What is DSD Audio? [How It Works, Play, DSD vs PCM]

What is DSD audio?

DSD (Direct Stream Digital) is an audiophile high-resolution audio format. It is a method of coding analog signal to digital form via 1-bit sigma-delta modulation.

Initially, the format was designed as an alternative to PCM (Pulse Code Modulaion), which is used in CD-audio, WAV, FLAC, mp3 and other formats.

An audio signal is an air oscillation (sound) converted to electrical oscillations via a microphone.

Digital form of an electrical audio signal is converted to a number sequence via analog-to-digital converter (ADC).

The sequence allows creating the electrical oscillations back via digital-to-analog converter (DAC).

 

Both DSD and PCM are a sequence of measured values (samples) of an audio signal's oscillation.

Sound/air oscillation each moment has a certain position (instant pressure level). The pressure level after the microphone is converted to an electrical oscillation.

The electrical oscillation at each moment has a certain position that refers to the air pressure level.
PCM consists of samples.  The sample is a measurement (number value) of an instant position of the electrical oscillation (voltage) at the moment of the measurement.

 

1 sample = 1 instant measurement of the voltage.

 

The voltage level at the microphone input is measured over equal time.

In sigma-delta modulation (a.k.a. DSD) each 1-bit sample shows a positive [1] or negative [0] altering of the pressure level relative its previous value.

And, as rule, DSD is explained as a saw (level grows or falls) between samples. But, it does not give an easy understanding of the basic DSD principle. Below we'll consider the easier explanation.

Read:

1. How DSD works...
2. About sound quality comparison with PCM...
3. DSD and PCM DAC.

 

DSD history

Audio CD optical disk (PCM modulation / PCM format) was one of the first digital formats. It was a source with low distortion and noise level comparing analog ones. I think, now many people forgot what is "real analog noise".

From CD (PCM) to SACD (DSD)

 

After CD, demands to sound quality improvements could be implemented by increasing sample rate or bit depth.

 

 

However, Sony and Phillips decided to use another kind of modulation - 1-bit sigma-delta modulation. At the first glance, using 1-bit is impossible, because such bit depth (resolution) causes a huge noise level. But, if high sample rates are used, noise energy may be pushed out of the audible frequency range (to ultrasound). That action is called "noise shaping".

Practically, 1-bit conception may be easier, than multi-bit, in a DAC implementation (read below).

When DSD music is converted to analog, ultrasound noise is filtered.

Medium, which contains 1-bit DSD audio stream was called SACD (Super Audio CD).

Look at DSD file infographic >

 

DSD specification

Direct Stream Digital is one of high-resolution audio formats to improve CD-audio dynamic range in the audible band.

 

How DSD works?

 

DSD encoding

As rule, DSD has been explained in the time domain: positive samples increase level, but negative decrease and analog filter smooth "saw" form of signal.

 

 

In DSD analog-to-digital converter (ADC), measuring the "saw" signal is compared with the input analog signal.

At the ADC output "1" is present. And measuring-signal level grows until it exceeds current level of the input analog signal.
It causes the output signal to switch to "0". And measuring signal begins to reduce level.

When the measuring signal level is a lesser input signal of the ADC, its output is switched to "1". And measuring signal grows until the exceeding the input signal.

Read how to sigma-delta modulator works...

 

 

Such an explanation causes difficulties in understanding what is actual difference between PCM and DSD and how to process DSD. Probably, it creates the myth about "native" DSD processing. About the processing read below in "DSD editing software" part.

Instead of the explanation, in the author's opinion, the easiest way to understand how to DSD works is its spectrum consideration.

To estimate DSD and PCM sound quality, the quantization-noise level is the main criterion.

There is an explanation, that DSD has a super high sample rate and, thus, super low bit depth 1-bit does not matter for noise.

But DSD 64 sampling rate (2,8 MHz = 44.1 kHz * 64), it is not enough to be better CD audio (see details).

To decrease noise level, noise shaping is used.

1-bit quantization-error (noise) energy has a significant level.

However, there is, so-called noise shaping of the spectrum is used. And quantization-error energy is re-distributed.

 

Noise shaping (NS) of 1-bit signal (spectrum)

 

The quantization-noise spectrum (at the left of the picture) has a level comparable with a musical signal. The sigma-delta modulator pushes a significant part of the energy from the low- to high-frequency range, out of the audible band (0 ... 20 kHz).

Noise shaping is implemented in a sigma-delta modulator (a.k.a. DSD modulator).

 

What is DSD decoding?

When the 1-bit record is played back, a low-frequency filter into a sigma-delta demodulator (a.k.a. DSD demodulator, DSD decoder) cut the noise.

 

DSD decoder (demodulator)

 

Spectrum error is noise level.

Therefore, DSD error into the audible range is comparable with the error of multi-bit pulse code modulation.

Also, sigma-delta modulation may have a multi-bit resolution. Read the details below and watch the video on this page.

 

 

Sample rates

The format use standard range of sample rates based on 44100 Hz:

• DSD64     = 44100 *   64   =   2'822'400 Hz =   2.8 MHz
• DSD128   = 44100 *  128  =   5'644'800 Hz =   5.6 MHz
• DSD256   = 44100 *  256  = 11'289'600 Hz = 11.3 MHz
• DSD512   = 44100 *  512  = 22'579'200 Hz = 22.6 MHz
• DSD1024 = 44100 * 1024 = 45'158'400 Hz = 45.2 MHz
• Etc.

Also, 48000-kHz base is possible. There are no technical limitations for the sample rate value. But hardware/software compatibility issues are very probable.

 

DSD and Nyquist Theorem

For the Nyquist theorem no difference between DSD and PCM:

the spectrum above [sample rate]/2 is
the same as the spectrum below [sample rate]/2
that flipped along the frequency axis.

 

Noise, Maximal Level and Overload Stability

When a sigma-delta modulator is designed, the engineers pay attention to two main parameters:

• the noise level in the audible range and
• tolerance to overload.

To solve these issues the engineers have:

• bit-depth,
• sample rate,
• noise shaping.

 

These parameters should be considered comprehensively.

 

Bit depth

Bit depth reduces the quantization error level as itself.

 

Noise shaping

NS "pushes" a significant part of the quantization error energy out of the audible range.

We can suggest that more energy may be pushed out of the range in the sigma-delta modulator. But it requires a steeper noise shaper.

 

Sample rate

We remember that quantization error is noise spectrum level.

A higher sample rate distributes the same noise energy into a wider band.

It reduces noise level or "quantization error" of DSD.

Also, wider band allows using sloper noise shaping.

 

 

In the left and right pictures, the squares of the noise energy figures are the same. But the figure, that is more expanded in the horizontal axis, gives a lesser noise level.

A higher sample rate allows for reducing the noise level in the audible frequency range. It allows for reducing noise shaping's steepness, that increases the overload tolerance of the modulator.

 

Resume

We can see that lowesr noise and higher stability to overload can be achieved in different ways.

As an example, better quality is noise shaping implementation matter for the same bit depth and sample rate. But, on the other hand, we can increase the sample rate and/or bit depth to decrease the error level for the same NS method. It allows improving of the audio quality.

 

 

DSD in figures

Pro audio modulators have noise level in audible frequency range for sample rates (read details):

• D64 about -125 ... -145 dB (comparable with PCM 24 bit)
• D128 about -165 dB (better than pulse code modulation 24 bit)
• D256 and higher about -170 ... -200 dB (comparable with PCM 32 bit)

Noise level in the audible frequency band almost don't depend on demodulator. But the noise should be maximally suppressed out of the band. Ultrasound noise can cause audible intermodulations distortions.

 

Read more about DSD vs DSF vs DFF >

 

DSD myths

Myth 1. DSD is better PCM and vice versa

No. Both format quality is defined by implementation in a device and software.

Also played back record is matter.

 

Myth 2. DSD has low noise level due to high sample rate

DSD's low noise level is a result of noise shaping.

 

Myth 3. Multi-bit DSD may be edited natively

DSD bit depth define noise level abilities. After DSD editing sigma-delta remodulation is need.\

Read more about DSD editing...

 

Myth 4. DSD editing with decimation dramatically degrade sound

The editing with decimation is implemented with low-frequency filter. The filter cause ringing audio.

However, no serious researches, that author know, studied the real impact of ringing to ears.

Also, the ringing depends on filter implementation.

So, currently, we don't know the exact answer to the question.

 

 

DSD vs FLAC, WAV, PCM comparison

 

 

Bit depth define audible noise. More bit depth is lesser noise.

At the picture, we can see that bit depth decreasing achieved through using only part of the full signal frequency band. Other words, if we want to reduce bit depth, we must increase the sample rate to keep the audible noise level.

Read details of the format comparison in the table: DSD vs WAV vs PCM vs FLAC vs DXD

Feature	DSD	FLAC	WAV	PCM	DXD
Coding	sigma-delta modulation	pulse code modulation	pulse code modulation	pulse code modulation	pulse code modulation
Sample rate	44100 x 64 x N	up to 384'000 Hz	up to 2'147'483'648 Hz	no limit	352 / 705 kHz
Bit depth	1 bit, sometimes multibit	16 ... 24 bit, 32 bit some applications integer only	16 ... 64 bit integer, 32/64 float point	multibit	24/32 bit
Band for audio signal	Low part of the band	Full band	Full band	Full band	Low part of the band
Medium	file, optical disk: SACD	file	file	file, digital tape, optical disk: CD, DVD

Note: WAV and FLAC are PCM implementations.

Read which is better DSD or FLAC (Infographic) >

Read more about audio file formats >

Direct Stream Digital (sigma-delta modulation) is like to pulse code modulation, but quantization error spectrum is shaped for decreasing noise into the audible range.

We can apply NS for usual PCM. But the difference here is band reserve for pushed noise out of audible frequency range.

 

 

PCM have lesser band reserve (above audible range) than sigma-delta modulation format, but pulse code modulation has higher bit depth.

Noise shaping for pulse-code modulation is implementation matter too, like sigma-delta modulation.

Therefore, no format advantages as itself. But implementation makes a difference.

Sigma-delta-modulation decoder (demodulator) is 2-position (1 / -1) voltage generator and low frequency filter. It is simpler than pulse-code-modulation hardware demodulator. Because pulse-code demodulator contains multi-voltage matrix or 1-bit decoder(s). So we have more abilities to make cheaper 1-bit DAC better than multibit one.

 

 

 

PCM vs DSD  sound quality

There is no univocal answer. There is several reasons:

• Quality of a record
• Mixing/re-mixing of the record (including quality of the processing)
• Playback software/hardware implementation
• DAC implementation.

These reasons trigger infinite discussions "what is better PCM or DSD".

Technically, DSD and PCM are incomparable. Even as single DSD/PCM compatible DAC is used for the test, the difference may be caused by different mixing/post-production of records, and the DAC uses the different circuits (see here).

General answer: "Each case is individual and depend on playback system implementation and listened to record".

 

DSD sound quality and other [brief F.A.Q.]

Are DSD downloads worth it? Are DSD files better?

There is no unambiguous answer to the question. It depends on record quality, your software and equipment.
 

Is DSD better than FLAC?

There is no answer. Theoretically, DSD has better potential than FLAC and other PCM formats. Recording, certain equipment makes sound quality. Read details...

 

How big are dsd files?

1 minute of DSD64 stereo is about 40 Mbytes.

See more...
 

Are all SACD DSD?

Yes. Hybrid SACD also may contain CD layer compatible with usual CD player.
 

What are DSD music files?

.dsf, .dff, .iso (sacd iso), flac/wav (DoP). Read details...
 

Why is DSD sounds better than PCM?

Sound is defined by record quality, your playback program and apparatus.
 

Why upsample to DSD?

Upsampling can optimize audio file resolution to optimal (minimal playback distortions) for your equipment. Read details >
 

Where to buy dsd music downloads?

Read DSD store site list here >
 

Where to download DSD music free?

Look at:

• free DSF audio files (up to DSD1024) >
• free DSD music download links >

Also read: DSD player F.A.Q., DSD converter F.A.Q., Myths

 

Where can I listen to DSD audio?

You can listen to .dsf (DSD audio files) here:

• free DSF music files >
• DSD audio downloads >

 

How do I listen to DSD files?

To listen to DSD files, you can download for free or buy special audio player software or hardware.

Read details...

 

 

PCM versus DSD ADC

 

Both kinds of DAC contains sigma-delta modulator. It converts the analog voltage to digital samples in a format like to DSD.

Before modulator analog filter ["DSD" sample rate]/2 is applied. Looks details here >

PCM ADC is more sophisticated and contains multibit modulator.

To reduce sample rate "multibit-DSD" signal should be filtered (low-frequency filter) and decimated (removing part of samples). The filter also eliminates shaped noise of "DSD signal".

Read more about PCM and DSD difference >

 

 

PCM versus DSD DAC

 

To easier providing of PCM DAC precision/linearity into this kind of DAC, a digital sigma-delta modulator is used. After it, sigma-delta de-modulator convert digital "DSD" to an analog signal.

In the general case, DSD DAC is simpler. It contains sigma-delta de-modulator only.

It is technically impossible to compare PCM and DSD DACs, because they use different processing / electrical circuits.

Read more what is DSD and PCM DACs and their comparison >

 

Is native DSD editing possible?

DSD editing is cutting, merging, gain altering, equalizing, etc. of file(s).

"Native editing" (without conversion to multibit and DSD re-modulation) is possible for cutting and merging DSD records only.

All other kinds of editing demand conversion to multi-bit values and re-modulation. In this case, loses of the editing in itself, comparable with PCM resampling.

Read details here >

 

 

File formats and compression method

1. Sigma-delta modulation is applied on optical disks SACD (Super Audio CD).
2. The modulation contains into files DSF, DFF, SACD ISO (SACD disk image).
3. WAV, FLAC as DoP (DSD over PCM) container.

SACD disc may be losslessly converted to SACD ISO [1], [2], [3].

SACD ISO image may be extracted to DSF and DFF files. Lossless extraction may be applied.

Read more about DSF and DFF.

1-bit audio files (DSF, DFF, SACD ISO) and disks may be either uncompressed or compressed with DST method.

DoP is an open protocol that allows pack 1-bit audio as multibit for compatibility with software and hardware [4]. DoP cannot be played as usual pulse-code modulation.

 

Also, 1-bit audio may be streamed via a network.

Uncompressed DSD64 demands capacity 2.7 Mbit/sec = 44100 Hz * 64 / 1024 / 1024.

 

 

Also, index file CUE + DSF/DFF audio files may contain 1-bit album.

Look at "DSD files" infographic >

 

How to play DSD files?

DSD may be played at a mobile phone, portable players, music servers, SACD-players and other devices.

Some device can support native DSD feed of DSD DACs. Other ones demand pre-conversion to PCM or make conversion "on fly".

Sound quality is a complex matter. Read details about the resolution of audio files and sound quality.

Read details how to open, play DSD on Mac, Windows, iOS, Android, Linux: player list >

Read how to download DSD music and how to get free DSD files here >

 

DSD audio players (hardware and software) can playback all or some of the 1-bit file formats.

1-bit files may be played back directly on DSD DAC/player or converted to PCM "on fly" to playback to PCM DAC/player. About SACD conversion read more here

1-bit playback may be performed via special ASIO-driver under Windows, including DoP (DSD over PCM) digital audio packing format (example).

SACD optical disks may be played back at hardware player. Author knows nothing about available SACD-drives for consumer computers to playback/record SACD optical disks.

A stereo player may downmix multichannel to stereo. As alternative multichannel files may be pre-converted to stereo. It allows saving space on the hard disk of an audio player. Downmix is lossy audio processing. Its quality defined by an implementation.

Read more about the players here > and here >

Read DSD player software list >

 

DSD player [brief F.A.Q.]

How do you play DSD audio?

To play DSD audio, use DSD audio players...

 

Can iTunes play DSD files?

Yes with additional software. Read details here
 

Can foobar2000 play DSD?

Yes. Read details here...
 

Can VLC play DSD files?

As the author know, not. Read details...
 

Can Jriver play DSD files?

Yes. Look at the player list...
 

Can Vox play DSD?

As the author know, Vox convert .dsf and .dff files to PCM on fly without native DSD playback.
 

Can Plex play DSD?

As author know, Plex can playback DSF. Details
 

Can Musicbee play DSD?

As the author know, yes. Details
 

Can Amarra play DSD?

Yes
 

Can Audirvana play DSD?

Yes
 

Can iPhone play DSD files?

Yes. Look at the player list
 

Can iPod play DSD?

As the author knows, there is conversion to PCM files is necessary.
 

Can Mac play DSD?

Yes, Mac can play DSD...

 

Also read: DSD converter F.A.Q., DSD F.A.Q., Myths

 

 

How to convert DSD?

Read details how to convert DSD on Mac, Windows and other platforms: converter list >

How to create, edit DSD files read here >

How to rip DSD from SACD (to SACD ISO) read here

 

DSD converter is software that can perform (depend on implementation):

• conversion DSD to PCM,
• conversion PCM to DSD,
• extracting SACD ISO to DSD,
• extracting SACD ISO to PCM,
• resampling 1-bit audio,
• altering volume,
• volume normalization,
• click suppressing on track borders,
• other processing.

Read how to works the converters here >

 

Converter list (convert some or all of DSD files [DSF, DFF, SACD ISO])

• AuI ConverteR 48x44
• Audiogate
• dff2dsf
• iso2dsd
• JRiver
• Foobar2000
• TASCAM Hi-Res Editor
• See more converters...

 

DSD converter [brief F.A.Q.]

How to convert to playback at iTunes?

Convert DSF/DFF/SACD ISO to *m4a (ALAC, Apple Lossless). Read also (conversion DSF/DFF/SACD ISO to ALAC(m4a) is same) DSF to FLAC, DFF to FLAC, ISO to FLAC.
 

Conversion DSD to PCM degrade sound?

Conversion with processing audio (including DSD to PCM) adds distortions. But final distortions is a matter of used playback distortions. Read details here
 

Conversion DSF to DFF and back is lossless?

It may be lossless when audio converter doesn't process audio stuff (resampling and other) in conversion.
 

Do various DSD converters have different sound quality?

Yes. There is noise level, frequency/phase distortions and tolerance to overload are estimated. Read details here.

 

Also read: DSD player F.A.Q., DSD F.A.Q., Myths

 

DSD editing software

Read main article about DSD editing >

DSD editing is sophisticated issue due modulation noise. Non-linear processing can cause audible intermodulation distortions by ultrasound noise.

Currently no information, that is known for the author, about "native" 1-bit processing (example: gain altering, resampling, etc.) without conversion 1-bit to multibit and back. Except, merging/dividing the audio file.

 

 

 

PCM here may be considered as "multibit DSD". Pulse code modulation is not obligatory to mean "24 bit / 352 kHz" or so on. Author recommends use 32- or 64-bit float point bit depth. This PCM contains high frequency modulation noise. But for conversion, this "multibit DSD" to 1-bit need re-modulation with NS.

Losses of editing with 1-bit/multibit conversion are comparable with resampling.

Recording studios may distribute 1-bit records without editing.

 

What is DXD?

DXD  is PCM (as rule "24 bit / 352 kHz" or so on) with high sample rate and bit depth and legacy DSD noise. However, the noise can cause audible intermodulation distortions. Before non-linear processing, the high frequency noise cutting is recommended.

 

Is DXD better than DSD?

DXD is PCM with noise hump in high frequencies. DSD DAC is simpler than PCM one in theory. From DAC point of view, DSD is ideal format. But, actual result is refer to digital-to-analog converter model. Read details here...

 

What is DoP (DSD over PCM)?

There are compatibility and other issues of tranfer 1-bit and multibit audio data from computer to PCM or DSD DAC.

All audio interfaces (USB, in instance) are designed for multibit data. And 1-bit data packing into ordinary multibit value was suggested.

DoP (DSD over PCM) is a format providing compatibility with some DSD hardware (USB DAC, for example). The format allows packing 1-bit DSD data in usual multi-bit words (like PCM).

These multi-bit words are transferred as usual PCM. Upper bits of the multi-bit word contain special "DSD over PCM" marker code.

DoP receiver should recognize the marker code and interpret lower part of the multi-bit word as raw DSD bits.

DoP format may be stored into usual lossless PCM file: WAV, FLAC, AIFF.

DoP coding may be chosen in audio player settings.

 

DoP specification

 

DSD audio samples

Audio samples may be downloaded here:

1. Demo tracks #1
2. Demo tracks #2
3. Test simple signals

Check more DSD downloading resources >

 

Conclusions

1. DSD (SACD) appear as improvement of CD-audio.
2. Sound quality is not DSD/PCM format matter, but depend on implementation and quality of a musical record.
3. "Native" DSD editing is possible for limited cases. For other cases, the own editing loses is comparable with PCM resampling.

Read the detailed article about DSD >

DSD is 1-bit audio data (sigma-delta modulation) format for hi-fi audio.

For the same sample rate and bit depth, the format may have different quality, that depends on implementation.

DSD digital-to-analog converter is simpler than the PCM one. It allows getting the better quality simpler way.

DSD may be edited via 1-bit to multibit and back conversion. The edition is lossy, except merging/dividing.

Read more about 1-bit format

1. DSD vs. PCM. Real competitors? >
2. DSF vs PCM. What is common base? >
3. DSD Decoder Audio >
4. How work sigma delta modulation in audio >
5. DSD Converter of Audio Files: What Inside? >

Frequently Asked Questions [general]

What means DSD?

DSD has multiple meanings. In audio, DSD means Direct Stream Digital format. Read details...

 

What is DSD audio format?

DSD audio format is way to store sound recordings into computer files. This format is intenged for music lovers.

Read more...

 

Is DSD the same as SACD?

SACD is optical disk that contains digital audio data in DSD format. Read more...

 

What is DSD in DoP format?

DoP format is protocol for audio unit interaction. The protocol contains DSD audio data. Read details...

 

How common is DSD?

DSD is well known audiophile format. It allows achieving high sound quality and often used for classic and jazz music recording.

Read more...

 

 

What is the best audio quality?

The best audio quality has 2 definitions:

• most low distortions, or
• most"nice" sound.

When correct scientific approach is applied, both definitions may be used.

Read more...

 

 

Which is better PCM or DSD?

Both DSD and PCM have advantages and disadvantages. Its discussing is theoretical rather. Read details here...

 

Is DSD the best audio format?

No. DSD is alternative audio format to PCM one. Read more information here...

 

What is the highest quality audio file?

DSD and PCM lossless files are the highest-quality audio files. Read details here...

 

Is DSD better than 24 bit?

DSD and PCM bit depth may be compared by quantization noise level in the audible band. However, equipment and software play big role there. See approximate comparison DSD and PCM bit depth...

 

Is CD better than FLAC?

FLAC format supports high-resolution audio. It give technical abilities to better sound quality.

Read details here...

 

Can you stream DSD?

DSD streaming service you can find here...

 

What is DSD and FLAC? What is DSD vs FLAC?

DSD is family of high-resolution audio formats. FLAC is one of PCM audio formats.

Read details...

 

Is DSD better than mp3?

DSD is lossless audiophile format. mp3 is lossy PCM format. Also, mp3 is hi-fi format at high bitrates.

Technically, DSD is better than mp3.

Read more...

 

How do I play a DSD file?

You can play DSD files with special hardware and/or software.

Read details...

 

How can I play DSD on my computer?

DSD music can be played on a computer via DSD player software...

 

What do you need to play DSD?

To play DSD you can use DSD audio player or iOS/Android mobile phone.

Also, you can play DSD on computer with ordinary PCM audio card.

It's possible either:

• use playback software capable to inline DSD to PCM conversion, or
• convert DSD to PCM audio file with high sound quality.

If you have external DAC (DSD or PCM), you can connect it to the computer or player device.

Read details...

 

Can you play DSD without a DAC?

DAC is required thing to playback music. However, you can play DSD at traditional PCM DAC.

You can:

• use player, that is capable to convert DSD to PCM inline, or
• preconvert DSD to PCM with high sound quality.

 

What is DSD over PCM?

DSD over PCM is packing method of 1-bit audio to ordinary PCM format.

Read details...

 

Can Windows play DSD?

You can play DSD music under Windows. Read more...

 

Does VLC play DSD?

As the author know, VLC player software can't play DSD files. Read the discussion...

 

Does Spotify have DSD?

Spotify doesn't support DSD audio. Read about DSD streaming service...

 

Does Qobuz stream DSD?

Qobuz does not providing DSD streaming. Check out DSD streaming service...

 

Where can I get DSD music files?

Here you can look for DSD music files:

• link #1...
• link #2...

 

 

Author: Yuri Korzunov,
Audiophile Inventory's developer

November 23, 2022 updated  | since December 25, 2017