Latency Compensation explained

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The "Merging Cellar" is the place where you can share your tasting experiences and discuss everything from technique, artistic matters or even business practices, but not necessarily about Pyramix. Feel free to pick the brains of the talented Merging forum users. Enjoy.
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J.Wajer
Posts: 1679
Joined: Tue Dec 18, 2007 10:25
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Latency Compensation explained

Postby J.Wajer » Fri May 28, 2010 22:14

Latency Compensation in Pictures

Many DAWS claim to have zero samples latency systems, but Pyramix is the only DAW that has proven this with 100% certainty. its implementation however is rather complex, and has never been explained for a broad audience as far as I know. Even some colleagues in the field still wonder in the dark... This is my feeble attempt.


Observe the following simple setup.

1. 4 stereo tracks, 4 busses, one Framebeep on (Stereo) Track 1. Each mixer strip is routed to a bus which is on its turn fed back to the next strip. Note the use of the Internal Busses and the Input field below Dlay 0 on each channel strip.

Image

1. Framebeep is fed back on Strips through internal busses





2. A recording is made. Observe the offset on each subsequent Track. This is not as it should be, but is in fact the way most DAWS handle affairs.

Image
2. Recording is out-of-sync






3. The same result Zoomed In. Notice only the first Bus is actually properly compensated.

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3. Recording is out-of-sync. Zoomed In.






4. The same Setup only now the Input field mentioned earlier has been assigned to the proper Bus returns. Bus 1 Ret, Bus 2 Ret and Bus 3 Ret.

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5. Another recording is made. Voila, no Offsets! Zero Samples Latency.


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4. Recording has 0 (!) Samples latency






6. Zoomed in. Zero Samples Latency!


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4. . Zoomed In. Zero Latency







7. Another Setup, this time the Busses are stacked with hungry VST Plugins, like Guitar Rig, Waves X-Hum, Waves X-Noise and my favorite Reverb of all time: the Redline Reverb. Total latency of the system 133 mSec. Recording is still 0 samples Latency. All signals arrive at the right moment on the last bus.

Image
4. Recording with 6 hungry VST's is still 0 (!) Samples latency.








8. Same situation. Zoomed In.

Image
4. Recording with 6 hungry VST's is still 0 (!) Samples latency. Zoomed In.





This is Latency Compensation in its simplests form. There are more ways of forwarding or delaying audio in PMX using Strip Delay, External Insert Delay of Multibuss Delays, but all must obide this rule: reconnect the Busses to the Strips using the Input field!
If you follow this rule carefully, you too will have a sample accurate environment.
...Gracefully Ignored...

tas
Posts: 307
Joined: Sun Jun 10, 2007 15:41

Re: Latency Compensation explained

Postby tas » Fri Mar 18, 2011 21:31

I wish those pictures were still visible....
PMX 8.0.12 Native, Windows 7 Ultimate, MacPro, Bootcamp 4.0, RME MadiFX