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DSF File Format Audio [ .dsf File Extension - open, convert, edit ]

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Audio Basis - educational articles

DSF file (.dsf extension) is DSD (1-bit audio) file format for ♫ music ♫ and other sound stuff. Read about audio quality, conversion, playback, editing issues, data structure, etc.
It is one of audiophile file formats. DSF format audio support stereo and multichannel music.

What is DSF file format

DSF file features >        DSF file quality issues (DSD vs. PCM) >       DSF vs. DFF >

How to edit DSF file >       DSF file converters >       DSF file players >      Metadata editor >

 

 

 


DSF file features

DSF file features

  •  
  • DSF file format support sample rates:

    2.8 MHz (DSD64, D64, CD sample rate 44100 Hz x 64),
    5.6 MHz (DSD128, D128),
    11.2 MHz (DSD256, D256),
    22.5 MHz (DSD512, D512).
    45.2 MHz
    (DSD1024, D1024),
    etc.

  • Read details below and read more about sample rates.
  • Bit-depth: 1 bit / 8 bit (see below bit number discussion) [1]
  • Modulation type: sigma delta modulation (a.k.a. DSD)
  • Channel number: 1 ... 6 (see below)
  • Metadata (song, album names, year, performer, artwork, etc.): ID3v2 format

 

More details

Sample rate DSD calculated as 44100 Hz x K (coefficient: 64=2^6, 128=2^7, 256=2^8, 512=2^9, 1024=2^10, etc.)

Example: 44100 Hz * 64 = 2 822 400 Hz = 2.8 MHz

Also DSD sample rate may be based on 48000 Hz [2] (non-standard range). However the range can be implemented in DSF files too.

 

DSF audio file structure is:

  1. Header
  2. Audio data
  3. Metadata block

The audio data divided by blocks. Last block may be filled partially. Wrong values into header can cause reading of unfilled place of last block. In some cases it can cause click at end of the DSF file.

Channel number is integer value. So channel number more 6 may be supported too. DSF have specified channel types and channel position in file structure from "mono", "stereo" to "5.1". However, the channel variable have reserved unspecified range for custom types. Of course, using custom types may cause issues with different software and hardware.

 

 


DSF file format quality issues (DSD vs. PCM)

DSD vs. PCM

If we want to compare quality DSD (sigma delta modulation) and PCM (pulse code modulation), we consider ear tests. As example, dsf vs flac or other. However, not all so simple.

First, mathematical models and hardware implementation should be separated.

Sound file is pure mathematical implementation of theoretical model of sigma delta modulation. As final criteria here quantization noise level (QNL) is considered. The level depend on frequency.

Hardware implementation distorted the mathematical model by non-linearity of real electronic components, their frequency characteristics, electrical hum, electromagnetic interference.

Software implementations have different resampling, modulation and demodulation algorithms, that can cause different features and sound.

 


Read other articles about audio issues

 


 

Abbreviations

BD - bit depth

NS - noise shaping

PCM - pulse code modulation

QE - quantization error

QNL - quantization noise level

SDM - sigma delta nodulation

SR - sample rate

UMB - useful music band

 

 

Bit depth (BD) and sample rate (SR)

DSD bit depth may have any positive integer value theoretically. Bit depth and sample rate may be considered in complex only. Both these values impact to quantization noise level:

higher BD or SR => lower QNL.

Higher bit depth have lower quantization error (QE), and, therefore, QNL.

Higher sample rate provide wider signal band and the noise energy distributed in wider band. So QNL is reduced.

Quantization error and QNL are different things. QNL depend on QE. But for same QE, QNL may be different. At different frequencies, as example.

 

Noise shaping (NS)

To reduce the quantization error energy at useful music band (UMB), sigma delta modulator "pushes" the energy to high frequency range. It is . Band reserve shall be provided for NS. It reduce UMB into fixed SR/2.

There are ways of expanding signal band:

  • more steep the shaping;
  • more high sampling frequency value.

Steeper NS can cause modulator stability breakdown in overload (read below).

Higher SR is larger file size, more computing resource and electrical energy consuming.

Can we reduce bit depth and keep quality?

Yes. To keep UMB level noise, noise shaping is applied. Quantization error energy from low frequency range "pushed" into high frequency area. However we lose part of high frequency band in full range [sample rate / 2].

NS can cause audible artifacts at some apparatus due non-linear distortions (intermodulations).

 

Overload

Sigma-delta modulator is sensitive to overloads. After overloading it may go out stable condition and don't return to stable state until forced restarting. Read more below.

For avoiding overload DSF records may have 6 dB headroom for guaranteed avoiding of overload. For demodulator (DAC) it have no sense. So signal may be increased up to several dB. Such function may be called called as auto level normalization.

Auto level normalization

Auto level normalization of DSF audio file

 

 

Quantization

DSD QNL depend on sigma delta modulator and demodulator implementation.

Generally, DSD 64 have the higher QNL than DSD 128, DSD 256, DSD 512. Because DSD64 have lesser noise band reserve than higher sample rates. The band reserve placed at high frequency range. The range intended to pushing noise energy. Lesser sample rate - lesser band reserve - lesser noise energy may be pushed without delta sigma modulator's stability breakdown.

In this part the article we will consider noise level in useful music band. Above UMB noise-shaped level grow significantly.

In the table below trends bounding with DSF discretization frequency increasing. It was important to remember, that the trends depend on modulator and demodulator implementation.

DSF sample rate trends
  Noise floor in useful musical band Useful musical band width
CD about -100...120 dB 20 kHz
DSD64 about PCM 24 bit about 20 … 22 kHz
DSD128 lower DSD64 wider DSD64
DSD256 about PCM 32 bit wider DSD256
DSD1024   about 100 kHz

 

 

Conclusion

From point of view mathematical model DSD and PCM have differences:

  • Noise level,
  • Transmitted band.

I.e. no difference between PCM and DSD, between kinds of pulse code and sigma delta modulations when they are considered as formats.
Because format is abstract mathematical model, that give potential abilities for implementation in the real life.

These features may be implemented differently as hardware and software.

It is developer's choice what increase to reduce noise: sample rate or bit depth.

I.e. instead BD increasing, designer can increase SR, and contrary. Or noise shaping can be apply instead.

Thus no univocal advantages of PCM or DSD as format (mathematical abstraction).
But implementations may have advantages.

 

 


How to edit DSF file

How to edit DSF

 

To the author's knowledge, there is no information (patents, publications), what DSF file may be edited "natively" (straight in 1-bit format) without conversion to PCM format and back to DSF. Here PCM has more wide meaning than WAV file in 24 or 32 bit / 352 kHz.

Editing DSF audio file

Editing DSF file audio

 

As example, DSF format may be:

- converted to PCM 352 or 705 kHz, 32-/64-bit float point,

- edited in usual audio editor, and

- converted back to DSF.

It is lossy transformation. But, professional editing software have loses comparable with resampling.

There is ringing audio matter. However, the author still don't know about exact researches of the ringing impact to ear perception.

Advice: To minimize the loses, use conversions DSF to PCM and PCM to DSF once.

 

Audio data may be cut by block without changing of binary content.

 

Conclusion

To edit .DSF file format need convert DSD to PCM and back. Quality of conversion resembles resampling quality.

 

 


DSF vs. DFF

DSF vs. DFF

DSF file format's binary audio content may be exactly copied into DFF.

However DFF have no standard storing metadata way.

DFF consists of blocks. It allow to insert block with metadata. However, DFF software should recognize metadata block.

Warning: some software can convert DSF to DFF or back with modifications (non-bit-perfect mode). So checking of every converting tool is recommended.

 

 


DSF file converters

DSF converters

Distinguished by noise level, aliases, processing, service functionality and price.

 

Conversion may be applied to adaptation of resolution and file format to used software (audio player or editor) or hardware (music server, computer, DAC, portable player, mobile phone, etc.).

Converter DSF audio files for audio devices variety

Converter DSF audio files for audio devices variety

Conversion DSF to PCM and PCM to DSF applied with quality losses.

Conversion of audio file's formats don't improve quality of the audio file as itself.

But some playback modes/resolutions for an audio devices (sample rate + bit depth) may cause lesser distortions during playback. Thus conversion of files to such resolutions (sample rate + bit depth) can improve playback sound quality (lesser noise/distortions).

As rule, non-real-time conversion (via audio file converter) is not restricted by real-time performance of software / hardware and there possible applying more exact digital signal processing.

With one time offline conversion of DSF audio file before playback, we can save electric energy, that consumed for "heavy" conversion processing during each playback seance.

 

 

 


DSF file players

Music players DSF

DSF may be played back at:

  • computer (software player),
  • music server,
  • portable audio player,
  • mobile phone (software audio player),
  • car audio.

 

DSF and DFF files can playback with:

 

For "native" playback DSF need DSD DAC. 

For playback DSF at PCM DAC need conversion DSF to PCM.

Playback DSF audio file

Playback DSF audio file

 

How open DSF with software audio players described in the article: [How to open DSF audio files] >.

DSF audio player software:

  • Foobar 2000 (Win)
  • Audirvana (Mac)
  • JRiver (Win, Mac)
  • Amarra (Win, Mac)

 


Metadata editor DSF

Metadata editor

 

DSF contains metadata in ID3-standard.

DSF metadata editors

 

 


Read more about DSF
  1. How open DSF files audio >
  2. How to playback DSF files in Foobar2000 [Step-by-Step] >
  3. DSD vs DSF vs DFF Files Audio >
  4. DSF to FLAC converter audio >
  5. DSF to PCM converter >
  6. DSF File Converter >
  7. DSF oversampling. D64 vs. D128 >
  8. Audio Converter DSF to FLAC >
  9. How Impact to Audio Quality of PCM to DSF Conversion. 1-bit DSF vs. PCM >
     

Read other site parts

  1. DFF File Format Audio. DFF File Extension >
  2. FLAC file format >
  3. Audio converter >
  4. DSF DFF WAV FLAC AIFF mp3 ... converter >
  5. ISO converter [1-bit audio] >
  6. CD ripper audio >
  7. Metadata editor >
  8. Tutorials >
  9. Audio Basis - educational program >

 

 


 

References

[1] DSF file format specification

[2] DSD technology review

 

 


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