What Is DSD Audio? | Read Quick Explanation >

DSD (Direct Stream Digital) is audiophile high resolution audio format. This article may open new unclear details for you. Read below essential points, that explains how DSD works, compare with PCM sound quality, what is DoP, what inside DSD and PCM DAC. If you want more details, also read the detailed educational article "What is DSD music file format?"

DSD history >   How DSD works >   DSD and Nyquist Theorem >   DSD vs FLAC, WAV, PCM >   PCM versus DSD DAC >   DSD vs PCM sound quality >   Is native DSD editing possible? >   DSD audio players, converters >   What is DoP (DSD over PCM)? >   Conclusions >   DSD vs PCM >   DSD download sites >

Audio CD optical disk (PCM modulation / PCM format) was one of first digital formats. It was 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 improving could be implemented by increasing sample rate or bit depth.

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

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

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

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

Look at DSD file infographic >

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

In the author opinion, easiest way to explain DSD is looking to spectrum. To estimate DSD sound quality, quantization noise level is main criteria.

There is explanation, that DSD have super high sample rate and super low bit depth 1-bit is not matter for noise.

But for DSD 64 it is not enough to be better CD audio.

To decrease noise level, noise shaping is used. Read details here >

For Nyquist theorem no difference between DSD and PCM: spectrum above [sample rate]/2 is the same to the spectrum below [sample rate]/2 and flipped by frequency axis.

What is DSD? Quick explanation

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 full signal frequency band. Other words, if we want to reduce bit depth, we must increase sample rate to keep audible noise level.

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

Note: WAV and FLAC are PCM implementations.

Read which is better DSD or FLAC (Infographic) >

PCM vs DSD DAC

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

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

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

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

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 an infinite discussions "what is better PCM or DSD".

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

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

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

• Are DSD downloads worth it? Are DSD files better?
      There is no unambigous answer to the question. It depend on record quality, your software and equipment.
   
• How big are dsd files?
      1 minute of DSD64 stereo is about 40 Mbytes.
   
• Are all SACD DSD?
      Yes. Hybrid SACD also may contains 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 DSD music download links >

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 the editing demands conversion to multibit values and re-modulation. In this case, loses of the editing in itself, comparable with PCM resampling.

Read details here >

Read details how to open, play, make DSD files on Mac, Windows and other platforms: player list > and converter list >

How to create, edit DSD files read here >

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

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

DSD player brief F.A.Q.

• 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 author know, not. Details
   
• Can Jriver play DSD files?
      Yes. Look at player list
   
• Can Vox play DSD?
      As author know, Vox convert .dsf and .dff files to PCM on fly without native DSD playback.
   
• Can Plex play DSD?
•     As author know, Plex is able to playback DSF. Details
   
• Can Musicbee play DSD?
      As author know, yes. Details
   
• Can Amarra play DSD?
      Yes
   
• Can Audirvana play DSD?
      Yes
   
• Can iPhone play DSD files?
      Yes. Look at player list
   
• Can iPod play DSD?
      As author know, there is conversion to PCM files is necessary.
   
• Can Mac play DSD?
      Yes
   

DoP (DSD over PCM) is format to provide compatibility with some DSD hardware (USB DAC, as example). The format allow to code 1-bit DSD in usual multibit words (like PCM).

These multibit words are transferred as usual PCM. Upper bits of the multibit word contains special "DSD over PCM" marker code.

DoP receiver should recognize the marker code and interprete lower part of the multibit word as raw DSD bits.

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

DoP coding may be chosen in an audio player settings.

DoP specification

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 musical record.
3. "Native" DSD editing is possible for limited cases. For other cases, the own editing loses is comparable with PCM resampling.

Read detailed article about DSD >

Author: Yuri Korzunov, Google+,
Audiophile Inventory's developer

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