Skip to main content
A
ABBloch
Known Participant
October 10, 2017
Question

FFT Filter Bug with MultiChannel (Polyphonic) Clips

  • October 10, 2017
  • 1 reply
  • 628 views

I filed a bug report on this, but I figured I'd post it here, as well.  The FFT Filter now nukes the last channel in any clip that has more than two channels in it.  This is a real annoyance for me, as batch-applying "Kill the Mic Rumble" is usually my first step in a film sound edit.

Here are the steps to reproduce the bug:

  1. In the Waveform Editor, open a clip with more than two channels.
  2. Apply the FFT filter


Results:

As soon as the filter finishes processing, the highest numbered channel will become silenced.  Waveform and spectral display will now be blank for that channel, and no sound will be audible from it.


Expected Results:

All channels should simply receive the application of the filter.  None should end up silenced.

Workarounds I can think of are:

  • Split out to multiple mono files and apply the effect to each
  • In the Multitrack Editor, use the filter in the effects rack, so that it doesn't have to be applied.

Neither of these workarounds is a particularly good solution.  The first one is time consuming, and negates the benefits of the new multichannel workflow.  The second one adds significant processing overhead, over the course of a feature film sound edit (hundreds or even thousands of clips).

Anyone have any better ideas?

    This topic has been closed for replies.

    1 reply

    SteveG_AudioMasters_
    Community Expert
    SteveG_AudioMasters_Community Expert
    Community Expert
    October 10, 2017

    I've just tried that here with an 8-channel noise file, and one of the presets from the FFT filter, and it doesn't happen at all on this system - it works perfectly...

    A
    ABBlochAuthor
    Known Participant
    October 10, 2017

    Interesting, Steve.  On my end, it's happening every time.

    On the one hand, as an altruistic human being, I'm glad to know that not everyone is suffering from this.  But on the other hand, the inconsistency will likely will make the bug all that much harder to squash, which could be really bad for me.

    Would you mind listing your system specs?  I'm curious what might be the cause of the different behaviors, and that's as good a place to start as any.  Thanks.

    ryclark
    ryclark
    Participating Frequently
    October 10, 2017

    I have just tried it here with a 5 ch surround file and I get the same result as ABBloch with the last channel silent after processing with the FFT filter. However adding a sixth channel and it worked OK. Maybe it is something to do with working with pairs of channels. Even numbers OK, odd numbers last channel goes silent.

    Haven't tried it with any other odd/even number of channels since I don't have any others to hand

    Terms & ConditionsAccessibility statement
    Using the community Terms of use Privacy Cookie preferences Do not sell or share my personal information ad choicesAdChoices