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  1. Member
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    I've got a question that's been floating around in my head for a few years. I realize it is the ignorance of data formats and such, but I figured if anyone could tell me why this is not possible, some of ya'll could.

    Why can't you capture, in some way, the raw data stream coming off of a DSS dish BEFORE it goes into the reciever? Then pump the captured stream through a reciever to decode it effectively recording all channels at once.

    I know this can't be possible, otherwise it would have been done because it's so obvious.

    If anyone could give me some kind of idea so I could let this die in my head, I sure would appreciate it. Thank you very much.

    Kyle
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  2. There are many reasons why it's not possible. Some of them I can think of are:

    * There isn't any bridge or connection that can take the signals off a typical RG6 cable to a computer.

    * With the amount of data that every channel takes up, you could fill a 120Gb drive in a matter of seconds. That would be contigent on having a data connection that's capable of feeding that much data at once and having a computer that could handle that.

    * Those signals are encrypted. The receiver, along with the smart card or decryption mechanism (DCII or Nagravision, depending on the satellite distributor).

    I'm sure there are many other reasons that I haven't thought of yet.
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  3. Banned
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    That's not necessarily true

    The question was asked in an isssue of 2600 journal, and the data rate was more on the order of, I think, will dig it out, 100 gigs for 8 hours.

    The problem the writer had was what you would use for an input You can connect coax to a vid card, but apparently the signal is unrecognizable, so not captureable.

    I had the dish and was going to try it, but Comcast kinda coerced me into going cable TV or paying 15 more for internet.

    I do know my cap card will see the non-digital channels, but not the digitals, as I have it split before the box and can view 2 channels at the same time, but only the box shows the digitals.
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  4. Video Restorer lordsmurf's Avatar
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    This post is already discussing digital satellite capture. I suggest reading this one.

    https://www.videohelp.com/forum/viewtopic.php?t=181249
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    Lordsmurf,

    Look more closely at the first post and compare to the other.

    This one is about recording the whole data stream, basically a time shift of the whole day's programming, then feeding it back through the Dish box as though it were the sat feed.

    Someone, somewhere on the forum, had mentioned the data rates of the different downfeeds, and they were nowhere near the gigabytes per second in the post above, actually quite low for the percieved quality of the displayed movie/show.

    I don't recall if it was you, BJ_M, SaSi, Satstorm, one of you. Remember?

    Cheers,

    George
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  6. Video Restorer lordsmurf's Avatar
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    What on earth would they do with the whole stream? That's not even video data. The whole stream is huge, full of sub info, guide info, etc etc. A full day would be several hundred GB at minimum.

    In terms of video data only, I see little difference between the two threads.
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  7. A simplified explanation on data rate. DTV has a license for 32 transponder frequencies from the 101W orbital position. Max data rate per transponder is 30.3 mb/sec. Therefore you would need to capture at that data rate. (Add in the other sat positions and it gets bigger)

    As others have indicated, you can't do anything with this data unless you could figure out how to play it back into a sat receiver and decrypt the signal.
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  8. Video Restorer lordsmurf's Avatar
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    And there are three satellites. And don't forget the spot beams! Yikes. Hope this person has a multi-terabyte computer. Each channel would only take a few hundred GB. Each transponder has dozens of channels.
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  9. Originally Posted by gmatov
    they were nowhere near the gigabytes per second in the post above, actually quite low for the percieved quality of the displayed movie/show.
    But he said that he wants to know if it would be possible to record all channels at once. If you have 400 channels, that's a lot of data to push through at a time, plus it's constantly streaming, so there's no end to it.
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    Originally Posted by SatStorm
    4.000 KB/s can support much higher resolutions than 352 X 576/480! Just imagine that most of the DVB transmissions are about 544 X 576 @ 3550kb/s!

    The best bitrate (in the book) for CVD is 2300kb/s, but the encoders we use are not that good (even CCE...), so you need more bitrate for good picture. 2520 kb/s still ain't enough (unfortunatelly) if you use TMPGenc and the source is a bad VHS. If you use CCE you eliminate a bit the noise, but still isn't "block - free" in action/moving scenes.
    Based on my tests and what I see in DVB transmissions, I could say straight that the best choice (with today's technology) is about 3100kb/s for a resolution like 352 X 576/480. But this is far away CVD, so we talking for xCVD here.

    If you live in Europe and recieve Hotbird satellite, then you can easily see how 352 X 576 is capable to show on your screen, if you have the pro hardware. There is a full digital Italian music channel, with the name "102.5 Hit channel" (Freq: 11623V, S.R.: 27.500, F.E.C.: 3/4). This channel transmits 352 X 576 @ 3100kb/s and looks amazing! No blocks, perfect picture, amazing sharpness! They spent a lot of ???? in hardware so it is the perfect example for this! I never succeed that quality in any of my encodings!

    For 1/2 D1 DVD (a format we gonna play a lot in the VERY near future), my best settings are 1900 min - 3100 average- 4400 max.
    CVD as you see is 600kb/s less average than this, so don't expect perfection....
    Lordsmurf,

    You guys are jumping on me for making a comment saying that it should be possible to download the entire sat stream

    I don't know what kind of input you would need, but if there is one, then surely there is the reverse, an output, which you would feed into the dish box, exactly as the sat dish itself does. If your dish is "authorized" to recieve the channel in the first place, it should decode-decipher, whatever, the feed from your output device.

    Satstorms bitrate of 3100kbps for a superb pic seems to argue that other feeds are less than this, due to compression or whatever..

    If Cat 5 can handle 100 mbps, that would be about 33 of thosse video data streams, and we know Cat 5 is not the fastest there is, ie gigabit ethernet, optical fibre, whatever. By the same token, the RG 59 or 6 coax from the dish to the reciever is carrying all the signals simultaneously, so the wire will handle it

    This would simply be an all day time shift. Watch your 3 o'clock movie, watch your 3 o'clock Oprah, go back and watch your 3 o'clock MTV

    I don't have the smarts for this but I'm sure some of the other members could say whether it is possible or not, rather than just snicker and say "What an ******* idea, you'd need googlebytes just to record the noon news!"

    Thnk about it rather than just snicker. I'm sure some of you guys have the tech smarts to figure this out if you approach it with an open mind instead of an "It can't be did.."

    Cheers,

    George

    Aside: Lordsmurf, I'll get back to you one of these days; I'm a put offer.
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  11. Video Restorer lordsmurf's Avatar
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    Originally Posted by gmatov
    You guys are jumping on me for making a comment saying that it should be possible to download the entire sat stream
    Hmm. I don't think I made it seem that way, as I certianly didn't mean for it to be.

    The problem is that the datastream is huge. I mean, HUGE! It is always beamed. You can only zero in on some of it. Ever notice how the receiver waits a second or so for the channel to come in? Or how it makes you wait for the guide? Especially if you try to go hours ahead?

    Well, it's because you are finally calling it up. You are only getting that ONE channel worth of data (and supplements of the stream as needed) and even then, the info is discarded as soon as it is shown. It is not saved, but rather processed, shown and dumped.

    The boxes are hot to the touch because the CPU and chips are ALWAYS on (the off button just control the video input/output, only unplugging the receiver powers it down).

    If you tried to save the data of that one channel selected on the receiver, it would arrive at a size and pace faster than the computer could write. Especially not the whole stream. Even the upload center never writes the data to disc. It's all on-the-fly encodes and transmission. This is fine since chips and RAM and hardware operate faster than a drive could ever write (at this time).

    So is it possible? Sure. Going to Mars is possible (I'm not trying to be mean). But it's not likely, at least not with the equipment we have now.

    And I mean this in the nicest possible way.

    Does this make more sense now?
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    Lordsmurf,

    I gotta disagree with you. I may be wrong, but you do NOT have a choice of what is downstreamed. The entire output of the sat is beamed down,and only the auth on your particular card says you can decrypt this or that.

    True, the data stream is huge, but, Jesus, man, we have 3 gig + comps today, they can't keep up?

    I say again, gigabit ethernet. Gigs per second can't handle it? They keep the good stuff for the 2 or 3 companies that can, by their estimate, use it?

    No, if there is a tech developed, they try to sell to the early adopter, for a premium price.
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  13. Video Restorer lordsmurf's Avatar
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    It's similar to the radio...
    All the stations are always there...
    But you can only tune in to one at them at a time...

    The data is be blasted through the air. And while the radio can get them all, it's not necessarily being forced to get all of them all at once.

    It's not so much your choice as much as it is the ability of the machine to only do one thing at a time. Again, the delays in the receiver are because it is acquiring the information from the datastream. It does not and cannot assimilate all that data at once. It's only a 32-bit CPU, and even a 64-bit CPU could not handle all of that at once. Even the uplink centers have dozens of specialized hardware systems (vaguley similar to computers) that upload the datastream to the satellite.

    The computer can keep up just fine with fast data processing, up to a point. Remember, this must be done real-time. It's the writing to a drive that cannot. Using data and storing data are different concepts. It doesn't have to be stored to be used. That's in effect what takes place with satellite tv. Large amount of data in use, none of it being saved (except updates to the Wink or the EEPROM in the CAM).

    Even hackers that download the datastream can only access the non-video parts of it (and it fill up systems quickly even at that). Adding the audio and video would fail.
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    Lordsmurf,

    I'm sorry, I just replied to the crux of your reply, no attention to the rest of it
    I don't get your comment about the data stream being more than a modern comp can handle

    It's as though you are saying we are still limited to a 16 meg buss, we can only write at X meg per sec.

    I don't know what CPU is in a dish box. I doubt it is a 3gigahertz, you should have NO delay in a lineup request

    My 8 year old box took some time to give you the data. My cable takes a few seconds to give you the data, also.

    Dish iss a one way deal You do NOT transmit to the sat and say what is on.


    This IS what is ON, and this, or a PPV IS what you may watch.
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  15. Video Restorer lordsmurf's Avatar
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    Originally Posted by gmatov
    Dish iss a one way deal You do NOT transmit to the sat and say what is on.
    Absolutely. You have no say. It all comes to you. But your box can only zero in on the information you request. You're not asking the satellite anything. It's information overload. You're telling the receiver which piece of data to look at. Because all the information is arranged neatly like a file cabinet, it goes right for the folder (channel, guide, whatever) that you request.

    It took countless systems to uplink the data, so understand it would take countless system to download all of it. One machine cannot handle all of the information all at once, nor do hard drives exist that can write that amount of data that fast. We are talking many terabytes per per day when you talk about all 800 or so channels on the box (yes, even if you do not pay to get them, they are beamed to you - it's you card that unlocks them, again part of the datastream).
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  16. krg765

    to answer your specific question - yes this can be done, yes the commerical/military grade equipmrnt is available - no you probably cannt afford it. search the web for companies that make wideband recievers/recorders. i am no longer close enough to this industry to give specific recommendations but watcom is one company that comes to mind.
    watch the military surplus sites, as some of this kind of equipment will show up from time to time.

    regards
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    Thanks to all you guys for enlightening me on the subject. Like I said, I was just curious if it could be done. I don't really have a reason to do it, other than the fact that I think it would be cool. More of just a curiosity. I knew if anyone would know, it would be you guys. Thanks again.

    Kyle
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  18. Sat. TV isn't extremely high quality anyway, just better than cable.

    You'll see pixelation if you get close to the TV (provided its more than a 9" tv)
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  19. All I know that the data stream sent to the box is encrypted mpeg...now I could imagin how much space it will take to save on my comp a 1 houre program in good quallity mpeg... so I agree with the ppl before me that for now its quite impossible to capture and save the hole data from all of the channels sent on that stream in a PC or any other home computer.
    and its kind of useless all that data anyway.

    but i'm interested in this subject and i've heard its possible to use the computer insted of the digital/satalite box and capture the stream data on to the comp as flowing data like the box does, and watch it, and have the option to save 1 channel's data. I would like to know if that is possible and if its simple and cheap enough for me to do it
    You are what you iS
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  20. I believe the processors are very slow in the PVRs that are out... I seem to recall mine are under 100 Mhz, and I heard that the new series two Tivo runs at 200 Mhz. And to go further I seem to recall that series 1 Tivos have 16 Mb ram

    How can they do it? It's all dedicated silicon that does the work. Decoding , encrypting encoding etc.

    The problem you would run into capturing an entire data stream would be getting it onto the drives without loss.

    SO could it be done, yes affordably no. Only if money were no object.

    Cheers
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  21. Member nick101181's Avatar
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    I have an idea and I'm wondering if it's possible. I saw on some website a r6 to cat5 adapter( it even said watch video thru cat-5). So if i can send the video from the Sat reciever out thru an r6 cable with the adapter directly into my network card, Could I capture some dtv streams? My cpu is not fast enough for a good enough mpeg2 capture so could this be done ?
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    In a nutshell. All data does not go to a receiver all the time. when you tune to a station, it will go to a certain trasponder and sat. this will give you the feed for that channel. Yes I am sure there is something out there that is too much money and probley illegal. A data logger will let you do it by the channel . A DVI, hooked to a HD box will feed into your computer one channel at a time .Hope this helps.
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