Storage Medium

Video—especially digital video—can be stored on more than just videotape. The characteristics of the storage medium determine playback and recording capabilities. For example, magnetic and optical disc media (such as CDs, DVDs, and hard disks) are capable of nonlinear reading and writing, whereas videotape is inherently linear. Videotape is still a very efficient means of storing large amounts of digital data in a small space, but other types of media are quickly gaining ground.

Tape Size, Cassette Shape, and Tape Coating

The width of a videotape is directly related to how much information can be stored. In analog formats, wider tape usually yields higher quality, but other factors can help reduce tape size with minimal loss of quality. For example, Betacam SP and VHS both use 1/2"-wide tape, but Betacam SP uses a high-quality component video recording method that keeps luma and chroma information separate, whereas VHS uses a composite method that mixes these signals into one, causing interference between the two. The physical formulations of these two kinds of tape are also different, which accounts for some of the quality difference.

The size of the cassette itself can vary as well. For example, the Betacam SP format comes in both small and large sizes. The small tapes are used for camcorders, and the large format is used in studio VTRs.

Aspects of the physical composition of magnetic tape, such as density of magnetic particles, limit the data rate and track size that can be recorded on the tape. The magnetic coating on a videotape is formulated to work with particular camcorders and VTRs. If you choose the wrong tape coating, the tape can actually clog the video record heads of your video equipment, leading to video signal dropouts during recording and playback. Always read the documentation that comes with your video equipment before purchasing a particular brand of videotape stock.

About File-Based Media

Historically, video footage has been recorded on videotape. As digital acquisition replaces analog technology, some camcorders now record footage as files on non-tape-based media such as hard disks, solid-state cards, and optical discs.

Today, some common file-based media formats include:

  • DVCPRO HD and AVC-Intra (solid-state Panasonic P2 card)

  • AVCHD (hard disk, miniDVD, Secure Digital card, and memory stick)

  • Sony XDCAM, XDCAM HD (optical disc), XDCAM EX (SxS memory card)

  • Sony Video Disk Unit devices (hard disk)