Monday, April 21, 2014

exaU2I USB to I2S Interface Features

ASIO Driver Advantages

Using ASIO brings unique advantages that are hard to achieve and reliably verify with other Windows driver technologies.

Automatic Sampling Rate Switching

PCM data is always streamed without re-sampling. Native Windows 7 drivers require manual sampling rate selection and apply implicit re-sampling when the source rate differs from the rate set in the Windows Control Panel.

Bit-perfect operation independent from the Windows volume control and mixer

The native Windows volume control and mixer are optimized to provide wide compatibility and easiness of use. These features come at the expense of sound quality. The resulting output is not bit-perfect or bit-transparent.

Third party proprietary Windows drivers are hard to be verified as bit-perfect because factors beyond the control of the user can change the Windows sound processing chain.

Our proprietary ASIO implementation is completely independent from the Windows sound system and always operates in Exclusive Mode. Only one player can take control of the ASIO driver. When playback starts the player sets the driver sampling rate to be the same as the native rate of the current media file. The sound data stream is delivered to the exaU2I FIFO memory buffer without any processing or manipulation.

The general mixed output of the Windows sound system can be inconvenient or harmful when powerful full-range amplifiers and speakers are used.

Our approach separates the processing of general purpose computer sounds like beeps and voice communications from the dedicated output of high-end music player.

Asynchronous USB Mode eliminates jitter caused by the PC or the USB interface

Asynchronous USB is a two-way communication method between a computer and an external USB device. In this method, the USB device is running as a master, and the PC is acting as a slave that delivers data only when requested by the master. The USB interface delivers data much faster than the USB device data output rate. When the data is delivered, it is stored in the external USB device memory buffer.

In the case of the exaU2I USB to I2S Interface, sound data is requested by the FPGA core and stored in the device FIFO memory buffer. The FPGA core makes sure that the buffer never gets empty during playback. Data from the buffer is streamed to I2S output. The precision of the timing of the output stream is determined only by the DAC oscillators and it is not degraded in any way by the PC clocks or by delays caused by the USB interface.
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exau2I USB to I2S Interface 384 kHz 32 bit


exaDevices delivers innovative and alternative solutions for highest-quality music playback to leading-edge DIY enthusiasts.  Our products are built and supported for personal hobby use only. Commercial use, duplication or distribution in any form is not permitted.

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