Gain effect

[pri-yan-shu]

Simple one knob effect for audio gain.

[pri-yan-shu]

Currently it allows to change the gain from -24 db to 24 db, would it be better to have additional parameters to set the range of the gain, like minimum and maximum gain?

[Eve00000]

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What do you understand as 'gain'?
Gain is not an effect, what would a gain-effect do in your opinion?
See the manual for more info about gain.

IMO if you want to adjust the gain of the samplers in a more visible way than in the smaller control in the GUI (and maybe eq, pan ...) it would be better to add a dedicated sampler-channel in the mixer. A powerful gain can create distorted music and even damage equipment, there should be a safety/limiter to not 'overgain' the input (clipping).

[pri-yan-shu]

Thanks for the response, I signed the agreement.

I forgot to mention, this effect is related to the issue #14679, about having a dedicated utility effect for controlling the gain at any stage in the effect chain itself. I'm open to discussing and implementing a better way to implement this if possible.

About overgain safety, I can add clipping to this effect as a toggle button.

[daschuer]

Hard clipping like that creates extra audible artefacts.
It sounds better if you introduce a tanh clipper.

mixxx/src/effects/backends/builtin/distortioneffect.cpp

Line 7 in 1bd3c43

inline CSAMPLE tanh_approx(CSAMPLE input) {

[pri-yan-shu]

Makes sense

[pri-yan-shu]

@daschuer can you review the changes?

[acolombier]

@daschuer could you please confirm your change request has been addressed?

[daschuer]

The clipping feature works good:

Here a the clipped 440 Hz sine:

This is the same without clipping:

Ramping when enabling this effect cause a crackling because of missing ramping:

We need to avoid rectangular changes, because they contain all frequencies.

The same happens when the effect is stopped:

Gain changes itself are already well ramped:

[daschuer]

Btw. I use Audacity to create a 440 Hz test sound and to visualize the recordings.

[daschuer]

TODO: Add ramping when enabling and disabling.

[pri-yan-shu]

Good tip about audacity, much more accurate than judging by ear. I'll keep this in mind while testing for ramping or similar issues.

[pri-yan-shu]

@daschuer Can you review the changes made?

[daschuer]

Works like a charm now. And LGTM. Well done.