Posted Fri Dec 4, 2009 at 11:45 AM PST by Joshua Zyber
Editor's Note: Each Friday, High-Def Digest's own HD Advisor will answer a new round of questions from our readers. If you have home theater questions you need answered, send an email to [email protected].
Answers by Joshua Zyber
Why No 5.1 PCM over Toslink?
Q: I find the argument that Toslink to not have enough bandwidth to do 5.1 PCM insulting. Fiber should have more than enough bandwidth for any audio format that is thrown at it. In fact, several PS3 games I have pass audio to the receiver over Toslink in 5.1 PCM, and my HD DVD player will sometimes internally decode soundtracks and pass the information to the receiver in 5.1 PCM. So why is there no 5.1 PCM over Toslink on Blu-ray? It seems to me that the only suitable argument is that Toslink does not provide HDCP, and therefore the studios are blocking it. I really do not see any reason over why they would block PCM over Toslink but not block DTS-HD Master Audio and Dolby TrueHD that was internally decoded from the player being sent over Toslink.
A: I think you have a couple of misconceptions here. Your HD DVD player will not internally decode movie soundtracks and output them as 5.1 PCM over Toslink. It can only do that over HDMI. HD DVD players worked the same as Blu-ray players in this regard. The player may decode a soundtrack to PCM and then transcode the signal to standard Dolby Digital 5.1 or DTS 5.1 for Toslink output, however. Or it may output them as 2-channel PCM, which your A/V receiver can run through Dolby ProLogic II processing to create a pseudo-5.1 simulation. But the player will not output PCM 5.1 over Toslink.
I'll be honest that I'm not enough of a gamer to know whether there are any PS3 games with PCM 5.1 soundtracks. I was under the impression that they were all DD 5.1. Regardless, the console will also not output 5.1 PCM over Toslink. It will only do that over HDMI.
As for why this is the case, the official answer has always been that S/PDIF (in either Toslink or digital coaxial type) doesn't have enough bandwidth to carry more than 2 channels of PCM. I have previously heard the argument that S/PDIF actually does have more than enough bandwidth, but that the evil Hollywood people prohibit it from being used for more than 2 channels of PCM due to the lack of HDCP encryption. That theory doesn't really hold a lot of water for me. The inability of S/PDIF cables to carry more than 2 channels of PCM goes back to the DVD and even Laserdisc formats, both of which predate HDCP encryption. Further, I can't understand the logic that the music and movie studios would be so paranoid over copy protection that they can't allow multi-channel PCM to be transmitted without HDCP, yet they don't seem to have a problem with stereo PCM (which is, after all, the format that all music CDs are encoded in). Also, a great many Blu-ray players are able to decode a soundtrack and output it in full quality over multi-channel analog connections with no copy protection. Why would that be allowed?
But I'm not an audio engineer. Perhaps if one of our readers is, he or she can shed some light on the situation in the forum thread linked at the end of this article.
'Starship Troopers' Playback Problems
Q: I recently purchased the 'Starship Troopers' Blu-ray disc. When I brought it home, I discovered that when I placed it in my Blu-ray player (Sony BDP-350), it would only load as far as the loading screen. The "Loading" bar plays, followed by nothing but a black screen. I left it on for ten minutes and nothing happened. I upgraded my firmware to no effect before finally assuming the disc was in some way defective. I exchanged it for another copy, only to discover the same issue when I got home. When I took the second disc back, the store tested it on their own Blu-ray player - also a BDP-350 - and the same disc that gave me trouble played perfectly! As a result, they wouldn't give me another replacement disc. I don't entirely blame them, but now I'm stuck with a disc that I really want but can't seem to play. What could possibly be wrong?
A: It turns out that the 'Starship Troopers' Blu-ray has an authoring glitch. When inserted into a BD-Live capable Blu-ray player, the disc attempts to confirm the player's BD-Live status, regardless of whether you plan to use the BD-Live features or not. What this means is that your player must have internal memory installed for BD-Live, or the disc won't play.
The Sony BDP-S350 doesn't come with any internal memory out-of-the-box. You must install that yourself via a USB stick. (Some brands may take an SD card instead.) 1 GB should do. Once you do that, 'Starship Troopers' will play.
Fortunately, this should be an inexpensive fix. However, I agree that this is a tremendous nuisance. Frankly, it astounds me that major hardware manufacturers like Sony (Panasonic, Samsung, and other brands have also had the same problem) would ever build BD-Live Blu-ray players that don't have the required memory built-in. 1 GB of memory certainly wouldn't have added much to their manufacturing costs. Thankfully, this seems to be less of a problem in current models, but was very much an issue at the time yours was released.
Cleaning a Blu-ray Disc
Q: What is the best way to remove smudges from a disc? Is it okay to use warm water, hand soap, and a microfiber cloth to clean them?
A: Blu-ray discs are manufactured from the same types of materials as CDs and DVDs. Any cleaning instructions for those formats will apply equally to Blu-rays.
Depending on the type of dirt or smudge, it's usually best to start with the simplest, least invasive procedure. Breathe on the disc to fog it up a little, and then wipe it with a microfiber or similar soft, lint-free cloth. Always start from the center and wipe straight outwards. Do not rub in circles or length-wise across the disc. If that doesn't do it, try a little water. If something is really caked on there, some mild soap, preferably diluted, may also help.
And if all of that doesn't do the trick, only then would I try to bring in a cleaning product. Any cleaners that specifically claim to be formulated for these types of discs should be fine, but I wouldn't spend a lot of money on them. Common rubbing alcohol is actually very good for this sort of thing. Whatever you use, pour the liquid onto the cloth before wiping, not directly onto the disc. Be sure to avoid heavier solvents, which may damage the disc.
Make sure that the disc is completely dry before putting it back in the case or playing it. That's really all there is to it.
The HD Advisor knows many things, but he doesn't know everything. Some questions are best answered with a consensus of opinions from our readers. If you can help to answer the following question, please post your response in our forum thread linked at the end of this article. Your advice and opinions matter too!
Connecting a Blu-ray Player to a Laptop Screen?
Q: Do you know of a good way to use a laptop's screen to hook up a Blu-ray player (or any high-def video equipment)? For instance, say I want to watch a Blu-ray movie using my 17" laptop's 1080p-friendly screen. The only device I seem to find offer composite or S-Video inputs at best. If you know of any way to go HDMI or component in into a laptop screen, it'd be much appreciated.
Check back soon for another round of answers. Keep those questions coming.
Joshua Zyber's opinions are his own and do not necessarily reflect those of this site, its owners or employees.
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