CoralVision
Level 1 (38 points)
Video

Q: AUDIO PHASE TOOL

Hi All,

 

I just submitted a feature request to support and I wanted to come over and share it, and see if anyone else has the same concern or idea:

 

"I frequently mix audio from several sources in my programs (e.g. wireless mic & on-cam shotgun, or stage-mix & ambient mic) and often have problems with sound "phase" where audio is out of sync by a sub-frame amount of time (caused by audio signals traveling different signal paths on the way to the camera or recorder). (This creates an unwanted "phase" effect.) I solve by detaching audio, splitting/duplicating lines as separate attached clips and then nudging them by sub-frame amounts. This is SO tedious and sketchy. Can you make it so that I could adjust the phase/timing of tracks (e.g. mono 1 & mono 2) on a clip, without having to break apart the clip from the audio? NOTE: This has NOTHING to do with the "phaser" effect which is actually ADDS this artifact to audio."

 

Anyone else ever think about this? Is there an easier solution already in place that I have been blind to?

 

Thanks as always,

 

Eric D - CoralVision

Final Cut Pro X, OS X El Capitan (10.11.6)

Posted on Aug 12, 2016 8:40 AM

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Q: AUDIO PHASE TOOL

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  • by BenB,

    BenB BenB Aug 14, 2016 6:32 AM in response to CoralVision
    Level 6 (9,816 points)
    Video
    Aug 14, 2016 6:32 AM in response to CoralVision

    Sounds like all your recording devices could be off from each other.  Verify the settings are correct, 48kHz at 16-bit, which are video standard.  Sample Rate, 48kHz is the vital one to keep in sync.  Otherwise, in all my editing I've never had such rampant phase issues.  I'd want to know more about the actual recording, how all that is set up.

  • by CoralVision,

    CoralVision CoralVision Aug 15, 2016 9:00 AM in response to CoralVision
    Level 1 (38 points)
    Video
    Aug 15, 2016 9:00 AM in response to CoralVision

    Hi Ben,

    How are you doing down there? I hope your home is safe and dry today.

    Everything is definitely set to 48kHz/16b - I'm talking about signals from different lines reaching the recording device at different times.

    Example: Recording a band at an outdoor concert. At most small scale shows the sound operator doesn't do a full "stage mix" but instead relies on some of the sound from the stage amps and the drum set to reach the audience on it's own - a "volume support" mix I would call it. In this case I take a line from the board and I also place my own mic on stand in the audience area and then mix for best effect in post. Taking the two lines into the same recording device (either the BMD hyperdeck or cam1 internal or both), the signal from the board arrives at the recorder offset in time from the signal from the mic - usually about 1/3 of a frame sooner (at 29.97fps).

    I wouldn't say the problem is rampant, just common for me, and it's not a show-ruiner, since most people who have never mixed sound professionally wouldn't really recognize the artifact as anything other than "that tinny metallic effect I hear on some (poorly/cheaply done) concert video" - but I find that my sound is just nicer if I fix it. Audio waveform interference can even end up muting some EQ frequencies, when the temporal offset is equal to 1/2 of the frequency, resulting in an inverted/cancelled out frequency range in your mix. I run a PEG TV station, and so many of my productions proceed under less-than-ideal conditions, that I've become very concerned with audio quality, it's a major factor in viewer experience, and doing all I can to make it nice is important to me.

    In PrPro, which I also use daily, the fix is easy because of the tracks - I just unlink audio, nudge things around til I get the effect I need, and then re-link the audio. The procedure in FCP is functionally similar, but far more awkward - detaching audio, adjusting timing, and then wrapping the fixed clip in a new compound clip.

    It would be a help with my workflow if I could adjust the relative timing of audio tracks on a clip without detaching the audio. I know it's asking a lot, but I'm just suggesting a tool I might use.

    How are you doing down there, Ben? I hope your home is safe and dry today.

    Have a nice Monday,

    Eric D