DSF oversampling. D64 vs. D128. Real advantage of sound?

Educational line

Many times people ask me about necessity of oversampling DSF (1-bit HD audio files) from D64 to D128. This is a complex issue. Many links in viewed chain. But we try to watch possible advantages of D64 to D128 conversion. At least theoretically for almost ideal conditions.

How compared D64 and D128

1. As source file took WAV-file (sample rate 176 kHz) contains sweep sine 0 ... 20 kHz.

2. Source WAV was converted to files DSF D64 (further DSF-D64) and DSF D128 (further DSF-D128) via AuI ConverteR 48x44.

3. File DSF-D64 was converted to file DSF D128 (further DSF-D64-D128) via AuI ConverteR 48x44.

4. Files DSF-D64, DSF-D128 and DSF-D64-D128 was converted to WAV files for comparing in spectrum analizer.

Attention: All pictures showed below depend on algoritms of spectrum analizer (FFT length, applied window, overlap, ...), encoding and decoding PCM to DSF and DSF to PCM.

For experiments you can download AuI ConverteR 48x44 FREE

 

Comparing

Here showed cuts by level of sonogramm (frequency-time spectrogramm). Vertical axis is frequency, horizontal axis is time.

Level -4 dB. Peak of sweep sine signal lower this level.

Original PCM                  DSF-D64                        DSF-D64-D128              DSF-D128

 

Level -5 dB. Here we watch sweep sine signal (green arrow point it out). Its frequency grow with time.

Original PCM                  DSF-D64                        DSF-D64-D128              DSF-D128

 

Level -132 dB. Here we watch noise (red arrow point it out) at DSF-D64. Other files while haven't noise.

Original PCM                  DSF-D64                        DSF-D64-D128              DSF-D128

 

Level -137 dB. First noise peaks appear at DSF-D64-D128. DSF-D128 has pure sweep sine as before.

Original PCM                  DSF-D64                        DSF-D64-D128              DSF-D128

 

Level -140 dB. DSF-D128 has pure sweep sine as before.

Original PCM                  DSF-D64                        DSF-D64-D128              DSF-D128

 

Level -164 dB. DSF-D128 has first noise peaks. DSF-D64-D128 almost hidden under noise. DSF-D64 hidden.

Original PCM                  DSF-D64                       DSF-D64-D128              DSF-D128

 

Rapidly

Noise floor of DSF-D64 begin at -132 dB, DSF-D64-D128 at -137 dB, DSF-D128 at -164 dB.

 

Resume

1. Noise floor of DSF-D128 better DSF-D64 converted to D128 at 27 dB.

2. Noise floor of DSF-D128 better DSF-D64 at 32 dB.

3. Noise floor of DSF-D64 converted to D128 better original DSF-D64 at 5 dB.

 

Thus

If we convert PCM to DSF, using of D128 give us gain of useful loudness range 32 dB.

If we convert DSF-D64 to DSF-D128 we have gain of useful loudness range 5 dB.

These values depend on audio conversion software and hardware used for playback and methods of measurement.

For DSF we get improvement of noise level when converting D64 to D128



 

 

Update: experiment was executed with old version of AuI ConverteR. Modified D64 modulator work better and currently not difference between D64 and D64, upsampled to D128.

 

 

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1. DSF file format. DSF extension >
2. How open DSF files audio >
3. How to playback DSF files in Foobar2000 [Step-by-Step] >
4. DSD vs DSF vs DFF Files Audio >
5. DSF to PCM converter >
6. DSF File Converter >
7. Audio Converter DSF to FLAC >
8. How Impact to Audio Quality of PCM to DSF Conversion. 1-bit DSF vs. PCM >

 

 

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