Comparing the DVRs? 335
zonker asks: "We are
getting hooked up with Dish
Network Satellite TV this weekend and opted to go with one of
their PVR
(personal video recorder) plans. I started wondering if anyone has
done any technical reviews or comparisons of the video quality (not
just features) of the various digital video recorders out there (TiVo, DishPVR,
ReplayTV, etc.). I am curious
mostly about recorded video quality compared to the source video.
All of them make claims to have various recording 'speeds' like
VCR's. VCR's analog output is predictable (fuzzy recording with bits
of static here and there, worse when signal quality is bad).
However digital recorders have varying levels of pixelization. I was
curious which ones fared the best and if anyone has comments on
either systems?"
Need a FREE version (Score:2, Insightful)
Hardware Codec... (Score:3, Insightful)
I hate the fact that they sell the systems with "30 hours of playback" 30 hours, you can stick 30 hours of video on a cdrom with low bitrates, it means NOTHING. What you want to check for if they don't give the true numbers, is the size of the hard drive and the minimal recording time (i.e. if they say you can record minimal of 20 hours on a 40GB drive, you do the maths for the datarate: (sorry if I don't multiply by 1024 or if I miss anything, this is intended as "raw".
So, 40GB for 20 hours.
40,000MB/(20 hours x 60 minutes x 60 secons) = 0.55MB/sec.
Mjpeg looks "okay" on a standard el-cheapo TV at about 1MB/sec. (its blocky on a vga monitor but depending on the quality of your tv, it's smooths a bit on the output so you notice it a bit less). Personnaly when I deal with video that I want to store with a good MJPEG codec, I don't go under 3-4MB/sec. For replaying with the video (i.e. decompress, add some effect, recompress) I don't go under 5MB/sec (if not uncompressed).
That's for MJPEG with 4:2:2 colorspace, if they use a DV codec, it's 4:1:1 colorspace so there's more pixel quality for the same given bandwith compared to 4:2:2 MJPEG.
Anyways I'm going off here, what you want to do is apply the above formula when you can't get the datarate and pick the highest number... you won't care if it means less storage, because you can ramp up the compression afterwars anyways. And besides, drives are going down in price everyday, and since your concern is about quality and not storage, this is one of the option you might want to look for.
I'm sure electronic-wise, aside from some extra stuff like component out or nice extras like that, the Codec level and overall theorical compressed quality is about the same from a machine to another, so probably the biggest difference (aside from the added features like component out if some don't have it) will be that number which will be hardcoded in the firmware. Some might want to go with lower values to be sure that the drive will follow (but then again most drives do over 10MB/sec sustained easily nowadays) or for any other reasons like marketting for more storage than the competition.
Re:Hardware Codec... (Score:3, Insightful)
Re:Tivo capture resolution (Score:3, Insightful)
Things worked quite well at 32 and 44.1KHz, though 44.1 had a tendancy toward more artifacts from the mp3 encoder at a given bitrate.
Which is to say that 32khz sounded better, all said. Nyquist be damned.
OTOH, I ended up running at 44.1KHz long-term, as it was more agreeable with portable mp3 players.
I've had TiVo for over a year now (Score:2, Insightful)
I didn't use/investigate the ReplayTV version because I am a Sony Bigot and I bought the Sony PVR which is TiVo based. I can say that the hacking side of TiVo is very thourough and if you want to tear apart your TiVo and upgrade the capacity, or add an ethernet card or something fun it's out there. Though I have not investigated the ReplayTV side of the house to see what they offer to the hacking community.
The guide information, and it's ability to 'learn' what you want to watch is very nice. It picks shows, sometimes stuff I've never heard of but ends up being something I like. I was able to catch every Babylon 5 episode and catch the few I missed during the real airing.
Also, it's great for new parents. Tape your shows while yer new two month old baby screams, and then when you are fighting them to sleep late at night you can watch stuff you TiVo'd instead of the 65 of 67 channels of Paid Programming that is on between 1:00AM and 6:00AM when your child is wide awake (at least mine is)
This highlights the quality issue... (Score:5, Insightful)
That's why I'm just going to build my own, as many others have. When I next upgrade my PC, I'll be cramming the old one into a small set-top case with a 10x DVD-ROM, a 100GB HD (or more, depending on pricing at the time), and an ATI All-in-Wonder Radeon (or Radeon 8500, depending on price at the time), a RealMagic Hollywood+ DVD decoder, an SB Audigy Value, and a NIC.
Most of those components I already have, and some of them aren't really necessary--like the H+ card, since the ATI card also has iDCT-assisted DVD decoding, or the DVD drive at all if you just want a PVR and not an integrated DVD playback. I included the H+ card on the list just because I already have one, and I prefer its image quality on a standard TV although the ATI decoder looks better on a high-res TV, and because some rare titles have gklitches on one or the other just as some rare titles have glitches on regular set-top DVD players. Back-ups are always good.
I can't speak for what Linux software is available, but I plan my device to be based on a stripped-down WinXP kernel once http://www.98lite.net finishes their Windows XP version of their famous installer, which lets you strip away almost any unneeded part of the typical install. As such, there's some great and polished software available that's perfect for this--the ATI card's MultiMedia Center, for instance, which includes an integrated Guide+ feature and DVR capabilities. The A-i-W 8500 card will even come with a remote that looks perfect, with an integrated mouse device and everything, and runs on RF instead of IR so you can even control the thing from another room through thick walls. Tom's Hardware recently gave a great review of a pre-release sample.
Best of all, when you roll your own there's total control over encoding and NO COPY PROTECTION. Why worry about losing saved shows in case of disaster or hard drive malfunction or hardware burnout requiring a return to a stupid company which reformats the drive? That's what the NIC is for. Transfer them to a back-up HD or when DVD-R drives and media get cheap enough, burn 'em to DVD. Lots of flexibility and expandability. And I know from personal experience that the All-in-Wonder cards encode a beautiful MPEG-2 stream in real-time with a decent Athlon processor.
The only feature my box won't have that a commercial PVR will is the record-shows-it-thinks-you-may-like feature, which I personally wouldn't find useful anyway. The only feature a DVR integrated with a satellite receiver has that my box won't is digital-to-digital transfer, which isn't such a huge boon when you remember that it doesn't save the digital feed from the satellite, it *re-encodes* it so that there'll be some quality issue anyway. sing high-quality analogue cables shouldn't introduce any more noticeable quality issues.
It's something to consider, and maybe someone else here can point to Linux software with similar functions?
If you care about digital audio, no choices (Score:4, Insightful)
But once you decide digital audio is important to you, then you MUST go with the integrated PVR since no external PVRs have digital audio input.
And as others have said, same with zero loss video. Any external PVR is going to have to redigitize the video instead of recording the original data stream.
You should have considered your PVR options before choosing DishNetwork since the DishPlayer software is not so great.
Re:Tivo Forum & Tivo FAQ (Score:3, Insightful)
I will note that if you have both cable and DirecTV like I do, you need the standalone Tivo. For the first time I can have my local channels and DirecTV all on one continuous rotation on a single remote!