Use cheaper filters in waveform analyser

Reported by RJ Ryan on 2012-05-11
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Mixxx
High
Owen Williams

Bug Description

We don't necessarily need to use the butterworth's when analysing waveforms.

Owen has a patch in Bug #996563

RJ Ryan (rryan) on 2012-05-11
Changed in mixxx:
milestone: none → 1.11.0
importance: Undecided → High
assignee: nobody → Owen Williams (ywwg)
status: New → In Progress
Owen Williams (ywwg) wrote :

My patch uses 4th and 8th order IIr filters and the results look good. Trying the even-cheaper second-order filters resulted in gross spiky artifacts. I would propose my patch as-is for the fix unless someone knows of another option.

Cool -- I want to try it out first and take a look at some waveforms
side-by-side but the patch looks good. As a side-note/TODO there is code in
src/waveform/waveform.cpp that records the filter frequencies in the
waveform protobuf when we save it to disk. I'm not sure what the bessel
frequencies are ... there are some comments that suggest 600Hz-4000Hz as
the bandpass region but I'm not sure how accurate those are. Whatever they
are the cutoffs need to be updated there.

On Fri, May 11, 2012 at 10:07 AM, Owen Williams <email address hidden> wrote:

> My patch uses 4th and 8th order IIr filters and the results look good.
> Trying the even-cheaper second-order filters resulted in gross spiky
> artifacts. I would propose my patch as-is for the fix unless someone
> knows of another option.
>
> --
> You received this bug notification because you are a member of Mixxx
> Development Team, which is subscribed to Mixxx.
> https://bugs.launchpad.net/bugs/997902
>
> Title:
> Use cheaper filters in waveform analyser
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/mixxx/+bug/997902/+subscriptions
>

Owen Williams (ywwg) wrote :

AFAICT the IIR filters don't have user-selectable frequencies. I think it's 0-600, 600-6000, 6000+.

RJ Ryan (rryan) wrote :

Yea -- the butterworths weren't user selectable either in this context --
they were hard-coded to 200/2000.

On Fri, May 11, 2012 at 11:05 AM, Owen Williams <email address hidden> wrote:

> AFAICT the IIR filters don't have user-selectable frequencies. I think
> it's 0-600, 600-6000, 6000+.
>
> --
> You received this bug notification because you are a member of Mixxx
> Development Team, which is subscribed to Mixxx.
> https://bugs.launchpad.net/bugs/997902
>
> Title:
> Use cheaper filters in waveform analyser
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/mixxx/+bug/997902/+subscriptions
>

RJ Ryan (rryan) on 2012-06-01
Changed in mixxx:
status: In Progress → Fix Committed
RJ Ryan (rryan) on 2013-05-09
Changed in mixxx:
status: Fix Committed → Fix Released
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