xanmod.org/ which offers it precompiled with a few other tweaks. It's aimed at gamer crowd, but I had a really good experience using it with music processing.

The default xanmod kernel is still not using the PREEMPT_RT features. They do note that "Real-time Linux kernel (PREEMPT_RT) build available [5.10-rt]." and that's how you get "as much RT as possible". The features in the normal version of their kernel will improve the user experience of latency, but will not address "realtime" in the way that PREEMPT_RT does.

Re: Elk OS – Audio Operating System

#72

Post by kbumsik »

snvzz wrote: post #58
PaulDavisThe1st wrote: post #19

Earlier quoted context omitted.

Almost all of the original PREEMPT_RT patchset are mainlined now, but the features are not (all) enabled by default. Low latency will always present a tradeoff with bandwidth, and Linux is used for so many different purposes that one is not clearly more important than the other. For more than 10 years, Linux with the PREEMPT_RT patch has been capable of more-or-less hard real time, with latencies in the 10's of usecs…

>more-or-less hard real time Also known as soft realtime. For hard realtime, you need guarantees. Linux is too complex and cannot possibly offer them; this is the territory of formal proof, with complexity growing exponentially with code size. Look at seL4 for hard realtime.

No. Soft real time can miss some real time deadline.

AFAIK Linux RT kernel is designed to hit every deadline, but they just cannot offer a formal proof.

So "more-or-less" hard real time.

Re: Elk OS – Audio Operating System

#73

Post by jancsika »

hsbauauvhabzb wrote: post #29
jancsika wrote: post #6

> 1ms round-trip Ooh, a rare latency claim that actually specifies which type of latency they mean! One millisecond round-trip latency, if true in practice, is quite impressive. I'm going to continue reading now... :)

I’ve never understood the latency requirement for professional gear, are you able to articulate why there’s a need for lower latency than average consumer gear?

Three things come to mind--

1. If you strum the strings of a guitar and want your laptop to make you sound like Jimmy Hendrix, it had better output sound quickly enough that you perceive it happening "immediately." (I.e., it should sound and feel just like an electric guitar that's hooked up to an amp.)

2. Such a laptop like the one above had better make you sound like Jimmy Hendrix for every moment you are playing the guitar. The website doesn't state it, but they are making a claim to 1ms round-trip latency in the worst case. If your first strum of the guitar convinces you that the resulting sound is happening immediately, then every subsequent strum must also sound like it's happening immediately, too. Users don't merely rant about a sporadically janky digital instrument as if it were your run-of-the-mill Windows 10 UI. They throw it out.

3. There's something I call El Dorado latency, which is always half the latency being claimed and is eternally sought after by users. (Works for system latency, round-trip latency, etc.) Since the unit for measuring audio latency is milliseconds, and since "1" is the last whole number greater than "0", a claim of 1 ms essentially short circuits the search. E.g., if they had claimed "2" then El Dorado latency requires the user to imagine how much better the system would sound at "1". :)

4. Okay, I'm being a butt in #3 above. Round-trip latency in audio seeks to go down to "ultra-low" latency measurements for the same reason gamers want frame-rates to go up to gazillions. In each case it means developers can choose one of the following for their end-users: a) add more hungry, hungry hippos per unit of time, or b) make the same number of hippos hungrier.

Edit: clarifications

Re: Elk OS – Audio Operating System

#74

Post by mjn »

spicybright wrote: post #54
moonchild wrote: post #31

Earlier quoted context omitted.

That's necessarily going to be aspirational in at least some respects, though—it's limited by the hardware.

I wonder if there's a way for computers to self-measure round trip. Even if you have to plug an aux cord between the speaker + mic jacks.

My first paper as an undergrad measured MIDI round-trip by tapping the input and output MIDI wires and then looking at how the signals were offset: https://www.kmjn.org/publications/MIDI_ICMC04-abstract.html

For keyboard input, one paper (whose citation I can't seem to find) used a clicky mechanical keyboard, pointed a mic at the computer, and measured the offset between each corresponding pair of keyboard click and sound output.

Re: Elk OS – Audio Operating System

#76

Post by fit2rule »

PaulDavisThe1st wrote: post #26

Although things may change a bit with the arrival of Apple M1 systems, the marketing mentions of VST in this context are fairly weasely. For users, good look finding more than a couple of plugin developers that make their plugins available for (a) a Linux based system AND (b) the ARM architecture. For developers, VST is just an SDK, and doesn't require OS support in any meaningful way. So sure, if you want to create…

No need to bother, LV2 is well supported by a growing mass of developers, and work very well together in, for example, ZynthianOS:

https://zynthian.org

Re: Elk OS – Audio Operating System

#77

Post by vinkelhake »

matheusmoreira wrote: post #10
protoman3000 wrote: post #4

It’s a Linux distribution with real-time kernel. Here’s a download link if anybody is interested: https://github.com/elk-audio/elk-pi/releases

So the real time kernel patches have been mainlined? How comprehensive are the real time features of Linux now?

Elk is using Xenomai, it's not just PREEMPT_RT.

https://elk.audio/audio-latency-demystified-part-ii/

Re: Elk OS – Audio Operating System

#78

Post by Namidairo »

michaelpb wrote: post #49
twobitshifter wrote: post #39

I remember Ubuntu studio being geared towards musicians. Does Elk have its own proprietary components? I noticed that the raspberry pie image is noted as open source but not the OS in general. https://ubuntustudio.org/tour/audio/

Looks like it uses a "Yocto" script - https://github.com/elk-audio/elkpi-sdk - https://www.yoctoproject.org/ I thought of Ubuntu Studio as well, but it looks like Elk is intended to be more lower-level / for appliances. I'm not totally sure though, but I'm guessing it doesn't come with the full suite of Ardour etc. I do wish there was something like Ubuntu Studio, except focused on audio-only (and more polished / sup…

> Mostly just because JACK + low-latency kernels are an ordeal to set-up and maintain on a normal desktop

I wouldn't call linux-rt from the AUR too hard to install, but I can see how it would be a pain for someone who just wanted to pick up their software and do their thing without a long setup. (Since there would probably be more things to setup aside from just the realtime kernel)

Re: Elk OS – Audio Operating System

#79

Post by andai »

phlakaton wrote: post #36
protoman3000 wrote: post #4

It’s a Linux distribution with real-time kernel. Here’s a download link if anybody is interested: https://github.com/elk-audio/elk-pi/releases

When I read things like this, I really wish BeOS, with its already pervasively multithreaded kernel, had won the audio OS wars. _Le sigh._

Does Haiku share these qualities?

Re: Elk OS – Audio Operating System

#80

Post by ComputerGuru »

kbumsik wrote: post #72
snvzz wrote: post #58

Earlier quoted context omitted.

>more-or-less hard real time Also known as soft realtime. For hard realtime, you need guarantees. Linux is too complex and cannot possibly offer them; this is the territory of formal proof, with complexity growing exponentially with code size. Look at seL4 for hard realtime.

No. Soft real time can miss some real time deadline. AFAIK Linux RT kernel is designed to hit every deadline, but they just cannot offer a formal proof. So "more-or-less" hard real time.

One of the problems is that the Linux RT kernel doesn’t stop you from using/writing devices/drivers that break those guarantees systemwide, as I understand it.
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