Digital TV Transmitter Using a VGA card 187
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."
ANOTHER one!! (Score:1, Funny)
By the way, who the hell is he?
Re:ANOTHER one!! (Score:5, Insightful)
Now lets get some NTSC (Score:5, Interesting)
It's a digital stream .... not NTSC (Score:2)
Guerrilla television in 2007 (Score:5, Interesting)
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?
Re:Guerrilla television in 2007 (Score:2)
Re:Guerrilla television in 2007 (Score:3, Interesting)
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 (
Re:Guerrilla television in 2007 (Score:2)
Re:Guerrilla television in 2007 (Score:2)
Re:Guerrilla television in 2007 (Score:2)
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
Re:Guerrilla television in 2007 (Score:2)
Re:Guerrilla television in 2007 (Score:2)
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!
Re:Guerrilla television in 2007 (Score:2, Insightful)
That's a joke, in my experience. My family rents out many (small) appartments, and several houses. Many of the tenants c
Re:Guerrilla television in 2007 (Score:2)
Re:Guerrilla television in 2007 (Score:3, Informative)
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
Re:Guerrilla television in 2007 (Score:2)
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!
Re:Guerrilla television in 2007 (Score:2)
"Hey, get in here! It's going to drop!"
10 . . . 9 . .
"Hey, what happened???"
[Which in turn leads to massive late-night
Wait... (Score:2)
Re:Now lets get some NTSC (Score:2)
Re:Now lets get some NTSC (Score:1)
Re:Now lets get some NTSC (Score:2)
The best part of TFA is at the end where he gushes about "This project can be the basis for foo, bar, and baz", then at the end "Where is the source code? It is currently not available, although I plan to release it someday, provided enough people ask me to." Sounds like "this pro
Re:Now lets get some NTSC (Score:4, Informative)
Re:Now lets get some NTSC (Score:2)
Re:Now lets get some NTSC (Score:2, Informative)
Re:Now lets get some NTSC (Score:2, Informative)
Re:Now lets get some NTSC (Score:2, Informative)
Re:Now lets get some NTSC (Score:2)
Then there is Séquentiel Couleur avec mémoire (System Essentially Contrary to the American Method to its critics).
It sends the luminance signal on every line, but only sends one of the two colour subcarriers on each line, getting the other subcarrier from the preceding line.
Invented in France, popular in the former Eastern Bloc. Dunno.
...laura
Re:Now lets get some NTSC (Score:2)
Re:Now lets get some NTSC (Score:2)
The reason there are more lines is because the frame rate is lower (because, as you say, the frame rate was linked to the mains frequencies - 60 interlace frames per second in North America and 50 virtually everywhere else) and there's longer time to display the lines. Essentia
Re:Now lets get some NTSC (Score:2)
Re:Now lets get some NTSC (Score:2)
Re:Now lets get some NTSC (Score:2)
The resolution is also slightly different.
Re:Now lets get some NTSC (Score:2, Informative)
Re:Now lets get some NTSC (Score:2, Informative)
The color sub-carrier is 3,579,545 Hz. This was chosen because it makes all the harmonics work to interleave the color and luminance spectrums.
There are exactly 227.5 phase changes per horizontal line. This is the source of the saying Never The Same Color. It is also why PAL inverts the phase on every other line. Their sub-carrier isn't the same frequency, but it's derived in
Re:Now lets get some NTSC (Score:2)
The correct analog (as in "analogy," not as in the opposite of digital) for this would be a mechanism for making an ATSC transmission. which could be tuned into from an OTA HDTV tuner. You could encode 1280x720 progressive ("720p") or 1920x1080 interlaced ("1080i") video signals into MPEG-2 then send that to an HDTV.
Not sure how far people have gotten rolling their own ATSC transmitters, tho.
Re:Now lets get some NTSC (Score:2)
b) The interlaced part wouldn't be the stumbling block -- 720p (aka progressive scan) is one of the ATSC standard modes. The hard part would be the 8VSB modulation, which is a totally different creature than the 16QAM modulation used in the european standard.
That said, WHAT A NICE HACK!
Re:Now lets get some NTSC (Score:2)
Re:Now lets get some NTSC (Score:2)
Errrr....
IIRC, PAL stands for "Phase Alternate Line" which basically means interlaced....
Kill those Utah lawmakers! (Score:2, Funny)
Re:Kill those Utah lawmakers! (Score:2)
Sorry for the bad link in the original. I should have previewed first, I know
Re:Kill those Utah lawmakers! (Score:2)
Re:Kill those Utah lawmakers! (Score:2)
Has been done with music for a while (Score:5, Interesting)
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.
Re:Has been done with music for a while (Score:3, Interesting)
Re:Has been done with music for a while (Score:2)
Re:Has been done with music for a while (Score:2)
hawk
Re:Has been done with music for a while (Score:5, Informative)
Link (Score:2)
Re:Has been done with music for a while (Score:3, Interesting)
Re:Has been done with music for a while (Score:3, Interesting)
Re:Has been done with music for a while (Score:2)
Re:Has been done with music for a while (Score:2)
I always thought that thing was pretty cool, even if a dongle would have likely worked faster (not to mention that NT systems
won't somebody _please_ think of the bandwidth (Score:2)
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
Neat Idea (Score:2)
Re:Neat Idea (Score:2)
It Won't Be Long (Score:3, Insightful)
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)
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)
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
Re:It Won't Be Long (Score:2)
Re:It Won't Be Long (Score:2)
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.
Re:It Won't Be Long (Score:2)
Re:It Won't Be Long (Score:2)
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...).
Re:It Won't Be Long-People start to learn. (Score:2)
Its only ten pages, so you should be able to wade through it in about two days.
Re:Slashdot lawyers. (Score:2)
I'm bookmarking your post for posterity. It is a classic.
I also said, if you cared to read the original post, that it would be illegal in the future. That would mean this device would *also* be illegal.
And Radioshack's attorneys would just advise the production staff to quit making them.
Radioshack - for legal advice... That's good.
very clever (Score:2, Interesting)
+1 point
shame he wont tell/show anyone how its done (ie. the source code)
-2 point
oh man.. (Score:2, Funny)
Mass panic (Score:1, Funny)
Re:Mass panic (Score:2)
The Lenna Story. (Score:5, Interesting)
Yes, that Lenna picture I assure you is still in use after all these years. A pretty "hello world" image.
Re:The Lenna Story. (Score:2)
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.
Re:The Lenna Story. (Score:2)
Re:The Lenna Story. (Score:3, Informative)
I had never heard of her before, but then again, I've never dealt with any kind of photography or video processing.
Re:The Lenna Story. (Score:2)
Re:The Lenna Story. (Score:3, Informative)
Watch out internet! (Score:1)
Porn just found a whole new outlet.
crap .. (Score:3, Informative)
On a side note: WARNINGS PLEASE!
Re:crap .. (Score:2, Interesting)
Is this new picture different?
Re:crap .. (Score:2)
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)
ATV (Score:4, Interesting)
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.
Re:ATV (Score:2)
Re:ATV (Score:3, Informative)
< Cool! So instead of pounding out morse code, you can instead send pictures of dots and dashes!
The original post has some questionable legality issues; I'm showing you a way to do it legally, and get peer support. It's still bog-standard TV modulation, not morse code. And you don't need to learn morse code to get a license to do ATV [arrl.org].
Probably the biggest problem is the use of harmonics -- the proposed system uses the 5th harmonic of a VGA output, which happens to fall in the VHF TV band. What abo
Re:ATV (Score:2)
NSFW?!? (Score:2, Insightful)
Re:NSFW?!? (Score:2)
Re:NSFW?!? (Score:2)
*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.
Other famous pr0n (Score:2)
Re:Other famous pr0n (Score:2)
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.
Re:Other famous pr0n (Score:2)
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 ;-)
Re:Other famous pr0n (Score:2)
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 don't understand...please explain. (Score:2)
This is great (Score:2)
Guys, this is no small feat (Score:5, Insightful)
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 !
Re:Guys, this is no small feat (Score:3, Informative)
Re:Guys, this is no small feat (Score:2)
Re:Guys, this is no small feat (Score:2)
Re:its simple, just reverse the polarity of the ph (Score:2)
Thank you Sir! , May I have another!! (Score:2)
All about Lena (Lenna) (Score:2)
Re:Killing a Cop to See Lena (Score:2, Informative)