Recording, Editing, and Playing Audio

Windows 98 multimedia services provide extensible, device-independent audio support. Windows 98 features services for sound control for computers that have sound cards and for waveform-audio, MIDI, and mixer devices.

With audio support in Windows 98, users can do the following:

• Use Media Player or ActiveMovie Control to play WAV or MIDI files.
• Use applications that take advantage of DirectSound audio acceleration.
• Use the Sound option in Control Panel to assign sound clips to play each time a specific event occurs.
• Use CD Player to play audio CDs.
• Use Sound Recorder to record sound.
• Use built-in Windows 98 OLE support to copy or link audio clips in other documents. For more information, see Chapter 25, "Application Support."

For more information about recording, editing, and playing multimedia files, see Help.

Windows 98 Support for MIDI

Musical Instrument Digital Interface (MIDI) is a serial interface standard that allows for the connection of music synthesizers, musical instruments, and computers. The MIDI standard is based partly on hardware and partly on a description of the way in which music and sounds are encoded and communicated between MIDI devices.

MIDI is used as a development tool for musicians. Virtually all advanced music equipment supports MIDI, and MIDI offers a convenient way to control the equipment precisely. MIDI is the electronic equivalent of sheet music. For example, if you buy a CD that contains a particular performance of a piece of music, the data on the CD requires no interpretation at all — it is straightforward playback. If you buy the sheet music and have someone play it, it requires very little data, but, depending on the quality of the instruments, the hardware, and the software, you can get a good or a bad interpretation of that piece of music.

Windows 98 supports the General MIDI Specification to request particular instruments and sounds. This specification is an industry standard that defines how MIDI should be used, and it is supported by Microsoft and most MIDI sound card manufacturers.

Windows 98 supports MIDI streams. This technology is used in advanced sound cards to play very complex MIDI sequences with less CPU use. This technology allows Windows 98 to receive requests for multiple MIDI instructions at once and process the instructions in the operating system. As a result, playing MIDI files now requires even less computing power than before, and it allows developers to process MIDI instructions, graphics, and other data even more successfully.

MIDI devices supported by Windows 98 include the following:

• FM Synthesis
• Hardware Wavetable Synthesis
• Software Wavetable Synthesis
• MPU401

For more information about playing a MIDI sound file and installing a sound card, see Help.

Recording Sound

If you have a microphone connected to your computer, you can record sound by using Sound Recorder.

When using Sound Recorder, you can use a real-time audio compression filter to reduce the amount of disk space required to store audio. For example, to turn on voice compression when recording so the file is compressed in real-time, use the GSM 6.10 format in the Convert Now dialog box in Properties from the File menu.

To enable real-time compression while recording

1. On the Start menu, point to Programs, point to Accessories, point to Entertainment, and then click Sound Recorder.
2. Click the File menu, and then click Properties.
3. From the drop down box, choose Recording formats.
4. Click Convert Now, choose a compression format, and then click OK.
5. Click OK to start recording.

For more information about recording sound with a microphone, see Help.

Controlling Audio Input Levels

Windows 98 includes a Volume Control tool that provides audio line routing services to manage the different audio lines installed on a computer. An audio line consists of one or more channels of waveform-audio data coming from one origin or system resource. For example, a stereo audio line has two data channels, yet it is considered a single audio line. A mixer control can take on many different characteristics (such as controlling volume), depending on the characteristics of the associated audio line.

The number of lines users can mix by using Volume Control depends on the number of audio source lines the computer has and whether they are using Volume Control for input or output.

For more information about mixing sounds, see Help.