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?

Comments

Eh?

[Masami Eiri]

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?

Open Source PVR is not as simple as people think

[noahbagels]

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...

One-channel-first, please?

[Tackhead]

Can we get the turnkey single-channel Linux PVR first? :-)

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.

Re:Open Source PVR is not as simple as people thin

[ChaosDiscord]

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...

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>)

Re:Why do you want it

[Lechter]

A couple thoughts off the top of my head:

• you want multiple people to be able to use the same cable connection
• everyone in your house wants a PVR but you don't want to duplicate it in every room
• you need to record multiple shows on at a given time for analysis (Comm doctoral students do this all the time)
• you own a TV store and want to stream programming to multiple show pieces
• you just want to be that damn 1337

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!

I dunno if it is possible but..

[Ice_Hole]

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