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Is it possible to Quantize Audio guitars?

Discussion in 'Studio Techniques' started by afavreau, Jun 30, 2009.

  1. afavreau

    afavreau Senior member

    I'm wondering...

    Is there a way to quantize Audio Guitars in logic?

    I know there's a way to quantize audio drums using the "Strip silence" feature because there is some space between each hit. But my nylon guitar part plays sustain arpegios in 8th notes as an accompaniment. It's therefore polyphonic.

    So I'm wondering, is there really a way to do that or only Melodyne Studio can do it?

    Thanks for your help...

  3. peterlemer

    peterlemer Senior member

    I have done this occasionally by hand-editing in the arrange window on maximum zoom, with a click or drums also in view on the adjacent track so I can visually line up strong bits.
    The guitarists I need to do this for are not pros by any means.
    I find that, given the amount of other material sounding at the same time, that besides cutting and moving single notes I can get invisible improvements by cutting and slightly moving regions, sometimes quite big ones.

    If there are enough repeats, I will replace poor bits with better bits from elsewhere.

    Very occasionally, I might use timestretch.

    ..plus lashings of crossfade :)

  4. Markdvc

    Markdvc Administrator Staff Member

    I'll gladly agree with what Peter wrote - Logic is able to time correct instruments such as Guitar, or even vocals, in the manner he describes. It can be a little time consuming and fiddly, but, cutting and nudging where possible, also copy pasting better parts, as well as reverting to time stretching short snippets cut into individual regions if absolutely necessary works well for me. The biggest danger doing this can be losing the overall picture and, even if you got everything lined up "visually perfectly" , you may also find that the groove can get messed up.

    kind regards

  5. Pete Thomas

    Pete Thomas Administrator Staff Member

    Peter and Mark are right, it can be done manually by various methods. For short audio files that don't work with strip silence or quantize engineI often do it manually with time and pitch machine.

    This manual method works well but is very time consuming.

    In this example it assumes all notes are 1/8th notes, but they could be anything

    1. Make a backup copy of the audio!
    2. Adjust start position so first note/chord is exactly at beat 1
    3. Make a selection from the first note to the next one. (if the 2nd note is early, the selection will be something like ". . 1 224"
    4. Open time & pitch, this ;ength will show in "destination length in bars" field
    5. Change this to " . . 2 0 " and process
    6. Your next note will now be on beat 1 1 3 0
    7. Repeat from this note to the next one.

    NB, once you have started this you usually need to go all the way to the end of the file.
  6. artofmixing

    artofmixing New Member

    You can use a combination of the bpm counter and beat mapper to create a tempo track for your guitar recording so that you can add other (eg. MIDI) instrumentation which will be in time with the guitars. Add the bpm counter to the guitar audio track (via insert) - it will work out the approx bpm - then open global track and select beat mapper from 'configure global tracks' menu and use this to analyze the audio, then line up the guitar transients with the nearest beats and bars.
  7. kayte

    kayte New Member

    Check out the Beta Version of Melodyne Editor. It can manipulate your guitar parts as easily as Melodyne Studio did with vocals.
  8. Eli

    Eli Senior member

    What about trying flex mode??? It isn't _only_ meant for drums in slicing mode ;) If the playing is only slightly off, try polyphonic mode and then apply quantization. It just might do the trick!
  9. afavreau

    afavreau Senior member


    Notice that this question was originally posted when I didn't have Logic 9. I'm not even sure it was out by June 29th. At that time, I did it with Melodyne Cre8. However, I had sync issues, so it wasn't easy.

    So... I'm happy now that Logic 9 has flex editing now. No sync problems anymore.

    I also love Melodyne, but I'll keep it for pitch only from now on.

    Thanks again Eli (Mmm.. de Montréal, hein?)

    André Favreau
  10. Eli

    Eli Senior member

    Yeah, Montreal!
  11. Peter Ostry

    Peter Ostry Administrator Staff Member

    I was never successful with quantization of guitars but since Flex exists I use it to manually correct nylonstring guitar and it works extraordinary well in polyphonic/complex mode. You must not really quantize all notes but only fix the rhythmically most important bits. The more you do, the more unnatural is the result.

    This doesn't sound like a lot of work but actually it is. If you move one wrong bit, the surrounding notes must often stay where they were. You need many Flex markers to isolate the corrected parts.

    If you have a rather simple rhythmical part that is seriously out of time you may have luck with a quickie: Set a Flex marker at the start and end and markers at each measure over the waveform display. Then simply move the markers to their correspondening measures in the timeline.

    Manual correction is no fun with a bad guitarist but it works well for a good player who spent the night in a pub.

    Considering the heavy phasing with long crossfades on sustained guitar tones you seem to be involved in rather mystic music :) (I like that sound)
  12. emgcarra

    emgcarra New Member

    ...Or you can reduce latency at the most and then re-do the take...I had performed some quantization on audio but results are not pleasant, not natural sounding, but that is me.

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