| 8. The X-Fi Hybrid Sample Rate Converter Quality |
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The expressed goal of the X-Fi sample rate converters is to provide audio quality limited only by the inherent analog noise of the analog-to-digital converters, while using many series and parallel sample rate converters.
The measured THD+N performance of X-Fi converting 44.1 kHz to 48 kHz is shown in figure 6. A full level sine wave at nearly any frequency produces distortion below -136dB (as measured by an Audio Precision distortion analyzer). The pass band ripple for this example is ±0.00025dB.
Figure 6 - Measured THD+N performance
The X-Fi sample rate converter supports a wide range of pitch shifts from zero to three octaves. The flexible audio routing of the X-Fi architecture means that audio can be taken through two sample rate converters in series to extend the pitch shift range even more.
Even with the advanced X-Fi hybrid SRC architecture this quality level doesn't come easy. The special purpose sample rate converter engine in X-Fi performs over 7 billion arithmetic operations per second.
9. Summary
Based on a novel architecture, the Creative X-Fi sample rate converters provide unprecedented audio fidelity, producing highly accurate 3D virtual environments and flawless synthesized music. Because of their extremely low ripple and exceptional THD+N performance, they form transparent digital patch cords, eliminating the headaches of sample rate synchronization. The Creative X-Fi audio processor provides flexible signal routing and the capability to operate at different sample rates to allow "bit-accurate" recordings when possible. When sample rate conversion is needed the user can simply listen to and record audio in an intuitive and creative way, thereby embracing the benefits of sample rate conversion and simultaneously enjoying phenomenal sound quality!
