Pure Vinyl™ Sample Rate Converter

Pure Vinyl Sample Rate Converter

Pure Vinyl Sample Rate Converter (SRC): Signal Integrity / Purity Test

A perfect result is a single spectrogram trace with no spurious generated tones (completely black background), and little or no "V" reflection (aliasing) after the sweep passes 22.05 kHz in the original 96 kHz file (this happens at about 19.5 seconds on the spectrogram display). Anything else represents garbage and distortion added to the signal.

Measurement Conditions:

Input Sample Rate 96 kHz, 24 bit resolution
Swept Sine Wave File, 20 Hz to 48 kHz, -1 dB vs. Digital Full Scale
Sample Rate Conversion to 44.1 kHz, 24 bit
Spectrogram amplitude scale -160 dB to 0 dB vs. Digital Full Scale
Test file duration 46 seconds (only the treble part of the analysis is shown)
Conversion time measured on 2.1 GHz G5 iMac

Sample Rate Conversion Processing Time: 15 seconds

Compare above with the other traces shown here, and with sample rate converters measured here: http://src.infinitewave.ca/ (The frequency axis is reversed in measurements at that website, where high frequencies are displayed at the top of the spectrogram, the opposite of what's conventionally used for spectrogram or "voice print" displays.)

Below are additional results, from testing the sample rate converters of some other Macintosh audio applications, using the same 96 kHz input file, resampling to 44.1 kHz, 24 bit, as above. Also note the conversion time when comparing the sample rate converters. If a choice of "highest" / "best" quality SRC was provided, the highest quality was used. Note that two of the applications apparently use the same SRC algorithm:

Sample Rate Conversion Processing Time: 268 seconds

Sample Rate Conversion Processing Time: 24 seconds

Sample Rate Conversion Processing Time: 21 seconds

Sample Rate Conversion Processing Time: 5 seconds

Sample Rate Conversion Processing Time: 5 seconds

Sample Rate Conversion Processing Time: 250 seconds

Sample Rate Conversion Processing Time: 16 seconds