Picking the right central processing unit (CPU)The standard Multimedia PC can handle the playback of audio quite well. But to prepare this audio for use in a title, you'll need more powerful software and hardware. The following sections describe some of the factors to consider when setting up your audio preparation environment. As with other sections, specific product recommendations are avoided.
When choosing your sound preparation software, first decide exactly what you need. Some products perform standard functions for recording and editing waveforms. Other products provide a digital signal processing laboratory that includes the standard functions, as well as advanced capabilities that can include cross-channel mixing and frequency analysis.
The MDK includes WaveEdit—a simple sound editor with recording capabilities to let you record in the 8-bit and 16-bit waveform format. WaveEdit also includes conversion utilities for Macintosh AIFF and PCM formats. The Convert tool also supports the conversion of audio formats.
Features included with sound preparation products appear in the following table. The left column shows standard features found in all the products. The right column identifies advanced features found in higher-end products:
| Standard Features | Advanced Features |
| Digital waveform recording up to frequencies of 22.05 kHz | Digital waveform recording of frequencies up to 44.1 kHz |
| Visual waveform editing (cut and paste waveform sections) | Cross-channel mixing |
| Mixing waveforms together | Adjusting waveform tempo without pitch change |
| Inserting Silence Fades (in and out) | Adjusting Pitch |
| Adjusting Amplitude | Defining Amplitude envelopes for a waveform |
| Mixing more than two channels of waveform data | |
| Frequency Analysis | |
| Defining playlists that sequence waveform segments for playback |
Once the sound file is complete, the file may need to be converted to a format supported by the multimedia software. Both the WaveEdit and the Convert applications provided with Microsoft's Multimedia Development Kit includes conversion capabilities for several types of digital sound files.
The primary concern when putting together an audio preparation system is that it handle digital audio. Windows with Multimedia only works with digital audio, so if you have any source audio in analog format, you'll first need to translate the analog signals into a digital format. After you have completed this process, you can then begin to clean up and embellish the audio for your application.
Another major concern you'll have when acquiring the hardware for your audio preparation system is performance. Audio preparation requires a lot of horsepower and disk space, so you better buy plenty of both.
Other issues to consider when acquiring a system:
Picking the right central processing unit (CPU)
Getting enough hard disk space
Choosing an Analog-to-Digital Converter
Picking a microphone
Acquiring tape backup
Summary: CPU
Editing audio data is a processor-intensive operation, and requires quick CPU and disk controller performance to handle the volume of data managed and collected. The base level Multimedia PC specifies an 80286 processor running at 10MHz. This would not be adequate for the audio preparation. Look for at least an 80386 or better processor. You should also consider configuring your PC with plenty of additional RAM and using a RAM disk to store temporary data during the data capture phase.
Summary: Hard Disk
Sound files are large and fill up a hard disk quickly. Provide your system with sufficient disk storage (at least 300-600 MB) to record, edit, and convert the sound clips used by your application.
Summary: Analog-Digital and Digital-Analog Converters
These devices are often delivered on a PC interface card. An Analog-to-Digital converter (ADC) converts incoming analog signals to discrete samples at regular time intervals. A Digital-to-Analog converter (DAC) converts outgoing digital signals to analog, for use by an amplifier, speakers, or other analog devices. The Multimedia PC specification establishes both an ADC and a DAC as standard equipment.
Capabilities of various available ADCs and DACs vary. For example, the interface card containing the converters may also contain additional circuitry for digital signal processing, especially in high-end products. A digital signal processor (DSP) chip provides added punch for such tasks as frequency analysis.
If you plan to record and play Red Book quality sound clips, verify that the capabilities of the converters can support a 44.1 kHz frequency.
Summary: Microphone and Cables
A good original recording source and good acoustics are part of making a good sound. But, if you are planning to record anything live with a microphone, purchase a good one—it can make a distinct difference in your final recording.
Microphones are very specific to their application. When you're ready to buy a microphone, tell the experts how you intend to use it and have them recommend the best type of microphone for that particular job.
Additionally, don't go bargain hunting when picking out cables for your audio equipment. Cheap, thinly-insulated cables pick up static from the equipment, which makes your audio sound worse. Buy quality cables—they're well worth the investment.
Summary: DAT Tape Deck
If you are recording full bandwidth Red Book audio and you are using a 100 MB hard disk, you're going to run out of space in about 19 minutes of recording. With all data you need a backup recording system, but this is particularly important with audio data, just so you can get all your work done.