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HDMI - What's What and Do I really Need It?

Old 10-10-06, 07:38 PM
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HDMI - What's What and Do I really Need It?

Just when I think I have this all nailed down, something else gets thrown into the mix... =/

I was thinking of starting a thread on this to get some answers, but I think Spiky already answered it in another thread pretty well, however I think an individual one is warranted. Plus I'd like to clairifty without threadjacking.

My mods are in red. Please correct me if I am wrong.

Originally Posted by Spiky
First, you are going to have to try to understand the audio outputs for HDDVD and Bluray. It is a little tricky, at least right now when all the HDMI stuff isn't worked out in the industry, yet. The new codecs are called Dolby Digital + (compressed), Dolby TrueHD (uncompressed), DTS-HD (compressed or uncompressed). Uncompressed is the best quality. Here are some additional points about connectivity.

1) The old optical/coax digital audio outputs cannot handle any of these three new codecs natively.
1a) All of these can be down-converted to DTS by the players. This DTS signal can be sent over the old optical/coax system. It may still sound better than an older DVD version, but not as good as the next 3 options.
3) They can also be converted to PCM, which is a more generic digital audio format that has been around for years, similar to good old CD, but higher resolution. This can be sent over pretty much any current HDMI setup (v1.0 - v1.2 ?) . For Bluray discs, they generally have the PCM right on the disc instead of TrueHD or DTS-HD, and HDMI works for them, too.
4) The three new codecs can only be sent natively (without conversion) over HDMI 1.3, which isn't quite out, yet. So if you have an XA-1 it's not even an issue since the player cannot send out TrueHD or DTS-HD even if the disc is encoded with those.
5) Also, these three new codecs can be converted to analog right in most of the players and sent over a 6-wire analog connection (or 8-wire in some) to a compatible receiver. This is usually called a 5.1 input/output on spec sheets. This should be at least as good as an HDMI connection, even if some like to claim digital is better. It often isn't.

So, to get the best benefit from the new HD sound, you need one of:
-HDMI 1.3 on both the player and receiver
-HDMI with high-rez PCM compatibility in both player and receiver (Not sure I agree with this based on what was said above....)
-5.1/7.1 output on player and input on receiver.

So, is it important to have HDMI? Yes, no, maybe. You have to pick your poison.
Superman07 is offline  
Old 10-11-06, 07:57 AM
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Here is my .02. I am not as technical as Spiky although I understand this great explanation.

I am waiting out the format wars, standards wars and every other kind of confusion. At some point this will be settled and until then I continue to enjoy what I have already got.
Brian Shannon is offline  
Old 10-11-06, 10:46 AM
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On the PCM via HDMI....it depends on the machine, but it does work. Some are using this right now with the A1 or the Samsung BD machine, it's been discussed in the HD Forum. I believe any version of HDMI can send up to 192/24 PCM data in at least 5.1 channels. But the receiver has to be able to decode it. Current BD discs have 48/16 PCM, a couple are just coming out with 48/24 PCM. I'm not sure what flavor the A1 converts to when changing TrueHD into PCM.

For a comparison example on some older equipment: my DVDp can send up to 2 channel 192/24 PCM over optical (if I had such a disc), but my receiver can only decode up to 48/16 PCM for some mythical legal reason. Similar issues will come up with HDMI and 5.1 channel PCM. The connection/wiring system can handle it, but your specific equipment has to handle it with an appropriate DAC, too.

Yes, the XA1 doesn't have HDMI 1.3 and cannot send native TrueHD/DTS-HD digitally. Actually, nothing shipping or announced has 1.3, except the XA2 and the Playstation3. And there are zero receivers or preamps with 1.3 so far, so there's nowhere to send it, anyway. (unless I missed some announcements, I've only seen vague promises) Well, Apple did announce the iTV, but that's a little unclear as to what it does on audio. This is why HDMI 1.3 is not much of a factor right now.

If you want to try to buy one player and be set for awhile, the XA2 is probably a good choice. But you will be ahead of the game. Some will just want to wait, like Brian. Personally, I'm waiting too, but it's more based on the contents of my wallet than the connection issues.
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