High-Def FAQ: Is HDMI 1.3 Really Necessary?

[jed]

In his latest "High-Def FAQ" column, Josh Zyber unravels the mystery that is HDMI 1.3

Read it here:
http://www.highdefdigest.com/news/show/853

[Arkadin]

Yes the whole issue with "supports" these features versus what it actually DOES support is a complete and total sham, and probably the No. 1 most deceiving and confusing issue regarding the entire HD market at this point in time.

[Brian2]

Bah, that info about Deep Color ruined some fantasies...

[Megasquidd]

What do I need to look for on a new receiver that will allow it to take advantage of the listings on discs that says PCM 5.1 or PCM 7.1?

[Arkadin]

I'd say re-ask this in home theater for a better response. people go in there all the time to answer questions. or post in Blu-Ray hardware.

[Pisto]

With HD DVD, soundtracks can be authored in the 'Advanced' mode, which allows multiple content streams to be live-mixed (mixed in real time). You don't need another soundtrack for foreign languages. Just swap out the English centre channel stream with one of the foreign centre channel streams. You don't need another soundtrack for commentary. Just reduce the level of the main soundtrack and mix in the commentary stream. Same with button sounds and other interactive features, like picture-in-picture.

In the case of King Kong, does this means that foreign languages are using 4.1 channels of the 1.5 Mbps original mix? In other words, instead of 3*1.5 Mbps, it's actually 1.5 Mbps + 2*center channels?

[kanefsky]

There is some data lost in the conversion from lossless codecs to PCM. The raw streams contain metadata that guides the decoding process so it can be optimized for different speaker configurations. dynamic range settings, etc. Once the conversion takes place, the metadata is lost. That's why it's nice to centralize the decoding in a receiver where you can have one place to maintain all those settings.

It's similar to RAW files versus TIFF files in digital photography. The RAW file contains the information directly from the camera sensor, before the color profile, white balance, sharpening, etc. is applied. Some cameras can convert the RAW file to a lossless TIFF file, but if you do that you've lost the ability to send the original RAW file to your computer and use a better color profile, different white balance settings, a better sharpening algorithm, etc.

--
Steve

[Blurry]

Josh, this was a truly excellent article and summarizes a number of points that I have been trying to explain for the longest time, and you have done it very clearly. Also, the inclusion of Sanjay Durani's insight is excellent as well.

Now when these questions come up, I can just reference your article.

There is one minor point which is not correct. Your article says:

If using one of those cable types, the HD DVD or Blu-ray player will downconvert the DD+, TrueHD, or DTS-HD signal to standard Dolby Digital or DTS quality.

While this is true for all HD DVD players on the market which will indeed down-convert to standard DD and DTS, this is not true of any Blu-ray player that I know of (even the PS3). These Blu-ray players will decode some of these formats but will not re-encode them into DD and DTS for legacy connections. Now, TrueHD and DTS-HD will seem to work with Blu-ray players as you describe, but only because Blu-ray mandates that a DD stream be included with every TrueHD track (exactly because of this limitation) and DTS-HD has a core stream embedded, so while they are not being re-encoded, you will still get a legacy DD or DTS stream with optical connections from these audio sources. However, raw PCM will not be re-encoded and can only be output as stereo PCM via optical on Blu-ray players.

An additional problem with the above Blu-ray implementation is that using the included stream or the core stream works only in basic mode, once titles come out in Advanced mode, then they will need to be decoded into PCM for audio mixing. Unfortunately, since these current Blu-ray players cannot re-encode, that means that users using the optical connection will not be able to get 5.1+ channels of sound when any audio mixing is done in the player - only stereo PCM.

Fortunately the designers of HD DVD had thought this out well in advance so the above issue is not a problem for any existing HD DVD player, they can all re-encoded into DD or DTS or both if necessary, complete with secondary audio channels mixed in.

[Blurry]

Originally Posted by kanefsky

There is some data lost in the conversion from lossless codecs to PCM. The raw streams contain metadata that guides the decoding process so it can be optimized for different speaker configurations. dynamic range settings, etc. Once the conversion takes place, the metadata is lost. That's why it's nice to centralize the decoding in a receiver where you can have one place to maintain all those settings.

Remember, that metadata is part of the bitstream and will be sent along with it to the receiver, so whether the decoding is done in the player or the receiver the metadata will still be used. Also, it is typically used to adjust levels not alter the fundamental resolution of the sound, much as the volume control on your receiver will change the source (or even just the level calibrations that your receiver does for each channel for level balancing and distance compensation - as well as delays which are added), but that does not make it lossy...

[kanefsky]

Originally Posted by Blurry

Remember, that metadata is part of the bitstream and will be sent along with it to the receiver, so whether the decoding is done in the player or the receiver the metadata will still be used. A

AFAIK, the metadata is unique to the specific codec and is not sent with the PCM data after decoding. It's too late to do anything with the metadata then anyway, because it's most useful *before* decoding has taken place.

--
Steve

[WesleyTech.com]

Thanks for the great article Josh. Well worth the read.

[Cochise]

Thanks, Josh, for a very educational and well-written article.

However, I'm not sure the debate is quite settled as to if TrueHD / DTS-HD MA can be be transmitted via bitstream from current HD DVD's. You say "Sure, the player will be able to transmit the bitstreams of those formats, but only if the disc is authored in Basic mode, which no HD DVDs are, a fact they conveniently neglect to mention."

But, in the AVS Insider thread, when asked: "Toshiba and Onkyo have announced players that can output the non decoded bitstream for all the advanced audio codecs. Has Toshiba found a workaround for that limitation, or will this streaming feature be useless with practically all the disks?"

Microsoft Ben Waggoner replied:

Originally Posted by benwaggoner

There are lots of potential workaround, but I don't know which they're doing.

Basically what you'd do is always output the "native" main audio, and then when other sounds or commentary track comes up, then mix and recompress to that main audio. So, as long as all you're listening to is the main audio, you get it as native bits. Of course, reencoding from a lossless codec to a lossless codec is lossless, so it's not like you'd ever know if the player was always decoding and reencoding .

Given all the "jitter" info from Amir and others a few weeks ago, I'm now thinking that TrueHD over HDMI could be an interesting audio option over PCM for audiophile listening.

So, as I understand it, these new players claiming to be able to output TrueHD / DST-HD MA to the receiver may have a function to "turn off" advanced content mode, not allow any mixing or input of any secondary audio streams, and just output the main movie soundtrack. To enjoy any interactive / special features, you will have to go back to the player decoding & mixing.

That would be just fine with me.

[Hale]

Terrific article. Bookmarked!

[Dhawkins541]

seems funny that all the PS3 supporters talks so heavily about having hdmi 1.3 and deep color support in there player and game console but to me seems rather useless to have i guess my hdmi 1.2a is just fine for me in my elite and my hd dvd's look great too boot on thing i would change is to have a bigger tv but you cant have everything

[Blurry]

Originally Posted by kanefsky

AFAIK, the metadata is unique to the specific codec and is not sent with the PCM data after decoding. It's too late to do anything with the metadata then anyway, because it's most useful *before* decoding has taken place.

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Steve

I had a slight misinterpretation of your original statement. I had thought you were somehow saying that it lossless if it is decoded in the receiver, but your emphasis was really that you wanted to centralize your settings in the receiver, which is a valid desire even though IMO it is still necessary to do the decoding in the player for reasons mentioned in the article (and it is not that big of a deal to put your settings in the player). Sorry for my mis-interpretation.