USE

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| USE |

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Type in a terminal :

$ spectrum3d

or run it from 'Menu->Applications->Sound & Video->Spectrum3d'

The 2 most important things to do first are :
- to select the type of audio source : either microphone or audio file; microphone is the default;
- set if analyse will be done in real time or not : if 'analyze in real time' is checked, harmonics will be retrieved and displayed on the fly, while the sound is being played; if 'Analyse in real time' is unchecked, harmonics of the whole audio file will be retrieved and displayed first, then the file can be played afterwards. When source is set to microphone and 'Analyse in real time' is unchecked, recording can be made; it will be analysed and displayed like for an audio file; similarly it can be also played afterward.

The 'reload' button allows to reload (i.e. analyse and display its harmonics) without reselecting the file.

You can record from the microphone and have the generated audio file analysed and displayed by selecting 'microphone' as the audio source, then unchecking the 'analyse in real-time' button; then the record button will be usable; a 'record window' will then pop up; after recording, a click on 'OK' will load the file as for an audio file.

If 'Use JACK' is checked, everything explained above can be done with Jack (Jack-Audio-Connection-Kit).

Another window that commands different filters can be displayed :
- a 10 bands equalizer; the filtered frequencies and their range can be adjusted; the amplification goes from -72dB to +36dB;
- a band-reject or band-pass filter;

The lowest displayed frequency is 0 Hz by default, and it can be increased. The default range is 2000 Hz. It can be decreased to 40 Hz or raised to 20000Hz. To change this, you can either change it by using the 'Range of Display' scale, or increase it by changing the factor that is on its right : this factor multiplies the frequency range. The smallest possible step between 2 analyzed and displayed frequencies is 2 Hz.

From the menu :
* you can choose between 3 types of view : - a 3D view that shows frequency, intensity and time; It is possible to rotate or translate the display along the X, Y and Z axis, either by keyboard commands, or by mouse (+/- keyboard) commands, or by touch gestures (if enabled). All the analyzed values are kept in memory, which implies that even if zoom or perspective changes, any value can be retrieved at any time, even when playing is paused.
- a 2D 'flat' view : that shows time versus frequency; the intensity however is represented by the amount of red color;
- a 3D 'flat' view that is somehow a compromise between the two previous views.

* the perspective can be reset, set to a 'front' view (frequency versus intensity), or set to values preset by the user. The text can be displayed or not, as well as the line scale. A 'pointer' can be displayed, showing a location on the scale and its exact numerical value as well as the intensity of the frequency (fot the 3D view).

* you can chose to display text and lines or not and also a pointer that will point to a specific frequency; it will display it frequency value, and for the 3D perspective its intensity value;

* you can play a test sound which is a sine wave from 1 to 20000 Hz;

* you can set, in 'preferences' : 
    - the distance between frames : the biggest this value is, the 'deeper' the image will go;
    - the number of displayed frames, the biggest this value is, the 'deeper' the image will go and the more cpu will be used;
    - the interval of time (in milliseconds) between each refreshing of the display; the smallest this value will be, the nicer the display will look, but the more demanding it will be on the cpu; every change in this will require Spectrum3d to be restarted to be effective;
    - the color of the display (when analyse in real-time is selected);
    - whether you want that the actual display is saved as preset;
    - the interval of time (in milliseconds) between each new analysis of the spectral data; as for display, the smallest this value will be, the more demanding it will be on the cpu; this value should match the interval of time between 2 displays for better display but this is not mandatory.
    - the activation of multitouch gestures commands (activated by default);

All those preferences are kept in a 'preferences' file that is created at first use of Spectrum3d and placed in the home directory : ~/.spectrum3d/spectrum3d.pref. Everytime Spectrum3d starts, it check some values of this 'preferences' file for consistency; if out of range value is found, a new 'preferences' file with default values is created.

You'll find below a summary of the keyboard, mouse and gestures commands.