转帖一则，本人以为说得比较到位，帖子很新。（英文）

shy888

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20-bit and 24-bit digital systems in the studio
Submitted by JohnSiau on Wed, 2010-09-08

Here is my personal take on the quality of CDs produced over the past 30 years:
Pre 1991 - high probability of good quality due to direct transfer from analog master tape to digital master

1991 - 1997 - increasing probability of poor recordings due to proliferation of 16-bit multi-track recorders

1997 - 2002 - the dark ages of digital audio - high probability of poor recordings due to 16-bit DAWs and 16-bit recorders

2002 - present - increasing probability of freedom from digital artifacts

The above is purely based upon the equipment and procedures used by recording studios over the past 30 years. It is not based upon any evaluation of the finished product. Your CD library may roughly follow the above timeline, but excellent CDs have been made in each of the past 30 years. I would never dismiss a recording just because it was produced in a certain time period.

Here is a brief history of significant changes that have occurred in the process of producing CDs:

Prior to 1991 virtually all CD were recorded on analog multi-track tape and then mixed down to two-channel analog tape.  This two-channel tape was then transferred to a digital two-channel master using a Sony PCM recorder.  This process was capable of producing very good results as it only used one relatively high-quality 16-bit A/D converter.  During this period, a few "all-digital" CDs were produced in a "digital direct to disk" recording process that eliminated any mixing and editing.  These "digital direct to disk" recordings also may be relatively free from digital artifacts. In general, the CDs produced on or before 1991 may be much better that what followed between 1991 and 2002.

What happened in 1991?

Multi-track digital recording became affordable in 1991 when Alesis introduced the ADAT 8-channel 16-bit digital recorders that used Super VHS tape.   In 1993 Tascam introduced the DA-88 -  a similar product that used Hi-8 tapes.  These recorders included built-in 16-bit converters and were low-cost (and low performance) replacements for multi-track analog recorders.  Between 1991 and 2000, many studios transitioned to 16-bit digital tape to reduce costs.  Recordings from this period that were made on 16-bit digital multi-track machines may fall short of what was being produced by analog-only studios.  In general, the quality of CDs probably declined between 1991 and 2002 due to the use of 16-bit multi-track machines and their built-in converters.

Two things happened in 1997 that helped to improve the situation:

1) Outboard converters:

Benchmark and others introduced  20-bit digital A/D converters in 1997.  However, at that time,  20 or 24-bit recording devices were very rare, and, for this reason,  it was common to dither down to 16-bits at the output of the A/D converter.  It was also nearly impossible to find any digital audio workstations (DAWs) that operated at 24 or more bits.

2) 24-bit recording:

24-bit recording began to enter the mainstream in 1997 when Digidesign introduced a 24-bit version of its popular Pro Tools workstation.  This probably marked the beginning of a significant migration to 24-bit systems.

But - digital mixing gained popularity in 1998, and introduced more digital artifacts:

In 1998 Digidesign introduced digital mixing to their systems.   Many early DAWs produced poor results when mixing in the digital domain, and the Pro Tools system was no exception.  This was largely due to a limited bit depth and a lack of headroom in the digital signal processing (DSP).  Prior to 1998 most digital recordings were mixed on analog consoles (a practice that is still common in many studios).   However, the convenience of "mixing in the box" often outweighed any concerns about quality. Some recording produced between 1997 and 2003 were mixed in 16-bit DAWs and suffered from repeated truncation to 16-bits (without dither).  Some of the worst CD recordings may come from this period.

High-resolution digital systems go main-stream in 2002:

The most abrupt transition to high-resolution recording probably occurred when Digidesign introduced Pro Tools HD in 2002.  At the time, Digidesign launched an aggressive trade-in policy that replaced many of the existing Pro Tools systems.  By the end of 2003, many studios had upgraded to 24-bit recording (and 24+ editing and mixing).  These systems are capable of producing recordings that are very free from digital artifacts.  Many of these systems are outfitted with outboard A/D and D/A converters to further improve the sound quality.  In-the-box 32-bit, 48-bit and 64-bit mixing can significantly outperform analog mixing. These systems mark the first step forward since the pre-1991 analog recording process (analog master to digital master).

leslieleslie

翻译一下塞

忽然散步

20位和24位数字系统在工作室
提交于周三，2010年9月8日JohnSiau

这是我个人承担了在过去30年生产的光盘质量：
预1991年 - 高概率优质母带由于从模拟到数字直接转换大师

1991至1997年 - 适当的16位多轨录音机扩散概率增加穷人的录音

1997年至02年 - 数字音频 - 正当16位DAW系统和16位贫困录音录像机高概率的黑暗时代

2002 - 现在 - 自由的概率增加从数字文物

以上是纯粹依据的设备和记录，在过去30年的工作室使用的程序。它不是基于任何成品的评价。您的CD库可大致按照上述时间表，但优秀的光盘已在过去30年，每年提出。我永远不会解雇只因为它是在一定时间内产生的记录。

下面是那些在生产过程中发生的重大变化光碟简史：

1991年以前几乎所有的CD都记录在模拟多轨磁带，然后混合到双通道模拟磁带。这两个通道磁带，然后转移到一个数字双通道主使用Sony的PCM录音机。这个过程是能够产生很好的效果，因为它仅使用一个相对高品质的16位A / D转换器。在此期间，少数“全数字”光盘制作了一个“数字直接到磁盘”录音过程，消除任何混合和编辑。这些“数字直接到磁盘”的录音也可能是由数位文物相对自由。在一般情况下，制作的CD或1991年之前可能会好得多的东西从1991年和2002年之后。

在1991年发生了什么事？

多声道数码录音于1991年推出可负担得起的时候了Alesis的ADAT 8通道16位数字使用的超级VHS磁带录像机。 1993年的Tascam推出的DA - 88 - 1类似的产品，使用高8磁带。这些记录包括内置的16位转换器和较低成本（低性能）为多轨道模拟录像机的替代。 1991年至2000年，许多电影公司过渡到16位数字磁带，以降低成本。从这一录音被16位数字多轨机作出可能达不到正由模拟只制片厂的时期。一般来说，光盘质量可能下降1991至2002年间，由于16位多轨机和使用其内置的转换器。

1997年发生的两件事情，有助于改善这种情况：

1）外置转换器：

基准和其他在1997年推出20位数字A / D转换器。不过，当时，20或24位录音装置是非常少见的，基于这个原因，它是共同的抖动了在A / D转换输出为16位。这也是几乎不可能找到任何数字（DAW系统），在24个或更多的操作位音频工作站。

2）24位录音：

24位录音开始进入1997年，Digidesign的推出了其流行的Pro Tools工作站的24位版本的主流。这可能标志着一个重要的开始迁移到24位系统。

但是 - 数字混合于1998年获得了普及，并推出更多的数字文物：

在1998年推出数字Digidesign的混合，以他们的系统。许多早期的DAW系统产生时，在数字域混合效果差，以及Pro Tools系统也不例外。这主要是由于在有限的位元深度和一个净空在数字信号处理（DSP）的不足。 1998年以前大部分的数码录音是在模拟混合控制台（这种做法还有很多工作室常见）。然而，“在框中混合方便”往往远超过对质量方面的隐患。 1997年至2003年生产的部分记录被混合在16位和DAW系统反复遭受截断为16位无抖动（）。一些最严重的唱片可能来自这个时期。

高分辨率数字系统在2002年进入主流：

最突然过渡到高清晰度记录可能发生在2002年推出时，Digidesign的Pro Tools的高清。当时，Digidesign最新推出了积极的贸易政策所取代现有系统的Pro Tools很多。到2003年底，已经有很多工作室升级到24位录音（24编辑和混音）。这些系统的录音制作数字文物有很大的自由的能力。这些系统都配备了外置的A / D和D / A转换器，以进一步提高音质。在开箱即用32位，48位和64位混合可大大优于模拟混合。这些系统标志着自1991年以前的模拟录音过程（模拟到数字掌握主踏出第一步）。

yamuling

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shy888

原帖由 leslieleslie 于 2010-9-13 09:52 发表
翻译一下塞

这是非常通俗的英文了，还是看原文吧。