Free Idea for a Clever Hacking Project
Write a driver to encode hi-def video on your home coax to all the TVs in your house!
A few years ago, a clever guy named Fabrice Bellard figured noticed that video card output signals and VHF TV are close in frequency. He did this.
Pretty sharp, eh? The trick is in those grayscale images. They contain a DVB-T encoded image, DVB-T is a television broadcast standard used in places where beer is sold in half liters. The idea of using a video card as a transmitter is pretty much entirely explained in that page.
If only I had a free modulator for ATSC, the television standard used in North America and South Korea. Oh wait, GNURadio has one.
Your project: plug these two ideas into each other. In particular, you might need to manipulate your MPEG-TS so you're not putting data in your blanking intervals. For various technical reasons revolving around video cards being intended to be connected to monitors, you need to blank intervals for every "row" of your image, and an additional blank interval for every "frame." In Mr. Bellard's example for DVB-T, he had 0.2μs every 47.8μs, and an extended 96μs blanking period every 62,736μs. You can fiddle with how often these blankings occur, but not the fact of them. So better put something unimportant in your MPEG-TS there! Fabrice's video mode updated at just under 16Hz, so at least you have a little time to write your signal down.
Let me know how it goes. You'll be a star!
For bonus points, encode three signals at once. All on channel 5 of course. We'll make a special VGA cable with two heterodyne tuners, sell it with our software, and the two of us, we'll be rich!
I advise using the Linux kernel framebuffer interface, not an X server.
A few years ago, a clever guy named Fabrice Bellard figured noticed that video card output signals and VHF TV are close in frequency. He did this.
Pretty sharp, eh? The trick is in those grayscale images. They contain a DVB-T encoded image, DVB-T is a television broadcast standard used in places where beer is sold in half liters. The idea of using a video card as a transmitter is pretty much entirely explained in that page.
If only I had a free modulator for ATSC, the television standard used in North America and South Korea. Oh wait, GNURadio has one.
Your project: plug these two ideas into each other. In particular, you might need to manipulate your MPEG-TS so you're not putting data in your blanking intervals. For various technical reasons revolving around video cards being intended to be connected to monitors, you need to blank intervals for every "row" of your image, and an additional blank interval for every "frame." In Mr. Bellard's example for DVB-T, he had 0.2μs every 47.8μs, and an extended 96μs blanking period every 62,736μs. You can fiddle with how often these blankings occur, but not the fact of them. So better put something unimportant in your MPEG-TS there! Fabrice's video mode updated at just under 16Hz, so at least you have a little time to write your signal down.
Let me know how it goes. You'll be a star!
For bonus points, encode three signals at once. All on channel 5 of course. We'll make a special VGA cable with two heterodyne tuners, sell it with our software, and the two of us, we'll be rich!
I advise using the Linux kernel framebuffer interface, not an X server.