MPEG2 vs. Digital Video Tapes

Misconception: A DVD has more storage capacity than a DV tape.

Reality: DVDs have around 10% of the capacity of a DV tape.
Many people think that the digital video stored on their DV, DVCAM, or DVCPRO is the same as the digital video stored on a DVD. This is not true. These widely used DV formats all record the video to the digital tape at 25 Megabits per second (Mb/s). The DVD specifications only allow DVDs to be a maximum of 10 Mb/s. That 10 Mb/s includes the audio and video. A Mini-DV tape that can record 60 minutes of video can hold approximately 11.25 Gigabytes of computer data. The DVD-R media that HomeMovie.Com uses only holds 4.37 Gigabytes of data. In order to fit your 60 minutes of video from your Mini-DV tape onto a DVD we must use MPEG2 compression. As we encode your video we compress the digital video to in order to make it fit onto a DVD. Currently MPEG2 compression offers the best quality compared to MPEG1.

The fact of the matter is that, while a DVD can store many times more data than a CD, it still has very limited capacity compared to almost any kind of tape. The main reason that DVD is becoming the popular choice for video is it's convenience and durability. Any video on a DVD is instantly accessible since it is being played in a computer (even a set top player is a computer) and is spinning around thousands of times per second. To find a spot on a tape, you may have to rewind or fast forward for minutes. But the technology that has made DVD preferable to tape still has not given it the capacity. The chart on the left shows the number of discs needed to hold 2 hours of video in three formats: DV, DVCAM, DVCPRO (25Mb/s), DVCPRO50 (50Mb/s), and MPEG2 (the compressed video used by DVD: 5Mb/s). In order to get 2 hours of DVCAM or Mini-DV to fit on a DVD, the video must be compressed by a process called "Encoding".