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Logic 9 Automation out of time with waveform

Discussion in 'Logic 9' started by Antiphones, May 18, 2013.

  1. Antiphones

    Antiphones Member

    I'm having a problem where automation is not in time with the waveform display. This makes it impossible to draw accurate automation. This is not a problem I've had until recently.

    I've attached a screen shot so you can see the problem and my audio settings.

    If you look at the waveform and the volume automation below you can see the problem. It is necessary to move the automation a full second after the waveform starts in order for it to actually match up when you listen (or bounce). If I move this automation to the start of this transient, you can hear it turning up the volume a full second before the transient (there is a quiet sustaining note before the transient).

    If anyone can help me it would be greatly appreciated.
     

    Attached Files:

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  3. Eli

    Eli Senior member

    You probably have some latency inducing plug-ins somewhere in your signal chain. Check for Linear Phase EQ, Ad Limiter, MultiPressor, etc. Remove them and all should be fine.
     
  4. Pete Thomas

    Pete Thomas Administrator Staff Member

    You should probably change the preferences of sample Accurate Automation to include plugins, currently it does not.
     
  5. Antiphones

    Antiphones Member

    Thanks to everyone for their help on this.

    A couple of interesting things I found out by experimenting.

    This problem only occurs when when the latency inducing plugin is on a bus. I took this plugin (a linear phase EQ) out of the bus channel and the problem was gone. Automation lined up with the waveform.

    I put this same plugin in four input channels and the automation still lined up perfectly with the waveform. So the problem only occurs on bus channels.

    Even if you bypass the plugin on a bus, it still causes latency. This seems strange, but it is the case, I tried it several times.

    What I was doing was sending four tracks to a bus as a subgroup and then putting a linear phase EQ on all of them there. This is clearly not something that can be done if you intend to use any automation in the song. When you do this, all automation on all tracks, for the whole song goes out of time as far as I can tell. A complete disaster.

    So a workaround was to take the same EQ and put four instances of it, one on each mic channel, before they go to the bus. This has limitations, for one I'm not sure if this will give an identical result as the EQ will be applied to each before they are summed, I guess it should be close though. Also you loose the chance to send the channels pre-EQ, though in this case that's not a problem.

    I wonder why this problem only happens with buses... I'm sure there must be a logical reason.
     
  6. Antiphones

    Antiphones Member

    After some more experimenting I've discovered another interesting detail, which I think explains the situation more clearly.

    Say I add a high latency plugin to aux 3, this will cause the sound of the entire arrangement to be delayed with respect to the waveform display. However only aux 3 will have a problem with automation timing, specifically the automation will not be in time with the waveform - so you could say adding the plugin breaks the automation on aux 3. All other automation on other aux channels and audio channels will still be in time with the waveform - they will not be broken by the plugin.

    This is a little confusing so I'll explain it in a different way incase I'm not making sense.

    The latency on an aux channel has two effects which are separate.
    1) there is the delay of what you hear relative to the waveform display.
    2) the is the timing of aux automation relative to the waveform display.

    No.1 happens for the whole arrangement regardless of which aux you add the plugin to. No.2 happens only on the aux channel with the latency plugin, not on any of the other channels.

    This is a little complicated, but it appears to be what happens.

    Here's a rule I've come up with for myself which should help me in the future (If I can remember it). Latency inducing plugins will not cause a problem with automation unless they are places on an aux channel. Placing a latency inducing plugin on an aux chanel will break the automation on that aux channel but will not affect the automation on any other channel (not even on other aux channels).
     

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