Omnifi DMS1 Wi-Fi Media Receiver Page 3

Tech Notes

In sharp contrast to some similar devices we've tested, the Omnifi did well when fed the highest-quality WMA and MP3 files we could muster - our standard suite of CD player test tones encoded by the codecs supplied with Adobe Audition 1.0 (formerly Cool Edit Pro 2.1), a professional-grade audio editing program. For example, with "98-quality" variable-bit-rate WMA files, frequency response varied only +0.3, -0.2 dB from 20 Hz to 20 kHz, and the noise level was approximately that of a very good CD player (-75.6 dB).

A special tone had to be used in getting the noise figure, since WMA turns our usual dither signal into "digital black" (an all-zero signal). WMA encoding artifacts also led to higher-than-CD distortion numbers. Similar behavior attended MP3 playback. In all cases the ultimate sound quality is determined by the encoding, not the Omnifi's performance. It's therefore too bad that it could not decode files in the ultra-pure WMA 9 lossless format ("100-quality") or uncompressed Windows WAV files, even though the Ethernet interface should, theoretically, support the higher data rates these would require. It's also too bad that the encoding options offered by the Omnifi's SimpleCenter software do not include variable-bit-rate encoding for either MP3 or WMA ripping, which would have offered the best combination of quality and encoded file size.

-David Ranada

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