HDTV On Your PC And Hard Drive

Jack Kolesar writes: "So, you want to watch HDTV but you don't want to shell out thousands of dollars for a new television. Well, AMDPower.com has a review of the AccessDTV HDTV tuner card. Not only does it let you watch HDTV, but you can also record it on your harddrive. Yes, the full 19.4Mbps stream of 8VSB is stored in raw format. Now, if somebody out there could just make some linux drivers for it ..."

Comments

SGI

[BoarderPhreak]

FWIW, SGI workstations supported the HDTV format for nearly ten years now... In most video and 3D applications, "HDTV" was also an option - for generating content for this "new format."

Re:HDTV Protections?

[thud2000]

According to the article, the recorded video is in fact encrypted - only the specific card that did the recording will be able to play back that particular stream.

Ah! What timing

[renehollan]

Sure, now I'm made aware of this, after shelling out relatively large sums of money for an HDTV-ready set and an HDTV receiver (terrestrial and satellite).

The thought of building up a personal A/V library accessable anywhere in my home has always been a dream of mine: I have about 220 CDs (approaching the limit of my custom stereo cabinet designed to hold "enough") and countless VHS video tapes. I HATE contemporary storage solutions: expandable usually means ugly, and elegant (like my stereo cabinet) usually mean limited. If anything, I want original media archived away generally out of site and out of mind. Thus, the desire for a remote, unobtrusive, media server.

Timeshifting broadcast programs to some fraction of this server's space is a natural extention of the idea.

So, such technology would be a welcome addition to my media server idea: besides my main (expensive) HDTV setup, I could have lesser playback equipment in other rooms that could leverage this technology (server side), and perhaps dedicate yet another satellite receiver or two for timeshifting purposes (quite willing to pay another $10 a month for the privelege).

So, bring it on

They encrypt, folks; you don't get raw format

[A nonymous Coward]

A bunch of posters haven't bothered to read the article and wonder why the MPAA etc don't clobber them. This card encrypts using its serial number, so it can only be played back by itself. If this encryption and decryption happens in the hardware, it might not be feasible to reverse engineer it and get the raw stream.

Re:They encrypt, folks; you don't get raw format

[bn557]

forgive me for I am no security/encryption afficionado, but, if it's displayed on your screen when you play it, havn't you decrypted it, and I KNOW that there is software out there that will allow you to do a screen capture on this. I'd be worried if it used overlay to do the displaying, but since it's not also a graphics card(although I'm sure some gcards will come with DTV support eventually, or maybe now for all I know), the Decoded stream has to pass through drivers somewhere to get to the card, and those drivers could be hacked.

Pat

Re:They encrypt, folks; you don't get raw format

[spudnic]

This is exactly what Total Recorder does (in Windows) for audio. It adds itself as the primary audio driver for the system. All audio directs to it, then it forwards it to the driver for your sound card.

The upshot to this is that you can get Total Recorder to record this stream in just about any format at whatever rate you want.

I use this for the audio books I get from Audible. The books come down in some encrypted format that requires a special plugin for Windows media player or RealPlayer, or you can push them to an Audible enabled device (like the Rio).

Before going to bed, I start the book playing in media player with total recorder saving it out as an mp3 as it goes. The next morning I convert the mp3 to wav and burn it to a standard audio cd.

This type of circumvention is very easy as long as the stream has to be decrypted somewhere on the motherboard. Having the stream sent encoded to the card and having it decrypt it is another matter. I'm sure that someone will come up with a way to decrypt it.

Re:They encrypt, folks; you don't get raw format

[apnar]

Some work is already underway to reverse the encryption scheme. Check out http://groups.yahoo.com/group/AccessDTV. Not too much activity, but there were some decent things figured out already. Mainly that it looks possible to pull the unencrypted stream from the file.

Also there is another card that does mostly the same thing (no PVR functions) but doesn't encrypt the stream at all called the HiPix

Re:They encrypt, folks; you don't get raw format

[Noehre]

Have you ever tried taking a screen capture while playing a DVD?

All you get it a black box.

What the DVD Consortium decided what that a DVD video is sent directly to the video card as an overlay. Basically, the DVD is invisable to the rest of the system. You can't bypass the video somewhere inbetween the disc and the monitor.

I'm sure they can/will/already do something like this with HDTV.

Re:They encrypt, folks; you don't get raw format

[inburito]

That is really just a minor problem. True, the actual framebuffer portion that displays your desktop is not going to have anything but a black/blue/purple/whatevercolor box but still all modern videocards have over 16megs of ram and some of that is going to be used for video overlay buffer.

Before I continue I should say that I programmed most of the v4l-drivers of voodoo 3500 tv so I do know what I'm talking about.

Registers in that videocard are going to point exactly to where that buffer is located and accessing it is no different than just mapping that portion into your address space and copying the data from there. There's going to be a lot of data but technically it is possible. And, this way you'll actually get the clean data instead of something that has already been stretched/filtered/de-interlaced/etc by your graphics card..

To summarize.. If you can see it, it resides somewhere in memory. If you can hear it, it resides somewhere in memory. It might not stay in one place for very long but definetly long enough for someone with intermediate hw-programming skills to capture.

Hard Disk Space

[JohnHegarty]

As this is a 19.4Mbps raw format file. I persume that bits.

So.

19.4 x 1024 = 19865.6 Kbps
19865.6 x 1024 = 20342374.4 Bits Per Second

Now lets divide by 8
20342374.4 / 8 = 2542796.8 Bytes Per Second
2542796.8 / (1024 x 1024) = 2.425 Mega Bytes Per Second

Now, I would like to record a move of 2 hours

2.425 x 60 x 60 x 2 = 17460 MB
or 17460 / 1024 = 17.05 Gb

Thats alot of space , evan for a 80mb hard disk.

Just a question someone might be able to answer, how well will this compress ?

If its a good level of compression, will it allow a new way for the napster type people to break into a new medium.

Re:Hard Disk Space

[bowb]

MB with a big B is megabytes
Mb with a small b is megabits

kB is kilobytes
kb is kilobits

(I don't think it matters much whether the K is big or small, but the convention in the sciences and engineering is to use a small k for kilo, big M for mega, and big G for giga.)

Also note that hard drive makers always use multiples of 1000 for their units:

1kB = 1000B
1MB = 1000kB
1GB = 1000MB

(RAM of course is always measured in multiples of 1024, e.g. 1GB = 1024 * 1024 * 1024B . And before anyone starts whining that the HD makers are ripping you off of those extra bytes, remember that using multiples of 1000 is an older convention in engineering.)

I'm glad I've got that off my chest. Now that you understand these conventions, I WON'T HAVE TO COME OVER AND KICK YOUR ASSES.

If I have an HDTV...Can I....?

[swordboy]

If I was to purchase an HDTV, could I use it as a 1920 x 1080 (1080i standard) monitor? I have seen that some of the high end units have DB15 inputs on the back. This would make for the ultimate entertainment center when equipped with any of the new high end Dolby Digital sound cards.

There will never be linux drivers for this card

[Kagato]

This PC Card, like most PC HDTV solutions uses the Teralogic Janus chipset. It's pretty slick, and has actually been aorund for several years. Many major companies use Teralogic, including Tivo.

I've been trying to get information on the chipset from Teralogic for several months. On Dec 29, 1999, David Auld of Teralogic posted to the video-4-linux mailing list. "We at TeraLogic are interested in encouraging the development of Linux
drivers for the Janus DTV card." The company went so far as to offer reference cards and driver sets, and was in favor of having a total GPL driver set. You can do a google search to find the archive.

A couple months ago I e-mailed David on this subject and got a fairly kurt thanks but no thanks response.

The obvious reasons for pulling out support for the Linux driver are all MPAA based. The content controls comming down the pipe won't be in the Janus Chipset. It would have to be software based. With a linux driver could could patch an HD-Tivo, or your Windows based solution to ignore the content control flags. Most interesting would be trying to wield the DMCA against people on this. It's doubtful a linux driver would ever ack the content flags in the first place.

Re:Hauppauge?

[cmowire]

Yes, but the Hauppauge card doesn't decode the full HDTV stream. They just convert it to NTSC and let you see that.

Hauppauge Linkage inside

[Argyle]

Here is the Hauppauge WinTV-D (pdf) linkage.

It appears to do the same thing.

Digital TV/Radio musings

[Aztech]

Just like the Hauppauge DVB boards... I have one here in the UK and the kick ass, Linux TV not only produce Linux drivers for them but a whole suite of utilities that do PVR functionality, time shiting and 'dvbstream' that actually lets you redirect the MPEG2 transport stream to various other PC's over the network.

On a related note, I picked up a DAB (Digital Audio Broadcasting) digtal radio receiver the other day, I can save the MP2 baseband strem directly to disk... no loss of quality, you can actually record all the stations within the same multiplex at once since they all come through the same COFDM transport stream. The datacasts are pretty smooth (and quick) too.. take a look at radio, if they get this into portable devices then this will give 3G a run for its money when it comes to rudimentary information like news, sports scores etc :)

TV on computer. Wow!

[goober]

Compaq's already got it...you can read about it at The Onion

Re:what exactly gives hdtv ?

[cmowire]

HDTV is 1920x1080 at a few different frame rates.

It was going to be 1050 with slightly non-square pixels (i.e. 1920x1050) but they wised up.

And the frame rate is 24,25,29.97, or 30 progressive frames per second, depending on the source material, and twice those numbers for interlaced frames per second. Which means it will actually be able to do movies at the right frame rate so that it will look better.

You aren't going to see anything really taking advantage of the quality of HDTV for another few years. But when they start to show movies at the form factor the producer intended, it'll be great. ;)

DMCA would not be applicable here

[Sloppy]

Most interesting would be trying to wield the DMCA against people on this.

DMCA would not apply to this, and is completely impotent against this.

The capture card itself is what does the encryption. The HDTV signal is sent in the clear, and accessible to anyone who knows how to build the hardware to receive it. Thus, there is no "technological measure that effectively limits access" to the copyrighted content, so 1201 doesn't come into play if you chose to undo (or prevent) the card's encryption.

Why can't we build our own?

[dschuetz]

Everyone's bemoaning the fact that these HDTV cards don't have linux drivers and use encryption. Well, is there any reason why we can't just build our own cards?

If the people at SlimDevices can create their own network-based MP3 player with off-the-shelf chips, why can't they (or someone similarly talented) create a little device that takes off-air HDTV signals, feeds it into standard chipsets, and outputs compressed (MPEG-2?) HDTV video over ethernet? Get the little thing responding to simple commands over IP (maybe port 80, just have something in your browser that can handle video/mpeg-2 streams), and you've got a great thing going.

Make 'em cheap, put a few of these in your basement, have 'em all stream to a big RAID box, and then all you need is for the same guys to build a nice ethernet-to-video box for the set-top.

Seriously, though -- how available are these chips? Could someone easily build something that takes "GET CHANNEL 37.3" on an IP port and streams MPEG back? If I recall correctly, off-air HDTV streams are *not* encrypted, right?

Re:Hauppauge?

[ddennedy]

I have a WinTV-HD. Yes, it outputs full ATSC through component output. The big difference between WintTV-HD and WinTV-D is that the -HD has a hardware MPEG-2 decoder so it is not dependent upon the CPU for decoding and so it is not dependent upon the video card for the proper video out signal.

The PVR function of the WinTV-HD software is quite weak, but I can record MPEG-2 transport streams to the hard drive as long as I do not use the component output mode. Instead, I must use the RGB output mode. I can not hear sound while capturing unless I use the direct AC-3 SPDIF output to my amp, but my amp only has one connector, which I usually leave connected to the digital out connector on the Soundblaster Live for
DVD playback.

IIRC, The Telemann HiPix also records standard MPEG-2 transport streams to the hard drive.

I purchased a 34 inch, 4x3, direct view (tube) HDTV monitor for $1495 from a maker called Sampo. It has VGA input and can display computer RGB output at 1024x768. I run my WinTV-HD at 1440x1080i with the component output.

The biggest problem I have is with reliable reception even with a decent powered antenna in the attic. Some channels never work unless there is a low pressure weather system.

Adam Williams' Linux mpeg library can decode MPEG-2 Transport Streams that he can record using a WinTV-D that does have Linux drivers.

bad tech background in article

[s.o.terica]

Wouldn't trust AMDPower's tech history too much -- for example, the reason that monitors flicker at 60Hz while TVs don't has nothing to do with progressive-scan vs. interlaced (in fact, all else being equal, 60 frame-per-second progressive scan should flicker less than 30 frame-per-second, 60 field-per-second interlaced).

Instead, the reason that TVs flicker less is that TVs have higher-persistence phosphors, i.e. after the phosphors are excited by the CRT's electron gun, the image takes longer to fade away -- a phenomenon that's totally acceptable with full-motion video but not when you don't want your mouse pointer looking smeary.

For proof of this, ask anyone who has a progressive-scan DVD player connected to a progressive-scan TV -- it certainly does not flicker more than a non-progressive scan player (would be somewhat defeatist, no?)

Re:Ah! What timing (off topic but don't mod down)

[renehollan]

Actually, I've always preferred to own rather than rent. But, to each his/her own. I had lots of gadgets when I was single (and renting), but didn't want to raise a family in an apartment, so bought a house when I got married. Gadget accrual slowed down significantly then.

As for the HDTV satellite feeds, DirectTV has few, and only if you pay for some silly "everything" package. But, I hope this will change over time, so I sprung for the twin dual-LNB 18x24" elliptical dish (besides, it was cheap future-proofing over the standard single dual-LNB 18" dish). I am fortunate in that I can get about 8 local terrestrial DTV broadcasts out of Dallas, TX, and some of them are starting to broadcast in HD. FWIW, I have a Sony 32" HD-ready direct-view set, and HD-DTC100 receiver, purchased from Crutchfield (only $9.95 inside delivery!). I stayed with a 4:3 format because most material my wife watches is still either analog 4:3 or DTV 4:3. We have a horribly large collection of VHS tapes (mostly movies for the kids). The Sony does a nice job of upsampling 480i to either 960i or 480p as well.

I haven't set up a media server yet, primarily because of the lack of a quiet MPEG2 playback device (i.e. not a PC with noisy fans) that looks like a hifi component. I have wired 6 rooms for 2xRG6 and 2xCat5e though, and recently installed a DSL connection. There's nothing like sinking your own email. Headend includes a 8 port 10/100 Mb/s firewall/switch and Trunkline 5x8 multiswitch. Terrestrial DTV is via an attic-located Terk antenna with a ChannelVision 15db RF amp.

Re:HDTV Protections?

[Happy Monkey]

Please forgive a possibly dumb question, but why would the Motion Picture Association give a rat's ass about what TV show you are decrypting?

A question that has plagued us for decades.

And dear lord please tell me people have better things to do than spend $$$$ on a HDTV just to watch "Weakest Link"!!!

Another question that has plagued us for decades, but substituting the latest technology and crappy-but-popular show.