Audio samples are processed with the highest precision (64-bit float) and with the most accurate algorithms for the best audio quality.
Audio Engine uses very high quality SoX resampler. See information about the SoX resampler at SoX - Sound eXchange | Resampling.
EZ CD Audio Converter uses SoX resampler in all sample rate conversions. SoX resampler is also used with the Opus and MP3 encoders that usually use their own built-in resamplers. SoX resampler provides better audio quality than the built-in resamplers.
20-bit precision 95% passband (SOXR_20_BITQ)
High Quality mode has perfect audio quality when the output is CD-quality; 16-bit lossless or lossy format (MP3, AAC, Opus, Vorbis, ...), even when the original input bit depth is higher than 16-bit.
32-bit precision 95% passband (SOXR_32_BITQ)
Very High Quality mode has very good audio quality for high resolution output (>=24bit). It is safe to use Very High Quality also for 16-bit conversions, but it is slower than High Quality.
32-bit precision 99% passband (SOXR_32_BITQ | SOXR_STEEP_FILTER)
Ultra High Quality has the best audio quality. It is safe to use Ultra High Quality for all conversions, but it is slower than other modes.
If EZ CD Audio Converter needs to reduce the bit depth, then there will be 'rounding off' errors. If simple 'rounding' is done by simply taking each sample value and converting it to the nearest (24-bit, 16-bit, or 8-bit) value, then the 'steppiness' in the output may be audible, particularly with extremely quiet sounds. To avoid this, EZ CD Audio Converter can apply 'dither' in the conversion - this is often likened to "anti-aliasing" in graphics which is used to smooth the steppiness of curves. Rather than always rounding the values to the nearest value, dithering will apply a degree of randomness to the rounding off so as to prevent causing steps.
Dither will be applied (when enabled from the Settings) if converting from ORIGINAL source of
· 64-bit, 64-bit float, 32-bit, 32-bit float to 24-bit
· 64-bit, 64-bit float, 32-bit, 32-bit float, 24-bit to 16-bit
· 64-bit, 64-bit float, 32-bit, 32-bit float, 24-bit, 16-bit to 8-bit
Noise-shaped dither has a higher peak amplitude than other forms of dither, but the noise is concentrated in the very high frequency range where it is less audible. Noise-shaped dither implements Lipshitz minimally audible noise shaping.
Triangular dither produces a lower peak amplitude of noise than Noise-shaped, but the noise is concentrated less in the higher frequencies.
Rectangular dither produces a similar noise amplitude as triangular, but with very small amounts of randomization. The frequency distribution is fairly even, such that it approximates white noise. Unlike the other two forms of dither, rectangular does not add noise to absolute silence.