Why "show clipping" looks worse than it is

[steve]

When "Show Clipping" is enabled in the View menu, users are frequently alarmed by the amount of red, especially if the music in question was commercially purchased.

I've also noticed that when "Show Clipping" is enabled, it often looks much worse than it really is.

Here is an example of some audio that is quite badly clipped ("Show Clipping" off):

clipping0.png (9.77 KiB) Viewed 1617 times

Clipping is evident by the way that the waveform slams into the top/bottom of the track.
Nevertheless, although distortion can be heard, it is not as bad as is suggested by the appearance when "Show Clipping" is enabled:

clipping1.png (5.09 KiB) Viewed 1617 times

I was wondering why it looked quite so bad, so I looked more closely and noticed that it is because of the way that the clipping lines are drawn.

If the waveform hits +1.0 OR -1.0, then a red line is drawn across the full width of the track.
This is misleading in cases where the waveform just touches +1.0 OR -2.0 as, (even if we ignore the question of whether 0.0 dB is "clipped), it is indicating twice as many clipped samples as there really are.

A more informative and realistic way to show (possibly) clipped samples would be if we drew clipped lines from the centre line to the clipped sample, rather than across the full track width:

clipping2.png (6.03 KiB) Viewed 1617 times

[Gale Andrews]

Another way to make Show Clipping look more like it sounds would be to allow Show Clipping to discriminate between clipping runs of different length (show runs of only one to three samples in a different colour or provide an option not to show them at all).

If I ever post the proposal for improved display of clipping http://forum.audacityteam.org/viewtopic ... 20&t=81802 on Wiki, should your idea of distinguishing positive and negative clipping be included there?


Gale

[steve]

If I ever post the proposal for improved display of clipping http://forum.audacityteam.org/viewtopic ... 20&t=81802 on Wiki, should your idea of distinguishing positive and negative clipping be included there?

If that ever gets written up as a proposal, then I think this could certainly be mentioned (unless this has already been implemented by then), but I wouldn't want this only as a sub-feature of that larger proposal. This feature could be implemented whether or not other features in that proposal are implemented. As such it is a stand-alone enhancement.

[Gale Andrews]

This feature could be implemented

So I moved this to "Adding Features". Thanks for the idea.


Gale

[waxcylinder]

Another way to make Show Clipping look more like it sounds would be to allow Show Clipping to discriminate between clipping runs of different length (show runs of only one to three samples in a different colour or provide an option not to show them at all).

Gale, do you have any suggestions for bandings and appropriate color-ways?

I'm guessing red would be reserved for the worst-case scenario.

Peter.

[Gale Andrews]

Another way to make Show Clipping look more like it sounds would be to allow Show Clipping to discriminate between clipping runs of different length (show runs of only one to three samples in a different colour or provide an option not to show them at all).

Gale, do you have any suggestions for bandings and appropriate color-ways?

I'm guessing red would be reserved for the worst-case scenario.

Yes.

I think there was some feeling that Show Clipping should always be able to show a single clipped sample, so perhaps the groups could be one sample, two to three samples, four samples or more (which is what Meter Toolbar shows).

A lot depends on how colours show against the light and dark blue. I had in mind an orange for one sample, pink for two to three samples and red as now for four samples or more.


Gale