High-Def FAQ: Blu-ray and HD DVD Audio Explained - High-Def Digest Forums
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Old 10-12-2007, 04:46 PM
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Default High-Def FAQ: Blu-ray and HD DVD Audio Explained

Josh Zyber's latest "High-Def FAQ" is up. This time, Josh presents a comprehensive overview of the myriad different audio formats and configurations currently offered (and planned) for Blu-ray and HD DVD.

If you've got questions about the new high-def audio formats, this one's a must-read.

Full story here:
http://www.highdefdigest.com/news/show/1064
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Old 10-12-2007, 05:25 PM
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Great article Josh, but one error I spotted:

Quote:
PCM
What it is: A PCM track is an exact replication of the studio master, encoded on disc without compression.
It only matches the studio master if it has not been downmixed.

Spider-man 3 for example. The studio master is 24-bit, the PCM track is only 16-bit. In this case it is the TrueHD track matching the master.
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Old 10-12-2007, 05:28 PM
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Quote:
Originally Posted by HD Guru View Post
Spider-man 3 for example. The studio master is 24-bit, the PCM track is only 16-bit. In this case it is the TrueHD track matching the master.
hence the review stating that the trueHD track sounded better...
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Old 10-12-2007, 05:40 PM
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Quote:
Originally Posted by HD Guru View Post
It only matches the studio master if it has not been downmixed.

Spider-man 3 for example. The studio master is 24-bit, the PCM track is only 16-bit. In this case it is the TrueHD track matching the master.
I think this may be a matter of semantics. The studio has both a 24-bit master and a downsampled 16-bit master. The PCM track in this case is a replication of the 16-bit version, but they are both technically "studio masters".

Yeah, I know, it's a weasely technicality.

I'll go into more detail about bit rates and bit depth in a future column.
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Old 10-12-2007, 05:52 PM
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Quote:
Originally Posted by Josh Z View Post
I'll go into more detail about bit rates and bit depth in a future column.
next i need you to explain string theory...

lol

not that I would understand if you did... or really care... i just want to see people on these forums try to argue with you about that!
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Old 10-12-2007, 05:59 PM
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Right now I am without hdmi on my receiver, and if I am going to buy the Samsung Combi player, I would rather not get a new receiver until that's paid off. So, my 6 year old Denon has 7.1 analog inputs. II think what's being said here is that it's up to the player if it decodes the Dolby True or DTS master audio and converts it to the same quality for output in 7.1 analog? (The Samsung combi will have 7.1 analog outs, LG's are only left and right stereo). So if this is true, the thing to do would be to try and find out from Samsung what they are going to output to a receiver with 7.1 in(s). That could be difficult to find out.
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Old 10-12-2007, 06:03 PM
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Josh,

or
Quote:
(on selected player models) may be able to transmit the codec bitstream to a receiver using HDMI 1.3
How does this relates to your article:High-Def FAQ: Is HDMI 1.3 Really Necessary?

I thought this is not possible, because of advanced mode of hd-dvd and some new blu-ray discs.

Pieter
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Old 10-12-2007, 06:20 PM
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Good article overall! Here are some comments:

(1) I definitely and strongly agree with HD Guru: A 16 bit PCM track is *not* an "exact replication of the studio master", if the original movie master has more than 16 bits. The studio also has a 640kbps AC3 master. So are the Blu-Ray AC3 tracks also an "exact replication of the studio master"? That doesn't make any sense. And I find it very important to make this clear because there is more than enough confusion in the forums about this already. Many many people say "PCM is perfect, it doesn't get better than this" without even looking at the bitdepth. In fact some AVSForum insiders prefer high bitrate DD+ 24 bit tracks over 16 bit PCM tracks! So this is a very important thing to clarify! Another reason why bitrate must be mentioned in the article is that 99% of the HD DVD lossless tracks are only 16 bit while many Blu-Ray lossless tracks are 24 bit. E.g. all DTS-HD Master Audio tracks on HD DVD are only 16 bit, while all DTS-HD Master Audio tracks on Blu-Ray are 24 bit!!

(2) The conventional DTS format is not named "DTS Encore" but "DTS Digital Surround" as you can check on the DTS homepage.

(3) TrueHD is only bit for bit identical to PCM if the studio encoded the track without dialog normalization metadata. Sony does that. All other studios still have dialog normalization enabled. That means that the TrueHD decoded data goes through digital post processing which reduces the volume (and destroys bit for bit perfectness). And it can even get worse: If the firmware is bad, the player might even apply DRC (Dynamic Range Compression). This has happened before, namely in the Xbox HD DVD player (with E-AC3).

(4) Conventional Dolby Digital is used by many HD DVD discs - but only in the extras. Deleted scenes, trailers etc are often MPEG2 + AC3.

(5) I'm not sure (couldn't find any specific information), but is PCM support really limited to 2.0 on HD DVD? I rather think it supports 5.1, too, but I'm not sure. It's not a good idea to use it on HD DVD, anyway, so it's not really important.

(6) The DD+ bitrate used on Universal and Paramount HD DVDs is actually 1536kbps and not 1509kbps, I believe. Not that those 27kbps matter much, though...

(7) DD+ also supports 768kbps (and maybe some more rates in between). E.g. the German DD+ track on the German Serenity HD DVD is 768kbps.

(8) SPDIF does have the bandwidth to transport DD+ (it can also transport DTS at 1509kbps, after all!). There's just no specification for DD+ over SPDIF, sadly.
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Old 10-12-2007, 06:24 PM
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Quote:
Originally Posted by madshi View Post
(5) I'm not sure (couldn't find any specific information), but is PCM support really limited to 2.0 on HD DVD? I rather think it supports 5.1, too, but I'm not sure. It's not a good idea to use it on HD DVD, anyway, so it's not really important.

No I do not believe it is.

A Might Heart from Paramount comes out in two Tuesdays and is spec'd here to have PCM 5.1

http://hddvd.highdefdigest.com/1094/mightyheart.html
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Old 10-12-2007, 06:30 PM
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Quote:
Originally Posted by Josh Z View Post
I think this may be a matter of semantics. The studio has both a 24-bit master and a downsampled 16-bit master. The PCM track in this case is a replication of the 16-bit version, but they are both technically "studio masters".

Yeah, I know, it's a weasely technicality.

I'll go into more detail about bit rates and bit depth in a future column.
The majority of major hollywood movies over the last 4-5 years have been using 24-bit masters with 48 kHz sampling. That is the studio master. You need a 24-bit encode that is lossless to match that studio master.

Anything that is downsampled is not the studio master as you cannot have two masters. One is a downsampled version of the original master.

For the majority of movies it is unlikely we'll see Hollywood transition to anything above that, because you immediately double everything - Hard disk drives, etc. Also above 24/48 you really would have trouble discerning any further increases of quality in your average movie.

The music business is a different kettle of fish. To master in 32-bit/384kHz is now possible at most of the large studios, but again the amount of storage used is ridiculous. That's why 24/96 to 24/192 is the normal limits in professional music, with 24/44.1 being the norm in more DJ-related genres like techno as most samples used are mastered on CD.
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