Electronic music - notes on audio APIs

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On drivers and APIs

Windows APIs

On ASIO wrappers

This article/section is a stub — probably a pile of half-sorted notes, is not well-checked so may have incorrect bits. (Feel free to ignore, fix, or tell me)

ASIO in itself usually refers to a driver talking directly to the sound hardware, exposing just the ASIO API, much of the point being ignoring windows's sound architecture completely.

ASIO wrappers are different (and in this context, the above is often called 'native ASIO' in contrast).

ASIO wrappers open a sound card via a regular Windows sound API (in practice typically WDM/KS or WASAPI), force settings that are lower latency (small buffer, exclusive if possible), and present it via ASIO API.

Yes, this is counter to ASIO's shortest-path-to-the-hardware principle.

And yes, you will only get latencies that were always possibly to get from that underlying sound API anyway.

So why add a layer?

Convenience, mostly.

• It lets you have just one place to configure a small-buffer, possibly-exclusive way to these existing APIs.

You figure out the details just once, in the wrapper's settings, rather than for every DAW-soundcard combination you have, which is usually more work, and the config details may vary somewhat between DAWs which is sometimes more fiddly and/or confusing.

and some programs (basically, things that are not the most common DAWs) may not allow all that tweaking - but can still talk ASIO

also not unimportantly, using that wrapper can also be easier to explain to people who care more about music than decades of programing history.

• There's also some DAWs/software that speak mainly or only ASIO, because their approach is to figure out low latency in something external, and talk to that.

There's a few more useful reasons hiding in the details, like

• you can often force WASAPI cards down to maybe say, 5-10ms without exclusive mode, which means you don't have to dedicate a sound card, to a DAW that only talks ASIO.

Which is good enough e.g. for when playing some piano on a laptop on the go, so pretty convenient

• some ASIO wrappers can talk to on different sound cards for input and output, at the cost of slightly higher latency (will probably glitch at the lowest latencies), which DAWs talking native ASIO will typically refuse to do (for latency and glitch reasons).

As far as I can tell

• ASIO4ALLv2 is a WDM/KS wrapper.

needs to force exclusive mode

can talk to different sound cards for input and output

• FL Studio ASIO (a.k.a. FLASIO) is a WASAPI wrapper.

Comes with FL studio (including the demo), also usable in other DAWs

can talk to different sound cards for input and output

• "Generic Low Latency ASIO Driver" is similar to ASIO4ALL but with different options

Comes with Cubase

• MAGIX ASIO - (verify)

And there appear to also be ASIO multiclient wrappers, basically ASIO in ASIO.

ftp://ftp.steinberg.net/Download/Hardware/ASIO_multiclient_driver/

Why latency exists (the long version)

Latency and physics

Latency in the real world exists because of distance and the speed of sound.

For some context of how long a millisecond is, and what distance does with sound:

a mic on a guitar cab has maybe 1ms to get sound from speaker to mic.

talking to someone at one or two meters is 3ms to 6ms

a smallish practice space easily has ~15ms of delay from one wall to the other

opposite ends of a 15m bus would be 40ms

two frames in 24fps movie are ~42ms apart

halfway across a sports field is easily 100ms

Most of that is just length divided by the speed of sound. Use wolfram alpha if you're lazy.

So distance alone is

why bands tend to watch their drummers

why in larger spaces you may want to use headphones instead (but not bluetooth ones)

one of a few reasons orchestras have conductors

In musical context

Lowering latency

In general

tl;dr

zero latency does not exist, a few milliseconds of relative offsets happens all over the place

amounts of added latency can matter, though

latency matters when hearing yourself live, or syncing to something live (e.g. looper pedals)

digital input, output, and/or processing have some latency

In ways that are (looking at forums) usually partly misunderstood