Reducing Latency

[Raider]

Hi guys,

I'm new to home recording / midi music and am having trouble trying to reduce latency to an acceptable level.

I'm using Sibelius at the moment and have managed to get the latency down to 69.99ms by switching to a PCI USB 2 card, but want to reduce it further if I can. It's OK when using a midi keyboard through a midi to USB converter, but it's noticeable when using a drum kit which connects via USB.

Would changing the sound card be the next step? If so, what would people recommend for a reasonable sound card?

Thanks in advance

Raider

 

[TimOBrien]

Here's a good guide and tested suggestions that will work: http://www.tweakheadz.com/soundcards_for_the_home_studio.htm

(you'll want to bookmark and read through all of Tweak's Guide while you're there...)

 

[philbagg]

I'm not sure if this is the solution, but is there a "Buffer Size" setting or something similar that you can change? If so, lower buffer sizes produce less latency.

 

[Raider]

Thanks for the replies guys.

I've got 2 gig of memory coming in the post so will stick that in and see if it helps and I'll have a look at the buffer size, although last time I tried adjusting that I had to restart the package and thought I'd broken the installation, but will give it another go.

I probably will get a soundcard at some point as I'm using the onboard sound at the moment which I've read can cause problems with latency, but I need to do a bit of reading and have a chat to someone about how the connections work before I buy - like I say, I'm new to all this.

 

[Raider]

The memory arrived today, and other than speeding up the loading of the application there was no difference to the latency (although I guess that was expected)

I had a look at reducing the buffer size, but the smallest it can go to is 4096 which is what it was set to.

The only other option for change is the Sample rate. This was set to 44200 Hz (I think) but increasing it to 48000 Hz improved the latency dramatically. If I went higher on the sample rate the latency reduced further but the sound was awful, so it's a trade off.

Can anyone see any issues with using a higher sample rate?

Would getting a MIDI friendly soundcard give further improvements?

 

[mattr]

There's probably negligible input latency from the USB-MIDI interface... I'd hazard a bet that most of the latency will be coming from the processing within the computer but mainly from the soundcard at the output. Latency is just one of the areas where cheap/onboard soundcards just don't cut it.

I assume you're not using ASIO drivers if its an onboard soundcard? 4096 samples is a really high buffer size, but if that's the lowest setting then that should be more evidence that your onboard soundcard just isn't up for the job... most soundcards intended for recording can go down to 64 samples, or even as low as 32 (so long as your computer can handle it)!

But the sums don't quite add up at the moment. You say you're getting 69.99ms of latency, but 4096/44100 = ~90ms... maybe its a discrepancy between the reported and actual latency?

And yup, increasing the sample rate will decrease the latency... obviously 512 samples @192khz is going to last a lot less time than 512 samples @44.1khz! But running at higher sample rates will require greatly increased computing power and you may find your audio begins to stutter and crackle if your computer can't keep up, and there's no audible benefits with recording at stupidly high sample rates anyway.

Unless you can decrease that buffer size, you're not going to get your latency down much more. You really need to be looking at investing in a better soundcard that is intended for these kind of purposes.

 

[Raider]

You are correct - I'm not using ASIO drivers. I've read that they are better which is why I thought a PCI soundcard would be better.

Would something like the M-Audio Audiophile 2496 be a reasonable card for home use?

The one thing that confuses me with this card is could I still use the USB input for the instruments or would I need to use the midi in on the card?

Interestingly, on my laptop the latency is coming out at 10.67 ms with 4096 samples at 48000 Hz. The laptop is a lot newer than the PC which probably explains the dramatic decrease in latency, but the laptop doesn't have ASIO drivers either.

 

[mattr]

These reported latencies still don't quite make sense... 4096 samples @48khz should give at the very least (forgetting hidden safety buffers, etc, that you sometimes find) a one-way latency of ~85ms. Where are you getting these reported latencies from?

And yup, the M-Audiophile 2496 would be the right kind of thing to get you going with.

 

[Raider]

The latency I'm reporting is displayed in the software, so I'm not sure how it's calculated. I do know that if I make the number bigger (by changing the interface) then the latency is worse.

From what you are saying it does seem that the latency reported in the software is off, but it's the only indication of what the latency is that I have.

I'll keep my eye on e-bay for one of those cards at a decent price, unless anyone has a suggestion for a different card in the same sort of price range.

Cheers

Raider