The invention of the VCR (video cassette recorder) revolutionized the way television programmes were broadcast. Prior to their creation in 1956, all shows had to go out live but following the introduction of the VCR they could be pre-recorded and shown later. This would, in the future, allow for 24 hour broadcasting and the use of special effects. In 1975 Sony released the first mass production VCR system named Betamax, and had the market to themselves for one year, selling 30,000 units in the USA over that period. In 1976, JVC released their creation, VHS (video home system) which had twice the capacity of Betamax, being able to record 2 hours of television per tape. This became the defining point between the two systems and in 1977 a 3 hour capacity VHS system prototype was developed and quickly released soon after. Except for the capacity advantage, Betamax always remained ahead of the other system by about 6months. When Sony released a new unit with new features (such as Betamax hi-fi) JVC would catch up half a year later (in this comparison JVC released VHS hi-fi). In 1981 pre-recorded media started being produced for both systems but the selection was broader for the VHS system. The first year sales reflect this with pre-records on the Betamax format making up only 25% of the market. In 1988 Sony admitted defeat of the Betamax system as the market share of the hardware dropped below 1%.

        The VHS system works similarily to the way audio cassettes are recorded and played except the amount of tape required increases dramatically due to the introduction of the visual component. sound is recorded to an audio cassette in a long linear stream on the tape, known as Progressive recording. If this method was implemented for a VCR system the tape would need to hold roughly 500 times the amount of data per second. The change in speed of tape would be huge also with video requiring dramatically faster speed. The solution that JVC found was the creation of a play back and record method known as interlace. Here the tape is wider and although still recorded linearly, there are several lines recorded parallel to one another across the tape. There are two heads on the recorder/player handling alternate ‘interlaced’ bands. This method is achieved by reading/writing onto the tape with a rotating drum head. The diagram below explains the setup.

To solve this problem, two recording heads are mounted on a rotating drum that is tilted with respect to the tape. If you have read the HowStuffWorks article How Television Works, then you know that a television image is divided into a series of 525 horizontal scan lines, half of which are displayed every 60th of a second. Each pass of the VCR's rotating head reads or writes the data for one field (262.5 scan lines) of the television image. Therefore, the data recorded on the tape looks like this:

•An 800-foot (244-m) long, 1/2-inch (1.3-cm) wide piece of oxide-coated Mylar tape that acts as the recording medium

•Several low-friction rollers to guide the tape across the front of the shell

This was the same year that the Moving Picture Experts Group (MPEG) was formed and after 4 years of development, the audiovisual format MPEG-1 was completed with a bit rate of 1.15Mbit/s and a quality similar to VHS. A year later the system was demoed at the Midem show in southern France. The MPEG-1 format is used on video CD’s and is designed to fit a film onto two compact discs. The main advantages of MPEG-1 over previous physical forms such as VHS was that it could be viewed many times without the quality suffering. With the cassettes used in VHS systems, the tape can get stretched and damaged because the plastic is in contact with other components when played. This minor friction between the two materials may damage the tape over a long period of time. As CD’s are read optically no contact is made and so no can deterioration occurs.

Development of new systems being created were united together in 1995 and MPEG-2 was unveiled. Included in this was a method of encoding multi channel (surround) sound named Advanced Audio Coding. MPEG-2 is the format used by DVD’s and for digital television.

MPEG-4, released in 1998 is the next thing in VCR technology (although strictly speaking it is no longer a video cassette recorder). The initial development header for MPEG-4 was ‘very low bitrate audio-visual coding’, to allow the viewing of video via low capacity bandwidths. This has been realized within MPEG-4 in that it allows the same MPEG-4 file to be viewed at an appropriate bitrate. Named Fine Granularity Scalability, the same video can be transmitted at different bit rates varying from 5kbit/s up to over 1 Gbit/s. This high end bitrate is used when another new development within MPEG-4 is used.

Rather than capturing a 2 dimensional rectangular frame of pixels, objects within the video can be individually coded. This results in the user being able to interact with a scene and move objects or animate them differently to their programmed/recorded movement or action. The extent to which this feature can be used to enhance the viewing experience is unknown but is likely to change the way films are watched.