What does “20-bit remaster” mean?
A “20-bit remaster” usually means that the audio was transferred, processed or mastered at 20-bit precision before the final release was prepared. On a normal audio CD, the finished disc is still 16-bit / 44.1 kHz PCM.
The short answer
20-bit remaster describes the mastering process, not the CD storage format. A mastering engineer can work at greater internal precision and then reduce the finished master to the 16-bit format required by Red Book CD.
The extra precision gives the mastering chain more room for calculations such as level changes, EQ, fades and other processing before the final 16-bit version is produced.
The CD format did not become 20-bit
Standard Compact Disc Digital Audio stores two-channel PCM at 16 bits per sample and 44.1 kHz. A label such as 20-bit remastered does not alter that delivery format.
This is the same distinction seen elsewhere in digital audio: production precision and delivery precision are different layers. The mastering workstation may operate at 20, 24 or higher internal precision while the consumer format remains 16-bit.
Why use 20-bit mastering if the CD is only 16-bit?
Higher internal precision reduces rounding error during processing and gives the engineer more headroom for intermediate calculations. This matters because every gain change, fade, EQ operation or digital filter can create values that do not fit neatly into the original 16-bit grid.
The goal is not to make a 20-bit CD. It is to perform the work at higher precision and make the final reduction to 16 bits as carefully as possible.
How does a 20-bit master become a 16-bit CD?
Simply chopping off the least-significant bits is called truncation. That can turn low-level quantisation error into signal-related distortion. A better mastering path normally uses dither, and may also use noise shaping, when reducing the bit depth.
| Stage | Example |
|---|---|
| Transfer / processing | 20-bit PCM master or higher-precision internal processing |
| Final bit-depth reduction | Dither and optionally noise shaping |
| CD delivery | 16-bit / 44.1 kHz PCM |
Sony Super Bit Mapping and the 20-bit era
One prominent 1990s example was Sony's Super Bit Mapping (SBM). Sony described SBM as a way to reduce 20-bit source material to the 16-bit CD format while shaping quantisation error toward frequency regions where it is less audible.
The important point is not that 20 bits were somehow stored on the disc. The technique attempted to preserve more of the perceptual benefit of the higher-precision master within a standard 16-bit CD signal.
Does “20-bit remastered” guarantee better sound?
No. It tells you something about the production chain, not whether the mastering choices were good. A 20-bit remaster can still be over-compressed, clipped, excessively bright, poorly transferred or made from an inferior source.
Common misconception: “20-bit remaster” is not the same thing as “20-bit audio on the CD.” It is a mastering-process label.
Frequently asked questions
Can a CD player output 20-bit audio from a 20-bit remastered CD?
The disc still carries 16-bit samples. A player may use higher internal precision, oversampling or a DAC with more than 16-bit capability, but that is playback processing rather than extra bits stored on the disc.
Is 20-bit remastering obsolete?
Twenty-bit mastering was especially visible during the 1990s. Modern mastering commonly uses 24-bit or floating-point processing, but the same principle remains: work at higher precision and reduce carefully for the delivery format.
Is 20-bit remastering the same as HDCD?
No. HDCD is a separate encoding/decoding system carried in standard 16-bit CD PCM. A 20-bit remaster can exist without HDCD, and an HDCD release is not automatically a “20-bit CD.”
Related pages
24-bit remaster · Dither and noise shaping · Audio bit depth · SPARS codes · Preserving HDCD