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HDTV via GNU Radio

Posted by michael on from the giddy-with-anticipation dept.

NortonDC writes "High Definition TV has been successfully captured in its native data stream from an over the air broadcast by a software defined radio that is Free and open source from the GNU Software Defined Radio project."

52 of 306 comments (clear)

  1. Oh great. by Big+Mark · · Score: 5, Funny

    GNU TV, where the scripts are open-sourced before the show airs and you know all the jokes before the intro starts rolling.

    Mind you, if you knew when to cringe in Nerds (the competitor to Friends, where housebound geeks spend their days in an eternal LAN party with the occasional visit to the pizza parlour) at the "jokes", it mightn't be so bad...

    -Mark

    1. Re:Oh great. by Fulcrum+of+Evil · · Score: 5, Insightful

      GNU TV, where the scripts are open-sourced before the show airs and you know all the jokes before the intro starts rolling.

      How is different from network tv, where the scripts are rehashes of something from 10 or 20 years ago and you know the entire plot (painful jokes included) in the first two minutes.

      --
      "We returned the General to El Salvador, or maybe Guatemala, it's difficult to tell from 10,000 feet"
    2. Re:Oh great. by generic-man · · Score: 3, Funny

      GNU TV would feature some of the funniest shows on television, powered by the Internet's funniest humor archive.

      --
      For more information, click here.
  2. hmmm by Anonymous Coward · · Score: 5, Insightful

    Sounds too useful to exist.

    It will taste the blade of DMCA before the end of the month.

    1. Re:hmmm by DoraLives · · Score: 3, Insightful
      It will taste the blade of DMCA before the end of the month.

      Which ordinarily might goad myself and others to scramble around and get it before the lid gets clamped down good and tight.

      Except for one small problem.

      When all is said and done, you're receiving television.

      Never mind.

      --
      Is it fascism yet?
  3. Cool, but..... so? by AvantLegion · · Score: 5, Funny

    Why am I looking at 4MB images of Lenny Briscoe?

  4. GNU/Correction by Amsterdam+Vallon · · Score: 3, Funny

    "GNU/High GNU/Definition GNU/TV GNU/has GNU/been GNU/successfully GNU/captured GNU/in GNU/its GNU/native GNU/data GNU/stream GNU/from GNU/an GNU/over GNU/the GNU/air GNU/broadcast GNU/by GNU/software GNU/defined GNU/radio GNU/that GNU/is GNU/Free GNU/and GNU/open GNU/source GNU/from GNU/the GNU/GNU GNU/Software GNU/Defined GNU/Radio GNU/project."

    --

    Reply or e-mail; don't vaguely moderate. Ex-O'Reilly/MIT employee, now a full-time Google employee.
    1. Re:GNU/Correction by u38cg · · Score: 4, Funny

      Gnu are not gnu/funny.

      --
      [FUCK BETA]
  5. Totally 1337 stuff by Amsterdam+Vallon · · Score: 3, Informative

    Here is the entire collection of mailing list conversations for the entirety of this project's lifetime.

    You can see how tough roadblocks were overcome by a dedicated and brilliant team of GNU coders.

    --

    Reply or e-mail; don't vaguely moderate. Ex-O'Reilly/MIT employee, now a full-time Google employee.
  6. Aspect ratio? by Anonymous Coward · · Score: 5, Interesting

    HDTV is either 1920x1080 (1080i) or 1280x720 (720p). Where did the 2730x1088 resolution come from? It's obviously wrong (the images are obviously scrunched vertically).

  7. resolition by Anonymous Coward · · Score: 3, Interesting

    Why does the image exceed 1920x1080? Isn't the highest HDTV resolution 1080p?

    1. Re:resolition by blair1q · · Score: 3, Funny


      Because they're receiving it from the future.

  8. What? by ziplux · · Score: 3, Interesting

    Is anyone else really confused about what has been accomplished here? What does GNU Radio do? The site's not too helpful.

    1. Re:What? by MBCook · · Score: 4, Interesting

      If I am reading it correctly, they used a special radio card under Linux to capture radio waves. Then they ran those waves through a piece of software that could decode them into video, because the waves they tuned into were an HDTV broadcast. The difference here is that they simply record the wave, it's not decoded in hardware. This way they can ues the same card to get FM, AM, HDTV, VHF, UHF, or whatever (in theory). Anyone actually know the answer to this question?

      --
      Comment forecast: Bits of genius surrounded by a sea of mediocrity.
    2. Re:What? by sulli · · Score: 4, Informative

      My understanding is that it is a fight against copy protection. Open (Free) software defined radio means that the user can pull down any (unencrypted) broadcast and save it - whether or not the "broadcast flag" (no-copy bit) has been used. In a future in which hardware televisions can't save copies of anything, this will allow the user to save copies and play back later (or do anything else) on a future PC or TiVo. Good stuff.

      --

      sulli
      RTFJ.
    3. Re:What? by josecanuc · · Score: 5, Informative

      It's not so much a special radio card as it is just any wide-banded data acquisition board and a little frequency-translation unit.

      There is a "tuner" that multiplies the incoming radio signals by a variable frequency. When you mix two oscillating signals (by multiplication) you get harmonics. If the variable frequency is just a sine wave (i.e., not modulated with any information), then the harmonics are identical in modulation to the original, but at a difference frequency. The tuning box is used to bring various radio signals down to a frequency that can be digitized by any ordinary data acquisition board.

      These data acquisition boards are designed to basically sample voltages of whatever is tied to their inputs, and to sample it very very quickly and very often. Since these boards (and computers also) are getting more advanced (i.e. faster), they are able to sample real radio frequencies (stuff in the ones of MHz ranges).

      After you get the signal digitized, it's just a simple matter of writing software that mathematically performs the functions that all the circuitry in the 'old-fashioned' receivers would do with their capacitors, resistors, and inductors (and more).

      That's pretty much how it works.

    4. Re:What? by NortonDC · · Score: 3, Interesting

      Explanation: What that means is that there is now a free-of-charge and user modifiable software system that can, in combination with hardware built to a freely available specification, use a normal personal computer to recieve and save bit for bit copies of the high definition television signals already being beamed out by broadcasters. That means you can create perfect copies, with color, fidelity and detail that far outstrips what you are used to from standard television or even direct broadcast satellite (like DirecTV), and use them at your convenience and in the full range of uses allowed under fair use, the legal doctrine that gives you considerable freedom to save, copy and even distribute copyrighted materials.

      In the long term fight for the maintenance of fair use against the MPAA and the RIAA, it's a very big deal. It's the DeCSS of HDTV.

      The current industry/legislature proposals do not lean on encryption, but on a "broadcast flag" that tags broadcast content with what level of freedom viewers have to capture, caopy, manipulate and distribute the broadcast material, with all of the available restrictions imposed at the whim of the broadcaster, to be enforced in the receiver.

      Wanna guess what the defaults would be like?

      Wouldn't it be nice to have an open, non-proprietary receiver that you have intimate control over?

      --

      Tastes Like Chicken
    5. Re:What? by Qzukk · · Score: 4, Informative

      It could be used for that (assuming you have a way to rebroadcast the signal later? Without the FCC hunting your signal down?), but the purpose of the software is to provide signal-processing software targeted at radio signal processing. If that signal is an HDTV signal, than so be it, but it could just as easily be X-Ray signals from space (assuming your sampling device could capture them) or some AM Radio talk show.

      If you look at the site you can see a number of other examples. Since you are no longer limited by a standard radio's hardware, you can do completely different stuff like receive two different frequencies at the same time.

      --
      If I have been able to see further than others, it is because I bought a pair of binoculars.
    6. Re:What? by Guppy06 · · Score: 3, Informative

      "It's the DeCSS of HDTV."

      Ehh... not quite. As I understand it, the standard is about copying/storing the radio transmission as-is, with no decoding of anything. It would leave any HDCP/"broadcast flags" (if present) in tact.

      This is less DeCSS and more copying DVDs bit-by-bit. You'll still need a decoder.

    7. Re:What? by wowbagger · · Score: 5, Informative

      A few nitpicks:

      You don't get harmonics (frequencies that are related to the fundimental by an integer multiple), you get mixing products, also known as "sum and difference".

      You get harmonics when you feed a single signal into a non-linear element - feed f1 in, get f1, 2*f1, 3*f1, 4*f1,... out. This is commonly used in tranmsitters to allow the use of a lower-frequency crystal to generate higher frequency carriers - you use a 10 MHz crystal, and the feed it into a non-linear element such as a squaring amp, and pick off the tenth harmonic to get 100 MHz.

      Mixing involves feeding 2 signals f1 and f2 into a multiplier - you get f1, f2, f1-f2, and f1+f2 out. Mixing allows changing a frequency by a non-integer relationship. You have heard this used in the voice distorters used on TV to mask mob informants - they mix the person's voice with a low-frequency signal to change the pitch of the speaker's voice. This is also the basis of any modern superheterodyne receiver - you mix two different (heterogenous) signals together.

      The idea is to take the signal from whatever frequency it is on, and move it to the frequency you have designed your circuit to work at - an "intermediate frequency", or IF. You then filter the signal, amplify it to a specified level, and repeat as necessary to get the signal where you want it. For example, a standard FM radio might go from the broadcast frequency to a 10.7 MHz first IF, then to a 455 kHz second IF, then finally to the FM detector circuit.

      Eventually, in a design like GnuRadio, you sample the signal. The tricky bit is you have to sample at a frequency not less than twice the highest bandwidth in the signal (Nyquist's criterion). For a 6MHz wide TV signal, that means you need to sample at not less than 12 million samples per second.

      Then, for a system like HDTV, you are dealing with a complex signal - and I mean complex as in sqrt(-1), not just as in "not simple" - you need both the real (in-phase, or I signal - the "real" part) and the quadrature (out-of-phase, or Q signal - the imaginary part). The signal is 8VSB - eight level vestigial sideband. So you have to do carrier recovery and tracking (because the carrier itself was removed - that is what makes it a sideband signal), then you have to convert the signals from the analog RF signal into one of 8 levels (slicing is the technical term). However, you have to slice accurately in 2 dimensions - you have to slice at the correct level (is .7 volts a 6 or a 5?), and you have to slice at the correct time (the symbols are only defined at certain times - any other time the signal isn't valid, it is a blend of the current and the (next|previous) symbol - what is called inter-symbol interference or ISI). So you have to do symbol tracking - figuring out when to sample, and at what levels to slice.

      Finally, once you have a symbol stream, you then have to do all the foward error correction - you have to de-interleave the signal (think of unshuffling a deck of cards) - interleaving is done so that a transient interference (like a lightning strike) doesn't scramble adjacent bits - the errors are spread out.

      Then you do your block error correction - this can undo a small number of bit errors per block (again, that's why you interleave the signal: so that block error correction needs to only correct a few bit errors per block).

      Then you do some more protocol recovery, and you have an MPEG stream.

      Normally, you do this sort of stuff with a big FPGA or an ASIC. The GnuRadio folks are doing it in software. The up side is that you can more easily tweak the code. The downside is that you are not going to be real-time for a few more iterations of Moore's "Law".

      What gets to be REALLY fun is when, in addition to all of the above, you have to compute parametrics on the signal - not just recover the bits, but measure how far out of ideal the signal was (that's the sort of stuff I do for a living.) When you do that, you have to do all of the above, THEN once you have an error corrected bit stream you have to regenerate an ideal signal and compare the received signal against it, and measure how far away from the ideal signal the real signal is.

      And THAT is when you start using multi-GHz processors, 10 million gate FPGAs, big-ass DSPs, and all sorts of other fun stuff.

      --
      www.eFax.com are spammers
    8. Re:What? by wowbagger · · Score: 3, Informative

      Yes, basically what you need is a tuner, a digitizer, and enough CPU to do the job. The last one can be the killer, though.

      Here's how you can receive multiple signals at once with one tuner - let's pick on ordinary FM, and let's say I want to receive 95.1 MHz and 96.3 MHz.

      The first requirement is that the two signals in question have to be reasonably close in strength - if one signal is coming in at -60 dBm (one millionth of a milliwatt) and the other at -120 dBm (one millionth of one millionth of a milliwatt) it's not going to work. But let's say both signals are coming in at -100 dBm, so there isn't a problem there.

      OK, so what I do is make a receiver that will amplify all signals around 95.7 Mhz (half-way between the two) and downshift that to a convenient IF, say 10.7 MHz. Ideally, I'd want to bandwidth limit the signal to about 1.5 Mhz - that way I get both the signals I want, and not much else.

      So my receiver is now outputting a signal at 0 dBm (1 milliwatt). If I look at that signal on my spectrum analzyer, I see 2 peaks - one at 10.1 MHz (the signal that used to be 95.1 Mhz), and one at 11.6 Mhz (the signal that used to be at 96.3 Mhz).

      OK, now I digitize the signal. I need to sample at more than 3 Msample/sec (Nyquist's criterion) - any less and the two signals will be "folded" into one, and it's game over. To keep it simple, I will digitize the signal at 40 MSample/sec.

      Now, I have a bitstream that contains the information for both signals. First, I multiply the signal by a mathematically generated cosine and sine wave at 10.1 MHz. This will give me two signals - I and Q. I is the "in phase" signal - the product of the cosine signal and the digitized signal. Q is the "quadrature" signal - it is 90 degrees, or a quarter circle out of phase with "in phase" signal (hence the name quadrature).

      Next, I lowpass the signal - I run I and Q through a digital filter that removes all frequency components above 75 KHz.

      Now, I compute a four-quadrant arctan() on the I and Q filters - this gives me the phase angle of the signal. I then differentiate that signal - subtract each sample from the previous sample. That gives me the instantanious frequency of the 95.1 MHz carrier - and there's your audio (if you want stereo I have to go trhough a few more steps....)

      Now, I do the exact same thing, except this time I use a mathematically generated 11.6 MHz cosine/sine wave. The end result is the 96.3 MHz signal.

      Now, as you can guess, that's a lot of math. Hoever, there are chips that do all of that for you. The Intersil 50216 I keep mentioning has 4 independant sections, each of which will do all of those steps, on a 40 MHz signal (or faster), in real time. If you do the math, the chip works out to about 5 to 10 billion operations a second, for 10 watts.

      Chips like the 50216 are used by cellular folks - the idea is they grab the entire cellular band, digitize it, and the pull the calls out of the mix. You have only 1 drify, nasty analog receiver section, and hundreds of nice, stable digital sections.

      There are a few problems with this approach, however:

      1) The wider the receiver, the more noise it picks up. A receiver that is listening to 1 MHz of the spectrum picks up roughtly ten times as much noise as a receiver listening to 100 kHz of spectrum. That extra noise limits what you can tune in.
      2) Strong signals in your receiver's bandwidth will prevent you from hearing weak signals - this is called "desense". It's one of the things that makes CDMA and TDMA cellular harder to do than dumb old AMPS - a phone near the tower has to be told to speak softly, so that the tower can hear distant phones.
      3) Faster is harder - digitizing a 455 kHz IF is dirt cheap. Digitizing a 10.7 MHz IF is harder. Digitizing a 100 MHz IF to be able to cover the whole cell band is a bitch.

      --
      www.eFax.com are spammers
  9. Neato.. by josh+crawley · · Score: 4, Informative

    Seems really neat, but I found that card on a science site. ONLY 1000 pounds (Great Britan). I suspect that this isn't much cheaper in the US either ;-(

    https://directory.adeptscience.co.uk/controller. js p?action=GetProduct&pid=91&sid=1

  10. Those aspect ratios are off. by kalgen · · Score: 5, Interesting

    The images on the site are at 2740x1088 resolution, but HDTV at max resolution is 1920x1080. You can tell from looking at the images that they're horizontally stretched, so something weird is going on.

  11. Nice by sulli · · Score: 3, Funny

    But will they implement the Broadcast Flag?

    --

    sulli
    RTFJ.
  12. Good And Bad by sidespace · · Score: 5, Interesting

    A Linux-friendly HDTV recording solution is definitely needed. Unfortunately, it seems that in order to record HDTV you need a $1300 Analog Input Board.

    Can anyone with more knowledge about this project please post a less expensive solution if one exists?

    1. Re:Good And Bad by Maxwell · · Score: 3, Informative

      The 20Mhz is the killer thing here. That is some Serious converting. Your Cd player converts DA 16bits at 44khz. A high end studio type- audio card does 24bits at 96khz, in either direction.

      This thing is doing 12bits at 20,000khz. Holy crap. That is hauling ass, hope your damn good with a sauldering iron !

      JON

  13. Re:Cool by Thing+1 · · Score: 4, Informative
    Can I FTP the second season of west wing yet? No? Okay then

    You can get many TV shows you might have missed by using BitTorrent .

    This site has a list of links to various sites which contain TV shows available through BitTorrent.

    A West Wing episode is available here (The West Wing - s04e16 - California 47th [ftv].mpg.torrent) (but you need to have installed BitTorrent prior to clicking on that link).

    I don't follow West Wing so I don't know whether that's from second season, and your comment is accurate -- that's the only one available from that site. One other is The.West.Wing.S04E14.Inauguration.Day.Part.I .

    Enjoy!

    --
    I feel fantastic, and I'm still alive.
  14. Top 5 reasons to process HDTV signals on your PC by Amsterdam+Vallon · · Score: 4, Funny

    5 -- You think a $3,500 computer with a 17 inch monitor is better than a $2,000 HDTV set with a 35 inch screen

    4 -- You wanna take screenshots of Joe Millionaire and set them as your desktop wallpaper

    3 -- You're unemployed and have nothing else to do aside from incessant blogging

    2 -- Regular TV is _so_ '90s.

    1 -- Record Cinemax skin flicks as part of the Masturbate For Peace campaign

    Courtesy of The *nix Top 5

    --

    Reply or e-mail; don't vaguely moderate. Ex-O'Reilly/MIT employee, now a full-time Google employee.
  15. Cost: $1,299.00 by jdclucidly · · Score: 4, Informative

    At $1,299.00 for the PCI card that their driver is written for, I do not see this in my future. For that matter, I don't see that in the future of many hobbiests which makes this project rather useless to the general population at present.

    See here for information on the product the GNU Radio project wrote the driver for: Measurement Computing

    Maybe some day...

    1. Re:Cost: $1,299.00 by cybermace5 · · Score: 4, Insightful

      By taking this defeatist attitude, you are creating a self-fulfilling prophecy.

      The card is $1,300. The reason is economics: people do not buy them in mass quantities, therefore they are rare and expensive. These cards are typically used in fringe high-tech situations, and honestly $1,300 is an awfully good deal considering what the same capabilities would have cost five or ten years ago.

      If the card is already down to $1,300, instead of $13,000 or $130,000, the price can be reduced to $130. Once software radio becomes a demanded product, the push to increase production will make the cards more available.

      Again, if you want to play around with cutting-edge tech, the card is pretty inexpensive. I've been dealing with high-speed video vendors who want $60,000 for essentially an overclocked VCR. And that's half of what they cost ten years ago.

      These guys have done something few are able to do: take an idea and actually follow it to completion. The first personal computers weren't cheap enough to give away in cereal boxes either, so give this some time and encouragement.

      --
      ...
  16. Board cost $1300 but computational time? by dmanny · · Score: 3, Informative
    Here is a link for the board. $1300 is a little high for my budget but increased quantities would drive that down.

    I have not yet got a feel for the computational power required to approach real time processing or typical performance. Does anyone else know?

    --
    All my previous sigs now look like this one, I wish they were permanetly recorded when used. :-(
    1. Re:Board cost $1300 but computational time? by Wesley+Felter · · Score: 3, Informative

      40 times slower than realtime (on unkown hardware).

  17. The most painful part of that? by Merk · · Score: 3, Interesting

    Looking at the images and seeing that huge ugly NBC bug in the lower-right corner. You'd think that at HD resolution the least they could do is make it smaller, but no. At least this was on the original broadcast network. When I watch The Daily Show on Canada's comedy network they plaster their opaque bug on top of the original comedy central one, and as a result I every so often miss out on something that the bug is crawling over. Is there any hope of HDTV killing these things? If it's a digital signal couldn't they transmit the bug out of band and let the TV reconstruct it when people change channels or something?

  18. Hardware.... by wowbagger · · Score: 4, Interesting

    Man, I wish the Gnu folks would build their own hardware card rather than the card they are currently using - it's quite expensive.

    I'd love to see them put a decent FPGA, an Intersil 50216 4 channel digital downconverter, and a nice 60 Msample/sec 12 bit flash A/D converter on the card - they could do that for a bill of materials of about US$200, and have enough power to do the capture properly.

    Before you say "Fine - why don't YOU design it?": I'd love to get more involved in GnuRadio, but I'm afraid of potential conflicts of interest both ways - contaminating GnuRadio with my professional work and possibly exposing my employer to problems with GPL infringment.

    Also, is anybody big in the Gnu Radio project going to be at IWCE (International Wireless Convenention and Exposition) March 10 - 14? If so, where? I'm getting in on an exhibitor's badge - maybe I could get pictures?

    --
    www.eFax.com are spammers
    1. Re:Hardware.... by wowbagger · · Score: 4, Informative

      Well, I DO do this stuff for a living, as well as being a computer geek and a ham.

      But really, $1300 for the digitizer card is a bit steep - I work with a system using a 40 MSamp/sec 12 bit flash converter and Intersil 50214. The Intersil is about $30, and I don't think the flash converter is much more. Add a $50 FPGA to do the interfacing to the PCI bus, and you could do scatter-gather busmastering capture to the main system pretty easily.

      Use a $50 Intersil 50216, and you could do most of the heavy lifting with it - Final IF filtering, I/Q recovery, post-detection filtering, symbol tracking, etc. That would remove a lot of the CPU load from the system, possibly allowing for real-time aquisition and decode.

      Go to one of the board fab houses, and you could probably get a board built for about $500, maybe less.

      Considering that people are spending $500 for video cards, this might not be so bad.

      --
      www.eFax.com are spammers
  19. Re:Price by Gabrill · · Score: 4, Informative
    PCI-DAS4020/12 Ultra High-Speed PCI-bus Compatible, 4-Channel, 12-Bit Analog Input Board with Two Analog Output Channels & 24 Digital I/O Channels $1,299.00

    a little expensive for my taste.

    --
    Always going forward, 'cause we can't find reverse.
  20. Rough Explanation by tweakt · · Score: 4, Interesting
    I'm not 100% up to speed about this, but I saw the project explained at Defcon last year...

    Bascially the aim is to drastically decrease cost and increase flexibility of radio signal reception and decoding by replacing lots of specialized electronics with software.

    Now instead of a very expensive ATSC decoder for your HDTV-Ready TV, you will now have a box with an antenna, maybe a preamp, and a powerful DSP running in software.

    The cool part is, you can reprogram or adjust the software as needed to create other capabilities, use other frequencies, or increase performance even after the product is shipped.

    I'm sure I drastically oversimplified this, and probably don't realize the full scope of the benifits. Read up on it, use google.

    But as applied to HDTV, this is an AMAZING accomplishment. We might soon have open-source HDTV decoding. I for one, would love to have the ability to directly access the native format of the TV signal, stream it to disk, multicast it on my home lan to the living room, whatever. COOL STUFF!

  21. For those who miss the point by tweakt · · Score: 4, Informative
    Here's the quick version from the site:

    GNU Radio is a collection of software that when combined with minimal hardware, allows the construction of radios where the actual waveforms transmitted and received are defined by software. What this means is that it turns the digital modulation schemes used in today's high performance wireless devices into software problems.

    Read the site! This is very important stuff and could have a huge impact on technology.
    1. Re:For those who miss the point by TheRaven64 · · Score: 3, Funny

      In my world, the phrase 'minimal hardware' does not include a $1300 PCI card...

      --
      I am TheRaven on Soylent News
    2. Re:For those who miss the point by exhilaration · · Score: 4, Interesting
      ... and lets you listen to your neighbor's cordless phone conversation, lets you peek into GSM/TDMA mobile phone traffic, lets you listen to your local police CB traffic, lets you control remote control cars/planes/etc., lets you open your garage door from your desk

      oh yeah, it also gives you TV/HDTV/FM/AM - maybe even satellite radio (but that's probably encrypted).

      This is a *universal* radio - you just have to write software to make it do what you want.

  22. Re:Slashdotted by ahaning · · Score: 4, Informative

    Try one of the GNU mirrors:

    http://gnu.sunsite.utk.edu/software/gnuradio/image s/hdtv-samples.html

    http://gnu.wwc.edu/software/gnuradio/images/hdtv-s amples.html

    http://gnu.mscnetworks.com/software/gnuradio/image s/hdtv-samples.html

    http://www.phildowd.com:4060/software/gnuradio/ima ges/hdtv-samples.html

    Basically, append software/gnuradio/images/hdtv-samples.html to any of the links from here: http://216.239.57.100/search?q=cache:1KyAbWv9nRAC: www.gnu.org/server/list-mirrors.html+gnu.org+mirro rs&hl=en&ie=UTF-8

    --
    Withdrawal before climax is very ineffective and those who try this are usually called "parents."
  23. Yeah. Until they make it illegal. by rice_burners_suck · · Score: 3, Insightful
    I give it not one month and the RIAA, MPAA and Microsoft will be jumping on this like flies on poop to make this illegal. I can already see all kinds of garbage being invented that will make HDTV more expensive and less flexible for consumers in order to protect the alleged rights of huge multinational corporations to eternal perpetually increasing profits.

    All of the above represent part of the reason that I have completely stopped watching television. Did I mention that I don't purchase software that has any sort of copy protection? That's true as well.

    The best way to fight DRM, copy protection, and all this trash legislation is to speak with your money: Don't buy products containing this crap. You could go further and do what I do: I buy the competition's product and then send a letter (not an email but a letter on real paper in a real envelope with a postage stamp and my real address on it) telling the company WHY I have just purchased their competitor's product as opposed to theirs. Nanny nanny boo boo.

    1. Re:Yeah. Until they make it illegal. by cpt+kangarooski · · Score: 3, Insightful

      I'd be happy to do so.

      Basically, I think that self-help is unacceptable in conjunction with the legal protections conferred by copyright.

      That is, a copy protected piece of software will never stop being copy protected. Even when the copyright holder loses their rights in the work. I'm fully prepared for copyrights to be granted, and for copyright holders to be able to pursue me for infringing on the rights.

      BUT only where I stand to benefit from this as an ordinary person or author. Which means that I expect that after a reasonable period of time, I should be able to use, copy, alter, and base derivative works upon it. Upon any copy, with no particular difficulty beyond something inherent in the medium and not used as a deterrant. (e.g. a CD needs a CD player, but there's little special about that; adding encryption to it is not ok)

      If someone wants to release copy protected works, then I think that they should do so without benefit of a single legal remedy. If they want the help of government and society in protecting themselves, they must acknowledge that it is a quid pro quo, and honor their end of the agreement. Copy protected works will never truly enter the public domain; they are an effort to cheat the public. Such publishers are much more reprehensible than the pirates that prey upon them, IMO.

      Similar arguments exist as to why software developers should be required, as a prerequisite to getting copyrights, to deposit a full, complete, and well-documented copy of the source code with the Library of Congress. (n.b. that this is NOT open source, merely 'disclosed' source.)

      --
      -- This and all my posts are in the public domain. I am a lawyer. I am not your lawyer, and this is not legal advice.
  24. Re:Broadcast flag? by Wesley+Felter · · Score: 3, Informative

    The broadcast flag is a proposal, not a regulation. But if the broadcast flag is issued, it sure looks like GNU Radio will be illegal.

  25. This is informative by mrhandstand · · Score: 5, Informative

    This has been covered here on Slashdot before. Some of the comments in the previous post are particularily informative.

    --
    Always value the individual over the system. --Bruce Lee "I don't need a Sig - I have a custom 191" - me
  26. What, no link? by Spunk · · Score: 3, Funny

    Masturbate For Peace

  27. almost perfect... by burns210 · · Score: 3, Funny

    Now all I need is an ascii version. Then I'll be all set.

  28. Re:resolution by linux11 · · Score: 4, Informative
    The following was taken from an online pdf file:

    "The actual resolution of HDTV streams transmitted will usually be 1920x1088, because MPEG-2 requires the number of lines to be in multiples of 16 (1088 lines = 68 x 16)."


    Also, keep in mind that the popular CRT and projection projection TVs will purposily overscan the picture such that some of the lines are pushed outside of the viewing area. So, while 1088 lines are broadcast, a projection TV may only show 1076 of them and clip 6 lines each from top and bottom. If overscanning results in only 4 lines being clipped then you will actually see only 1080 of the 1088 lines of MPEG-2 stream.

    The width of 2730 pixels appears to be intended get close to the correct aspect ratio when displayed on a computer monitor. Based on how the people's heads look on my monitor, it seems to be a little over stretched. But when I return the images to 1920x1088, they clearly look squeezed.
  29. 20 Msample/sec by wowbagger · · Score: 4, Informative

    Actually, 20MHz isn't so bad - I work with 40 Msample/sec 12-bit flash converters, and there are 100 Msample/sec 12-bit flash converters on the market.

    However, you DON'T build things like this with your brother's wood-burning kit and a old nail - These parts come in surface mount packages, and your board has to be carefully designed to maintain proper impedance matching on the RF traces, as well as having excellent grounding (RF and digital grounds meeting at one and only one point, ground planes cut as needed to prevent current loops, etc.).

    Lastly, you need a proper dithering circuit to introduce noise equivelent to 1/2 of the least significant bit, in order to shape the quantization noise out of the frequencies of interest. Otherwise, you end up throwing away a couple of bits of resolution.

    Those are the sorts of things you have top-notch RF designers laying out, and a top-notch fab build for you - either by having such a fab working for you, or by contracting it out.

    --
    www.eFax.com are spammers
  30. Re:Broadcast flag? by ColaMan · · Score: 4, Interesting

    Maybe it *will* be illegal in your country.

    But eventually Supply and Demand will kick in - someone will want to tape "Friends, 2009", so presto! the means will appear. Soon enough you'll be able to buy the equivalent HDTV VCR from China for $120 that "mistakenly" ignores the broadcast flag, a-la DVD zoning.

    Pity it means that some other country's tech industry gets the "3) Profit!".

    Side note:
    Sure won't be worrying about how illegal it is in my country (Australia) for a long while yet.
    Is "the switch" happening in 2008? And have we sorted whether we're going for SDTV or HDTV?
    Anyone with a set-top DTV box in .au care to comment on the current digital transmissions?
    Anyone? Anyone? Bueller?

    --

    You are in a twisty maze of processor lines, all alike.
    There is a lot of hype here.
  31. Very flexible software by LoRdTAW · · Score: 3, Interesting

    This project isnt just for HDTV but any radio signal one can capture, convert and sample to extract data. This software could be used as an XM radio or possibly a digital cable descrambler. All you need is a decent A/D card (one that can handle the bandwidth of the signal you wish to decode) and associated tuning circuitry. All the signal processing is done on the computers CPU. With SMP boxes, x86-64 and other CPU technology on the horizon the possibilities of building software recievers for most any digital signal is definatly something worth looking into.

    Another thing people have to realize is that its just a reciever, the digital stream has to be decoded by another program making it perfectly legal. The program that might have to crack encryption or remove/ignore copy protect bits to record or view that data stream is what will be illegal.

  32. What's it's good for... by vrmlguy · · Score: 3, Interesting
    I've seen several postings asking, "So what is GNUradio good for?" Here's why I'd want one.

    I've got a PVR; I leave it on all the time so when I walk into the room and I'm interested in what's on, I can rewind and watch it from the beginning. Unfortunately, that only works for the one channel that the PVR is tuned to. If I change the channel and see something interesting, I can't rewind it. What I want is is PVR that records the last hour or two of every channel that I get.

    GNUradio is the receiver for that PVR. The PVR records the unfiltered signal from the antenna. That gives you all the channels at once. When you want to watch a show, the GNUradio software reads the raw data and filters out the channel you want. If a show looks interesting, you can rewind and watch it from the beginning. Even if there are two or more interesting shows on at the same time, you can filter them both in parallel and re-record one or more while watching another.

    --
    Nothing for 6-digit uids?