HDTV via GNU Radio

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."

Comments

Aspect ratio?

[Anonymous Coward]

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).

resolition

[Anonymous Coward]

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

What?

[ziplux]

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

Re:What?

[MBCook]

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?

Re:What?

[NortonDC]

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?

Those aspect ratios are off.

[kalgen]

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.

Good And Bad

[sidespace]

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?

The most painful part of that?

[Merk]

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?

Hardware....

[wowbagger]

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?

Rough Explanation

[tweakt]

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!

Re:For those who miss the point

[exhilaration]

... 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.

Re:Broadcast flag?

[ColaMan]

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?

Very flexible software

[LoRdTAW]

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.

What's it's good for...

[vrmlguy]

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.