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Digital TV Transmitter Using a VGA card 187

Posted by timothy
from the useful-reuse dept.
An anonymous reader writes "Yet Another Project from Fabrice Bellard : with any PC and a standard VGA card, you can build a real Analog or DVB-T Digital TV transmitter by directly generating the VHF signal. The provided example shows a Lena picture transmitted as a real Digital TV channel."
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Digital TV Transmitter Using a VGA card

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  • by Anonymous Coward
    Wow, *another* project from Fabrice Bellard? DAMN!!!

    By the way, who the hell is he?

  • by ankhcraft (811009) on Monday June 13, 2005 @04:03PM (#12805790) Homepage
    Once someone posts how to do this with NTSC (which you'll need if you're in the U.S. like me), I'll be all over this! Anyone? Enlighten me...
    • it would be an MPEG2 encoded stream, not PAL nor NTSC ... the picture size and/or frame rate may be different but with any reasonable system you should be able to do exactly the same thing in the US
    • by Simonetta (207550) on Monday June 13, 2005 @05:10PM (#12806554)
      I suspect we may start to see illegal broadcasts in 2007 in poorer urban neighborhoods of the USA.

      With all broadcast television on VHF/UHF scheduled to cease on New Years Day 2007, there are going to be a lot of pissed off people who don't have cable getting nothing but static on every channel.

      This is assuming that UHF/VHF broadcasting actually does go off the air Jan 1, 2007. It doesn't seem likely at this time, but it is mandated by the TeleCom Act of 1996. And one never knows what the current administration is going to do.

      Let's assume that it does happen. All the middle-class people won't notice it because they are paying monthly cable fees and cable TV will not be affected by the VHF/UHF shutdown. However, let's assume that in poor neighborhoods the convertor boxes don't work well, or are prohibitively expensive, or are too technically complex for the general population. Suddenly there's no television.

      Well politics abhors a vacuum. We may find ourselves in a situation where people simply start pirate broadcasting on the unused television channels. This will probably cause problems with the new uses of the spectrum (private cell phone communications, I believe). The FCC will be really busy trying to track down pirate TV stations. Pirate TV stations are rare now because they can't compete with broadcast network quality, and there are outlets on local cable access for speciality and non-professional broadcasters.

      But with the UHF/VHF channels gone off the air, people will start filling it up with DVD broadcasts. Maybe even porn broadcasts. Unregulated, and without commercials. All illegal.

      These channels could become political if there is an economic downturn or a return of conscription into the permanent, endless war that the administration has promised the defense contractors and campaign contributors. Alternative broadcasts of police beatings at demonstrations made by tiny CamCorders alternating with current Hollywood movies downloaded from the DarkWeb could become common content on the new pirate channels.

      I wonder if anyone is considering the possibility of this happening before they decide to shut down UHF/VHF broadcasting in 2007?
      • Guess youy'll be watching a LOT of Canadian TV in 2007, eh? http://www.cdtv.ca/en/faq/index.htm#13 [www.cdtv.ca]
        How Long will Conventional Analogue TV Signals Be Available?
        ...

        The earliest that analogue stations may be allowed to shut down in Canada has yet to be determined but it is likely to be beyond the year 2010.
        ...
      • Sorry for disspelling your very original fantasies... but nothing of that kind seems to be happening here in Berlin, where they did shut down analog TV broadcasts some two years ago.

        The frequencies are reused for the new digital broadcasting -- there are now about five times as much stations available, and posing a considerable threat to cable television: As cable is still analog, you get the same number of channels in a better quality for free on air... Only thing you need to pay is buying the receiver (
        • In the US, many cable providers offer digital cable already, so that wouldn't be as much of a factor. Similarly, many cable boxes also have custom PVR/DVR capabilities and offer a much broader range of channels than broadcast stations in any locale in the continental US. Among people who watch TV, just about anyone who can afford cable (any many who can't) fork out the cash rather than watching broadcast, which generally consists of 4 to 8 channels, depending on where you live. (Although the only channel
        • Sorry for disspelling your very original fantasies... but nothing of that kind seems to be happening here in Berlin

          This may be cultural. Traditionally Germans do exactly what their superiors tell them to do.
          My comments were about American poor urban centers, primarily black and latino. The African-Americans have been resisting the destruction of their culture and their enslavement for 400 years. The Latinos are isolated by language and citizenship issues. Their only television is the ultra-conser
      • Well, I think that rather a lot of people in urban areas that have shall we say, a more liberal interpretation of copyright and broadcasting laws, are not paying for cable anyway, but that doesn't stop them from getting the pictures.
      • But with the UHF/VHF channels gone off the air, people will start filling it up with DVD broadcasts. Maybe even porn broadcasts. Unregulated, and without commercials. All illegal.

        I would be tempted to get satellite TV or something and rebroadcast the channels exactly as they were. I bet they would never see that coming!
      • Let's assume that it does happen. All the middle-class people won't notice it because they are paying monthly cable fees and cable TV will not be affected by the VHF/UHF shutdown. However, let's assume that in poor neighborhoods the convertor boxes don't work well, or are prohibitively expensive, or are too technically complex for the general population. Suddenly there's no television.

        That's a joke, in my experience. My family rents out many (small) appartments, and several houses. Many of the tenants c
      • The Telecom Act does not shut down analog TV in 2007.

        The FCC does have a mandate to shut down analog TV -- TV stations now have two channels, one analog and one digital, and once the transition is complete, new users of former channels 52-70 (some of which have already been auctioned off) can go ahead with them.

        But the date is not firm yet. The current rule is that it will be delayed a year at a time, until 2010 at the latest, until 85% of households have digital reception capability. That includes DTV
      • I wonder if anyone is considering the possibility of this happening before they decide to shut down UHF/VHF broadcasting in 2007?

        Don't worry! I'm sure more prisons are being planned as we speak. Meanwhile, the War On Spectrum Piracy can share the prisons that are being built for the War On Copyright Infringement, because the War On Drugs already filled up the prisons for the War On Crime. The War On Everything marches on!
      • With all broadcast television on VHF/UHF scheduled to cease on New Years Day 2007, there are going to be a lot of pissed off people who don't have cable getting nothing but static on every channel.


        "Hey, get in here! It's going to drop!"

        10 . . . 9 . . .[muffled by cheers] 7 . . . 6 . . . 5. . . . [lost to starlet's babbling] . . . 3 . . . [supposedly witty response to dingbat starlet by just as dingy star] . . 1 . . .[crackle-hiss]"

        "Hey, what happened???"

        [Which in turn leads to massive late-night
    • I think you mean ATSC [atsc.org]
    • NTSC is easy. You can get a kit from Ramsey Electronics and plug a camcorder into it -- whole thing comes out under $300 if you use a Hi8 instead of a DV camcorder.
  • by m50d (797211) on Monday June 13, 2005 @04:06PM (#12805823) Homepage Journal
    There's an X program that can transmit an MP3 to your radio by displaying pictures in certain ways. Quality's not too good, but it works. I guess it was just a matter of time before people did it with television.

    It also goes to show TEMPEST attacks are real. Your screen is transmitting what's on it in a way that's detectable over quite a distance. Shielding is worth looking at if you're doing something sensitive.

    • TEMPEST based attacks have been proven as viable a long time ago and I'm not sure this would qualify as a TEMPEST issue as you are purposefully broadcasting a signal for reception... Now if you are only considering sending the signal to your TV set and only your TV set then TEMPEST would be a concern (but considering the cost of some TEMPEST equipment I don't think that is much of a worry for a home user trying to mod out their home equipment).
    • by Rei (128717) on Monday June 13, 2005 @04:19PM (#12805986) Homepage
      You're talking about Tempest For Eliza" [erikyyy.de]. I never got the "broadcast an mp3" function to work, however - only the broadcast using their special midi-like files. A shame, really. Still, even the midi-like broadcasts make for a neat geeky party trick, and demonstrate the power of tempest ;)
    • by emkman (467368)
      It's called Tempest for Eliza [erikyyy.de]. I remember it being pretty cool when I tried it a few years ago in high school.
    • About ten years back, my brother had a very simple watch/PIM (Personal info manager, for those of you unfamiliar with term) made by Casio, IIRC. The unique feature was that you installed a driver which allowed the data input program to mess with your refresh rate (I'm guessing) and transmit the information to the watch. It usually took four or five tries to get it right, but I remember being pretty impressed with the unique method that helped avoid keeping track of a dongle/connector.
      • I used to have one of these as well. I always thought that it worked by displaying a pattern of lines on the screen, which the device then picked up.
        • Now that you mention it, I think you're correct. It's been a while, and I only remember seeing my brother holding it up to the screen. I suppose the line method would probably be easier to implement, as well.
        • I had one as well (It was Timex, by the way), and it did work by a pattern of flickering lines, but your parent post is right as well. When I upgraded from a Rage Pro to a Rage 128, I had to install a TSR (this was on Win98 btw) from Timex that allowed the DataLink software to override the graphics driver and use a pure VESA mode that matched a certain refresh rate the watch wanted.

          I always thought that thing was pretty cool, even if a dongle would have likely worked faster (not to mention that NT systems
    • When I opened up the image in GIMP, I could vaguely see two identical-looking images (only at 16% scaling though, the image being visible must have been an artifact of my laptop screen).

      Assuming that the two copies are the first and second frames of one interlaced tv frame, then we are talking about 4096 x 2048 x 8 bits = 8388608 megabytes of data to generate one tv frame.

      For motion picture, at 25 interlaced frames per second, thats just under 210 megabytes of data you'd have to move every second. And, mo
  • This is a great idea. If there is a way to make the signal just a bit stronger you can hack your own wireless media center.
    • Your mileage may vary depending on location, but the only thing you could get away with in the US is doing it on an amateur frequency. The Friendly Candy Company might turn a blind eye on a pirate TV operation that doesn't extend past a city block, but it's technically illegal.
  • It Won't Be Long (Score:3, Insightful)

    by geomon (78680) on Monday June 13, 2005 @04:12PM (#12805889) Homepage Journal
    Until this project is rendered illegal in the US under some DMCA-style bullshit. After all, you might be able to (gasp!) record something off of your incoming television signal.

    Of course, only pirates and pedophiles will have a use for this project.

    (The last part of this post is a JOKE, gawddammit!)
    • Re:It Won't Be Long (Score:3, Informative)

      by HTH NE1 (675604)
      Until this project is rendered illegal in the US under some DMCA-style bullshit.

      More likely it would be something originating from the FCC. Unlawful use of radio bandwidth without a license, use of a class B device to intentionally generate interference (a competing unlicensed coherent signal is interference, but I may have the wrong class of device).
      • Re:It Won't Be Long (Score:3, Interesting)

        by tylernt (581794)
        Consumer electronics that are unintentional radiators (FCCspeak for 'transmitters') are Part 15 devices. Actually, you can have intentional radiators under Part 15 was well, but the rules (power levels etc) are higher. Part 15 is usually where cordless phones and garage door openers operate.

        You are allowd to build up to, I think, 5 homemade Part 15 intentional radiators without getting them certified by the FCC. The maximum power levels are pretty low though, 100mW IIRC. A 100mW signal will go a few hundre
        • The rules are somewhat different for TV, and fairly complicated for Part 15 in general (the 100mW rule applies only on the AM broadcast band, for example). You might get away with a small local link that doesn't interfere with anyone else, but if you want to experiment with this stuff you're far better off getting an amateur radio license and doing your experimenting on the 70cm band -- that's where most of the ATV people in the US hang out (the allocation is different in Europe). The power limits are a lot
    • My HAM Radio license allows me to use a small portion of the UHF band to broadcast video at low power. However, I must have my call sign in the picture or as a 'bug' in the video image.

      Whatever method I use to generate the signal, as long as I remain within the power and frequency band, there's not going to be any major problems.

      I'd love to be able to generate an NTSC signal like this. Some of the transmitters for HAM radio are expensive.
    • ..or maybe you should have read the project page?

      it's not exactly.. hmm. shall we say, useful for anything. but a very fucking neat hack never the less.

      (not about recording at all - but creating tv signals from your vga cards vga-output...).
  • very clever (Score:2, Interesting)

    by Anonymous Coward

    +1 point
    shame he wont tell/show anyone how its done (ie. the source code)
    -2 point
  • oh man.. (Score:2, Funny)

    by p373 (689997)
    The slashdot effect + a nudie photo. Say goodbye to that server.
  • Mass panic (Score:1, Funny)

    by parasonic (699907)
    Now if I had some DV software and a little time, I could do a re-play of the "Martians are attacking us!" program. A re-creation of that 50's-ish alien invasion hysteria to my roommate or next wall neighbor. What advanced alien race wouldn't transmit digital TV?
    • Pretty much all of them wouldn't ... I mean, a truly advanced race would have evolved beyond the need for sitcoms, "Reality TV" and the 5 o'clock news anyway. The SETI project tried to use radio-frequency emissions to detect the presence of intelligent life elsewhere in the Cosmos, because they couldn't find any here.
  • The Lenna Story. (Score:5, Interesting)

    by British (51765) <british1500@gmail.com> on Monday June 13, 2005 @04:16PM (#12805947) Homepage Journal
    ....is more interesting than the main one. At my company when I started 6 years ago, I stumbled upon the Lenna picture, just thinking it was an ordinary pic. Few years later I saw the er, um "full" pictures. Didn't know she had a cult following.

    Yes, that Lenna picture I assure you is still in use after all these years. A pretty "hello world" image.
    • I've been tinkering with that business of hiding a greyscale image in the spectral data of audio (a la Aphex Twin, etc.). At the moment, it's still in Mathmatica code, and I've been looking for a decent test image.

      Seems like I've found it.

      Oh, and Lena looks nice on my desktop. I wonder what her image sounds like.

    • I'm wondering about getting it on a tshirt (with a program encoded in using dataglyphs), thinking it would be an instantly recognisable geek thing. Is it not so well known?
      • Re:The Lenna Story. (Score:3, Informative)

        by Qzukk (229616)
        The story of her pictures is apparently very well known in video processing circles, and /. ran an article some time ago about it which introduced her to everyone else ;)

        I had never heard of her before, but then again, I've never dealt with any kind of photography or video processing.
      • Everybody who's done image processing knows Lenna. Noone else does.
    • Re:The Lenna Story. (Score:3, Informative)

      by kureido (830125)
      Lenna is one of the many "standardized" images used in image processing research, akin to the well-understood strains of Norway rats used by medical researchers all over the world so that their peers can reproduce their experiments. For more examples of standard research images, see the USC-SIPI image database [usc.edu].
  • Watch out internet!

    Porn just found a whole new outlet. :/
  • crap .. (Score:3, Informative)

    by macaulay805 (823467) on Monday June 13, 2005 @04:17PM (#12805965) Homepage Journal
    I clicked on the link while I was at work, now I'm waiting for the network security people to remove me from my workstation.

    On a side note: WARNINGS PLEASE!
    • Re:crap .. (Score:2, Interesting)

      by harrkev (623093)
      The funny thing is that I saw the edges of that picture on the original web page. That looks just like the "lena" picture that I used to use at a target back when I took my image processing class. That "lena" was a picture of a girl's face wearing a fancy hat.

      Is this new picture different?
      • Is this new picture different?

        No. This "new" picture is the same one you used, just possibly a different crop of the original.
        You probably should have followed the other link [cmu.edu] in the article summary before posting.
    • Re:crap .. (Score:3, Insightful)

      by Bishop (4500)
      a naked shoulder will get you fired? Where the hell do you work?
  • ATV (Score:4, Interesting)

    by leighklotz (192300) on Monday June 13, 2005 @04:26PM (#12806068) Homepage
    You can do ATV [nasa.gov] legally in the US with NTSC, with a ham license.

    You can see this the video for yourself, with stuff you have at home right now. There are cable channels that are on ham bands, but it's OK because their signals stay on the cable.

    If you live in the SF ba area, hook a UHF antenna (vertically polarized) to your cable-ready TV or VCR with TV out, and tune to cable channel 57 (421.25 MHz), and aim it at Mt. Hamilton (east of San Jose).

    Here are some tests on 1.2GHz [nasa.gov], which is also a ham band.
    • I forgot to mention that the NASA Ames folks plan to re-transmit live space shuttle video from STS-114 over the K6BEN repeater, so you can pick it up on cable channel 57.
  • NSFW?!? (Score:2, Insightful)

    by natron 2.0 (615149)
    Hey editors, how about a NSFW warning on stories such as this!
    • What are you talking about? Yes, some of the Lenna pictures that can be accessed indirectly from the site are not safe for work but all the pages you open when clicking on the links in the story description are safe for work unless a portrait picture of a woman is not safe and in that case, please let us know where you work so we can avoid that place...

    • My workplace blocked the website, citing malicious software could come onboard.

      *sigh*. A digital tv tuner I don't have, being hosted on free web page service in France.

      It just simply wasn't meant for me to read this article.
  • Now can someone turn up the original photo that Tim Skelly used for the starfield in Star Castle... The stars are nice, but I'd like to see the actual photo he happened to have in the drawer to pick coordinates.
    • Now can someone turn up the original photo that Tim Skelly used for the starfield in Star Castle...

      Tim Skelly was the designer. Scott Bodden actually programmed "Star Castle".

      Scott traced the starfield from the February 1980 issue of OUI magazine.

      I don't know which model it was, Cleo Bergssen or Nelia Cozza.

      • "I don't know which model it was, Cleo Bergssen or Nelia Cozza."

        Right. Now if someone could produce the pictures from OUI we could just look and you'd know which one it is. Having written the first functional Cinematronics emulator, and having talked to both Tim and Scott, I've always wanted to see the original picture. At least it's a good excuse to check out some porn ;-)

        • Now if someone could produce the pictures from OUI we could just look and you'd know which one it is.

          Yeah, that was kind of the problem. I was unable to find the requisite nudie pics on the net.

          However, I was able to find places that sell the actual magazine issue. So, you could buy the print version, and have a collector's item!

  • I'm interested in this, but I don't understand the practical implications (mainly because I have no idea what most of the acronyms mean). Does this mean I could plug my computer into my digital TV tuner somehow and be able to watch it on my TV? If so, does it work with US digital TV equipment (such as the Motorola set-top boxes that Comcast provides)?
  • Just hook everything up to the pc and let it do the conversion and display your video at the native resolution on your DTV.
  • by o'reor (581921) on Monday June 13, 2005 @05:53PM (#12806957) Journal
    and yes, I am a (former) DVB-T engineer (and a consultant in digital video broadcasting at large -- yes, I know a bit about the US and Japanese standards too).

    What Fabrice is telling us here is that he has managed to produce a real-time (or close-to-real-time) DVB-T/DVB-H software COFDM modulator, the output of which may be broadcast via the DAC converters of the video board. Given the complexity of the generated signal (more than 6000 subcarriers, not including pilot subcarriers which are used as beacons for the demodulator, and paying respect to the guard interval -- sorry for the technical gobbledygook), this usually requires a dedicated ASIC. Don't forget to include the preliminary phases of the encoding : creating an MPEG-2 video channel, an MEPG-2 transport stream (OK, he did it using a modified MPEG library), then encapsulate this into MPEG-2/DVB frames, add the Reed-Solomon code, perform the interleaving procedure, pour in some Viterbi encoding for redundancy, and feed it to the input of the DVB-T modulator, phew ! you're done.

    I want to say hats off, ladies and gentlemen, to this outstanding performance. The Free Software movement definitely needs more guys like Fabrice, and we all need to encourage him into publishing more of his code.

    Chapeau bas, mon cher Fabrice !

    • by Anonymous Coward
      It's not realtime. He's rendering to a PGM file, and then by displaying it. Not easy, but it's not a replacement for custom hardware.
      • My mistake, I got a little carried away with what I was reading... Still, that is one of the possibilities for his project, as he mentions at the bottom of the page :"This project can be the basis of a real time low cost DVB-T and DVB-H modulator."

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