I have a Scientific Atlanta 8300HD DVR from TW running the SARA firmware. Picture-quality-wise the DVR works perfecfly for digital feeds. However, I am not at all happy with the quality of the recordings it makes from analog channels. The "Sa 8000" thread in this same forum has some discussion on this topic (in particular, the distinction in picture quality performance based on whether the feed is analog or digital).
As far as I am concerned, the recordings my SA DVR makes from analog feeds are substantially inferior to what I can make at EP speed with a decent VHS tape recorder - which is not very good to start with. In practice, I continue to record any show transmitted in analog on tape - usually at SP speed with Super VHS, in which case I can perceive practically no degradation compared to live. (For all my playbacks, I have a high-end JVC VCR which has a frame buffer and which does processing which eliminates most of what I call "VHS color noise". It can almost always play back a tape from another VCR with better picture quality than can the VCR which recorded the tape.)
I had been intending to buy a DVD recorder for recording analog channels, as I thought I would be happier with one of those than I am with my VCRs. However, having experienced the inadequacy of the encoders in SA's settop boxes, I am wondering if I will be happy with anybody's encoder in non-professional equipment.
The things that bug me are the compression artifacts. If you are watching an action sport like boxing or football, it is the things that are moving fast (fists, balls) that are most important things to watch. Yet it is these things which become blocky because the encoder cannot keep up. I am also distracted when the background goes blurry because the camera is panning. Things get even worse if the analog signal the box is trying to encode is noisy, as it is hard for the compression algorithms to know which differences are significant. My cable provider fails to provide a noise-free signal on many of the analog channels I watch, and SA DVR recordings from the noisy channels are extremely ugly with dynamic graininess - much uglier than live or a tape recording.
I am somewhat surprised by the fact that my concern about encoder quality and my conviction that tape remains a superior medium for recording analog TV are not things that I see others talking about much when discussing digital TV recording devices. Perhaps I am more sensitive to compression artifacts than most. But I do know that, with their professional equipment, the TV broadcasters can do a vastly superior job of encoding an SD digital data stream from analog than can my DVR - and at the same data rate.
What I hope to learn here is if others who are sensitive to digital compression artifacts can point me to DVRs and DVD recorders that have superior encoders. Are there any principles (specifications, key words) that would allow one to know about relative encoder quality issues without actually trying a product? Are there any reviews out there that concentrate on the encoder 'component', and can one determine whose encoder a box uses?
A related issue: A VCR can do fast and slow motion effects much more smoothly than can my SA DVR. Are there any DVRs which can do these effects smoothly? (Given the nature of the technology, I doubt it; but I hope to be surprised.)