198 Digital CCTV
The fi rst practical videotape recorder (VTR) was developed and
sold by Ampex Corporation in 1951. The Ampex VTR captured
live images from television cameras by converting the information
into electrical impulses and saving it onto magnetic tape. VTRs
were similar to reel-to-reel audio tapes, with large spools of multi-
track magnetic tapes measuring 1/2 to 2 wide and averaging
7,000 feet in length. The company demonstrated its Ampex-Mark
IV in April of 1956 at the National Association of Radio and Televi-
sion Broadcasters (NAB) convention. See Figure 13-1. Ampex sold
the fi rst VTR for $50,000 in 1956.
The lack of interchangeability among the very early VTRs
posed a serious problem. The same head assembly used to record
a program had to be used for playback, meaning that the recording
machine head assembly had to be shipped with the tape of evi-
dence in order to view the recorded contents. This problem still
exists in some systems today because many manufacturers use
proprietary compression codecs for their digital recorders.
Figure 13-1 Ampex-Mark IV VTR. Courtesy of Department of
Special Collections and University Archives, Stanford University

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