Windows 98 Audio Formats in Windows Media Player

When Microsoft released Windows 98, it included an updated digital media infrastructure powered by DirectShow, allowing Windows Media Player to natively play several primary audio formats without requiring third-party codecs. This overview details the specific audio file types and container standards that Windows Media Player could decode and play out of the box in Windows 98.

Waveform Audio (WAV)

The Waveform Audio File Format (.wav) was the primary system audio format for Windows. Windows Media Player supported uncompressed Pulse Code Modulation (PCM) audio as well as standard Microsoft ACM-compressed WAV files out of the box.

MPEG Audio (MP3, MP2, MPA)

Windows 98 shipped with built-in DirectShow decoders from the Fraunhofer Institute, providing native support for the MPEG standard.

  • MP3 (.mp3): MPEG-1 Audio Layer 3 files could be decoded natively.
  • MPEG-1 Layers 1 and 2 (.mp2, .mpa): Standard MPEG audio streams were natively supported.

Windows Media Audio (WMA)

Microsoft's proprietary streaming format, Windows Media Audio (.wma), was fully supported. Designed to compete directly with MP3, WMA files utilized Microsoft’s native audio codecs integrated into the operating system's NetShow and Windows Media architectures.

MIDI Files

Windows Media Player supported Musical Instrument Digital Interface files, which stored sequence data rather than recorded sound. Playback was driven by the system's sound card hardware or the included Microsoft GS Wavetable Software Synthesizer. Supported extensions included:

  • Standard MIDI (.mid, .midi)
  • RIFF MIDI (.rmi)

Audio CD Tracks (CDA)

Red Book audio CDs could be read directly from an optical drive. The player recognized the track shortcut format (.cda) and streamed digital audio straight from the CD-ROM drive to the sound card.

Sun and NeXT Audio (AU, SND)

Widely used across UNIX environments and early Internet sound archives, Sun Microsystems and NeXT audio files (.au, .snd) were supported via integrated DirectShow filters.

Audio Interchange File Format (AIFF)

Apple's uncompressed audio standard was natively decoded by Windows Media Player. Supported extensions included:

  • Standard AIFF (.aiff, .aif)
  • Compressed AIFF (.aifc)