All About DVD Encoding and Decoding
In every good spy movie, there is usually a scene where the hero must decode a secret message which was encoded by the bad guy. In this case, the message has been encoded from one format to another in order to conceal its true meaning. However, encoding and decoding are also part of the process of how DVD video discs work.
Most consumer video cameras record at a very high level of quality or even in high-definition. This raw footage is then transferred to a computer where it is edited to include music, transitions, and special effects. When it comes time to transfer the finished video from the computer to the master DVD disc, the footage must be encoded into DVD format.
In order to play in a standard DVD player, the video on the disc must conform to a very specific set of standards. In North America, the video frames must be 720 pixels wide by 480 pixels tall and played back at a rate of 29.97 frames per second. The video itself must be encoded into an MPEG-2 stream with a variable bit rate of between 3Mb/s to 9 Mb/s.
The problem is that most videos are captured and edited at a much larger size and quality than this. In order to be recorded as a DVD, the information must be compressed or “encoded” into DVD format.
There are a number of different software programs available for doing this. Some popular ones for Windows include TMPGEnc, CinemaCraft Encoder, and Adobe Media Encoder (which comes with Adobe Premiere video editing software). These programs have the ability to take a video from an input source and encode it into a DVD-compliant MPEG-2 video stream.
Unfortunately, DVD encoding software is not freely available; and the software programs which cost money are not especially easy to use. It can take a significant investment of money to purchase the software, and even more time in learning to properly use it. While some programs such as Adobe Media Encoder are comparatively easier to use, the advanced options found in Cinema Craft Encoder and TMPGEnc may be intimidating to inexperienced users.
Once the video files are finished encoding, the final DVD disc can be produced. In order to play the same disc back, we need to look at the other half of the picture: DVD decoding.
When talking about DVD encoders, the term primarily refers to a computer software program. The concept of a DVD decoder is a little more abstract. When playing a DVD video disc back, the decoder can be either hardware-based or software-based.
An example of a hardware-based DVD decoder would be the set top player in your living room. Inside that machine, there is a special chip on a circuit board whose job is to take the MPEG-2 data stream and “decode” or translate that into a picture which will be displayed on the screen. This is what allows the machine to play back DVD movies.
A software-based DVD decoder would be a commercially available program such as Intervideo’s WinDVD or CyberLink’s PowerDVD software. These programs allow desktop and laptop computers with DVD-ROM drives to play DVD video discs. The computer’s processor and memory are used to decode the information, rather than a dedicated chip.
As you can see, encoding and decoding are both vital steps which are required for creating and viewing DVD discs. This is very basic overview of the roles which encoding and decoding play in the DVD authoring process. You can learn more about encoding and decoding by researching the programs mentioned above.