Talk Back: HDMI Falls Short On Audio - For Now

[dang]

Checkout our latest Talk Back: HDMI Falls Short On Audio - For Now (http://news.designtechnica.com/talkback45.html)

[kepaloha]

I was not aware that the HDMI did not support the 5.1 sound. Very cool article.

[Ioman]

Neither did I. Kind of a waste IMO. Although there are few middle-end recievers that have HDMI in them yet. I think it will change in about a year so maybe its not that ig of a deal, I would certainly be dissapointed if I had a very high-end reciever.

[videobozo]

Hmm...something doesn't make sense here. I've been researching HDMI gear (any day now I'll be buying some!) but I haven't heard of any restrictions on 5.1, other than that the TVs that only have 2 speakers only support 2 channel PCM (as you would expect). Is that what the author means when he says "none of the connections currently on the market today are passing 5.1 audio"? In other words, since the HDMI receivers are all 2-channel TVs, then the DVD players are not sending 5.1?

I know that the Panasonic, Denon, Pioneer, etc. A/V Receivers all support a Dolby Digital 5.1 bitstream on HDMI and there are a variety of HDMI DVD players that do also because they were all demonstrating this at CEDIA. In addition, they were showing 6 channel from a DVD-Audio player across HDMI. That's 6 discrete digital PCM channels on HDMI , not 5.1 compressed. It was awesome!

All of the DVD players that I've looked at can send a Dolby (or whatever bitstream) out HDMI. There have been some complaints that their menus make it difficult to send it but I've never seen any that keep you from doing it entirely.

So which HDMI products is the article talking about (other than 2-channel TVs) that don't actually support 5.1 and are limited to 2-channel? I can't find them but I can't say I've done an exhaustive search. I'd love to know the specifics before I buy an amp with that restriction. In any case, it certainly doesn't seem like ALL or even MOST. There are some AVRs that do HDMI switching and don't process the audio at all - that's definitely something to watch out for! - but again, I haven't heard (until now) of any that supports only 2-channel and not 6-channel. We need names!

I've also never heard of any DVD player sending "Dolby 2.0" on HDMI (or on S/PDIF for that matter). Does that mean that the DVD player decodes Dolby 5.1-channel, downmixes to 2 channel and re-encodes to Dolby for transmission? That doesn't happen. When he says "Dolby 2.0" is the author talking about downmixed, which is actually 2 PCM channels (not Dolby at all)?

vbozo

[Ioman]

Not to go too far off topic, but I noticed my Pioneer DVD player (which plays SACD and DVD-Audio) will not let me play SACD or DVD-A using the digital optical. It wants me to hook up 6 seperate composite cables to the back of the unit. Not only would that look bad with all of those wires, but the sound would be a step lower than digital correct?

Perhaps 5.1 through HDMI is not out in current receivers because of DRM issues? And perhaps thats why my DVD player will not support SACD or DVD-A through the digital optical output?

[Ioman]

Knyo's top-of-the line NR1000 says it has HDMI video upconversion, but there is no mention of 5.1 sound in or out of this connection. http://www.us.onkyo.com/model.cfm?m=TX-NR1000&p=f&class=Receiver

This would be pretty confusing to a lot of people.

[videobozo]

If that Onkyo receiver doesn't support audio, that would definitely be confusing!

Either they just assume that people reading the specs would assume that the audio would be handled the same as S/PDIF (or would it be the same as IEEE-1394?) or they don't actually handle the audio. There's also a note on technofile.com that says
"...including the new HDMI (high definition multimedia interface) for optimal digital video connections, iLink (IEEE-1394) for digital transfer of high-resolution SACD and DVD-Audio..."
HDMI for "optimal digital video" and IEEE-1394 for "SACD and DVD-Audio" isn't sounding too good for HDMI audio!

That would be too bad - it looks like an awesome product otherwise (though a bit out of my price range unfortunately).

I've heard that initial HDMI implementations, like that Pioneer player, may be prevented from sending DVD-Audio and SACD because of content protection restrictions, not technical issues with HDMI. Any truth to that?

vbozo

[videobozo]

From the Onkyo manual...
"However in order to playback the audio signal with the TX-NR1000/ TX-NR5000E, make a separate digital connection with a DVD player or other devices, since the TX-NR1000/ TX-NR5000E cannot playback any audio signals supplied from its HDMI IN 1/2 terminals."

That's not a 2-ch vs. 5.1 ch. question! Oh well, I couldn't afford it anyway.

vbozo

[questionlp]

I've heard that initial HDMI implementations, like that Pioneer player, may be prevented from sending DVD-Audio and SACD because of content protection restrictions, not technical issues with HDMI. Any truth to that?
My information may be a bit dated, but I believe that many SACD players do not allow audio to be sent through any digital outputs on the player (for two main reasons: first being copy protection and second being limited bandwidth of SPDIF). If that is still true, I doubt if you will see SACD audio signals being sent across HDMI in digital format.

As far as DVD-Audio, there might be a SCMS-style copy protection that would allow the receiver or TV to decode the audio back to analog, in order to feed the speakers. If SCMS is in play, then the SCMS-compliant device cannot pass the audio stream as digital to the next device (as seen with MiniDisc and DAT). Of course, there are SCMS bit strippers available in Professional converters :)

Overall, the first version of HDMI seems nice, though the forced copy protection and the limited audio situation are turn offs for me. If they can resolve the multi-channel audio, then that will help a bit... but I still cannot bring myself to bear and use a locked-down protocol and specification that enforces strict copy protection.

[HughC]

I was not aware that the HDMI did not support the 5.1 sound. Very cool article.

HDMI does support 5.1, it is the manufacturers who may not include 5.1. You can verify this by going to www.hdmi.org

[mjohasteener]

Just a quick note. Don't compare HDMI with 1394. They are really different beasts. HDMI is a one-way point-to-point connection, just like good old RCA cables. It has the advantage of carrying virtually any kind of video or audio in all sorts of multiplexes, but you still have to connect the right "out" socket to the right "in" socket ... And if you don't do it, there is no way to find out what you did wrong other than follow the cable by eye/hand.

1394, on the other hand, is really a network. You can plug into any socket ... They are all the same ... as long as there is a path between any two devices (with up to 16 hops), then they can communicate. And since the higher layer protocols include all sorts of automatic identification, the end points can make the connections themselves ... The user doesn't have to get involved.

... and 1394 will support (does support) all audio formats (it's heavily used in the recording industry), and most video. The only place it comes up short is uncompressed HD video, since the current versions are limited to 800 Mbit/sec, while a 1080i HD stream (uncompressed) is about 1.5Gbit/sec. Fortunately, all the HD content is originally in some form of MPEG with data rates of 10-25Mbit/sec, so if your device includes an integrated MPEG decoder (i.e., you have a DTV!), then uncompressed is not required. The exception, of course, is locally generated content ... E.g., some sort of hyperPlayStationHD ...

[szhjcn]

What I find baffling about this new interface (HDMI) is all the devices I've seen on the Market have one output (i.e. DVD Players) or one input (TV's and Projectors). In my instance, I want to take the Video and send this to a Projector and the Audio and send this to a Decoder, but with just one Cable it can't be done. This means you would have to buy something like the new Denon Receiver (AVC-A1XV) that has multiple HDMI inputs and outputs, but replacing my High End Reciever now was not something I was comtemplating (have a Denon AVP-A1 with PAO-T2 & T3 Amps).

Guess for now I would just use HDMI to link a new DVD player (possibly a Poineer DV-868 AVi or Denon DVD-3910) with a new Projector (maybe the new Benq PE 7700 due out in March) and continue using a Digital Cable for Audio. Feedback on DVD & Projectors would be greatfully received.