Talk:Graphic EQ

Peter 28Aug19: Removed for 2,3,3:

A dropdown box lets you choose between three different interpolation methods:

B-spline tends to reduce somewhat the amount of gain set on the sliders, whilst spreading it to more of the surrounding frequencies.
Cosine - improved selectivity in comparison to traditionally implemented equalization functions, while also maintaining beneficial attributes such as a minimum phase response.
Cubic affects the surrounding frequencies the most, introducing a small opposite gain (for example an attenuation if you specified an amplification) at frequencies furthest from the frequency stated on the slider.

Peter 22Aug19: we are likely to remove the graph from this- as shown in the image above.

Graph Scale and Sliders

Vertical Scale: This scale is in dB and shows the amount of gain (amplification above 0 dB or attenuation below 0 dB) that will be applied to the audio at any given frequency.
Horizontal Scale: This shows the frequencies in Hz to which volume adjustments will be applied. Dragging the Equalization window wider displays some additional points on the scale and makes it easier to plot the graph accurately.
Vertical scale sliders: By default the vertical scale reads from + 30 dB to - 30 dB, but these two sliders to right of the scale let you adjust the upper and lower dB values so as to change the visible range on the graph. Note that moving either slider changes the horizontal position of the 0 dB line. Reducing the visible range lets you make a finer adjustment to how loud the frequencies sound, but the changes will be more subtle because the volume adjustment will be less.

Peter 27Aug19: removed for 2.3.3:

Length of Filter: How many samples of audio Audacity processes in each analysis step. Generally, it's best left at the default value of 4001 (a Filter Length, FFT, size) of around 4000 gives a good balance between frequency resolution and time resolution, for technical (Audacity code) reasons the number must be odd.).
- At high sample rates the actual time represented by a given number of samples will be less and the frequency bands will be broader so as to cover the increased frequency range. As a result, the green curve will fit to the blue line less closely at any given "Length of filter" than for lower sample rates.
- A shorter filter length may sometimes be preferable. It will take less time to process the effect, and the smoother curve produced may actually sound better, unless you are modifying very low frequencies.

{{ednote|Peter 22Aug19: removed for 2.3.3 - so commented out:

Select curve: Click the dropdown triangle to select from a list of preset equalizations. These are either your own saved presets (see "Save/Manage Curves" below) or built-in presets, such as filters to remove unwanted low frequencies that could cause poor sound, or the RIAA curve to equalize an LP recorded into Audacity without equalization. A curve will display as an "unnamed" curve if it is not yet saved as a preset, or if it is a modified preset.

There will also be the following instances where curves can only be matched approximately, so will display as "unnamed":

In "Graphic EQ" mode, built-in presets will display as "unnamed" because they were built using the differently calculated "Draw curves" mode.
Your own saved presets will always display with their saved name if loaded in the same mode you saved them in. In "Graphic EQ" mode, only presets saved in that mode will display with their saved name. In "Draw Curves" mode, a curve created in "Graphic EQ" mode can be displayed as its saved name if loaded from within "Draw Curves". If that curve is loaded in "Graphic EQ" mode and then switched to "Draw Curves", it will display as "unnamed".
Any curve in either mode will display as "unnamed" if there are points in the curve that are outside the range of the Horizontal Scale. For example, if you have a point at 10 Hz in a curve saved in linear view (where the scale starts at 0 Hz) then switch to logarithmic view (where the scale starts at 20 Hz), the curve will switch to "unnamed". In that case Audacity will put a point in at 20 Hz at the dB level you wanted at 10 Hz.