(This post is both technical and long, just for fair warning.)
Back when I was first setting up my lovely 1200 Watts of 8-channel glory, I was extremely disappointed to find out that my sound card, the now-ancient Sound Blaster Audigy, only supported two kinds of digital output: normal S/PDIF, and a proprietary Creative Labs-only digital connector. At first, I thought, "oh, good; I can finally use that S/PDIF output; it's digital." But, no. S/PDIF is only two channels of audio, which would leave five of my speakers and my sub very sad indeed. This seemed very strange to me: it's a digital connector. You use digital connectors to connect a DVD player to a receiver. You get surround sound from a DVD player. How does this happen?
It happens because the signals from the DVD player are technically in stereo, but they're "enhanced" stereo. Dolby Digital AC3 and DTS signals are really just stereo, but they're stereo that's encoded in a special way so that a receiver that knows what they are can expand them out into 5.1 sound. So, that's pretty cool. It's sort of how, back in the Napster hayday, people realized that they could share stuff that wasn't music if they just renamed the file to end in .mp3. Dolby Digital is the audio equivalent of a Photoshopped JPEG of XXX_Britney_Spears_nude with an .mp3 extension instead of a .jpg one.
When I first connected my sound card to my receiver using a digital out, I didn't know any of this. All I knew is that I was only getting stereo sound, which seemed pretty retarded considering how many speakers surrounded me. Then I realized that I actually got surround sound from DVDs, but not games. My next inclination was that some DirectSound settings were messed-up somewhere. But then my research punched me in the face: my digital connection was only in stereo. It would be impossible for a game to send multichannel audio over it. That is, unless it was encoded into Dolby Digital or DTS, something the receiver would understand. My receiver wants XXX_Britney_Spears_Nude.jpg, and all I had to do was rename it to .jpg, right?
Wrong. Unfortunately, encoding many channels of audio into Dolby Digital or DTS is more complex than you might initially imagine. One, it's computationally intense, and two, it's rife with patents, which means that any encoder would need to pay licensing fees. As it turns out, there's only one consumer-class product that can encode your arbitrary audio (from games and such) to Dolby Digital, and that's the nVidia nForce2 (and perhaps nForce3) motherboard chipset.
That was all very disappointing. I didn't have an nForce2 motherboard, and I'd have to replace a lot of hardware to get one. I was left with connecting my sound card to my receiver with six cables: my sound card only supports 5.1 audio, which leaves only two of my speakers sad. I need to upgrade. (This sucks, because I've got too many cables back there already.) Worse, these are analog cables. My receiver has four optical ports, and they're not doing anything.
Now that I've paid off a lot of the expensive things I bought when I moved out here (such as the Segway and the aforementioned sound system), and am putting together my media center PC, I once again started looking into getting hardware Dolby Digital encoding set up, even if it meant getting a new motherboard. I was doing this tonight when it hit me: I can't win. This is a battle that I am guaranteed to lose. Dolby Digital is not a lossless encoding: you lose some of the signal when you put your audio into Dolby Digital. It's kind of like MP3, but a higher bitrate. Even if I could encode my game audio to send it out over an optical connection, it would be compressed. I have perfect digital audio on my computer, and there's no way to get it to my receiver and have it still be perfect. I either have to put it onto analog cables like I do now, or compress it so that it can go on a digital cable. Either way, it's no longer perfect.
Surely, if we can teleport submolecular particles, we can send uncompressed audio from one device to another... of course we could. One easy solution is to use four fiber optic lines instead of just one (8 channels, 2 channels per optical line). There; I've solved the problem. So, why doesn't this exist already? Copy protection. It's the only answer that makes sense. The technical solution I just described is not only easy, but it's extremely easy, and would be cheap to implement. The only reason I can't take a convenient cable made of of four plastic wires and two four-way optical connectors on each end and connect my computer to my receiver is because of copy protection.
If something were accomplished by this, I would be less angry. But nothing is accomplished by this. All this does is prevent people from recording the full-quality output from a DVD movie or even the uncompressed audio from a DVD-A disc. (Heh heh, DVDA.) But you can still do this. Put the DVD in your computer. Decode the audio there. Bam; done. The only thing that has been accomplished by the studios is to degrade the quality of the experience. They haven't prevented anyone from pirating the movie or the audio track. I'm all for responsible copy protection measures that don't interfere with peoples' ability to use the software. For example, the activation scheme in Windows XP is perfectly reasonable—you get a long grace period, and it takes about three seconds to get out of the way. It doesn't hamper your ability to use the software that you paid for at all. But this—this story of technology gone idiotically wrong—is unacceptable. This is why intellectual property laws and patents get a bad rap (well, this and the complete inability of the US Patent and Trademark Office to tell between a valid patent and a frivolous money-making scheme). This is one of the biggest reasons why so many technologically skilled people don't trust big companies. Microsoft gets trashed a lot because they're so into digital rights management and copy protection—and yet they're one of the few companies doing it well.