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HDMI audio?
Nohbody8
Registered User regular
Registered User regular
For some reason, I never realized HDMI cables also carried audio until recently. My question is if audio over an HDMI cable is better than audio over a fiber optic or DVD coax cable?
[SIGPIC][/SIGPIC] "We're the middle children of history, man."
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HDMI cables can transfer everything digital optical cables can. They can also transmit the HD codecs in BITSTREAM form, which is the compressed, lossless form of 7.1 HD audio. HDMI cables can also transmit all 7.1 channels in uncompressed LPCM.
There is no difference between transmitting HD codecs in bitstream or uncompressed audio. The codecs are lossless, so they will be uncompressed the same way no matter what.
PSN: TheScrublet
I had no idea this was the case. I put the HDMI from my 360 through the TV and hooked up the TV <--> receiver optical and I've always gotten surround sound, but I never noticed that it's pro logic. I don't mind all that much, but stuff like this always makes me mad.
I see now that the "official" 360 HDMI cable also has the "audio adapter cable" that you can plug in at the same time as the HDMI without taking apart the connector casing; didn't know that before. Unfortunately my receiver only has one optical input and no HDMI support; maybe I'll have to get an optical switch.
Just out of curiosity, though - if I'm getting PLII from the optical out on the TV, the 360 must be putting some kind of surround sound audio through HDMI. If I had a receiver that had HDMI inputs/outputs, could I put the 360's HDMI output straight to the receiver (and then another HDMI from the receiver to the TV for video) and get digital 5.1?
The PS3 uses HDMI 1.3, which does support full digital 5.1 surround sound.
Please, correct me if I'm wrong, but I am pretty sure this is the case.
PSN: BuckySuperJew
Spoiler'd GamerCards
All versions of HDMI support 5.1 sound (up to 8 channels, actually). HDMI 1.3 adds support for DolbyHD and DTS-HD. So the 360 should support regular 5.1 surround sound just fine, unless there is some bug specific to the 360 or your TV.
Check this post: http://forum.teamxbox.com/showpost.php?p=10657054&postcount=6
INTERESTING! Thanks for the info... Maybe I will reconfigure my consoles now...
PSN: BuckySuperJew
Spoiler'd GamerCards
Hmm... that post is a year and a half old, and I know that some patches since then have twiddled with the HDMI output, specifically the audio (notably, that one bug that for some reason prevented a lot of people from getting ANY audio via HDMI). I'm wondering if this has been fixed, because I've never done anything like that and I get surround sound out of my 360's HDMI.
Now, as I said above, it's going through my TV which is sending to the receiver as encoded pro-logic (thanks to my TV, which doesn't just send stereo), so I'm not getting digital 5.1, but the directional audio works perfectly (definitely not "simulated") and the receiver shows it to be multi-channel pro-logic, so the TV must be getting a surround sound signal from the 360 via HDMI.
PSN: TheScrublet
Eh you may be right man, the site lists "Surround Sound: Yes" under the audio section of specifications for Vieras. That's about as generic and unhelpful as they could be, but there you have it.
PSN: TheScrublet
http://www.docs.sony.com/release/STRK7000.pdf
The multichannel in button has nothing to do with the optical. Try selecting the PS2 video output, but then pressing the input mode button to the up right of the dial.
PSN: TheScrublet
Hey, so you were exactly right - the optical out on my TV (TH-50PZ85U, 50" Pana Viera plasma) can do Dolby Digital for ATSC, but (and I quote the manual), "When audio from other equipment connected to this unit via HDMI is output using 'digital audio out' of this unit, the system switches to 2CH audio". I've had my Sony receiver set to PLII all this time, so that's where the surround was coming from, and the AFD stuff the receiver was pulling out low frequencies and sending them to the sub. I got the DD 5.1 running with the optical directly to the receiver and popped a couple rounds off in Fallout 3 and holy shiat the thunder.
I guess I don't understand Pro Logic very well - could you clear this up for me? I've always known that PL is "extracted" from 2-channel audio, but I have never understood the recording side of it, and Wikipedia hasn't made it very clear to me. Originally I thought that it was something that was in the mix, and worked, or it wasn't there, and it didn't. After a bit more reading, here is what I've been able to deduce (what follows is my current understanding; may be wrong):
A producer can "actively" support Pro Logic during recording by processing the mix with a set of algorithms so that when a Pro Logic-capable receiver runs the decoding on it it comes out exactly as intended. However, if they just record simple stereo, Pro Logic will still operate on it in a way that gets you decent "simulated" surround (from what I can tell, Pro Logic II was actually made to do this - running standard Pro Logic decoding on a regular stereo signal probably won't get you anything that great). Pro Logic encoding isn't something a receiver is going to auto-detect - you really just apply it to a stereo source and see what you get. If you like surround sound, just leave it on PLII all the time: that way you'll get decent simulated surround from normal stereo and you'll get actual multichannel sound from an audio source encoded with Pro Logic. This whole time I've just been decoding the standard stereo I've been getting from the TV. Is that all right? I'm no audiophile and I don't have high end equipment or good speaker placement so I'm pretty happy with PLII, but I see now that I can tell the difference.
I now also know that Netflix over 360 is only 2 channel audio as well. Had no idea. Been listening to it in PLII the whole time.
Hopefully this isn't too far OT for this thread.
PSN: TheScrublet
That said, native surround does usually sound better than simulated surround. PLII simulating surround from a two-channel signal won't sound as good as a native DD 5.1 signal (nor a native PLII signal). In Zoolander's example, switching to DD likely sounded better not because he switched to DD from PL, but because he switched from a two-channel signal to a five-channel one.
The point here is that Pro Logic isn't the devil . Most of the reason it gets a bad rap is because people have something set up wrong, but this doesn't mean it's intrinsically bad. In fact, many audio nerds overlay PLIIx over a DD signal to get 6.1 or 7.1 sound, which leaves the 5.1 DD untouched and simulates the back surround channels.
Forgot to mention this but pushing the input mode button just switches the display between a bright PS2 label to displaying analog dimly. According to the troubleshooting section in the manual, in order to change this feature, multi channel in must be off but I have no idea how to turn it off.
Not really man. Dolby Digital is going to sound superior to Dolby PLII in just about all cases. Your red statement is pretty much flat out wrong. Your green statement is getting closer, but veered off when you suggested that PLII is ever "native". It never is. Here's the long-winded elaboration.
The key thing to recognize here is that DD5.1 vs. PLII is not actually a 1-to-1 comparison. DD5.1 is an encoding. A compression of the LPCM representing 5.1 actual real defined channels of sound. It is lossy. But it will still be an accurate representation of where sounds are supposed to be. On the contrary side, PLII is actually not an encoding...it is a processing technology. You know computer-based things like EAX? That's actually closer than DD5.1 to the category of what PLII actually is. PLII can take any source material and simulate surround effects. Now you referred to a native surround PLII. There is NO SUCH THING. There are tricks designers can play to encode the sound such that it is tailored to how PLII will process it at output. This is what systems like the Gamecube and Wii do to get "surround sound"...they mix the stereo channels in such a way that PLII will put most of the sounds where they're supposed to be. But it still won't compare to actually defining separate channels.
Now here's where it gets REALLY fun. You mentioned that many audio nerds "overlay" PLIIx to upconvert native untouched 5.1 to 6.1 or 7.1. That's true. But it's still processing, and the important part of my sentence is the "native untouched" qualifier on 5.1. Then we have Dolby Digital EX. It matrix-encodes a sixth-channel of data onto the back two surround channels of 5.1. This is then decoded, much the same way as the games that output into Dolby PLII above. Thus EX is still actually doing some processing, but not as much as PLIIx is, and with somewhat better accuracy. (And for maximum confusion, the competing format DTS-ES, can do either the matrix shit of DD-EX OR it can add an actual sixth channel for true 6.1, making it the best true 6.1 encoding out there).
One small sidenote on matrix technology. DD usually seems louder because PLII is taking sounds that are sent for all speakers and spreads them. Since surround speakers are the weakest link in almost all speaker brands (audiophile and otherwise), and are usually HUGE pieces of shit in package deals from the store, weakening the signal through the matrix as a large effect.
That's all probably more than anyone ever wanted to know on the subject. The tl;dr here (besides the fact that sound formats are fucking confusing) is that DD IS inherently superior to PLII.
PSN: TheScrublet
What I got from that manual when I was looking earlier, is that the multichannel in button turns on the multichannel input in the back. That input is the set of 5 RCA-styled plugs. I have never actually seen anyone use those. So when you were pressing that button to turn multichannel on, you were actually telling it to use those empty plugs. So just press it again to turn it off. From what I understood, to get sound out of the optical:
1. Make sure multichannel is off
2. Make sure your input is tuned to your PS2 by using the dial selector (so you can see video)
3. Press the input BUTTON to select the appropriate digital optical cable.
PSN: TheScrublet
Regardless, I got away from my point in my previous post, which is basically that PL isn't automatically complete shite. I've played some damn fine-sounding PLII games. But yes, I can agree that this stuff is confusing as hell. In fact, I may be more confused than ever...
I had a post with similar content (the one I blew away above), which I deleted because I did a little more reading that indicates that things aren't quite as simple as the Wikipedia article makes them out to be.
I think Scrublet's point when he said there is no such thing as "native PLII" was that there is no way to extract surround sound with perfect channel separation using Pro Logic I or II.
AFAIK, you are basically right about Dolby Surround: The purpose of Pro Logic was to decode, not process, a 2-channel source that had 4 channels matrixed into it via Dolby Surround encoding. Pro Logic II does this also, but has three big extra features: 1) If you feed it a Dolby Surround source, it will "invent" a fifth channel via processing (Dolby Surround has only ever included four channels, as far as I know - PLII only changed the decoding/processing side, not the encoding side), 2) If you feed it plain-jane stereo, it will "invent" 5-channel surround from it via processing, and 3) Regardless of what kind of audio you feed it, it will do a better job with channel separation than Pro Logic (I) due to a ton of extra processing features.
How could it do a "better job?" What the Wikipedia article doesn't cover, and is something we should both probably let Scrublet clear up, is that I don't think dematrixing is a mathematically perfect process. Not only do you get signal loss because of the layering, which reduces the sound quality, but achieving 100% perfect channel separation via decoding doesn't actually happen because of the way the math works out. What you end up getting is sounds played across multiple channels at reduced volume when in the original mix they only existed in one channel. You still get sound out of all your speakers, and there is some semblance of directionality, but it's not accurate.
Pro Logic II fixed this to a great extent via processing, which is what I'm assuming Scrublet was referring to when he mentioned processing "tricks". Like Pro Logic, it does decode 4 channel Dolby Surround audio from 2 channel, but it uses a whole bunch of math to get a better idea of where sounds should be placed. The nature of the processing also made it possible for producers to "tweak" their mixes to guide the processing logic about which sounds get mapped to which channels, and most importantly for video games, developers could optimize the sound processing code to work with specially designed hardware to reach PLII nirvana. See - Factor 5 games on the GameCube.
At the end of the day, though, because dematrixing is not a perfect process, you can't beat discrete channels, even if they are compressed. What PLII is awesome for, in my opinion, is convenience - set your receiver on PLII and don't worry about it. You'll get decent surround from stereo, better surround from Dolby Surround-encoded stereo, and the presence of a digital 5.1 source should override any PLII processing you have enabled. People who aren't audiophiles will never know the difference, and people who are can live with it.
TL;DR: You are basically right, but when you pull 4 channels out of 2, it doesn't work perfectly. The Wikipedia article kind of makes it sound like channel separation is 100% preserved, but it's not.
I submit this for Scrublet's review.
This is mostly what I was getting at. I'm not going to get into what the best idea for a receiver setting is since that line of product is almost as confusing to the consumer as these fucking codecs. The main point I wanted to make is that ProLogicII has nothing to do with encoding/decoding, so you will never meet or surpass the completely accurate positioning of DD5.1. Nor will you meet the same quality of sound...you're trying to shove 5 channels worth of information into 2! But it saves a ton of transmission bandwidth and CPU overhead as compared to handling 5.1, which is why the PS3/360 use 5.1 and the PS2/Wii/Gamecube use PLII. And as mongo mentioned, games can do just fine with PLII performance.
Oh and I guess my other point was if you have a surround sound system and you're using sources that have 5.1 encoded, make sure you're using the 5.1, because it will blow PLII away when given the chance.
God I can't help myself one more edit. Matrixing can be useful for stuff too. For instance, these guys have never had a lot of regard for the matrixing that you are pretty much FORCED to do for 6.1/7.1, since virtually nothing outputs discrete 6th and 7th channels. However, they seem to like the matrixing the new PLIIz stuff does for height channels. Personally I don't think any married man will ever be allowed to put in either height speakers or width speakers that one of the new Denons allow.
PSN: TheScrublet
...okay, maybe 7.2.
I'm pretty sure I've already tried that. I think the problem with it is that I'm using the assignable video two component input in the back and outputting it as video three to the TV. There's ALSO an HDMI video two that the 360 is plugged into. The optical input I'm using is simply labelled video two in. It's a moot point anyway I suppose. Noticed that the blue multi-channel decoding indicator light above the display wasn't illuminated for the 360 input until I switched the optical cable from the PS2 back to it. I play my 360 way more so I guess I'll just stick with that.