X-Fi S-SRC (Super Sample-Rate Conversion)

The general audio community as a whole has seen sample rate conversion as a necessary evil that should only be used when absolutely necessary. Creative's ATC Engineers do not believe that this should be the case. Sample rate conversion plays an important role in digital connectivity, 3D audio modeling, music synthesis and the ability to play and mix multiple sounds recorded at differing sample rates. However some users still treat sample-rate conversion with suspicion at best and disdain at worst! So with X-Fi we set out to turn a perceived negative into a very robust must-have feature. The X-Fi Sample Rate Converter engine is incredibly powerful at over 7,000 MIPS equivalent processing power and has a new and unique hybrid architecture that produces outstanding audio quality. In fact the quality of the sample rate conversion is so high that it is effectively transparent. An audio clip could actually be converted many times with no detectable degradation.

For instance in actual tests we took a 997Hz tone recorded at 44.1kHz and sample rate converted it to 48kHz. The results are literally astounding as they showed a THD+N of better than -135dB, with as little as +/- 0.00025dB of pass-band ripple! To put this into perspective, this is significantly higher quality than even the best available DACs today can reproduce, in essence the DACs would generate more noise during normal operation than our new SRC will add to the signal!

Despite the transparent sample-rate conversion qualities of X-Fi we recognized that there would still be applications that don't require sample rate conversion of any kind and therefore the flexible routing architecture of X-Fi allows the sample rate conversion to be bypassed when not needed. Advanced caching technology is also used for low latency and excellent PCI bandwidth utilization, and the architecture is optimized such that there is near zero device driver overhead to control the sample rate converters.

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