What is the DDP image

Mastering engineers often speak about the DDP image, but what is it? A mastering studio may master both single tracks and complete EPs or albums. In these latter cases, it is possible to distribute EPs and albums in different formats: CD, vinyl, as files for online distribution (Spotify, iTunes...).
If the album has to be released on CDs, there are many methods for the mastering house to deliver the tracks to the replication plant. These methods are:

1. Audio CD delivery
2. Delivery of 44.1 Khz / 16 bit WAV files
3. DDP image delivery

Audio CD

The traditional method consists in the delivery of the master audio CD to the replication plant. All the duplicated CDs will derive from this physical master CD. The audio CD allows to insert all the metadata (track name, track artist, album name, album artist, UPC/EAN code, ISRC code...) and the possible pregaps between the tracks. However, the audio CD has an important disadvantage too, caused by its "physicality". Indeed, audio CDs are subject to errors which can lead to reproduction and duplication issues:

• C1 errors. These are the less serious errors, and are inevitable. CD players automatically correct C1 errors, so they become inaudible
• C2 errors. These errors could produce audible skips during the playback. CD players generally correct C2 errors
• CU errors. These are serious errors. CD players don't correct CU errors, so they always produce audible skips during the playback

Replication plants don't accept audio CDs with C2 or CU errors for duplication, and generally impose a maximum of 200 C1 errors per second.

44.1 Khz / 16 bit WAV files

It is possible to send to the replication plant the single tracks as 44.1 Khz / 16 bit WAV files, for CDs duplication. Today (2016) it is possible to insert metadata in WAV files too, but this method however presents some disadvantages:

• It is not possible to determine the pregap between the tracks
• There could be problems to identify the correct sequence of the tracks

DDP Image

A DDP image is an image of the audio CD. It is composed of a core file with ".dat" extension, while the other smaller ".dat" files contain the CD metadata. The software that makes the DDP image, allows to easily insert all the metadata, the pregaps and the correct sequence of the tracks. The DDP image can be sent online to the replication plant, avoiding the costs and the risks of a physical shipping. Today, almost all the plants accept this format.
In summary, I suggest the use of DDP images for CDs duplication; however, it is necessary to verify that the plant accepts this medium. I use HOFA CD-Burn & DDP software to produce this format.