The Difference Between Commercial and Home-recorded DVDs

You probably never gave it a second thought, but did you know that the commercial DVD movies you buy or rent actually use discs that have different characteristics than the DVDs you make at home on your PC or DVD recorder?

The recordable DVD formats available for consumer use are similar to, but not the same as, the format used for the movies and other content you get on commercial DVDs that you buy at your local store, which is referred to as DVD-Video. The main difference lies in the way the DVDs are made.

Although all DVDs (both homemade and commercial) utilize "pits" and "bumps" physically created (the pits on the unreadable side and the bumps are on the readable side) on the discs to store the video and audio information, there is a difference on how the "pits" and "bumps" are created on commercial DVDs vs the way they are made on a home recorded DVD.

DVD movies you buy at the local video outlet are manufactured with a stamping process. This process is sort of like the way vinyl records are made - although the technology is obviously different (vinyl records are stamped with grooves versus DVD being stamped with pits and bumps).

On the other hand, since it would be impractical for consumers to have to use commercial stamping equipment (plus go through all the preliminary recording onto film, tape, or hard drive, then feed a DVD stamping machine), DVDs that are made using a PC, or standalone DVD recorder, are "burned".

In the burning process, a red laser is employed in a PC record-able DVD drive or DVD recorder that generates the necessary heat to create the appropriate size bumps on the readable side (which automatically creates a pit on the unreadable side) of the physical disc and stores the desired data or video/audio information. The difference between the stamping and burning processes makes the actual physical reflective properties, and the way the actual disc reading instructions are recorded on commercial DVD-Video and home recorded DVD formats different.

Since the reflective properties of a stamped disc and recorded disc are different, in order for DVD players to be playback compatible with both commercial DVD-Video and one or more of the home recorded DVD formats, the player has to have both the proper hardware (red laser tuned to read both types in the case of DVD) and firmware that is able to detect the differences between the various disc formats. Also, DVD recorders need to have the capability of changing the function of the laser from a recording mode to a playback mode.

With reference to the compatibility of the various DVD recording formats with standard DVD players, the owner's manual of the DVD player usually lists which DVD recording formats it can play. In addition to the ability to play back commercial DVDs, almost all DVD players can also play DVDs recorded in the DVD-R format (except for some models made before the year 2000), while most DVD players can play DVD recorded in the DVD+RW and DVD-RW (video mode) format discs.

Although commercial DVD movies and home recorded DVDs outwardly look the same there are definite differences in their structure and the formats used to record content on them.

Also, other factors that affect playback compatibility of commercial DVDs include Region Coding and video system compatibility.

However, although DVD region coding is not a factor with home recorded DVDs, the video system that your DVD recorder or PC writer uses does affect playback compatibility in other countries in the world. So, if you are making a DVD for playback in a country other than your own, be aware of this issue.

Another factor that can affect playback compatibility of home recorded DVDs is how much video time (determined by a selected record mode) you have recorded on the disc.

If you encounter any issues with DVD format recording or playback compatibility and the documentation for your DVD recorder and/or player(s) do not provide sufficient information, contact tech support for your units, or check out reputable online sources for additional assistance on DVD players and recordable DVD discs.