YMF744B

6. Digital Audio Interface

DS-1S supports each system of the SPDIF input/output port compliant with the IEC958 specification.

6-1. SPDIF IN

DS-1S provides the SPDIF input capability by switch-over operation of the zoomed video port. SPDIF input sampling frequency is 32.0kHz, 44.1kHz or 48.0kHz.

In DS-1S, sampling rate of the SPDIF signal incoming from the SPDIFIN pin is converted to 48.0kHz in the frequency rate conversion stage in order to process all the signals at 48.0kHz frequency. If input sampling frequency is 48.0kHz, however, this is resampled at 96.0kHz, then decimated into 48.0kHz frequency. The input signal applied to the SPDIFIN pin can be also provided as outputs to the SPDIFOUT pin.

6-2. SPDIF OUT

SPDIF output is selected from three types of data indicated below:

A : Dolby digital (AC-3) encoded data

B : Output data (to be provided to the DAC slot on the AC-link) after digital mixing

C : Input data applied to the SPDIFIN pin

When the above A and B data are supplied as outputs, output sampling frequency is fixed at 48 kHz, and when the above C data is supplied as an output, output sampling frequency is dependent on the frequency available from the SPDIFIN input pin.

Control and category codes of the channel status are provided as sampling rate converter, copyright protection available and commercially available recorded software in accordance with the serial copy management system. Such a code arrangement allows output data to be digitally copied only to the next generation ones. When input signal to the SPDIFIN pin is provided as output, no modification is made for the channel status, etc., and output data is code-dependent available from the SPDIFIN pin.

February 3, 1999

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Yamaha YMF744B (DS-1S) specifications Digital Audio Interface, Spdif
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YMF744B (DS-1S) specifications

The Yamaha YMF744B, also known as the DS-1S, is a popular audio chip that emerged in the late 1990s, particularly known for its use in sound cards for PCs. This sound processor exemplifies Yamaha's commitment to delivering high-quality audio through innovative technology and user-friendly features.

One of the standout features of the YMF744B is its ability to support advanced sound synthesis methods, including wave table synthesis and sample playback. These technologies provide users with a rich audio experience, enabling high-fidelity sounds reminiscent of live instruments. The chip is also notable for its ability to emulate MIDI instruments, allowing musicians to create synthesized music that captures the nuances of traditional sounds.

The YMF744B integrates a 16-bit DAC (Digital-to-Analog Converter), which facilitates high-quality audio playback with a sampling rate of up to 48 kHz. This capability ensures that sound reproduction remains clear and devoid of distortion, appealing to both casual users and audio professionals alike. Additionally, the chip supports multiple audio channels, making it ideal for gaming and multimedia applications where spatial audio is crucial.

Another significant feature of the YMF744B is its support for various audio formats, including PCM (Pulse Code Modulation), ADPCM (Adaptive Differential Pulse Code Modulation), and even MIDI. The versatility in format support allows users to interact with a broad spectrum of audio applications, from game design to music production.

The chip also comes with integrated Sound Blaster Pro compatibility, which significantly enhances its usability with a vast array of software and games designed during the 1990s and early 2000s. This compatibility is crucial for retro gaming enthusiasts who seek an authentic audio experience with classics from the past.

Moreover, the YMF744B champions power efficiency, making it an attractive choice for mobile computing platforms. Its low power consumption means that it can be effectively used in laptops without significantly draining battery life, allowing users to enjoy high-quality sound on the go.

In summary, the Yamaha YMF744B (DS-1S) stands out due to its advanced audio synthesis capabilities, high-quality playback features, and compatibility with multiple formats. These attributes make it a favored choice in the audio processing domain, continuing to impact computer audio technology long after its initial release.
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