Re: [Audacity-devel] Reassigned spectrograms

[Steve t. F. <ste...@gm...>]

Thanks for the reply James,

On 18 August 2015 at 13:02, James Crook <cr...@in...> wrote:
> Spectral reassignment is in for 2.1.2.
>
> It is a super feature, and 'local' in that bugs in it are unlikely to affect
> anything else.  Its bugs are mostly likely to be around quality of its own
> display, i.e. not reassigning as finely as we might like.  It was being
> worked on already in 2.1.1 rather than being completely new.

I've just had my first look at spectral reassignment, and yes it looks
good (nice work Paul).

I'm not sure that we can really say that it doesn't affect anything else.
Until very recently, users that are not bold (or competent) enough to
dig down into Preferences were presented with 4 options in the Track
dropdown menu:

* Waveform
* Waveform (dB)
* Spectrogram
* Spectrogram (dB)

If we contrast that with the current options:

* Waveform
* Spectrogram
* Linear / logarithmic
* dB range
* Minimum / Maximum Hz
* Gain / Range / dB per decade
* Algorithm: Frequency / Reassignment / Pitch (EAC)
* Window size
* Window type: rectangular / Barlett / Hamming / Hanning / Blackman /
Blackman-Harris / Welch / Gaussian (a=2.5) / Gaussian (a=3.5) /
Gaussian (a=4.5)
* Zero padding factor
* Enable spectral selection.


> The track menu changes now give us something better than we had in 2.1.1,

I think that the ability to change the window size for spectrograms,
without digging into preferences, is a good thing. I'm struggling to
see how other changes to the track dropdown menu will benefit 'the
average user'.

One of the things that I really liked about Cool Edit Pro (if you
remember that app), and something that it was frequently praised for,
is that commonly used basic features were immediately available in
well thought out ergonomically satisfying menus. For more 'advanced'
(or 'adventurous'), plenty of advanced and/or technical features were
available by digging a little deeper. This model can provide a
terrific user experience for both novices and experienced users alike.
It is a model that I believe that Audacity should apply.

I'm very pleased that Audacity has 'advanced features' (As most on
this list are aware, one of my favourite features is Nyquist, which is
probably the most 'advanced' feature that we ship). I also think that
it is good to encourage users to 'dig a little deeper', but I get
concerned when we present basic operational choices mixed in with
advanced technical jargon, especially as we know that the vast
majority of our users have little or no previous experience of working
with digital audio.

> and (as RM) that's good enough to justify making them.  As me, I think there
> is still something not as good as it should be in how we select track
> options, but I can't put my finger on it, and it does not scream enough to
> me to worry about it for 2.1.2.
>
>
> I think Steve you are right to worry.  We have a tremendous amount of
> technical debt caused by the wx change.  3P1s, and 8 DEVEL-FIX-MADE P1s
> which are pending confirmation that they have been fixed (without breaking
> something else important).  Any changes as big as spectral reassignment
> intended for 2.1.2 from here on need to ask "Is it OK?" on this list and the
> answer is probably no.

Thanks. That alleviates one concern that we will be struggling to
document all of the recent changes. The documentation crew already
have a lot on their plate with essential Wx3 changes. I'm not sure who
is going to document "reassignment" - perhaps Paul can help with that?


> Minor features/improvements are definitely OK

Good - I've got a couple of little enhancements that have been
requested on the forum that I'd like to get in. I'll try to get those
in sooner rather than later.

> and in
> particular picks for these ones from Gale's wishlist:
>
> Option to turn off backwards scrubbing OR a modified click that
> automatically plays forward from the seek point. This is to reduce
> un-necessary RSI after seek.
> Some TLC for those who do large amount of daily export and import:
>
> Bug 550 – Add Directories Preference to export to directory the file came
> from
> Related to above, easier one-step overwrite of the same file you imported.
> Bug 549 – Add missing export formats to Chains and Chains export format
> parameters and sample rate
> Bug 551 – Export Multiple: Pass through common metadata to next window
> Support per-track metadata so that if you import multiple files you can
> export multiple using each file's metadata instead of export all files with
> only the last file's metadata
> Bug 701 - Embedded album art and lyrics discarded.
>
>
> I would like to see some more work on noise reduction to make it
> better/easier to use.  I would like Paul to set a colour for spectral
> selection that he is happy with to replace the yellow.  We are leaving
> 'rough edges'.  We do have until 30th August before Semifreddo.
>
> Steve, does this answer your concerns?

It certainly helps :-)
Thanks

Steve


>
> --James.
>
>
>
> On 18/08/2015 11:39, Steve the Fiddle wrote:
>
> I'm just wondering why we are seeing so many new features introduced
> for the 2.1.2 release. I thought that this release was about updating
> to Wx3. My concern with so many changes in this release is that either
> quality suffers or the release is seriously delayed. Perhaps James can
> comment and reassure us that it is all in hand?
>
> Steve
>
> On 17 August 2015 at 15:40, Paul Licameli <pau...@gm...> wrote:
>
> I don't think it's "experimental" any more, I think I got all the math right
> now.
>
> There are opportunities for more efficiency.  It is true that caching of
> results leaves something to be desired for some changes of view, but that is
> already true of spectrograms generally.  There is no caching of any
> spectrograms for changes of zoom level.  There is some caching only for
> scrolling left and right without changing the zoom, and that much won't work
> now with reassignment.
>
> I consider any such effort for performance a future project.
>
> PRL
>
>
> On Mon, Aug 17, 2015 at 10:28 AM, Steve the Fiddle
> <ste...@gm...> wrote:
>
> Is this an experimental feature?
>
> Steve
>
> On 17 August 2015 at 15:18, Paul Licameli <pau...@gm...> wrote:
>
> As of
>
> https://github.com/audacity/audacity/commit/3ddbbd375d6963838b91fe2f54c91df96d90e79a
>
> Now reassignment is a third algorithm choice in spectrograms preferences
> and
> view settings.
>
> This is an algorithm that sharpens the results of a spectrogram.  It
> works
> by computing two extra FFTs using different windowing functions.  The
> contributions that the usual FFT makes to pixels on the screen, are in
> effect moved slightly using results of the other FFTs.  This can
> counteract
> both the "time smearing" and "frequency smearing" effects.
>
> But not only is this spectrogram about three times as costly to compute
> -- I
> also had to disable the caching that allows horizontal scrolling of
> spectrograms to go faster.  This sort of caching is important for
> scroll-scrub with spectrogram on.
>
> The zero padding of spectrograms that I implemented in the last version
> was
> meant to accompany this.
>
> Try it out with tones and chirps -- you will find just a thin bright
> line,
> even if your window size is small!
>
> Try it with an impulse -- you will find a bright vertical line, even if
> your
> window size is large!
>
> Try it with real world examples -- and it is true there are strange
> artifacts from "cross terms" if you have two or more sources of sound,
> or
> inharmonic sounds, which make a sort of gauzy pattern as in this
> article.
> https://en.wikipedia.org/wiki/Reassignment_method
>
>
> PRL
>
>