dvr?

I have a typical tv set up, a flat screen, a set top box with built in dvr. The tv has multiple inputs/outputs of various connectors. The set top has rf input, rf output and hdmi output which feeds the tv. What I need is a discless (DVR?) unit with rf in/out, line in/out out and hdmi in/out. I plan to run the computer output to both the tv and dvr via a pc to tv converter using the line out at converter to the dvr line in and hdmi out to the hdmi in at the tv. In this way I can switch between set top box connection and computer connection. In the past I have used vcrs and dvd recorders. I no longer wish to create so many physical media. Vcrs do not use hdmi. DVD recorders probably do not either. I could use the rf out if need be. Please make a recommendation by TYPE, brand, model. A link to owners manuals for various units would help. Thanks.