Blu-ray Technology - Technical Questions

[Jules]

I searched and there doesn't appear to be a thread dedicated to queries regarding the Blu-Ray Disc format, so I made this. I have a question of mine to ask, but other users can use this thread in the future if they too have questions of a technical nature.

So, my father and I are considering purchasing a Blu-Ray player in the near future, but there's something that I need to know that I don't recall ever seeing adressed anywhere on the internet.

We already have an HD Ready TV, so that's not a problem. However, we have a small surround system, a Sony HTS-S600, to be precise. The receiver accepts Dolby Digital 5.1 and DTS 5.1 and is currently hooked up to our DVD player via a coaxial digital cable (we could also have used an optical cable but never bothered).

However, having bought the receiver back in 2005, it is not equipped to handle tracks like Dolby True HD or DTS Master Audio.

What I want to know is if Blu-Ray Players can convert the hi-def 7.1 surround sound signals on Blu-Ray discs into regular Dolby or DTS 5.1 for use with older sound receivers.

I hope so, as I would feel really stupid buying a Blu-Ray player, enjoying better picture, but listening to films over the television when I have a perfectly fine, not yet even 4 year old sound system in the room which I can't take advantage of.

[drfsupercenter]

While I don't know anything about your specific surround sound system or even how Blu-Ray works on surround systems (We use our PS3 on the built-in TV speakers...), I know that all Blu-Ray players can output sound via HDMI, and then many others can use optical audio cables.

Does your receiver accept HDMI? I don't think the player is what converts the channels, but the receiver. As I know receivers can also turn 2.0 stereo into a fake surround that uses all the speakers.

[ajmrowland]

IS your surround system is without HDMI, the core Dolby and/or DTS track will be extracted. You'll still get slightly better audio than DVD, but it's standard definition.

As for conversion of 7.1 to 5.1, it should be like 5.1 to tv speakers. It will be converted.

BTW, I find Home Theater in a Box Speakers aren't as good as the ones you purchase separately. If you have the time and money, you can think about that in the future.

My question is, from one source, I hear 1080p uses vertical scan lines, and from another, I hear it uses pixels. I'm confused.

[Jules]

drf and ajmrowland: No, my surround system does not accept HDMI.

However, if I've understood you well, ajm, I take it that there won't be a problem since as you said, Dolby Digital 5.1 and DTS 5.1 will be extracted from Dolby True HD and DTS Master Audio for older systems, like mine. I expect I'd have to connect the Blu-Ray Player to my receiver via a digital optical cable. How will the Blu-Ray Player know that the receiver should be fed standard Dolby / DTS and not their HDMI counterparts?

[drfsupercenter]

When they talk about "scan lines", they are the same as pixels... at least for digital stuff.

[DarthPrime]

You will still get Dolby Digital, etc... you just can't use the new HD audio formats. They will probably sound a little better than the audio from DVD as well. Optical or Coaxial really doesn't matter in my opinion. The player will have settings for audio that you can adjust.

You can still use the new HD formats on old receivers. The receivers need a set of analog audio inputs for each channel, and you need a Blu-ray player with analog audio outputs for each channel. The player will decode the signals and pass them though to the receiver.

If your receiver has these inputs I would look for a player with the outputs. If not your current setup will work fine when you upgrade to Blu-ray (minus the HD audio formats).

[Jules]

You will still get Dolby Digital, etc... you just can't use the new HD audio formats. They will probably sound a little better than the audio from DVD as well. Optical or Coaxial really doesn't matter in my opinion. The player will have settings for audio that you can adjust.

You can still use the new HD formats on old receivers. The receivers need a set of analog audio inputs for each channel, and you need a Blu-ray player with analog audio outputs for each channel. The player will decode the signals and pass them though to the receiver.

If your receiver has these inputs I would look for a player with the outputs. If not your current setup will work fine when you upgrade to Blu-ray (minus the HD audio formats).

I don't quite understand. You mean the Blu-Ray player can send Dolby Digital and DTS but through analog outputs? My receiver doesn't even have analog inputs for surround sound (it does have others for other uses). You can only feed it surround sound via coaxial or optical cables.

[KubrickFan]

I don't quite understand. You mean the Blu-Ray player can send Dolby Digital and DTS but through analog outputs? My receiver doesn't even have analog inputs for surround sound (it does have others for other uses). You can only feed it surround sound via coaxial or optical cables.

There are Blu-Ray players that can even decode the newer formats and send them through the analog outputs.
But what you want is bitstreaming, so you get the core from the DTS-HD track. I think most players can do that, but you might check that for certainty. With Dolby TrueHD it's a little different. That's not a core the player extracts, it's just a standard Dolby Digital track that's sometimes hidden in the menu.

[CampbellzSoup]

I'm sure if you dont' have the optimal settings it sort of "works with what you have" meaning you won't get the full experience, but it will decode for your system accordingly.

[I am the Doctor]

I can't help you much with audio questions, but there are other things to consider when picking a Blu-Ray player:

In my opinion, one of the biggest things to consider when buying a Blu-Ray player is firmware support. Unfortunately, Blu-Ray is still not yet at the point where one can simply pop a disc in the machine and have it play with no issues. Thus, most Blu-Ray players will require firmware (aka software) updates from time to time.

From personal experience, some manufacturers are fairly good about providing updates as needed, others less so. My first Blu-Ray player was an LG model, and the firmware support was terrible. Ended up eventually buying a Sony model, and the firmware support has been much better.

After all, it isn't much fun buying a disc, and then finding out it won't play until your manufacturer comes out with a firmware update. Since buying the Sony model, I haven't yet had an issue of a movie simply not working, unlike when the LG was my primary Blu player.

[ajmrowland]

I don't quite understand. You mean the Blu-Ray player can send Dolby Digital and DTS but through analog outputs? My receiver doesn't even have analog inputs for surround sound (it does have others for other uses). You can only feed it surround sound via coaxial or optical cables.

There are Blu-Ray players that can even decode the newer formats and send them through the analog outputs.
But what you want is bitstreaming, so you get the core from the DTS-HD track. I think most players can do that, but you might check that for certainty. With Dolby TrueHD it's a little different. That's not a core the player extracts, it's just a standard Dolby Digital track that's sometimes hidden in the menu.

Actually, the TruHD track will also have it's "core" exctracted and does sound different from the DD track.

And a digital optical is best recommended. Most receivers have PLII, but that's "fake" surround sound. You want native 5.1.

[DarthPrime]

I can't help you much with audio questions, but there are other things to consider when picking a Blu-Ray player:

In my opinion, one of the biggest things to consider when buying a Blu-Ray player is firmware support. Unfortunately, Blu-Ray is still not yet at the point where one can simply pop a disc in the machine and have it play with no issues. Thus, most Blu-Ray players will require firmware (aka software) updates from time to time.

From personal experience, some manufacturers are fairly good about providing updates as needed, others less so. My first Blu-Ray player was an LG model, and the firmware support was terrible. Ended up eventually buying a Sony model, and the firmware support has been much better.

After all, it isn't much fun buying a disc, and then finding out it won't play until your manufacturer comes out with a firmware update. Since buying the Sony model, I haven't yet had an issue of a movie simply not working, unlike when the LG was my primary Blu player.

I agree. Looking at future firmware updates is a great ideal. I've noticed that Sony and Panasonic seem to release updates faster than other manufactures.

[2099net]

Hi Julian,

I'm no expert so make sure you ask your reseller before commiting to a purchase but here's how I think Hi-Def Audio plays out on Blu-ray.

Most players have the ability to convert any Hi-def sound format into PCM which can be streamed via optical or HDMI cables. I think, due to the bandwidth requirements (a full uncompressed 7.1 soundtrack will require considerable bits) this can only be done on optical connections. However, if you are able to connect to the player via this cabling it shouldn't matter what format the soundtrack is encoded for most players as it will internally convert it if required.

if you do not have optical/HDMI you'll probably have to settle for a lower specified soundtrack encoding - which will of course be of lesser quality. The enhanced DTS codecs should have the core DTS 5.1 encoded within them, but in order to extract these, your receiver needs to be able to understand DTS encoding or your player needs to be able to convert it. (Universal only use DTS HD MA for their English soundtracks on their blu-rays and there's still occasionally people who post on Blu-ray.com that they cannot hear the soundtrack - presumably because their receiver and players cannot decode DTS).

Dolby TrueHD does not contain the basic core encoding, but any disc with TrueHD should have plain Dolby Digital 5.1 as an alternative. This should be without exception because as far as I know, it is a requirement of Blu-ray licencing. I don't know of any Blu-ray with a TrueHD soundtrack without the normal Dolby Digital 5.1 soundtrack too.

If your receiver can play normal DVDs Dolby or DTS soundtracks, you should be fine with any player.

Again, I would make an effort to ask your reseller. If you are going to buy over the internet, be cheeky and ask at a local shop, pretending you are interested and intend to buy the player from them.

[Jules]

Wow, thanks netty! It seems I'll be fine then, since:

1) My receiver can connect to a player (be it DVD, Blu-ray, etc.) via a digital optical cable.

2) It can receive and output both Dolby Digital 5.1 and DTS 5.1.

So (correct me if I'm wrong) if I insert a Blu-ray disc with Dolby True HD 7.1, the same disc should offer me the option of listening to a "lesser" Dolby Digital 5.1 track, which would be compatible with my system. If I insert a Blu-ray disc with DTS HD Master Audio 7.1, the Blu-ray player should be able to extract a standard DTS 5.1 signal from the track and send that to my receiver via the digital optical cable, right? Is that something it does automatically, or is it something the user must specify? And must the Blu-ray player have an onboard decoder to downconvert DTS HD Master Audio 7.1 to DTS 5.1 (and then send it to the reciever) in the first place?

One last question. Should DTS not work, do all Blu-ray discs come with Dolby, as backup?

[2099net]

Yes, any Blu-ray with a Dolby TrueHD soundtrak has to have either a PCM, DTS or "normal" Dolby Digital soundtrack option. As I understand it, this is a licencing requirement when making a Blu-ray disc, because TrueHD is not a "mandatory" codec.

See http://en.wikipedia.org/wiki/Blu-ray_Disc#Codecs

I don't know if the core DTS track is extracted automatically, or if you have to set the option on the player's set-up manual.

As for your last question, no, a disc with a DTS HD MA soundtrack does not need to have a seperate DTS or Dolby Digital soundtrack - this is because the HD track includes the "normal" DTS soundtrack. This is why some people buy a Blu-ray and are unable to hear the soundtrack - they must have equipment incapable of decoding DTS bitstreams.

See this post here for example
http://forum.blu-ray.com/showthread.php ... ht=decoder

[Jules]

OK. From the information you've posted and the links you provided I think I can safely deduce that I won't have a problem. My receiver accepts DTS, so I'll be fine whatever the player throws at it.

As you advised, I will ask and pester the salespeople in the store regarding the issue ... until I am satisfied. Thanks a million netty!

[KubrickFan]

Actually, the TruHD track will also have it's "core" exctracted and does sound different from the DD track.

That's a common rumor that's false. There's no decoding going on. It doesn't matter if you choose Dolby TrueHD or Dolby Digital, you're automatically reverted to the last one if your receiver can't handle the TrueHD track.

[I am the Doctor]

Julian,

Just out of curiousity, what kind of HDTV do you have. Is is a 720p TV or a 1080p?

The only reason I ask is that I originally bought into Blu-Ray, I was using a 720p set. The video quality was definitely improved over standard def DVD, but what I found was that upconverted DVD was just about as good as Blu on the 720p set.

It wasn't until I upgraded to a 1080p set that I really noticed a major difference between upconverted DVD and Blu Ray, at least in terms of video quality. Upconverted DVD is no match for Blu on a 1080p set.

Anyways, that was my experience. If your TV is only a 720p, it might be worth checking into a good DVD upconverter. However, if your TV is 1080p, time to "Go for it!"

[Jules]

It's 720p. When my father and I were shopping around I kept coaxing him to get a Full HD set. But he wanted a giant screen, a 50" plasma TV. At that size, the 1080p set was way out of our budget, unfortunately.

Strangely, you hear mixed stories about 720p vs 1080p. Some people claim there's a stunning difference between the two. Others say the benefits of 1080p are subtle, and not worth the extra cash. Who to believe?

Anyway, we've had our TV for almost a year now but it's only been used as an SD machine. I couldn't even hook-up the DVD via component video as the player doesn't output that. So I had to settle for RGB scart (which, in all fairness is very good but feels somewhat crude on an HD set ).

[KubrickFan]

It's 720p. When my father and I were shopping around I kept coaxing him to get a Full HD set. But he wanted a giant screen, a 50" plasma TV. At that size, the 1080p set was way out of our budget, unfortunately.

Strangely, you hear mixed stories about 720p vs 1080p. Some people claim there's a stunning difference between the two. Others say the benefits of 1080p are subtle, and not worth the extra cash. Who to believe?

Depends on how big the screen is, and how far away you're going to sit from it.
This is a good chart. And although it isn't decisive or anything, it's still a pretty good guideline.