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Building a Multi-Channel PVR System?
Dr.Ruud asks: "What would be good ways to build a multichannel VCR? Think of a cluster of 4 PCs, each having 4 TV-cards (with MPEG-hardware on each) and (if necessary) a separate harddisk per TV-card, and maybe a 5th PC that controls the others, holds a DVD-writer and any other necessary hardware. Could it be done in a simpler and cheaper way? See also linuxtv.org, linuxmedialabs.com and of course SouceForge-vcr-projects like Freevo." What would be the best way to go about cutting down the number of machines such a cluster would need? Could this be done by building an all-in-one-wonderbox without it getting really expensive?
I'm just trying to figure out why you would need 16 programs taping at one time... I am the only one who finds that a bit off the wall?
...just watch less TV?
Not that you'll have trouble cutting down with the amount of utter garbage out there.
Honorary Member of Jackie Chan's Kung Fu Process Servers
how do you plan to get 16 NTSC-composite video signals from your cable/sattelite/broadcast feed? Do you have 16 base-band converters? I'm curious.
Or perhaps are you capturing CCTV for archival? You may want to investigate how people do that (casinos capture immense amounts of high quality digital video for security purposes). The hardware is, doubtless, expensive, but it may give you some insight on how it can be done "on the cheap".
I have no great authority here, except that I have ran several linux systems, coded simple linux apps, and ran ATI's all-in-wonder (piece of crap) PVR solution for two years.
Every month or so, someone comes up with a newfangled linux PVR and posts it here and on sourceforge.
Last I looked, there were at least 4 seperate projects on linux PVRs. There was also something major wrong with each project!
One project has a cool interface but could not actually record!
One project could record and playback, but not record and playback at the same time!
Yet another project could record and playback, but even the author of the thing reported that the audio and video were badly out of sync.
Now: I don't know if the Ask slashdot question was a troll, or someone hoping to startup a dumb dot bomb that re-sells TV signals, but even a single P-1Ghz with an ATI all in wonder could barely record at broadcast quality - read: It didn't ever fully approximate broadcast quality.
I've got two coworkers who purchased PC PVR solutions, and guess what - all three of us now own: Tivo, Replay, and DishNetwork-PVR systems.
BAH. This is really stupid. Until someone hacks together something that actually works, and doesn't require a PHd in driver hacking, and syncs the audio properly, and has a 1/10^6 chance of working on someone else's build of linux/hardware, then let's not waste time discussing the *neato* applications of linux PVR. It's still a fantasy for private/OSS projects...
Word to developers - what you've done so far is great, but if you want to unseat MSFT, you've gotta make it so that Grandma can install it.
If we were talking about a new version of GCC or the latest kernel, with Visual Studio.NET and Windows Longhorn as the competition, it'd be fine to moderate this comment as (-1, Lazy n00b), but you're talking about a glorified VCR, and you're going up against TiVO.
For this kind of product, User Interfaces matter. Saying "RTFSource", and "It's skinnable", won't cut it.
Likewise, dependency trees can be a formidable barrier to adoption. Saying "Well, of course it compiles fine for me, I mean, who doesn't rebuild XFree86 from the CVS source tree on a weekly basis?" isn't gonna cut it either.
PCs are cheap enough these days, especially since folks in the DIY segment might want to dedicate one as a PVR. Given the appliance-like nature of such a device, I'd say a (set of, for each supported motherboard-chipset/video-chipset combo) binaries ought to be a design goal, and I might even go so far as to say that distribution as an ISO wouldn't be out of the question.
That would make it sort of difficult to record two different shows at once, wouldn't it?
Many people are posting things like "I can't see why you oould need 16 channel".
why would you post just that? I show a starttaling lack of imagination for nerds.
Just off the top, I can think of:
Archiving different channels takes on global events.
Perhape he is going to take 'orders' for recording, so instaed of settng your VCR, you just call this guy up and say "PLease record X for me"
Maybe he just thinks its interesting.
Perhaps he's going to hook it up to 16 continues camera feeds for security.
I'm sure some people here can think of more, and better ways to utilize this.
The Kruger Dunning explains most post on
http://www.titantv.com is an excellent online program guide and it has a convenient downloadable data file for shows. I don't know if they cover Bermuda, however. There is also http://www.digiguide.com, but I have not really used the service.
Chill. Relax. There is no need for longwinded rants with random bold words. No, the free software PVR projects are not ready for prime time yet. It shouldn't be suprisingly, they're all very new. Mozilla's few few years weren't terribly promising. Linux itself took many years before approaching general usability. For the software to reach a polished stage we need to start with the crappy first pass. There is lots of experimentation and playing around. Core components (like drivers to TV cards and MPEG encoders) are still early in the development stages themselves. Eventually things will settle down, all but a handful of projects will fold, and things will become ready for you. In the meantime, let other people do a little harmless cheerleading. We need early adopters and fans to help work out the bugs in the system, do development, and keep the developers inspired.
(If you feel a burning need to emphasize something, the <em> tag will generally give you a more subtle, easy to read result. Bold text tends to leap out, dominating the paragraph. If you really want readers to just focus on those key points, consider a bulletted list using <ul> and <li>)
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A couple thoughts off the top of my head:
Really folks, when someone asks a question they don't want to be told why they don't need to know the answer. So, come on, don't send off-topic replys about how pathetic or dumb a question is post a constructive answer!
credo quia absurdum
I've seen a lot of threads that say an application like this would be great for security cameras and the like.
Assuming this is even implementable (which it is not), lets look at a cost breakdown:
16 video capture cards - $100 x 16
16 120 gig hard drives - $120 x 16
4 cheap cases - $50 x 4
4 mb/proc/mem combos - $240 x 4
1 dvd burner - $200 x 1
other odds and ends - $100
which comes out to a grand total of approximately, oh, $5000
Now lets look at my solution:
16 VCR's purchased from circuit city- $50 x 16
one guy to switch tapes every six hours- $6.50/hr
$806.50.
Digital cable is basically just another way to modulate a given 6 mhz block that we call a channel. It makes this block able to carry multiple channles, dependant on the quality, and compression. A highly compressed channel can handle up to 40 channels (Of the cooking show variety), and a minimum of 4 (Die Hard quality).
But this is what I propose. You would have to get a card that is modded to recognize these blocks of channels (They all recognize the channels, but they won't recognize the individual digital channels, unless they are digital cards). BUT, take these cards, and record the 6mhz bandwith, NOT the actualy individual channels.
Lets put it this way, lets say HBO runs at the 550 mhz - 556 mhz range (Which is arrpox where it is for COX Cable Las Vegas) If we were to recorde this range, we would not just be getting the normal HBO that we want, but also all of the other channels on the same bandwith. On average thir are 8 high quality streams on any 6 mhx channel. So in this case, by recording one of these channels, we would be able to extract 8 channels, say HBO, HBO2, HBO Signature, HBO Latina, Cinemax, etc.
In this case, it might be able to record between 8 and 40 channels per tuner card. With specially modified hardware, and software to do this level of decodeing.
Also if you were to find a way to compress this data, you might be able to find an extremely efficient way to compress this data.
- Ice_Hole
"I couldn't give him (Bill Gates) advice in business and he couldn't give me advice in technology." Linus Torvalds
I disagree with this. 16 is a bit high, but I understand the problem. When I got a PC PVR, I ran into problems. The problem is pretty simple. For like 18 hours of the day, I don't want to watch or record anything. Maybe a show or two, like Lexx at 2pm. Or something on Toonami.
But certain days on primetime, there's like 7 shows I'd like to get a handle on to watch later, e.g. a slow weekend, the other hours of the day. Primetime plus ratings seasons equals a LOT of overlap of shows I'd to catch when *I* have the time.
For example, I liked watching Monster Garage, Mon 8pm on Discovery. But there was, for a time, Lofts on HDTV from 8-8:30. And I think Courage was on a 8pm for a while there. If you were a Third Watch person, as I was for a bit, that was on at 8pm for a while there.
Or Jag on CBS and Buffy on UPN, Tuesdays at 8.
Yes, a lot of TV if you're going to sit there and watch it that week. But given how TV runs, there is a lot of crap time, starting first with the other 18 hours of the day, and rerun season is pretty boring. Maybe I want to watch TV when I want to, not when the networks want me to.
I've only got extended cable. If you have HBO and some premium channels, there's potentially more.
Yes, the vast majority of stuff on TV is crap. But there is stuff on that's enjoyable. I use a PVR to REDUCE the amount of time I spend in front of the TV channel surfing, waiting for the show to come on, keeping track of what show switched to what time slot (SciFi bastards) or cancelled (Fox bastards).
You would want 16 channels recording at the same time so you could retro surf ....
... at least for the stations that are being recorded.
So as you surf around and you see something you like, you could rewind to the begining of the show.
I have Tivo now, and often I will turn on the tv and realize that the show that is currently on, is one that I wish I had seen from the beginning. Since my Tivo was on that station, I can rewind a half hour back in to the buffer, but when I change the channel each channel doesn't have a buffer, so I'm for those I am out of luck. 16 tuners all being recorded would fix that problem
I have to call BS on this post. You are a dirty dirty liar. Let's summerize the hardware you have mentioned: Two low power PCs - $500 each? With "various large (300GB+) multidrive RAID arrays" - Okay, $100 a pop for the SCSI cards, minimum. Let's say you have 3 100GB SCSI HDs in each, with no redundancy, and we're talking, what, $150 each? Two firewire cards - $100 each. 2 Canopus ADVC-100s - $300 each. Then you have 6 Sony DSS Receivers (I assume) at $200 a pop each. Oh yes, then there's the 3 MPEG converting machines, let's say $800 each, if we include a hardware encoding card. Or was that "6 or 7 MPEG encoder machines"? Make up your mind. Is it 3, 6 or 7? Let's pretend it's 7 after all. (Let's not forget the crying fit inducing 6 satellite bills, which for all of the extra channels would come in around $80 each every month. Yeah, 80 x 6 x 12 = $5760 per year on cable bills.) Your magic video editing system would have to cost at least $4000. So the bill comes in at a whopping $13700.
Okay, so let's assume that you're mister moneybags, and you go ahead and set up a system for this. My only question is: Why? Are you a big-time pirate? If so, why would you be advertising the fact? You're lying, and everyone knows it. Plus your website http://www.mp3smuggler.com/ doesn't go anywhere.
Fake. Liar. Troll.
Have a nice day.