The Amstrad's sound envelope commands are potentially one of its most powerful features. However, many users can be put off by the seemingly meaningless array of numbers that follow each command - up to 16 of them.
The program presented here (over two weeks) allows you to visually design volume and tone envelopes, test them out, load and save them. The program automatically works out the correct values to be added after the Envand commands, and will produce a Basic file containing complete commands which can be merged into your own programs.
On running, the screen display is split up into three main sections; the top lines of the screen show the current Env and Ent commands necessary to produce the sound designed so far, and are also used for the various menus that appear. The main part of the display is taken up with a graphical display of the sound designed, with 'vibrato' level meters displayed on the right. The bottom line contains the 'icons'used to select any particular option. A joystick is required to use the program as it is entirely pointer and 'icon' driven, making any use of the keyboard almost entirely unnecessary (except for entering filenames) Moving the pointer into the graphical area and pressing the joystick fire button will cause the next section of the current envelope to be added. The graphical display shows volume (vertically) from 0 to 15 and time (horizontally) in 1/ 100ths of a second.
The steeper you make a line, the faster the volume will rise (if the line goes up) or fall (if the line goes down). A horizontal straight line can be used to produce constant volume over a period of time, whilst a vertical straight line produces instant changes in volume in a note. The graph allows you to see the 'shape' of each sound - the 'attack', sustain', and 'decay' of the note.
Next to the graphical display are the vibrato meters, these allow you to specify the amount and speed of vibrato to be added to the sound - simply move the pointer to the new position required and press fire. The vibrato values affect the tone envelope parameters.
Along the bottom line are the six icons; to select a function, point to the required icon and press fire. The first icon is a musical note, when selected the program will play a scale using the current values of the volume and tone envelopes, this option allows you to try out your designs before saving them and incorporating them into your own Basic programs.
The second icon is an envelope; selecting this produces a new menu at the top of the screen. Four options are available, each one is selected by pointing to the blue box next to the option required. The current envelope number is displayed, this can be incremented or decremented using the 'Env Up' and 'Env Down' options - the full 15 envelopes are supported. The 'Cancel'option returns control to the main program and does not affect the current envelope number. The 'Edit' option selects the new envelope number to be edited. If the envelope is not empty then the graph of the current settings is displayed, together with the vibrato settings.
The next icon represents a cassette tape. Selecting this produces another menu at the top of the screen allowing files to be loaded or saved. Again selecting 'Cancel'will return control to the main program again. Selecting load or save will prompt for a filename, which must be given. When saving a file, only those envelopes which have been updated are saved, this is to prevent empty' envelope commands wasting space in a program. The files produced are Ascii Basic compatible files with line numbers starting at 500. The sound designer adds the extension '.Env' to all filenames, so a file saved as 'SoundsV could be merged into your own program, and the envelopes used by typing Merge"Sounds1.Env" from Basic.
Next week more listing and program notes.