Latency is 6ms with LTU, but 15ms with Kontakt4

[hpeterh]

Hello,

I am new in this Forum and wish the Best to you all!
I am from Germany and my english is not very good, I apologize for that.
I am a little bit in a hurry, because I have bought an audio interface and now must decide if I will keep it or send it back within 30 days.

I have got a Behringer FCA202 Firewire Sound Interface. The ASIO driver is written by Centrance.
Hardware and soundquality of this device is exceptionally well, especially considering the price of 99,- Euro.

Intended use is for Softwarepianos. I already have an Edirol UA 4Fx USB card and this delivers low latency but also crackles under high CPU load.
Firewire is much better, because DMA driven, and the Behringer soundcard is galvanically isolated from Computer and power and delivers unquestionable Signal/Noise ratio, I love that.

Currently I use Kontaktplayer 4 and Galaxy pianos.
While this gives good latency with the Edirolinterface (and also with the onboard soundcard and ASIO4ALL) it delivers only 15 ms total latency with the Behringer FCA202 and the Centrance driver.

The Kontaktplayer4 (in standalone mode) displays 5ms as "Processing latency" and 10ms or more as "Output latency". Sound quality is very fine, but I cannot see how to reduce the "Output Latency".
I have tested the FCA202 with Truepianos and I got fast latency, as expected. I also tested it with the Centrance Latency Checker and it reported a round-trip latency of about 6ms and that is very good, it is better than I need, I would be happy with 8ms one way latency.

Also I did not get low latency with Synthogy Ivory running as a VST under the Cantabile Host.

So it seems that the only applications that I can use currently with low latency are Truepianos and the Centrance Latency checker utility.

I can say this for sure, because I have my own method for checking real latency:
I activate the local pianosound of my piano, so this is mixed with the remote piano sound.
Then I adjust the latency until these two sounds "melt" together. That means, only one hammer stroke is audible and these two pianos sound like one piano with a lot of chorus. When this can be reached, then I am satisfied. Normally this is reached, when the Kontakt Player displays 8ms or less total latency.
I admit, this method is non-scientific, but it ensures optimal usability and is reliable

My OS is Vista 32 Bit and I have a Core2duo CPU 1,83 GHz and 4 GB RAM.

Is there a solution or a known fix for this problem? Is it possible that other drivers are interfering?

I would love to keep this soundmodule if there is some realistic and reasonable hope to solve the problem.
I have seen the offer for the Ideal driver, but unfortunately it is not Vista compatible.
I would be willing to spend some money for an alternative driver if I can test before buying and if the price is payable for me

Thanks in advance!

Peter

[Michael]

Thank you for your interest. Sounds like the hardware is capable of delivering a very low latency under the right conditions, so the hardware and driver are fine. I think the problem is not the hardware and not the driver, but rather the piano software you are using. If the software has to play large sample libraries, it needs to store them in the memory. Then, the computer has to work harder because it has is more data to process. So, the higher the quality of the sample libraries, the more work the computer has to do. When the computer is busy, you get higher latency. The only solution then is to upgrade the PC or use the software that is not as demanding on your existing PC.

Michael

[hpeterh]

Hi Michael,

thanks for reply,

As said, I get good latency with the onboard sound and ASIO4ALL and also with my external USB card Edirol UA4Fx and the Edirol driver.
These drivers should have quite higher CPU requirements than a DMA driven Firewire device. (that is why I want Firewire)

The computer is fast enough. I can test the latency playing a single note, say middle C and the CPU load is below 10% then, if not below 5%, if not near zero.

So that doesnt seem to be the problem. I believe there is a communication problem between the driver and between Kontakt4.
The reported "Output latency" of 10ms or more is unusual high. I have never seen this. Is there a way to reduce the "Output latency" ?

(In ASIO4ALL I can adjust the Output latency separately, and with my USB interface the Output latency is not adustable, but much lower per default)
Also, if the CPU load is high, I dont get higher latency. I get crackles. That happens only if I press sustain and play multiple glissandos over all white keys. But under the test conditions that I described, the CPU load is low.

Peter

[hpeterh]

I looked up the technical specs for the FCA202 in the web.
I found an article about it, and this said, that it has a Crystal CS5340 as DA converter.
I looked up the datasheet of this converter and found that the conversion delay should be less than 1ms in any case.

So the question is, where is the output latency of 10ms coming from?
Can firewire cause this delay? Is there a registry setting in Vista?
Is there any way to fix this?

I must also clarify my previous article and the subject of this thread: Yes I got latency of 6ms with LTU and a somewhat lower latency with Truepianos. But in this case I also had crackles. I did not care about and simply tried out the fastest time possible.

The extraordinary size of the output buffer respective the output latency seems to be the problem here. If that is reduced, the processing buffer can be increased and the crackles should go away and short latency is still maintained.

For comparison: Currently I use my Onboard soundcard with 7.2ms total latency sucessfully: Displayed processing latency is 4ms and output latency is 3.2 ms in Kontakt.

However, I have bought and promptly fully paid this product. I am willing to put a little bit of work into it, but not too much.
Without technical help I cannot solve the problem, and then I will send it back within the 30 day grace period or request warranty repair for it.
Behringer seems to be unable to help.

Peter

[Michael]

Thanks for researching this further. Please note that in general CEntrance does not support Behringer products, but I will provide some more info here. The buffer is needed to make sure that you don't hear skipping when playing samples. You are absolutely correct, when you lower the buffer you also lower the latency but at some point you start hearing crackles in the audio. This means that the computer is not fast enough to process samples and FireWire traffic at the same time. So you need to set the buffer size in the control panel to the lowest value that allows you to hear no clicks during playback. The on-board sound card will always be a little faster than FireWire. Don't forget that managing FireWire traffic takes a serious amount of resources from the CPU. DMA has nothing to do with that. Read up on protocol formation and you will see his much work the CPU needs to do to properly form FireWire packets. All this means is that unless you change to a different piece of s/w or a different machine, you may be at the lower limit of latency already.