Digital video recorders let you record your favorite TV shows or movies to later watch at your convenience. DVRs use hard drives similar to the one in your computer to store your saved programming. As with video files on your computer, higher quality recordings take up more storage space. The recording time for a 500GB DVR varies drastically depending on whether the programs you're recording are in standard or high definition.
A 60-minute television program in standard definition requires about 1GB of storage data. According to hard drive manufacturer Seagate, one of its 1TB DVRs stores about 1,000 hours of standard-definition television. Since a 1TB DVR has about twice the capacity of a 500GB DVR, the 500GB drive would hold about 500 hours of programming. However, Comcast states that its 500GB DVR holds 300 hours of SD programming, so there's no set standard and the actual capacity depends on the specific DVR.
Seagate surmises that HD programming requires up to five times as much storage space as SD programming. Ceton Corporation asserts that a 60-minute HD recording requires 6GB of storage space. Doing the math, a 500GB DVR should hold around 83 hours of HD programming. In a 2010 TiVo Premiere XL review on CNET, editor John Falcone said the TiVo 1TB model holds about 150 hours of HD programming. With a 500GB drive, the same DVR would hold about 75 hours of HD video.
Ceton says the actual recording space required by a program varies; it's not always as cut-and-dry as 1GB per one hour of SD television. The program's bit-rate, or how many bits of data are transferred during the broadcast, affect the quality and storage capacity needs of the program. Ceton uses sports as an example, claiming an hour of football may take up more space than an hour-long TV drama, since sports usually carry a higher bit rate to provide the best viewing experience, especially in HD.
Check the Specific DVR
Since the actual amount of recording time depends partially on the DVR itself, checking the individual unit's specifications or documentation provides the most accurate answers. DVR manufacturers usually list the number of hours a DVR can hold, often listing both standard- and high-definition figures. If you're eying a particular DVR, look for such figures on the company's website or the DVR's box, if you're buying it in-store. DVR reviews also carry this information and an unbiased review may provide more accurate information than a DVR box or the manufacturer's website.
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