User Guide

• Most audio compression algorithms will degrade the quality of the sound.
This is referred to as lossy compression since information contained in the
sound is lost when it is compressed. The amount of sound degradation is
dependent on the algorithm.
• Audio compression requires more processing time than uncompressed data.
The amount of processing time is dependent on the algorithm as well as
your hardware setup. As a result, opening and saving compressed files
usually takes longer than uncompressed files.
• Compressed files are not as portable as uncompressed files. If you are
distributing WAV files in a compressed format, you must make sure the
person receiving the files can use them. Also, not all audio software can use
compressed WAV files, which could make using other programs with Sound
Forge XP inconvenient.
In Sound Forge XP, any compressed WAV file can be opened as long as a
compatible ACM driver is installed and enabled. If there is no compatible ACM
driver available for a compressed WAV file, Sound Forge XP will inform you of
the problem when you try to open it.
Saving compressed WAV files is as simple as choosing the compression
algorithm in the Format drop-down list of the Save As dialog. Once a file has
been saved as compressed, Sound Forge XP will always save changes to the file
using the selected compression algorithm; you do not need to re-select the
compression format each time you save. Of course you can change the
compression format at any time with the Save As dialog. You can also revert to
an uncompressed format.
Experimentation is probably the most important step in deciding whether or
not to use audio compression for your projects.
AUDIO DATA FILTERING (DIGITAL SIGNAL PROCESSING)
The second piece of the ACM provides access to Digital Signal Processing (DSP)
algorithms. The ACM refers to these DSP algorithms as Filter drivers, though the
term Filter in this context is more generic than just frequency filtering (like
Graphic EQ). An ACM Filter can implement almost any type of audio DSP
algorithm. Reverb, distortion, and time change are just a few of several
possibilities.
APPENDIX E
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