speed up - I've just created a large(ish) project & pc grinds almost to a halt

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pleasebeus
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I usually record a piece and then use 'convert to region in place' to create beats to cut & paste. Some tracks are littered with these region pastes and I've notice I can expand each pasted region to be the full original. It struck me that this probably takes loads of resources. The whole system's creaking.

Is my editing process at fault?

I've got 10 tracks on the project, a sprinkling of pre plug-ins and a bit of post eq.

peder
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Can't help you here pal, but I guess anyone who can would want to know what kind of machine you're running;
a 1GHz Pentium 3 with 128MB RAM or a Core2Duo with 8GB RAM?
Also: what's grinding to a halt? DSP power, hard drive speed or something else?

You can check out how much DSP is used in the top right corner of Ardour. I guess the figure should be below 70-80%, otherwise you have to reduce the plugins, perhaps by putting some effects on a bus and route the tracks to that instead of having them on each separate ones.

pleasebeus
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Ah, of course. The machine has 3GB of RAM running a 2Ghz AMD Athlon.

DSP at 80.4% and buffers are showing both "p" & "c" at 100%.

The whole system becomes sluggish; I don't hear the HD swapping madly.

Yes, I'd read about buses - but can this be happening with just 10 tracks & 26 pre plug ins & 3 post plug ins between them?

peder
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I'd try removing some plugins and see if the load drops, perhaps you can switch from, say, one reverb to another one that is less CPU hungry.

See my reply in this thread (http://ardour.org/node/2371) as well

pleasebeus
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Wow - I deactivated the lot and things are swimming happily - DSP @ 10%. Thanks for the insight, peder.

I now want to track down the culprits. I'm generally using the TAP and C* delays, reverbs preamps and eq's.

Is there any documentation on how CPU hungry individual plugins are? Anyway to tell other than trial & error?

peder
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No particular docs I'm aware of.

I'd generally stay away from the TAP plugins. They haven't been updated since 2004 and are known to have some problems.
You have seen this (http://ardour.org/plugins) ?

pleasebeus
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Excellent link - thx for that

peder
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It's also on the top right tab of this site :D

hogiewan
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If you have two or more tracks with the same plugin and nearly the same settings, you should set it up on a bus and control the wet/dry mix via sends. This also gives a lot more control.

pleasebeus
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Can I vary the wet/dry across different tracks or does the bus have to send the same parameters for every track using it?

Benjamin Scherrer
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Hi,

you've got plenty enough ram, but a single core 2 GHz CPU is a bit slow. I had the same AMD and updated to the Phenom X4 2.5 GHz, it's very good ;)

But what I wanted suggest: Have you tried to increase the frames of jackd? If you set it too low (low latency), you will run out of DSP power very soon. You probably don't need low latency when mixing, so try to set it higher (maybe 1024) if you have a low setting and have a look if it works better.

Benjamin

hogiewan
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have the plugin on the bus output NO dry signal. The dry will be your track volume, the wet will be the amount you send to the bus.

What I really like about this setup is that you can pan the dry signal left, but send to the right so the effect is on the right side

hogiewan
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also, benjamin makes a good point. Use low latency settings for tracking, and raise it for mixing so that you can use more effects without hitting a wall

qharley
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Exactly what hogiewan said.

We are getting very wasteful with processing power, because we can get away with it ;-)
If you have ever worked on an analog desk before you will know how it works. Effects are placed on a bus, and applied with 100% wet. The sends from the channel to the effect will control the level of the effect.

I recently worked on an intense 26ch multitrack mix, and I put my busses to use. I had enough power to run a session of jamin on top of all my applied effects so I could do a "master" right after completing the mix, and check back and alter the mix on the fly.
I still had enough power left to read my emails and check my forums while the track rendered - faultlessly, and I am only running an Athlon X2 3800+

It can be done...

jimkets
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Awesome links are there ! thanks for sharing with us.
Latin Single

pleasebeus
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Some great tips on managing processing power; in fact on developing a decent process.

Thank you to all

Fully agree with qharley - I'm very much into elegant use of computing resources; it's a major reasons why I switched to Linux.

pleasebeus
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@ Benjamin & hogiewan: My latency settings on jack were default. I've set it to 1024 and it brought the DSP down to below 10%. There were options for jack latency on both the input and output side - what's the difference & relevance wrt working with Ardour?

peder
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Haven't even noticed those before...
From looking at the qjackctl tooltip, I guess those are settings to compensate for external devices with a known latency and have nothing to do with the internal jack latency.

The way to increase the internal latency is by selecting a higher frames/period (though I imagine raising the in/output latency might achieve a similar effect)

peder
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From what I understand the magic jack latency formulae is :
“periods per buffer” * “frames per period” * 1000 / “sample frequency”.

Ardour, however, calculates it as “frames per period” * 1000 / “sample frequency”. Dunno why.

pleasebeus
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odd - I just looked at the frames/period figure in qjackctl and it's already set at 1024. Whether this was because I set latency in/out at 1024 I don't know. I can't seem to reset the in/out latency back to 'default' as it demands a number. When I changed the values, I'm sure I saw a big drop in DSP but now I'm confused.

Uh well, for now I'll concentrate on setting up buses & sends properly - seems to be well worth investing time into.

peder
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Nope, the in/out doesn't affect the frames/period setting. To set them to 'default' just enter 0.

I tried changing the in/out values, but didn't see any DSP drop (~60% in my testcase on a 1GHz Pentium 3 ;).
Are you sure it wasn't due to disabling plugins?
Disabling the TAP reverberator on two of my three tracks (leaving TAP chorus/flanger on one, a Flanger on the other and C* Plate and TAP tremelo on the third) dropped DSP down to ~15%. Disabling all got me down to ~3.5%

So if you have a weak CPU, do avoid the Reverberator!

pleasebeus
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I'm sure you're right peder - in the melee of changing things around I probably lost sight of what my latency changes were doing. I'm going to keep an eye on the DSP values from now on whenever I add effects.

pleasebeus
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Just going back to peder's point about no docs being available on plug-in CPU use, I've been hunting around and found a really useful page on exactly this. It relates to SWH's plug-ins only, but since a whole bunch of his plugins come recommended on the Plugins page here, it's a good start:

http://plugin.org.uk/faq.php

I'd guess broadly speaking, plugins with similar purposes from other developers will deliver similar CPU usages.

Here's the data sheets for the *CAPS plug-ins (NB it's a PDF) http://quitte.de/dsp/caps-0.4.2.pdf

I've now completely solved my sluggish PC problems. So if you're lacking CPU power, definitely learn to use buses & sends first. If there are still issues, check the DSP rates your plugins are clocking up - look at SWH's guide to identify likely culprits.