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Does DSP have latency?

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Does DSP have latency?

Postby DigDug » Thu Jun 04, 2020 6:56 pm

Some audio interfaces have built-in DSP effects.
I read that DSP isn't really zero-latency. Is this true?
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Re: Does DSP have latency?

Postby desmond » Thu Jun 04, 2020 7:02 pm

It depends.

Generally, plugins in your DAW that run on external hardware DSP have any extra set of buffers to shuffle data through. You have your regular audio in and out buffers, which always add a certain amount of latency, but for every DSP plugin, the host has to buffer data to and from the DSP chips over whatever interface they are connected on. This was why you couldn't really use Universal Audio plugins while tracking for instance - the latency was too high.

In the case of something like the Universal Audio interfaces, this is true for them too, *but* they were designed to have an extra feature. In the Console application you can insert plugins there, and the *audio interface* directly passes audio through the plugins before reaching your DAW, and it does this with very low latency. So in this case, can can track *through* UA plugins on the way in, as well as use the plugins in the more usual way in your DAW (with high latency as usual).
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Re: Does DSP have latency?

Postby MOF » Thu Jun 04, 2020 8:11 pm

The processing speed of DSP is so fast that you wouldn’t notice it.
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Re: Does DSP have latency?

Postby Hugh Robjohns » Thu Jun 04, 2020 8:17 pm

DigDug wrote:I read that DSP isn't really zero-latency. Is this true?

Yes!

How much latency depends on the kind of signal processing required, but is usually a handful of samples. In many applications the latency is incredibly short and unnoticeable.
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Re: Does DSP have latency?

Postby CS70 » Thu Jun 04, 2020 8:49 pm

DigDug wrote:Some audio interfaces have built-in DSP effects.
I read that DSP isn't really zero-latency. Is this true?

Yes - your signal still need to be A/D converted, go thru a little computer for processing and come back the other side (which, if the other side is direct monitoring, means D/A conversion).

The main difference with a general purpose computer is that the DSP is set up to execute only a specific type of program, and its resources are sized to be able to do it in a consistent and fast manner.

It's not much tough.
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Re: Does DSP have latency?

Postby DigDug » Thu Jun 04, 2020 9:05 pm

Okay, great! Very informative!

What about analog mixers with built-in effects?
Isn't that DSP as well?

Is that suppose to be instantaneous or is there still some latency because it is DSP?
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Re: Does DSP have latency?

Postby CS70 » Thu Jun 04, 2020 9:07 pm

DigDug wrote:Okay, great! Very informative!

What about analog mixers with built-in effects?
Isn't that DSP as well?

Is that suppose to be instantaneous or is there still some latency because it is DSP?

Same! But too short for humans to notice.

There's some latency for analogue as well actually - the speed of EM waves in copper is finite! But of course is too small to be noticed by our brains in normal conditions.. try to send an analogue signal to the moon however.. :) (well, first you have to get a cable up there, which is not as simple as it sounds..)
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Re: Does DSP have latency?

Postby James Perrett » Thu Jun 04, 2020 9:29 pm

DigDug wrote:What about analog mixers with built-in effects?
Isn't that DSP as well?

Is that suppose to be instantaneous or is there still some latency because it is DSP?

Most DSP effects in analogue mixers are delay or reverb effects where the effect is used in parallel to the direct signal. Since these all use delays of some sort anyway a little bit of extra delay in the effects chain isn't a problem. The direct signal is still virtually instantaneous.
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Re: Does DSP have latency?

Postby DigDug » Thu Jun 04, 2020 9:37 pm

I just sold my audio interface.

I was planning on getting a new audio interface with a main out and 2 extra sets of outputs to feed to a cheap FX mixer so I could monitor with FX.


But you guys are saying an audio interface with DSP would achieve the same exact thing?
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Re: Does DSP have latency?

Postby MOF » Thu Jun 04, 2020 10:04 pm

There's some latency for analogue as well actually
Bucket brigade circuits - a series of capacitors are still used in some guitar pedals to create delays in the audio.
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Re: Does DSP have latency?

Postby MOF » Thu Jun 04, 2020 10:08 pm

But you guys are saying an audio interface with DSP would achieve the same exact thing?
Depending on how many effects you were hoping to use then most likely yes is the answer.
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Re: Does DSP have latency?

Postby Sam Spoons » Thu Jun 04, 2020 10:14 pm

CS70 wrote:There's some latency for analogue as well actually - the speed of EM waves in copper is finite! But of course is too small to be noticed by our brains in normal conditions.. try to send an analogue signal to the moon however.. :) (well, first you have to get a cable up there, which is not as simple as it sounds..)

There is a latency of about 1 ¼ seconds for a radio signal going from here to the moon. Obviously that is plus the latency added by any digital conversions or processing at either end.

My X32 digital desk claims an end to end latency of 1 ms, I guess that gets longer if you use insert fx but have no info. Whatever it is it's unnoticeable in practice.
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Re: Does DSP have latency?

Postby CS70 » Thu Jun 04, 2020 10:14 pm

DigDug wrote:I just sold my audio interface.

I was planning on getting a new audio interface with a main out and 2 extra sets of outputs to feed to a cheap FX mixer so I could monitor with FX.

But you guys are saying an audio interface with DSP would achieve the same exact thing?

Yes. With a DSP-less interface I use a separate small reverb unit between headphone out and headphones, but when I pick up my Steinberg UR28M, which has onboard effects, it's exactly the same result (at least for latency: you can't record the reverb of the 28M while obviously I can record the hardware reverb by putting it in the right place in the chain).

The main difference are the haptics - with an interface, you have usually to configure things on the computer.
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Re: Does DSP have latency?

Postby DigDug » Thu Jun 04, 2020 10:37 pm

CS70 wrote:
DigDug wrote:I just sold my audio interface.

I was planning on getting a new audio interface with a main out and 2 extra sets of outputs to feed to a cheap FX mixer so I could monitor with FX.

But you guys are saying an audio interface with DSP would achieve the same exact thing?

Yes. With a DSP-less interface I use a separate small reverb unit between headphone out and headphones, but when I pick up my Steinberg UR28M, which has onboard effects, it's exactly the same result (at least for latency: you can't record the reverb of the 28M while obviously I can record the hardware reverb by putting it in the right place in the chain).

The main difference are the haptics - with an interface, you have usually to configure things on the computer.
With the DSP-less interface, how are you able to monitor with reverb without involving the entire mix?

Does your interface allow for a separate cue mix/headphone mix for the headphone out?

In any case, that is very good news. Now I just need to get an audio interface with DSP!
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Re: Does DSP have latency?

Postby Music Wolf » Thu Jun 04, 2020 10:43 pm

DigDug wrote:I just sold my audio interface.

I was planning on getting a new audio interface with a main out and 2 extra sets of outputs to feed to a cheap FX mixer so I could monitor with FX.


But you guys are saying an audio interface with DSP would achieve the same exact thing?

One of the main reasons why I chose a Steinberg UR824 interface was the fact that it had direct monitoring with DSP effects. It works well and I no longer have a separate mixer, however, I find that I use effects whilst tracking less and less these days. If I was in the market for a new interface I would no longer feel constrained to choose one with DSP monitoring.
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