DVD (Digital Versatile Disc)
In the last post I talked about CD digital media and its uses. The next type of digital media that I typically use at Croom Video Services is the DVD. The confusing thing about a DVD is that, although it is the same physical size as a CD, it can hold far more information. That storage amount is 4.7 gigabytes per DVD vs. 700 megabytes for a CD. Now, my fellow techies will argue with me that the actual capacity is slightly lower. While there is structural overhead that affects the true capacity of a disc, as well as semantic differences regarding the way the prefixes ‘giga’ and ‘mega’ are actually valued, the overall concept is the same. A DVD can hold almost 7 times as much data as a CD. Because of all that extra storage, DVDs can be used to store video information.
If you are looking to transfer your VHS, Mini-DVs, 8mm video or film to disc, you will want to use a DVD.
We probably have all purchased DVDs of our favorite movies and TV shows at retail, electronics and local video stores (“Local what now?”) For some years now, recordable disc technology has been available for us to create DVDs from our own personal videos. A typical DVD disc can store about 2 hours of standard definition video. There are different recording modes and types of DVD discs that allow for longer playing times: like extended play, and dual sides or layering. However, for this discussion we’ll stick to single-sided and layered DVDs.
A video DVD has a specific structure that allows it to play in DVD players as well as computers equipped with DVD playback software. The menus and video content are stored in .VOB (video object) files along with organizational and backup content. A commercial DVD may also include copy protection that prevents its structure from being viewed, copied or converted. Croom Video Services customers often ask if they can drag and drop the content files (.VOB) from a DVD into a video editor, or upload them to sites like YouTube or Vimeo. The answer to that question used to be a definite ‘No’, but in recent years this has changed to ‘Maybe’. Increasingly, support for .VOB files has improved to allow direct import into other programs, but it is not universal. The best way to determine if a .VOB file will work for a particular website or program is to look at its support documentation.
Now (to add to the confusion) just like a CD, a DVD can also be used as a way of storing data. As you may have guessed, the storage capacity is also 4.7 gigabytes. Many times when a Croom Video Services customer has more digital pictures than will fit on a CD, I will burn them to a DVD instead. A DVD that is formatted for data will behave in a similar way as a read-only flash drive or thumb drive. Once the disc is inserted into the computer, its stored files can be viewed or copied as needed. One important thing to remember is that a DVD that is formatted for data is NOT a video DVD. It will NOT play in a DVD player because it does not have the proper structure.
Our customers also ask if they can copy video files like .MOV, .MP4, .WMV, etc. to a DVD disc. The answer is ‘Yes’, but because the disc is formatted for data, it is NOT a video DVD. The files that are stored on it will only playback on a computer, not a DVD player. I also instruct customers to copy a video file from disc to their computer’s hard drive before playing it. On many computers, especially older models, CD/DVD drive speeds are not fast enough to keep up with the demands of a video file. Playback is often jumpy, may have audio sync problems, or just plain won’t work.