THE picture quality of home movies transferred from a camcorder tape to DVD is often dreadful. But a new type of recorder means armchair directors will soon be able to make DVD home movies that have the same pristine picture quality as pre-recorded DVDs.
The expensive professional recording systems used to make pre-recorded DVDs rely on a system called variable bit-rate recording to get the clearest pictures using the smallest possible number of digital bits. This gets the most playing time out of a disc. More bits are allocated to each frame when the pictures are highly detailed and fast-moving than when the images are simple and still.
Professional recorders analyse the footage frame by frame before copying it to DVD using an appropriate number of bits per frame. Thus the movie takes the least space on the DVD without sacrificing picture quality.
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Consumer DVD recorders use the same, smaller number of bits for each frame, regardless of detail. As a result DVDs made at home from camcorder tapes show blur and mosaic patterning during rapidly moving, detailed footage.
When camcorder footage is fed into a new type of DVD recorder, which Sony is launching this month, the information is first copied to the 160-gigabyte hard disc at the high rate of 15 megabits per second. While the hard disc copy is being made, the recorder analyses the picture content and builds up a data file on how many bits will be needed for each frame when it is transferred to DVD. The hard disc recording is then copied onto a blank DVD, with the recorder continually adjusting the bit rate to suit the picture content.
The result is a home-made DVD of Hollywood picture quality. The recorder can also be used to improve the quality of DVD recordings made from TV broadcasts or old VHS tapes.
Robert Hull, editor of UK-based magazine Camcorder User, says, 鈥淚t鈥檚 early days, but it could kick start a new wave of interest in home movie-making. But of course if you shoot a boring movie, it will still look boring. No amount of clever technology can change that.鈥�
