Sample Rate Conversion Results
Bit depth, whilst a SRC might accept 64 bit floating point, internally it might process at a much lower bit depth, this test checks different bit depths:
16 bit 24 bit 32 bit 32 bit float 64 bit floatSRC routines can introduce a delay at the start:
Calculated delay 0 samples
Spectrogram of a sweep 1 to 22kHz
A sine sweep from 1 to 22kHz the ideal plot is a single strong red line. Issues with aliasing effects or filter cutoff would show as extra lines. Noise would appear as dots across the plot (instead of a black background). [96kHz source resampled to 44kHz]
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Spectrogram of a sweep 1 to 22kHz (extended)
The source signal included a sine sweep all the way up to 44kHz, however when downsampled to 44kHz the highest frequency which can be represented is 22kHz. This plot would show if the sine above 22kHz is filtering down into the plot, there should be nothing plotted after 10 seconds. [96kHz source resampled to 44kHz]
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Aliasing
A 23kHz sine at -4 dBFS with a white noise floor of -150 dBFS over 30 seconds. The ideal plot is a continuous line touching the -150dB line, many SRC routines engage a gradual filter at 20kHz which would be visible on this plot. [96kHz source resampled to 44kHz]
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Intermodulation Harmonic Distortion
Two sine waves one at 64.59 Hz, -6 dBFS and the second at 6998 kHz, -18.0412 dBFS, which equals quarter the amplitude of the first sine. This test will highligh aliasing and dynamic range of processing. It will also show it dither has been applied, look for high frequency signals on the plot. [96kHz source resampled to 44kHz]
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Intermodulation Harmonic Distortion (difference)
The difference between the idea and measured signals from the Intermodulation Harmonic Distortion test. [96kHz source resampled to 44kHz]
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Impulse Frequency
A frequency response displaying leakage beyond the ideal frequency response.
Impulses are at sample positions n so that {n mod 320} is a permutation of {0, 1, 2, . . . , 319}. All fractional differences in sample positions between input and output signal are addressed exactly once. The output signal is upsampled to 14.112 MHz and the impulse responses are added to obtain a high resolution impulse response. [96kHz source resampled to 44kHz]
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Impulse Response
Displays the phase response, most SRC balance the response with pre and post ringing, personal preference might prefer a minimum phase response where there is no pre-ringing. [96kHz source resampled to 44kHz]
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Impulse Phase
The actual phase across the frequency range. [96kHz source resampled to 44kHz]
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Impulse Passband
Displays the SRC filter used close to the nyquist frequency. [96kHz source resampled to 44kHz]
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Impulse Transition
A zoomed plot of the nyquist frequency showing the filter response. [96kHz source resampled to 44kHz]
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Gapless Sine
A sine wave is split into two, both are resampled independantly. This plot is the two signals joined back together. The blue line is the generated true sinewave as would be played. Any value over +1 would clip. A large deviation off the ideal sine, would be audible during gapless playback. [96kHz source resampled to 44kHz]
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Gapless Sine (frequency plot)
A frequency plot of the gapless sine test. [96kHz source resampled to 44kHz]
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