Input latency and NVIDIA audio

[meesbaker]

Hey guys, this is the second thread Im opening up. Im trying as good as I can to use the existing resources here to figure everythinh out and parts of this have been discussed several times here , however I can not compile a complete answer for what I am interested in.

Let us first talk real quick about lipsync/audio latency. Im reading that windows 11 struggles here because the ASIO drivers do not work for global audio so they would not affect for example video games.

However I do not understamd where exactly the bottleneck is. The hdmi output of my gpu will send the picture to the TV with an input lag of less than 10ms - since hdmi has the audio tied to it it seems the sound will come out just as fast right? At least I do not notice any lipsync problems in my TV through the TV speakers, only if I connect an external audio device.

So what if we just skip the USB route and just use HDMI audio from the gpu to the TV , then split audio and video with orei 929 right at the gpu and gg? Going into an integra or so from here over optical shouldnt add much extra latency.

Second question - if that were true - is Dirac able to grab and alter nvidia hdmi audio or does it need an audio interface?

 

[kyuu]

I'll be honest I'm not exactly sure what the issue you're having is based on your post. I can say that I've had zero issues with audio sync when using HDMI from my nvidia-equipped laptop to my AVR. Adding additional devices like an audio extractor seems like it would only increase the chances of having the video/audio out of sync.

As for Dirac, where in your chain is this? You mentioned an Integra, so you have a Dirac license for that receiver? If so, your computer wouldn't be connected to the receiver at all. It communicates with the receiver over your network (although for Integra/Onkyo devices you use a phone app I believe rather than the PC application). The procedure is outlined in the manual (link is for the 5.4, dunno which model you actually have of course).

 

[meesbaker]

Im sorry for being unprecise. At this point Im mostly theorising/learning/planning.

First, by integra I meant any integrated amplifier sorry.

The question - play games over the PC, use USB audio interface then connect to integrated amp.
Im reading usb interfaces have 50ms + audio latency in win11 if you cant use asio drivers. So in games you get lip sync issues because you cant fix if sound is behind picture.

Im wondering if audio extractor at the gpu into the amp is better/faster for latency.

And yea, using dirac just on the pc itself, either with audio interface or hdmi out not sure how that would work. No avr in the picture.

Sorry for being confusing.

 

[TurtlePaul]

Im reading usb interfaces have 50ms + audio latency in win11 if you cant use asio drivers.

That must be some worst case scenario. I game using several USB DACs (From JDS Labs, Topping and MiniDSP) albeit in Windows 10. They all seem to have a few ms lag at most. Lip sync issues are much more likely to be due to monitors having delay than USB audio.

Some USB devices allow you to set the buffer size. A buffer of 512 samples at 96 khz is 5.3 ms, which is manageable at about 1/3 of a 60 fps frame. A fast PC can be stable as low as 128 samples, which is 1.3 ms (nothing).

It looks like 50 ms would correspond with the absolute max buffer sizes some devices usually support. The RME ADI2 supports 4096 samples at 96 khz, which would be 43 ms of delay, but you would have to go out of your way to choose this - the max buffer isn’t the default.

 

[meesbaker]

Awesome so there would be no issues with videogames just hooking up a good usb interface to the pc and just give its trs outputs to dirac in windows and run the outputs straight to some kind of amp. In the other thread someone suggested a motu mk5 for multiple channels/subs.

That leaves one question left that I would have on this idea. Since it is tricky to run blu rays properly in win11, especially Dolby Vision seems to be problematic , I wonder could you run something like a UB9000 through the motu interface to get dirac using its analogue outputs?

 

[wwenze]

You mentioned sound lag, there's video lag too. If they lag together then they're in sync.

 

[meesbaker]

You mentioned sound lag, there's video lag too. If they lag together then they're in sync.

So as far as Im aware based on resources found on rtings.com it works like this:

Manual lip sync correction works by pushing the audio/adding delay to the audio. It is impossible to delay the video dynamically past the TV/monitors natural processing time.

When watching movies this is usually no problem because we can see that outside of game mode TVs have very high input lag - past 200ms in order to perform image processing such as 24Pjudder removal.

In this case audio video sync is easy to achieve because the picture is slower than the sound and sound can be manually delayed.

The problem is when you go into game mode and input lag drops to something around 3-7ms depending on the TV. Rtings shows that soundbars connected to the tvs earc in game mode will produce lip sync error because the picture now is too fast for the sound. They recommend to use passthrough and go into the soundbar first if the soundbar is able to.

Now I dont plan on using a soundbar or earc, but those tests show that synchronising audio and video is generally more challenging for gaming where video latency is very low because lip sync correction can only delay sound but not video.

A USB audio interface connected to the source seemed to be a smart solution to me but I saw people reporting issues with that as well. But according to mr. TurtlePaul that can work completely fine when using the right equipment and settings.

 

[TurtlePaul]

Awesome so there would be no issues with videogames just hooking up a good usb interface to the pc and just give its trs outputs to dirac in windows and run the outputs straight to some kind of amp.

USB won’t add too much latency, but DIRAC absolutely does. It can add 20 ms or more or latency.

I use minimum phase filters to have the lowest latency for gaming. My filters and sub integration are done via a MiniDSP, which I recommend for this purpose.

 

[meesbaker]

USB won’t add too much latency, but DIRAC absolutely does. It can add 20 ms or more or latency.

I use minimum phase filters to have the lowest latency for gaming. My filters and sub integration are done via a MiniDSP, which I recommend for this purpose.

That is interesting! Given that a pc has much stronger processing power I would have assumed using an audio interface like a topping ex4 and applying the filters directly on the pc would be the fastest.

So using a minidsp and doing dirac in hardware is less latency? How exactly do you have that set up? You hand the audio to minidsp over usb but then use dirac straight on the device?

 

[TurtlePaul]

So using a minidsp and doing dirac in hardware is less latency?

No. I don’t use DIRAC. DIRAC is the latency. Minimum phase DSP corrects for frequency response. Impulse response corrections like DIRAC correct the time domain too. DIRAC can’t move a sound back in time, so in practice it works by delaying most impulses to align with the worst group delay. It isn’t calculation time, it is that it needs to delay all of the sound to match the timing of the delayed frequencies (usually the bass).

 

[meesbaker]

No. I don’t use DIRAC. DIRAC is the latency. Minimum phase DSP corrects for frequency response. Impulse response corrections like DIRAC correct the time domain too. DIRAC can’t move a sound back in time, so in practice it works by delaying most impulses to align with the worst group delay. It isn’t calculation time, it is that it needs to delay all of the sound to match the timing of the delayed frequencies (usually the bass).

Oh!! So basically for when you play games no room eq?

 

[TurtlePaul]

Oh!! So basically for when you play games no room eq?

No! I use EQ at all time (minimum phase, parametric, IIR). I don’t use DIRAC. DIRAC adds delay. Parametric EQ is not synonymous with DIRAC.

 

[kyuu]

No! I use EQ at all time (minimum phase, parametric, IIR). I don’t use DIRAC. DIRAC adds delay. Parametric EQ is not synonymous with DIRAC.

I dunno how it is with running on the PC or miniDSP devices, but at least on my AVR Dirac does not add any noticeable delay (or if it does the AVR is automatically compensating for it).

 

[TurtlePaul]

I dunno how it is with running on the PC or miniDSP devices, but at least on my AVR Dirac does not add any noticeable delay (or if it does the AVR is automatically compensating for it).

DIRAC Live Whitepaper

Look at page 12. DIRAC fixes the impulse response by flattening the phase using FIR filters. That cannot be done without time delay, which they show in their graphic.

 

[kyuu]

DIRAC Live Whitepaper

Look at page 12. DIRAC fixes the impulse response by flattening the phase using FIR filters. That cannot be done without time delay, which they show in their graphic.

I didn't say there was no delay. I said no noticeable delay.

 

[meesbaker]

Some late update on this situation. I play guitar and I bought a Boss GT1000 Core as an amp sim and recording device. I noticed it also works extremely well just as an audio interface.

I worked with USB interfaces before and most of them were a rough experience. Lots off wiggling and tweaking, messing with ASIO drivers and proprietary control software etc....

This was literally plug and play. Jus had to double click the .exe from boss website, "install successful" and immediately the gt1000 was set as input/output device and working correctly both inside and outside my DAW.

I tested some videogames, 0 lip sync delay very impressive!!

So yea, you guys were right, there seems to be no delay issues whatsoever using a proper usb dac.

Now here is the interesting part:

The Boss GT1000 allows you to configure the return and send FX Loop 1/4 outputs as subwoofer outs. You can literally program crossover for the main audio of the connected PC and run dual subs off this thing!
So next my thinking went towards eq - would I be able to apply the effects on this device not just to guitar input but also to the usb audio routed through it?

And yes you absolutely can. The effects including Parametrical equaliser. So it appears when the time comes that I want to get some nice sound equipment I already have half of it!!

For now all my testing was done on Sennheiser HD 560 headphones which were recommended here - Love those btw.
But Im impressed how much audio gear is inside this guitar pedal!!