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Logic 9 determining latency from within arrange window

Discussion in 'Logic 9' started by Multispace, Sep 20, 2010.

  1. Multispace

    Multispace Member

    I use the plug-in Latency Fixer to compensate for time delays caused by room mics when mixing a drumkit.
    Thing is that I have to go in the Sample Editor to see where e.g. a kick is in a kick track and then compare that (in samples) with where that same kick is in a room mic.

    In Pro Tools I can just select straight from the Edit window the time difference between these 2 tracks and see what the length of this selection is in samples.

    Is this possible in Logic as well? I tried the Marquee tool to select the time-difference in the arrange window, but I can't see the length of the selection in samples. I can only see start and end times of the selection (in beat/bars or seconds).

    If anyone has a faster way of doing this than I'm doing, I'd like to hear it!
  3. georgelegeriii

    georgelegeriii Senior member

    Well, you could try this: Take your kick track, and your room track, cut them at the point of the first attack, then take your room track only, and cut it at the same place, where the kick attack is.

    You can then measure in ticks how long the region is. That would represent your delay.

    Q: the way we hear a "room" sound is by pre-delay, and early reflections. If you edit that out by doing this, you are loosing the actual ambience of the room, aren't you?
  4. Multispace

    Multispace Member

    Thanks for your reply.
    The drum tracks are 'flexed' quantized (maybe should've mentioned that), so cutting tracks doesn't seem like a good idea.
    Plus I would like to know the delay in samples, not ticks.

    About your question: it's a compromise. Either you have a more roomy, but not so tight (because of phase issues) sound, or you can have it the other way around. I normally try and listen what sounds best for the situation (e.g. type of music).
  5. georgelegeriii

    georgelegeriii Senior member

    Easy: convert your region into a new audio region, and double click to open the sample editor, and change the view to samples. You should be able to find out there.
  6. Multispace

    Multispace Member

    You mean not cutting the audio track, but option dragging the marquee selection to another track? That sounds like a good idea! Will try soon.

  7. georgelegeriii

    georgelegeriii Senior member

    No, do it the way I suggested the first time, take the audio region from the room track, convert to new audio file, open it in the sample editor, and change the overview to samples.
  8. Multispace

    Multispace Member

    yep, also possible, but option dragging the marquee selection saves the need to copy the audio file. It just creates a new region which you can open in the sample editor.

    Would be nice if in the future you could see the length (in samples) of a marquee selection (like Pro Tools).

    Thanks for thinking with me :)
  9. georgelegeriii

    georgelegeriii Senior member

    I understand that the Marquee tool can make a region, the reason I suggest the method I do is because using the scissors allows me to get as close to the start of the kick as I can when I zoom in.

    And when you make a region, it won't really tell you the length in samples. If you make a new audio file you will be able to find the correct answer without much effort. it would only take a minute....

    And yes I agree, it would be better to have things be seen in more ways: MS, samples, bars and beats, ticks, all at the same time. I don't know why they aren't available.
  10. Multispace

    Multispace Member

    Let's get to the bottom of this ;-)
    I can zoom in all the way and then make a selection with the marquee tool right?
    If I can then turn that selection in a region without cutting the original audio file (option dragging to an empty track), I can open that region in the sample editor showing me the selection in samples.

    Just tried it on my Macbook, it works.

    Both our options work :)
  11. michaelo

    michaelo LUG Emeritus

  12. Multispace

    Multispace Member

    interesting! will try it, thanks!
  13. JuanTahnahmahrah

    JuanTahnahmahrah Senior member

    Interesting thread, which brought up a concern that you posters hopefully can resolve for me. In reading another thread, it was brought to my attention that the arrange window needs to be tweaked to be truly sample accurate (when overdubbing). Although the topic here relates to dealing with flanging resulting from multiple microphones, it seems that the alignment of overdubbed tracks relative to existing ones is especially important when the session calls for the level of precise editing involved with Flex edits.

    So, I would like to ask you three if I understand this procedure correctly. Although Logic can be configured to adjust for plugin latency, a different issue remains because it works with a variety of hardware. The "round trip" delay caused by the A/D converters (during record) simultaneously with the D/A (during playback) must be manually adjusted in Logic's main menu Preferences --> Audio --> Devices --> Core Audio window by way of entering the number of samples created by the hardware latency.

    I did this by importing a percussion track onto an audio track, disabling plug-in delay compensation as well as making sure there were no plug-ins, and then created a new audio track with a mic input but no active output. Then I played back the existing audio while recording the output from the studio monitor back into the second audio track. Next, I zoomed in on both tracks to the sample level to calculate how many samples the new audio track would have to be shifted in order to get both tracks lined up to their equivalent peak transients. This number of samples was then entered into the "recording delay" in the Core Audio pane of Logic's audio preferences window (as a negative number). The amount will presumably vary depending on both the speed of the CPU, the speed of the converters in the hardware employed and the settings of the I/O buffer size and the I/O safety buffer, etc.

    Do I understand this correctly? My son says this procedure is unnecessary with Protools because Protools always recognizes the hardware it is connected through.

    Additionally, under the Preferences --> Audio --> General tab, plug-in delay compensation should be set to "All" so Logic will play back tracks properly when using plug-ins.
  14. musiclab

    musiclab Member

    you shouldn't have phase issues with room mics, if they were placed far enough away from the direct mics. If you want the drums to be tighter use less room.

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