Let's talk Latency

Discussion of music production, audio, equipment and any related topics, either with or without Ableton Live
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metaman

Let's talk Latency

Post by metaman » Tue Dec 02, 2003 7:54 am

Greetings. I've been running Live on my G3 'Pismo' powerbook (500mhz, 512 MB RAM, OS 10.2.8), with the M-Audio Audiophile USB interface, for about 8 months, and now that I'm starting to gig with it more the ~ 22 ms of latency that I'm getting is really bugging me. Is this normal for this system? (I'm running up to 9 tracks, most of them mono, minimal fx) What would be the be the best way to get it down? (Would a G4 or a new interface help more? Which one?) I recently bought M-Audio's firewire 410 thinking it might help, but it eats up about 6% more of my CPU, and the latency is no better.
If you could give a quick reply with your setup and latency, we could amass a little database here that would be a big help to people shopping for gear...
Thanks,
Joe
www.metaman.us

benjamin

Post by benjamin » Tue Dec 02, 2003 1:37 pm

the problem is, there is a fixed overhead when live processes buffers
so, if buffers are smaller (lower latency), then the CPU usage will slightly increase. However, on a rather slow machine such as yours (i am allowed to say that since i own a pismo 400 :p ), this can make an embarassing difference. I assume your firewire interface works with smaller buffers, hence the 6% extra cpu.

you should try your interface on a newer i/p-book and check the latency results there

(of course if the drivers are badly written , then you can get higher cpu usage without even having the advantage of lower latency. i don't have this interface so i can't comment on this..)

Per Boysen
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Post by Per Boysen » Tue Dec 02, 2003 8:18 pm

If you don't have to play acoustic/electric instruments THROUGH Live (for effects) there is this solution to simply split the input signal. One going directly into the hous PA system (no latency at all ;-) and the other going into laptop/Live for recording, looping, mangling etc. Of course you have to set the Live audio preferences to "Monitor thorugh Live = no". Otherwise you will get a double signal with horrible phasing problems to the PA.
Greetings from Sweden

Per Boysen
http://www.perboysen.com

Vercengetorex
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Post by Vercengetorex » Thu Dec 04, 2003 10:11 am

There are only two ways do reduce latency in a host based (running on CPU) digital audio processing environment.

1) Decrease your hardware buffer size. As this determines how many samples (chunks of digital audio) are stored in ram before being sent to your audio interface, it directly determines the amount of time it takes for audio to get into and out of your computer.

2) Increase your sample rate. As this determines the number of samples used to represent one second of audio, it directly affects the amount of time it takes to fill your hardware buffer. However this option is likely less desireable in your situation, being that incresed sample rate = incresed CPU usage just for audio playback.

Personally I find very good, portable capabilities in my Aluminum Powerbook 15" @ 1gHz w/ MOTU 828 MkII firewire audio interface.
Running at 48kHz sample rate with a buffer size of 256 samples I get 5ms latency in, and 5ms out. Humans do not preceive audio / visual or audio / physical delays under 10ms very easily (that is not to say one cannot ever tell), and I find this configuration extremely useable (not to mention the capabilities of CueMix DSP in the 828 {look it up, www.motu.com}).
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nz
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Latency

Post by nz » Thu Dec 04, 2003 2:54 pm

Personally I find very good, portable capabilities in my Aluminum Powerbook 15" @ 1gHz w/ MOTU 828 MkII firewire audio interface.
Running at 48kHz sample rate with a buffer size of 256 samples I get 5ms latency in, and 5ms out.
Actually, this is something that I have been wondering. I have been having so many issues with Direct i/o in OSX, that I was pondering if I used another interface besides my 002r if I could get low latency without the Digidesign hassle? Would I be bypassing Core Audio and just using the MOTU unit directly with it's own latency parameters (a sort of "MOTU direct i/o", if you will)? What are the best specs concerning latency on this? I usually set my buffer size at 128.

Thanks so much...

Neil

raapie
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usb and firewire

Post by raapie » Thu Dec 04, 2003 10:19 pm

I heard that usb and firewire causes more cpu load than using PCMCIA devices. but when using Live+BIdule+Reaktor I have to use large buffer sizes than when using Reason and Live. don't understand why.
Marco Raaphorst

music, sound & story maker

https://melodiefabriek.com

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