Software In Review

Commodore World Issue 3, Vol. 1, Number 3, page 30

by John Serafino

Digimaster

An all-new program for processing digital sound samples on your Commodore 64 or 128 in 64 mode, Digimaster uses new techiques to reproduce eight-bit digital sound samples, previously considered impossible on a 64/128 without additional hardware. Eight-bit digitized audio is sexteen times more accurate than four-bit, and produces sound with less noise and distortion.

The package includes an editor, a utility to convert Amiga IFF sound files into a Digimaster-compatible format, relocatable machine language player modules for both 64 and 128 modes, and sample BASIC programs to demonstrate how to use digitized sounds in your own programs.

The digimaster Editor is mouse or joystick driven, and uses an intuitive graphical point-and-click user interface with pull-down menus, dialog boxes, and requestors. This makes the operation of the program a breeze, especially while editing the sound files.

After the program loads, the screen displays a menu bar acros the top of the screen, and a "scope" window. The scope window contains buttons for playing all or a portion of the current sound file. A digitized sound file is loaded into the program by selecting "Load" from the File menu, then choosing the desired file from the directory list. While the file requester will display all files on the disk, only the "dff" sound files can be loaded. After the sound file loads, the program will display the entire sampled waveform in the scope window. A section of the waveform display can be highlighted (or "marked") for use with the various editing and sound effect tools.

The Edit menu contains six selections, five of which are used to manipulate portions of the sample. The sixth selection allows you to choose your default and "clip" file disk drive, and select a low pass filter cutoff frequency. The filter control allows you to adjust the "tone" to remove aliasing or quantization noise during playback. Aliasing noise occurs when frequencies above half the sampling rate are present in the digitized sound. Quantization noise occurs when portions of the sound are very soft.

The editing functions generally require that you highlight a portion (or all) of the waveform. This is done by moving the pointer across the waveform while holding the mouse or fire button down. Four buttons on the scope window allow you to fine-tune the beginning and end of your highlighted range. This range can then be copied or cut tothe clip file, erased, or mixed with a previously saved clip into the current wavewform data. The editing functions can be used to trim silence or noise from the beginning or end of the sound sample, or even jumble the words of a sentence around. It's also possible to create new sound samples from pieces of other samples.

The Sound/EFX menu contains six selections. Volume changes the volume of a highlighted range. This lets you create fade-in and fade-out effects, or increase or decrease the overall volume of the entire sample. It's also possible to use this function to change the volume of a portion of the sample, which may be necessary when overlaying or combining clips.

Resample alters the sampling rate of the entire sound sample; this can be used to decrease the size of a sound file, and is also useful when combining clips of samples that were recorded at different sampling rates.

Backwards will flip the marked range of data so that is till play backwards. While this feature has little practical use, it can be used to create interesting sound effects.

Loop Range will simply play the highlighted range in a continuous loop.

Sample Audio lets you record live sound directly into the computer with the help of an audio digitizer. The manual provides some information on obtainig and attaching such devices. [Also not the hardware digitizer plans elsewhere in the issue - Ed.] Digimaster has three sampling rates, labeled Slow, Medium, and Fast, which translate to 8K, 10K, and 12K respectively.

All in all, the sound quality of Digimaster competes well with some of the sound boards designed for newer computers, especially at the medium and fast sample rates. I found the program's user interface intuitive and easy to use, and best of all, I had it up and running very quickly.

One of the best features of Digimaster is the ease with which you can use the sound samples in your own BASIC or ML programs. This raises the status of this package from a quickly-forgotten novelty item to a truly useful programmer's tool. Even the novice 64 or 128 programmer should be able to incorporate eight-bit digital sound iinto his or her own programs with the supplied routines.

I really don't have any negative comments about Digimaster, although I'd like to see a few more on-board sound effects functions such as echo, chorusing, and flanging. While these effects can be accomplished manually using the copy and paste editing functions, it's diffucult and time consuming getting exactly the correct delay time, volume, and number of repeats.

Producing a simple echo effect on a short sample required repeatedly reducing the volume of the sample, cutting the entire sample to a clip file, loading the original sample, then overlaying the clip at the right point. Hopefully, the author will include such functions in a future version.

Another nice addition would be the ability to have multiple clip files to ease constructing sounds from a number of different samples. These minor shortcomings aside, Digimaster is sure to please and amaze anyone interested in editing digital sounds.