Baseline Audio for PC 97

This section defines the requirements for baseline audio, which is typically implemented as a system board solution for business PCs. Although audio is not required on a PC 97 Basic or Workstation system, if baseline audio is implemented in the system it must meet the requirements defined in this section.

3. General device requirements for PC 97

These include the standard PC 97 requirements for a Plug and Play device identifier, automated software-only settings for device configuration, standard device drivers and Windows-based installation, and icons for external connectors. For more information, see the "Basic PC 97" chapter in Part 2 of this guide.

4. Minimum standards for output

• 16-bit digital-to-analog converter (DAC)
• Support for monaural output

  Recommended: Support for stereo (required for PC 97 Advanced audio)

• Support for 8-bit and 16-bit linear pulse-code modulation (PCM) digital audio
• Required sampling rates: 8 kHz, 11.025 kHz, 22.050 kHz, and 44.1 kHz

  Recommended sampling rates: 16 kHz, 32 kHz, and 48 kHz (required for PC 97 Advanced audio)

• Support for MIDI playback; if implemented as music synthesis, the minimum support must include 16 voices plus 6 timbres for basic audio

5. Minimum standards for input

• 16-bit analog-to-digital (A/D) converter
• Support for monaural input

  Recommended: Support for stereo (required for PC 97 Advanced audio)

• Support for 8-bit and 16-bit input
• Required sampling rates: 8 kHz, 11.025 kHz, 22.050 kHz, and 44.1 kHz

  Recommended sampling rates: 16 kHz, 32 kHz, and 48 kHz (required for PC 97 Advanced audio)

6. One line out and one line in, minimum

At a minimum, the system must include support for one line in and one line out. The minimum line-in support can include 3.5-mm microphone in or 3.5-mm line in. The minimum line-out support can include 3.5-mm headphone out, line out, or speaker out.

Typically, a baseline audio implementation will include additional line-in/line-out support, but this bare minimum is defined to allow alternate solutions for designs sensitive to form-factor issues.

7. Minimum audio performance characteristics

The following is required for input (record) and output (playback):

• 75 dB signal-to-noise ratio (SNR).
• Frequency response: 20 Hz to 20 kHz, A-weighted.

  For mobile PCs, the signal-to-noise requirement is 75 dB from 20 Hz to 15 kHz, A-weighted.

• 0.02 per cent total harmonic distortion.

Signal-to-noise (S/N) ratio is defined as the ratio of the RMS output level with 1 kHz full scale input to the RMS output level with all zeros into the digital input (AES17-1991).