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Building a Multi-Channel PVR System?

Cliff posted more than 11 years ago | from the it-doesn't-HAVE-to-be-a-single-box dept.

Technology 344

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?

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Eh? (4, Insightful)

Masami Eiri (617825) | more than 11 years ago | (#5138835)

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?

Re:Eh? (0)

Anonymous Coward | more than 11 years ago | (#5138848)

because some programs air at the same time

Re:Eh? (2, Insightful)

Anonymous Coward | more than 11 years ago | (#5138886)

Move out of the basement. Kiss a girl. GET A LIFE.

TV sucks.

IN SOVIET RUSSI (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#5139061)

VCR replays TIVO!

Re:Eh? (1)

AresTheImpaler (570208) | more than 11 years ago | (#5139082)

Move out of the basement. Kiss a girl. GET A LIFE. TV sucks.

I prefer to kiss the TV, if the girl then...
rigo

Re:Eh? (3, Interesting)

pythorlh (236755) | more than 11 years ago | (#5138854)

I could maybe understand for archive purposes. As for me, I don't think I've ever had more than 3 things on at any one time that I wanted to watch, and even very seldom more than 1. But a single machine of this hypothetical cluster would do it for me, quite happily.

Re:Eh? (1)

Thud457 (234763) | more than 11 years ago | (#5138904)

I don't get it either...

Just one channel of 'reality' programming should be enough to drive the AI insane!

Re:Eh? (1)

jemenake (595948) | more than 11 years ago | (#5138990)

I'm just trying to figure out why you would need 16 programs taping at one time
Personally, I can't even name 16 channels that ever have something good on... much less at the same time.

Re:Eh? (0, Redundant)

Neumann (240442) | more than 11 years ago | (#5139036)

To never miss a simpsons episode of course!

No doubt... (1)

YoJaUta (67458) | more than 11 years ago | (#5138840)

... needed in order to record shows off of HBO, HBO2, HBOMovie, and HBO Brasil all at the same time.

hmm (4, Interesting)

twiggy (104320) | more than 11 years ago | (#5138841)

In theory, you'd also need an array of hard drives, because the thrashing of four or more things being recorded at once would be painful...

This would mean you'd have a maximum of 4 hard drives, unless you buy an IDE card that lets you support more, wouldn't it? (Each IDE chain can have only two devices, right? or is that outdated info now?)

An interesting idea for certain though...

Save data before it is decoded (4, Interesting)

maddogsparky (202296) | more than 11 years ago | (#5138880)

For the amount that you are talking about spending on hardware, you might be able to afford a high-bandwidth A2D converter configured to capture the raw signal (you may have to frequency shift it). Then you can decode it off-line and in slack time when you figure out what you want.

Same idea for for HDTV, except save the data stream.

Re:hmm (2, Interesting)

Wesley Felter (138342) | more than 11 years ago | (#5138924)

I think you could record quite a few channels to a single disk if you use good enough scheduling. Let's conservatively assume that each stream is 8Mbps (1MB/s), the disk can write 20MB/s, and every seek costs 20ms. If you have a 1-second buffer for each channel, then writing that buffer takes 20+(1000*(1/20)) = 70ms. Thus you can write 14 streams to one disk.

Re:hmm (2, Informative)

Dajur (168872) | more than 11 years ago | (#5138951)

no matter what the manual told you, you can't write 20MB/s.

Re:hmm (1)

dhartman (635124) | more than 11 years ago | (#5139091)

This all depends on the desired quality. I think yould be hard pressed to do more than one channel on anything below an Athlon XP 1800 if you want full DVD quality. If VCD quality is acceptable, you'd probably get away with a few simultaneous recordings. You'd definately want a stripped array for the hard disks to maximize write speed. I have two 40 GB ide's striped with a hardware raid to do DVD quality video editing. Even then, if I try to access the drive at all while it's capturing the video, I'll drop frames, sometimes lose sync on the audio.

If you were doing something useful like surveillance, then I can see the reason for multiple encoded streams at the same time. Even then, most surveillance programs capture a snap shot every X seconds until motion is detected, then dedicate all the resources to that one camera instead.

frost pist!!!! (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#5138844)

There's a house at the top of a tree In the house there's a room In the room there's a chair And sitting in the chair is youuuuuuuuu.

YOU SUCCEEDED IT! (0)

Anonymous Coward | more than 11 years ago | (#5138910)

Now be quiet.

Hmmm.. (1)

SpectreGadget (465507) | more than 11 years ago | (#5138849)

Is there really that much 'good stuff' on tv to watch, let alone save?

Re:Hmmm.. (0)

Anonymous Coward | more than 11 years ago | (#5138906)

maybe the poster is trying to do it for security cameras.

Re:Hmmm.. (4, Informative)

pe1rxq (141710) | more than 11 years ago | (#5138935)

maybe the poster is trying to do it for security cameras.

If that is the case he should have a look at motion [sourceforge.net] it can handle multiple videodevices and even use multiple inputs on each device.

Jeroen

Re:Hmmm.. (1)

jemenake (595948) | more than 11 years ago | (#5138974)

Is there really that much 'good stuff' on tv to watch, let alone save?
Actually, according to Nielsen's extrapolations, it is expected that there will be 16 good shows airing at the same time sometime around March 12, 2034...

... but that's only if they can find a good location for filming Survivor XXXVII.

PC Stereo Component (0, Offtopic)

pez (54) | more than 11 years ago | (#5138850)

On a semi-related topic, does anyone have good recommendations on PC encosulres (or complete systems) that are suitable for a home a stereo rack? I'm looking for something that is both functional and esthetically pleasing.

Thanks in advance.

Re:PC Stereo Component (0)

Anonymous Coward | more than 11 years ago | (#5138909)

Shuttle PC cases are awesome...

Re:PC Stereo Component (2, Informative)

slandis (97422) | more than 11 years ago | (#5138911)

You could try the ATC-620 [coolermaster.com] from Coolermaster. Looks nice, available in silver or black. Not super-cheap, but reasonable at least. I'm leaning towards a couple of these myself for home a/v use.

Re:PC Stereo Component (1, Informative)

jrsmith (318084) | more than 11 years ago | (#5138913)

http://www.whiningdog.net/Reviews/PC/Accessories/C ases/20020912-LianLiPC9300/

and this page has a couple...

http://www.tomshardware.com/howto/20021109/pc_fo r_ tv-01.html

Re:PC Stereo Component (-1, Troll)

Anonymous Coward | more than 11 years ago | (#5138919)

I am also interested in this. You can check out coolermaster's ATC 600 series [coolermaster.com] .

They look alright.

Re:PC Stereo Component (2, Informative)

Osty (16825) | more than 11 years ago | (#5138930)

I like my Cooler Master ATC-600 [coolermaster.com] , but it looks like they have a number of other options [coolermaster.com] as well (look under "Desktop"). The ATC-600 is just slightly too big for my entertainment center, but it perches nicely on top of it. Now I just need to find a reason to use the thing (now I have a high definition cable feed, the HTPC is useless for recording shows). Also, it's a Micro-ATX form factor, but if you're planning on doing an HTPC, that should be more than enough. Especially if you want the case to fit well in your entertainment center.

Re:PC Stereo Component (1)

Black Copter Control (464012) | more than 11 years ago | (#5139010)

A Cobalt Raq looks pretty nice. If you're just using it for stereo, then you could probably hunt down something from the dot-bust period.. A couple hundred bucks; asthetically pleasing; nice LCD panel. I'm pretty sure it has a single PCI slot (for a sound card). Upgrade the hard disk and you're flying...

It'd be a little bit harder if you want to do both sound and video, but I'm pretty sure you could get a pretty Cobalt box with multiple slots.

Unless you're doing something nasty, a 500MZ processor should be more than enough for most work.

Yes. (1)

benjamindees (441808) | more than 11 years ago | (#5139085)

I spotted one of these at CompUSA [compusa.com] , although, now that I see the price, it is quite expensive. Very slick, though: all metal, with doors that are held closed with magnets like an upscale stereo. Now you just have to find room for the watercooling kit.

16-channels at once? (2, Interesting)

Anonvmous Coward (589068) | more than 11 years ago | (#5138853)

Well, I gotta admit, I'm baffled as to why one would want to record 16 channels at the same time. Why is that interesting to you? What's your goal here? Are you providing a service for somebody? Is this something you'd just like to do at home? Answer that for me and I might be of more assistance.

Personally, I can't help but think that 4 cards capturing at ideal quality would saturate the PCI bus unless each card directly controlled a hard drive.

Re:16-channels at once? (0)

Anonymous Coward | more than 11 years ago | (#5138934)

security?

Re:16-channels at once? (4, Informative)

pe1rxq (141710) | more than 11 years ago | (#5138975)

motion [sourceforge.net] can do that easily.

Jeroen

Re:16-channels at once? (5, Funny)

goatasaur (604450) | more than 11 years ago | (#5138937)

An explanation:

Basic digital cable provides different premium services... there are 6 HBO channels, 4 Cinemax channels, 4 Showtime channels, and a couple of 24-hour pr0n channels.

Obviously, the poster's intent was to record more porn. This drive for increased pornography consumption has inspired such innovations as the light bulb (for reading porn), the telephone (for listening to porn), and of course the cotton gin (for making more tube socks).

Re:16-channels at once? (4, Funny)

Anonvmous Coward (589068) | more than 11 years ago | (#5138986)

"Obviously, the poster's intent was to record more porn...."

Oh shit, I didn't realize that.

Okay okay okay okay.. lemme think.

Okay, I can help him, but I'll need sample videos from him to perform anal...ysis on. (sorry about the pause there, was distracted for a moment.)

Re:16-channels at once? (3, Interesting)

mlyle (148697) | more than 11 years ago | (#5138952)

720 horizontal pixels * 480 vertical pixels * 32 bits per pixel * 29.97 frames per second = 331MBytes/second.

32bit, 33MHz PCI is 105MBytes/second. Most PCs have this, which is not capable of even supporting one uncompressed card. Of course, for this reason, TV cards do compression.

DVD quality video is 9 Mbit/sec. Assuming the encoder on the card is not as good, you can get plenty good video at 10-12mbit/sec. And you can fit pretty much as many of those onto a PCI bus as you have slots, I'd think, if the software is decently efficient and supports it. Likewise, this is pretty slow compared to typical disk I/O rates, assuming you do some buffering to allow decent-sized writes to occur and aren't seeking all the time.

331MB/s? re-do your math (NT) (0)

Anonymous Coward | more than 11 years ago | (#5138994)

No text

Re:16-channels at once? (1)

Anonvmous Coward (589068) | more than 11 years ago | (#5139012)

"720 horizontal pixels * 480 vertical pixels * 32 bits per pixel * 29.97 frames per second = 331MBytes/second."

Where do you get 32 bits from? Heh. Best I've ever seen is 24, but you could easily drop that to 16 and nobody'd ever know better.

Other than that, you're right. Personally, though, I'm not a fan of MPEG2. Besides finding a player for it, it's not as efficient as say MPEG 4. I'd prefer to have the CPU do the compression in real time. One of these days I want to put together a dual-processor PVR just to do that. (The other processor is for viewing the footage on my TV without interrupting capture...)

Re:16-channels at once? (1)

benwb (96829) | more than 11 years ago | (#5139065)

You didn't carry your units through. If you multiply out your numbers you end up with 331 mbits/s, which is ~40 mbytes/sec. You also don't really lose anything by recording 480x480 given the crappy quality of most broadcast signals, which would move things down to ~26mbytes/s. (Also if you think my $30 ati tv wonder ve is doing compression I have a bridge for sale...)

Re:16-channels at once? (1)

endikos (195750) | more than 11 years ago | (#5138993)

The security industry could use something that can capture 16 individual channels in thier entirety. A lot of video surveillance is done with one camera captured at a time, and switching among the many feeds; or by trying to do some sort of mutitrack where you lose quality on the video. Instead you could build a cluster of capturing PCs, and along with burning software and some sort of index built into the stream as it records, you could have quite a sophisticated system for building/campus/city surveillance and archival.

Think Hotel scale TiVo. (2, Interesting)

mckwant (65143) | more than 11 years ago | (#5139020)

I played with this idea briefly. Imagine a high end hotel offering "whatever" on demand for sum of cash $x. Networking to the rooms is a solved problem (see spectravision, etc.). Only question is how to get the content.

Well, that, and selling and servicing it in a scalable fashion to hotels that aren't terribly interested in giving you much of a cut.

Not a bad idea, but you run into trouble with the marketing and the amount of time you need to keep things vs. your affordable drive space. Not to mention the copyright issues the networks will come up with.

Re:16-channels at once? (0)

Anonymous Coward | more than 11 years ago | (#5139032)

What are you smoking? 33 mhz PCI pulls down like 132 MB/s in theory/spec, even on some later bad implementations that utterly blow you still easily get 70 MB/s.

The linux mpeg2 kfir project or whatever seemed to capture, if I recall, at 15 mbit/s. The icompression iCTV15 chip in most implementations (what I know to be capable of because I have a card that uses it) captures 12 mbit/s, CBR, around 90 MB/sec.

Even with 6 PCI cards at 12 mbit/s, you're talkin 9 MB/s thereabouts.

Let's say you have a sloppy setup, and it goes from the card, to memory or some crap, then back to a PCI card. Ooo, 18 MB/s. Add overhead, and you have plenty of room to spare.

The thing you have to worry about, as others have pointed out, is disk thrash. Writing multiple longish files (think 4 gigabytes for a half hour at over the top quality) means OS and disk layout becomes somewhat important. But I doubt a decent RAID setup with buffer is going to fail, but that, in most cases, lowers your bandwidth requirements since you reduce 1 capture card for every IDE, RAID, or SCSI controller you slap in there.

Has there ever been 16 good shows on at once ? (0, Redundant)

www.2cups.com (642654) | more than 11 years ago | (#5138866)

When in the history of television has there ever been 16 decent things to watch on TV ?

Re:Has there ever been 16 good shows on at once ? (1, Funny)

Anonymous Coward | more than 11 years ago | (#5138888)

With the over 200+ channels you can get now a days, im sure there has to be something good on.

I see where you're going! (1)

spammeister (586331) | more than 11 years ago | (#5138873)

You probably wanna buy a T3 as well and basically make copies of everything on DirecTV...

mind you you'd need 16 receivers, and like well thats a little out of anyone's leagues since the remotes would be insane (but cool)...

Anywho if you were actually able to find that much stuff, you would basically turn yourself into the pirate TV capital of the world! That would be the only reason i see (but my tiny brain is unable to comprehend anything other than "stealing" stuff. Good luck buddy! The evil empires are going to your house right now to brainwash that idea out of yer head hehe!

And the answer, again, is "MythTV" (5, Informative)

mbourgon (186257) | more than 11 years ago | (#5138874)

Version .8 will allow you to have several machines, each taping its own channel(s), controlled by any of the machines in the network. The goal is to allow you to have one gigantic server in the basement, and 1 fan-less machine in the living room.

Far more interesting is what ramifications (if any) are there to having 2/3/4 tuner cards in one PC. After all, each tuner card probably needs its own sound card... what else is involved?

Re:And the answer, again, is "MythTV" (1)

Idimmu Xul (204345) | more than 11 years ago | (#5138945)

After all, each tuner card probably needs its own sound card... what else is involved?



Each TV card doesn't need it's own soundcard, the TV card's have a line out, so the lineouts from all TV cards could all be plugged into one large multitap which in turn is plugged into the soundcards line in.

Re:And the answer, again, is "MythTV" (2, Insightful)

benwb (96829) | more than 11 years ago | (#5139017)

That would make it sort of difficult to record two different shows at once, wouldn't it?

Why do you want it (3, Interesting)

btempleton (149110) | more than 11 years ago | (#5138875)

While I see the occasional need for 2 tuners, frankly sometimes even that sounds like overkill. I find when there are two shows on at once it's a subtle message from the TV gods that I shouldn't watch so much TV.

I've also never figured out why you need the DVD burner. With so much disk in my Tivo, there is always stuff to watch, and my need for archiving stuff to watch again later is so small as to be unimportant. If I _really_ need it, a lot of it is at the video store for rent.

Is the 16 tuners so you could have a box shared by a whole LAN of people? I guess if you have the bandwidth that would make sense.

Right now the public thinks PVRs are too complex, so the big vendors will probably be working to make them simpler rather than more complex.

What we really need is a component architecture, with lots of little pieces, all with 100mbit ethernet (firewire and USB 2.0 are too "smart" for their own good. ether is the
way to go.)

Then just add what you need. Tuner boxes (OTA, digital or satellite as needed.) Decoders, mounted right on the inputs of the TV that plug in ethernet and spit out component video or NTSC. The ethernet of course leads you to drives running NFS or SMB, and an always on processor to control it all that's simple.

That way you can start simple, with just a tuner, a decoder and a controller (these 3 might be in the same box) and a networked drive or a drive-in-a-box, and add what you want.

PVR Advice... (5, Informative)

NanoGator (522640) | more than 11 years ago | (#5138877)

A dual 500 machine is more valuable as a PVR than a single 1.6 gig machine. Ideally you'd want 1 processor for playback and one to handle the other stuff (compression, etc...)

16 channels? Err. Okay. If you really want to capture that many at once, you'd likely be better off having one computer per card. You don't need expensive/new hardware to do that. If the card does the processing and funnels the compressed data down to the hard disk, then the processor is little more than a manager. Last I checked, a P3 500 would easily handle a PVR card with hardware compression.

If you have space considerations, go with a dual I suppose. But I wouldn't do more than 2-channels per PC.

Re:PVR Advice... (0)

Anonymous Coward | more than 11 years ago | (#5139066)

Last time I checked, the limiting factor on PCs was the memory bus, followed closely by the PCI bus. AGP was an attempt to solve this problem for displaying graphics.

I'd worry about the I/O bandwidth on the machine LONG before I worried what the mhz of the processor is.

Read up on NUMA architectures, MPI, and PVM if you want to learn where I'm coming from.

The Cheap Way. (0)

Anonymous Coward | more than 11 years ago | (#5138878)

VCRs are cheap. Buy 16 of em...goes without saying.

Obligatory (0, Offtopic)

Anonymous Coward | more than 11 years ago | (#5138881)

Can you imagine taping 99 channels at the same time with a Beowulf cluster of these?

Some limitations to keep in mind (5, Informative)

Omega Hacker (6676) | more than 11 years ago | (#5138885)

Doing any of this without hardware compression is, of course, not even remotely viable. Given that, you have some serious limitations imposed by common hardware.

Many of the PVR cards use the KFIR encoder chip in conjunction with a Conexant bt8x8 video capture chip. The bt8x8 does the NTSC->PCM, and sends it to the KFIR encoder, which sends the MPEG data back to the bt8x8. The limitation comes from the fact that there is no hardware-assisted DMA for the data coming from the KFIR chip. That means the host process has to repeatedly poll the PCI memory address for the bt8x8 GPIO ports in order to capture the data.

Putting more than one or may be two of these cards in a single machine would swamp the machine so badly it wouldn't be able to do much else at all, let alone sending the video to disk or a network-attached storage device.

If you can find a PVR card (supported under Linux, good luck putting multiple *anything* in a Windows box) that doesn't blow the PCI bus to pieces when capturing, and you should be able to put quite a large number in a single machine, limited by PCI slots. The KFIR chip captures up to 12Mbps, which is 1.5MB/sec. PCI can peak at 132MB/sec, so as long as busmastering overhead across a dozen cards isn't fatal, you could put them all in a PCI expansion cage on a single machine.

Re:Some limitations to keep in mind (1)

Lechter (205925) | more than 11 years ago | (#5139043)

I may be wrong, but last time I checked, I thought that video4linux cards didn't necessarily support the level of hardware compression available on some cards.

There's a question in and of itself: Which TV output/recording cards work well and quickly? With the low cost of various cards, would it be advisable (possible?) to reserve one for recording and another for playback

Re:Some limitations to keep in mind (2, Interesting)

Zurk (37028) | more than 11 years ago | (#5139055)

yes and where are you going to dump 132MB/sec coming off the PCI bus ?
no hard drive or raid array on a PC can do that and no network can support that without using the PCI bus.
motion.sourceforge.net sounds like a better idea.

too much free time? (0)

Gandalfar (599790) | more than 11 years ago | (#5138887)

And then you'd have time to watch all this recorded content? Most us have trouble finding time to watch just one show, and you're recording 4 at a time _and_ burning dvds.. Isn't there something better to do in life than watching tv shows for most of the day (and night)?

TV Listings? (2, Interesting)

AssFace (118098) | more than 11 years ago | (#5138895)

I have a TiVo right now and it is great.

I've seen the software to do it yourself and also machines that also do it (but aren't the TiVo service).

TiVo calls up a number every night and gets the listing information, is there a way to get that for the free programs and/or other machines?

I know that TV Guide has a web page with the listings - do they have an XML stream that you can grab and parse - or someone else?

If so, I'm not exactly a power user of TiVo and that would be a nice thing to have - but I don't want it as just a VCR sort of thing where I have to manually tell it "record XYZ at 4pm every thursday" - I am spoiled by the listings intelligence that TiVo has.

If there is something out there like that, esp avail over the net, that would be a lifesaver when I move to Bermuda since they don't have TiVo there and I would love to have that or something like that there.

Re:TV Listings? (2, Insightful)

p7 (245321) | more than 11 years ago | (#5139075)

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.

5 PCs?!? (4, Interesting)

nuxx (10153) | more than 11 years ago | (#5138897)

I highly doubt you'd need five PCs. What you would need, though, is four MPEG2 hardware capture cards with built-on TV tuners. Remember, a MPEG2 isn't all that big... From rough estimates in my head, any modern DMA100 IDE disk should be able to handle the bandwidth of four MPEG2 streams. You also won't need that powerful of a CPU, either. I'd say that with a little bit of special capture software (that can address four different cards) that will do tuning and scheduling and a TV-out device (Composive, S-Video, and Component) with hardware MPEG2 decoding (or a fairly fast box), you'll have all you need. If they are combination capture / playback cards, you could technically have four outs, too. Might be nice for family time. Queue it up so capture takes priority on all cards but one, or...? The possibilities are endless.

But anyway, I personally would think that you would only need two or MAYBE 3 streams at once, but if you already have software to address more than one card, why stop with just two? As long as the hard drive and PCI bus can handle it, you're set.

Possible Hack (4, Interesting)

nukey56 (455639) | more than 11 years ago | (#5138901)

I recall a conversation I had with the digital cable installer awhile back. He had never heard of PVRs before, and as I was talking about them, he suggested that since the data for all the channels is coming in on the same line at the same time, it could be possible to modify a cable receiver to capture multiple channels at once. This wouldn't solve the problem of how to record them all, though I'm guessing a 8/16/(insert number of channels here) SCSI hard drive setup would work nicely.

Virtual machines? (0)

Anonymous Coward | more than 11 years ago | (#5138902)

You could try setting up a machine with 4 scsi drives 4 pci tv capture cards and 4 seperate virtual machines like vmware or some other virtual machine software.

Why not... (1, Insightful)

The Gline (173269) | more than 11 years ago | (#5138912)

...just watch less TV?

Not that you'll have trouble cutting down with the amount of utter garbage out there.

Re:Why not... (5, Interesting)

Ssolstice (198935) | more than 11 years ago | (#5139068)

Why watch less tv? So he can just put useless posts on Slashdot like yours? The guys asked for technical advice, not for gripes.

Besides the computer... (2, Insightful)

ALecs (118703) | more than 11 years ago | (#5138915)

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".

A cluster? (4, Funny)

spoonist (32012) | more than 11 years ago | (#5138917)

"Think of a cluster of 4 PCs..."

A Beowulf Cluster of PVRs? Sweet!

Use PiP functions to half the number of cards? (1)

Sgs-Cruz (526085) | more than 11 years ago | (#5138918)

The LeadTek TV2000 XP [leadtek.com.tw] (ugh, I hate the acronym XP -- used way too much...) can do Picture in Picture. Now with custom software (ie. not the included software) such as Freevo or something, somebody could possibly hack the code to record both streams (the main stream and the PiP stream) since to have PiP, by definition there must be two tuners on the card.

Of course, this doesn't help with the fact that you'd still need eight of these things (and you'd saturate the PCI bus, as someone else mentioned), but it would (possibly?) cut the number of cards needed from 16 to 8.

Re:Use PiP functions to half the number of cards? (1)

Wesley Felter (138342) | more than 11 years ago | (#5138997)

From that Web page: "Supports PIP(picture in picture) function. One for live and the other for captured program."

Looks like it only has one tuner.

Open Source PVR is not as simple as people think (5, Insightful)

noahbagels (177540) | more than 11 years ago | (#5138925)

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...

DUDE, I NAILED YOUR SISTER. POPPED HER CHERRY, TOO (-1)

Subject Line Troll (581198) | more than 11 years ago | (#5139051)

Re:Open Source PVR is not as simple as people thin (0)

Anonymous Coward | more than 11 years ago | (#5139073)

Interesting. I've seen a P3 450 with an All In Wonder 7500 running just fine. It has a few artifacts, but generally speaking it was never anything worse than watching one of the digital channels on my cable box.

The software is fairly cruddy, although useable, but there are some (non-free) solutions out there that are reported to work quite well. Also, the RF remote is a killer app, especially when combined with a wireless keyboard and gyro mouse.

How much RAM did the machine in question have? Im curious what could be causing the poor performance.

Re:Open Source PVR is not as simple as people thin (5, Insightful)

ChaosDiscord (4913) | more than 11 years ago | (#5139094)

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>)

I have often thought that BeOS (4, Interesting)

teamhasnoi (554944) | more than 11 years ago | (#5138939)

would be perfect for such a multitasking box. It's exactly what Beos was designed to do. Multiple video streams would most likely be cake to a low end Beos box.

I talked to some developers over at BeBits about the idea; one said that he had no interest in updating any of his Beos apps and that he had entirely moved over to Windows. (ugh)

The other was intrigued, but had far too much stuff going on already.

Any ideas? Anyone thought this too? I would dive on in, but I am a musician and left programming behind with Apple II basic...

P.S. Trolls: Oh yes, Beos is dead, what am I thinking, I should learn to code, I smell like cats, blahblahblah.

All I need is a Tivo with dual-outs or builtin pip (1)

asscroft (610290) | more than 11 years ago | (#5138954)

I have DirecTV with Tivo Dual Tuner, and it's great. I can watch two channels at the same time, and thanks to the built in buffer I get to scroll back in time and see what I missed. Great for sports. The problem is that I have a nice TV with dual video inputs that wants to run PIP, but the Tivo doesn't have dual outputs. If tivo were to either add dual outputs or make their own pip control I'd be living large. There are only a few times where I want to watch more than 2 channels at one time. It would only happen the one week when all 4 sports are happening at the same time. ESPN ESPN2 CBS ABC ESPN NEWS FOX SPORTS TBS WGN that's 8, I could see up to 12 for extreme fans, or if you buy one of those full court passes or NFL or NBA or what have you packages then maybe you'd want more.

Please help if ou can, be kind and kick its arse. (0, Offtopic)

PyroX_Pro (579695) | more than 11 years ago | (#5138955)

I know this is offtopic, but its the fastest way I can think of. Will everyone be so kind as to beat the hell out of my server: [pyroxpro.com] [pyroxpro.com] [pyroxpro.com] so I can get a quick stress test? I have no paid ads, or popups, or crap like that, just want slashdot effect stress tested. *PLEASE*

Next week on Ask Slashdot... (4, Funny)

orichter (60340) | more than 11 years ago | (#5138964)

orichter writes: does anyone know how, with a with a few minor adjustments, you turn a regular gun into five guns?

Ultimate TV (1)

Flamesplash (469287) | more than 11 years ago | (#5138966)

Doesn't Ultimate TV already do this, the multi channel that is. Get 2 and I'm sure you're still cheaper then 4 computers, though if you need to tape more than 2 channels I think you should really watch less tv

One-channel-first, please? (5, Insightful)

Tackhead (54550) | more than 11 years ago | (#5138976)

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.

How about multi-channel FM stereo recording? (1)

smcdow (114828) | more than 11 years ago | (#5138978)

I like this idea, except I want it for recording mult-channel FM stereo. That is, recording more than one FM station simultaneously.

There's a couple of good stations in Austin, and they both run shows that I'm interested in at the same time on Sunday.

So, I multi-channel FM stereo recorder would be a good thing.

careful... (1)

Mephie (582671) | more than 11 years ago | (#5138980)

ATI might sue you under the DMCA for using the terms "building" and "all-in-wonder" in the same sentence...

Insider's scoop: What Killed FreeBSD (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#5138983)

The End of FreeBSD

[ed. note: in the following text, former FreeBSD developer Mike Smith gives his reasons for abandoning FreeBSD]

When I stood for election to the FreeBSD core team nearly two years ago, many of you will recall that it was after a long series of debates during which I maintained that too much organisation, too many rules and too much formality would be a bad thing for the project.

Today, as I read the latest discussions on the future of the FreeBSD project, I see the same problem; a few new faces and many of the old going over the same tired arguments and suggesting variations on the same worthless schemes. Frankly I'm sick of it.

FreeBSD used to be fun. It used to be about doing things the right way. It used to be something that you could sink your teeth into when the mundane chores of programming for a living got you down. It was something cool and exciting; a way to spend your spare time on an endeavour you loved that was at the same time wholesome and worthwhile.

It's not anymore. It's about bylaws and committees and reports and milestones, telling others what to do and doing what you're told. It's about who can rant the longest or shout the loudest or mislead the most people into a bloc in order to legitimise doing what they think is best. Individuals notwithstanding, the project as a whole has lost track of where it's going, and has instead become obsessed with process and mechanics.

So I'm leaving core. I don't want to feel like I should be "doing something" about a project that has lost interest in having something done for it. I don't have the energy to fight what has clearly become a losing battle; I have a life to live and a job to keep, and I won't achieve any of the goals I personally consider worthwhile if I remain obligated to care for the project.

Discussion

I'm sure that I've offended some people already; I'm sure that by the time I'm done here, I'll have offended more. If you feel a need to play to the crowd in your replies rather than make a sincere effort to address the problems I'm discussing here, please do us the courtesy of playing your politics openly.

From a technical perspective, the project faces a set of challenges that significantly outstrips our ability to deliver. Some of the resources that we need to address these challenges are tied up in the fruitless metadiscussions that have raged since we made the mistake of electing officers. Others have left in disgust, or been driven out by the culture of abuse and distraction that has grown up since then. More may well remain available to recruitment, but while the project is busy infighting our chances for successful outreach are sorely diminished.

There's no simple solution to this. For the project to move forward, one or the other of the warring philosophies must win out; either the project returns to its laid-back roots and gets on with the work, or it transforms into a super-organised engineering project and executes a brilliant plan to deliver what, ultimately, we all know we want.

Whatever path is chosen, whatever balance is struck, the choosing and the striking are the important parts. The current indecision and endless conflict are incompatible with any sort of progress.

Trying to dissect the above is far beyond the scope of any parting shot, no matter how distended. All I can really ask of you all is to let go of the minutiae for a moment and take a look at the big picture. What is the ultimate goal here? How can we get there with as little overhead as possible? How would you like to be treated by your fellow travellers?

Shouts

To the Slashdot "BSD is dying" crowd - big deal. Death is part of the cycle; take a look at your soft, pallid bodies and consider that right this very moment, parts of you are dying. See? It's not so bad.

To the bulk of the FreeBSD committerbase and the developer community at large - keep your eyes on the real goals. It's when you get distracted by the politickers that they sideline you. The tireless work that you perform keeping the system clean and building is what provides the platform for the obsessives and the prima donnas to have their moments in the sun. In the end, we need you all; in order to go forwards we must first avoid going backwards.

To the paranoid conspiracy theorists - yes, I work for Apple too. No, my resignation wasn't on Steve's direct orders, or in any way related to work I'm doing, may do, may not do, or indeed what was in the tea I had at lunchtime today. It's about real problems that the project faces, real problems that the project has brought upon itself. You can't escape them by inventing excuses about outside influence, the problem stems from within.

To the politically obsessed - give it a break, if you can. No, the project isn't a lemonade stand anymore, but it's not a world-spanning corporate juggernaut either and some of the more grandiose visions going around are in need of a solid dose of reality. Keep it simple, stupid.

To the grandstanders, the prima donnas, and anyone that thinks that they can hold the project to ransom for their own agenda - give it a break, if you can. When the current core were elected, we took a conscious stand against vigorous sanctions, and some of you have exploited that. A new core is going to have to decide whether to repeat this mistake or get tough. I hope they learn from our errors.

Future

I started work on FreeBSD because it was fun. If I'm going to continue, it has to be fun again. There are things I still feel obligated to do, and with any luck I'll find the time to meet those obligations.

However I don't feel an obligation to get involved in the political mess the project is in right now. I tried, I burnt out. I don't feel that my efforts were worthwhile. So I won't be standing for election, I won't be shouting from the sidelines, and I probably won't vote in the next round of ballots.

You could say I'm packing up my toys. I'm not going home just yet, but I'm not going to play unless you can work out how to make the project somewhere fun to be again.

= Mike

--

To announce that there must be no criticism of the president, or that we are to stand by the president, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public. -- Theodore Roosevelt

FreeBSD is dying

Wow. That's a lotta TV. (1)

Fazlazen (626923) | more than 11 years ago | (#5138992)

Each machine needs to record 4 channels simultaneously. Taking a look [maxtor.com] at throughput requirements for storage, it looks like to record at "normal" TV speed, you're talking about 15 megabytes/sec in storage.

With needing nearly 4 gigabytes per hour of TV recorded at that rate, a 160 gigabyte HD would only yield 40 hours of recording time, or 10 hours per tuner card.

Writing to a HD at 60 MB/sec means that you're probably not going to be reading from it at the same time to watch something that you have previously recorded. Therefore, you're going to want to break this out into multiple IDE channels, perhaps one drive per channel.

Something seriously has to be asked here -- if you're recording 4 hours of TV per hour, when are you going to watch all the stuff? Even assuming that you're skipping commercials (turning a 30 minute program into a 22 minute program), you're still going to be falling behind at a good clip.

If you're doing that with four machines, 16 hours per hour of realtime, what the hell are you going to do with all the data? I think the editor has been trolled with this article.

Re:Wow. That's a lotta TV. (0)

Anonymous Coward | more than 11 years ago | (#5139054)

Something seriously has to be asked here -- if you're recording 4 hours of TV per hour, when are you going to watch all the stuff? Even assuming that you're skipping commercials (turning a 30 minute program into a 22 minute program), you're still going to be falling behind at a good clip. And thats a long time with no /. Can you handle that??

Replay TV would be a lot cheaper and better (0)

Anonymous Coward | more than 11 years ago | (#5138998)

There's no decent or even marginally workable channel guide software currently available for a "roll your own PVR". A PVR without good guide software is best a PITA and at worst a door stop.

I've researched it pretty thoroughly and both Replay TV and Tivo have the PC-based systems beat hands down. The only one that comes close is Microsoft's Media Center XP, and it's not scalable and is locked down to specific hardware. It won't meet your needs.

Your best and cheapest bet is to buy a few Replay TV 4k or 5k's. They locally network to each other, so you can each record a discrete video stream on each one and you can watch streams live from the other units. They share over the net, copy shows to PC, use your PC as storage space, burn to SVCD or DVD etc...

Buying a few Replay TV's is probably far cheaper than the parts cost of the custom unit you plan to build, not even counting your labor costs.

Once your labor costs are in there, there's no competition.

Hmmm (1)

radiumhahn (631215) | more than 11 years ago | (#5139003)

Interesting concept if it is being built for multicamera systems like security in vegas and to come in at a reduced cost.

My wish list... (1)

Whomp (46822) | more than 11 years ago | (#5139016)

...has for years included the "full bandwidth VCR", something that would basically record everything that's on the cable. Playing it back would allow you to change channels just like you were watching TV, just at a different time.

Maybe I just like being simple, but.... (1)

mao che minh (611166) | more than 11 years ago | (#5139019)

It would be cheaper to just live with a single PVR for day-to-day recording, and buy DVDs and/or VHS tapes of the content you want. You might not be able to catch all of your desired programs, and it might not be possible to order all of the content you miss on DVD or VHS, but it certaingly is more simplistic and cheaper then building a friggin cluster and hacking code in order to tape stuff off TV.

possibly viable, "off-the-top-of-my-head solution (0)

Anonymous Coward | more than 11 years ago | (#5139021)

1)new lindows boxes being sold at wall mart for $99 + 2)said mpeg capture cards + 3)bonded(coupled...?) ethernet connections for a virtual 500-1000mbps bandwidth = huzzah!! possibly cheaper than tivo pvr able to run open/free guideware, allowing tivo like ease of use, but the media sharing capabilities of a computer. oh yea, anyone know anything about proggress being made in "black box" emu's or descrambling algorithms??? last i checked the few ones that existed worked only for PAL signals(asian? european?), not NTSC. the signal format american cable providers and televisions transmit and recieve=(or is it the other way around...?). although unethical in many ways, for some this would make the homebrew solution a much more attractive alternative. i'm not suggesting or encouraging piracy or thievery, just pointing out reasons some may choose a diy option. also, is there anyone looking into uploading descrambling algorithms or emulators into tivos themselves? Just a few thoughts.

Galen

CPU Power (1)

nmg196 (184961) | more than 11 years ago | (#5139022)

Err, this may be a silly question, but where are you going to get the CPU power from to encode 4 video streams?

My 1Ghz Athlon is at 80% encoding HALF-frame video into MPEG4 and it drops seriously large numbers of frames if I try and encode at the native resolution (720x576 for UK PAL).

I tried using MPEG2 but that uses up seriously massive amounts of hard disk space, just to get it up to VHS standard.

Unless someone makes a hardware MPEG4 encoder, I can't see how you can easily encode 4 video streams at once unless they're done in a fairly low quality/resolution.

Nick...

Re:CPU Power (2, Informative)

geekoid (135745) | more than 11 years ago | (#5139053)

go to SCSI 160, use at least 3/4 G Ram.
Thats what I have in mine, and it record Native just fine.

More then one channel (2, Insightful)

geekoid (135745) | more than 11 years ago | (#5139025)

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.

in Germany (0)

Anonymous Coward | more than 11 years ago | (#5139027)

in Germany we have mostly digital tv. And many people use "dbox2"-type SetTopBoxes. We put Linux on them, and they have an ethernet interface so u can directly record anything u want at a touch of a button. Of course directly taken after the demuxer. Mpeg Cards is a pain in the ass, tv today should be(is) digital, and so no digitizing and recompressing (both means quality loss) is needed.

a perfect combination here would be a dbox2+linux and an xbox+linux. record all u want, play all u want.

VDR + NFS (0)

Anonymous Coward | more than 11 years ago | (#5139039)

To save some money, I would use 4x diskless PCs connected each to a dedicated 100MBit card in a central NFS server with lots of disk space.

Put up to three none-MPEG DVB-S card (if you are lucky enough to be able to use that) in there, a single DVB-S card with MPEG decord, and be done with it.

Also, you will need some switches for your digital signals to be distributed to each of the DVB-S cards.

Oh, before I forget: Get a live. Why 16 programs add once?

Multimedia Surveillance/Security systems (0)

Anonymous Coward | more than 11 years ago | (#5139062)

Check out Taiwanese vendor http://www.provideo.com.tw/ . They sell a variety of video capture PCI boards and USB boxes. They have surveillance systems that use single or multiple PCI cards to monitor and capture up to 16 sources simultaneously. They also have a new four-port MPEG-4 based PCI capture card that they claim supports Linux. However I don't think these boards include tuners, just line inputs, so you would need an external source to do all the channel tuning.

Record signal before it gets to the tuner (1)

peter hoffman (2017) | more than 11 years ago | (#5139063)

I seem to remember reading about a guy who was recording the signal before it got to the tuner. Then he played it back into the tuner and selected the show he wanted to watch. He had recorded all the available channels at once.

I read about this a long time ago. Probably back in the 1970s because I think it was when VCRs were coming out and the idea of recording a show was a new idea.

Streaming video (1)

matt_wilts (249194) | more than 11 years ago | (#5139064)

One reason I can think that you might need this many channels would be if you were streaming a feed to a corporate or dorm LAN. OK, so the poster didn't mention streaming they mentioned PVR, but lots of people are asking "why do you need that many?". Well, that's a reason.
Now, can anyone point me towards a decent media streaming solution for Linux please? (I'm serious!)
Thanks, Matt

You'd probably want at least 2 computers for noise (1)

sprior (249994) | more than 11 years ago | (#5139074)

If you want multiple program capability you'd probably need multiple hard drives whether they're in one "superbox" or a cluster. Because of this you might want to have one machine possibly without a hard drive as the piece that sits under the TV and provides the user interface and is networked to the cluster or superbox located in the basement or closet.

That way your fans/hard drives aren't drowning out your soaps.

so basically what you want... (1)

jrstewart (46866) | more than 11 years ago | (#5139077)

...is a Beowulf cluster of PVRs?

sorry, but it had to be said.

Maybe he wants distributed capture (4, Interesting)

t0qer (230538) | more than 11 years ago | (#5139084)

I've read all the comments about the limitations on the PCI bus, basically there's no way around the lack of bandwidth.

What if he wanted to do distributed capture though?

Think about it, you have 4 machines capturing alternating frames. Machine 1 does frame 1,5,9 machine 2 does 2,6,10, machine 3 does 3,7,11 ect.

This thought occurred to me last night while doing some kazaa downloading. Maybe a better P2p capture system would involve each client downloading 1 frame per movie, and sharing that with the world. The clients could assemble the movie from a distributed network, much like a frame server does in premiere.

The real advantage to doing this would be movies that are stored in a lossless format.

Here's a thought... (0)

Anonymous Coward | more than 11 years ago | (#5139089)

Get a life.

VDR (1)

elrond1999 (88166) | more than 11 years ago | (#5139090)

There is one Project that realy delivers PVR to linux. Video Disk Recorder (http://www.cadsoft.de/people/kls/vdr/) is aimed at people with DVB satelite or terrestial cards. The DVB cards also have a very nice open source driver :) The cards them self are rather expensive for now, but the "budget" cards (without the tv-out and mpeg2 decoder) is around $150. VDR can easily control 3 or more DVB cards and automaticaly choose which can recieve a timed recording. It can even pause live TV with a single DVB-S card (Something the windows version of the DVB software can't :) Electronic Program Guide is integrated. You do need a big hard drive tho as the recordings are in DVD quality. They can be converted into SVCD or DivX after they have been recorded of course.

More on the DVB cards: http://www2.arnes.si/~mthale1/dvb_english.html
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