What is CD Production?
CD Production occurs immediately after the Audio Mastering stage and is a manufacturing process that provides methods by which an individual or group can commercially obtain and distribute an audio product on Compact Disc.
There are two ways that this can be achieved by 1.Replication 2. Duplication. Replication and Duplication are terms that should be understood as they are two unique manufacturing processes and usually relate to the amount of product required. Replication often being higher than that of Duplication. Both products require the Audio Engineer or Mastering Engineer to provide a CD-R Pre-master or CD-R Master in-order for either processes to commence.
CD-R Pre-master or CD-R Master?
The CD-R Pre-master and CD-R Master are identical formats, they both exist as Compact Disc - Recordable (CD-R) format. However, the terminology used determines the outcome of the Audio Mastered to CD-R. After the Mastering process the Stereo tracks are recorded and then burned by laser to a CD-R and it is this CD-R that is used as either a CD-R Pre-master or CD-R Master.
- Audio Mastered to CD-R = CD-R Pre-master
- Audio Mastered to CD-R = CD-R Master
The Mastering process is identical and the resulting CD-R can be used for both CD Manufacturing processes. At this point the job of the Audio Engineer and Mastering Engineer is complete and the process of manufacturing the CD product commences using the Audio Mastered to CD-R. At this stage the Audio Mastered to CD-R could be used as either a CD-R Pre-master or CD-R Master.
The CD-R Pre-master is the CD-R used to produce a CD Master or Glass Master and CD's are pressed or stamped, this process is for high volume CD production. This process is called Replication.
The CD-R Master is the CD-R used as a Master to produce Slave or Copied CD-R's similar to burning a CD copy in your PC and involves the use of a laser. CD's aren't pressed. This process is called Duplication.
Note: The above information is a basic explanation to help differentiate between two CD manufacturing processes. Below is an exposition of the above. You can skip these last few paragraphs if you choose.
CDDA (Compact Disc
Digital Audio) is in reality a Laser Disc that carries digital
information, the data consists of Binary Code 0 and 1 (Zeros and
Ones). In fact any number
can be represented in Binary Code. Binary numbers are used to represent all
information in the digital world. They are similar to our decimal
system, which uses the digits 0 to 9, except in Binary Code
we will use only a 0
In binary code:
Decimal number 0 is binary 0
Decimal number 1 is binary 1
Decimal number 2 is binary 10
Decimal number 3 is binary 11
Decimal number 4 is binary 100
Decimal number 5 is binary 101
And so on...
A CD or Laser Disc is made up of Microscopic PITS and SPACES:
PITS = 0
SPACES = 1
The Audio Production page uses terminology such as analog-to-digital conversion (ADC) and digital-to-analog
conversion (DAC). Compact Discs only offer digital-to-analog
conversion (DAC). The PITS and SPACES on the CD (Laser Disc) are converted via the digital-to-analog conversion (DAC) process to play back the music
or sound, the stream of numbers is converted back to an analog
analog wave produced by the DAC is amplified and fed to the speakers to
produce music or sound.
As long as the Binary Code can be converted into a format that we (humankind) can understand we might appreciate the outcomes, in fact the entire world system now relies on Binary Code, if we consider what we do in our daily lives even simple tasks such as speaking on a telephone is all reliant upon the Binary System.
Of course there is so much data that needs to be processed
therefore data integrity is so important when we consider the amount of
data on a single CD. In fact
the whole digital recording process consists of data so it is important
that careful steps be taken to preserve the original CD-R Pre-master and
CD-R Master data. Data corruption is the enemy here and in order to
preserve High Fidelity all Zeros and Ones must remain intact.
For example this Binary Code below. What do you think it means when converted from Binary Code into Text (ASCII)?
Now imagine if just a small amount of this data was removed? In reality it is not likely that we would be able to interpret this at all, as the data would be jumbled. Here is the same Binary code with a zero removed:
This data is so bad that the text is no longer recognised by the website server:
Can you imagine what the audio data on a CD might sound like if this were to happen. This is why the CD Production process is so important and must be done in such a way that it is absolute in all respects. Data integrity must be preserved at all costs, it is paramount.
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