Optical Audio Out - Multi-Channel PCM - HDTV - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 23 Old 08-23-2013, 09:47 AM - Thread Starter
Newbie
 
spidertaker23's Avatar
 
Join Date: Feb 2010
Location: Greendale, WI
Posts: 11
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I am considering buying a new HDTV. I am finding that alot of tvs won't pass anything other than 2 channel PCM via the optical port. Some will pass 5.1 dolby, but not multi-channel PCM. This is becoming increasingly frustrating in a world where most people want to hook everything up their HDTV that has 4 HDMI ports.

I have a PS3, Xbox 360, Wii, Direct TV Genie, and soon to be either a PS4 or Xbox One. I was considering buying a new 55" HDTV and connecting everything to my HDTV and then routing an optical cable to my sound bar. Right now I have a Sony HT-CT500 soundbar. This system has only 3 HDMI inputs and doesn't pass through 3D.

So when it comes down to it is there any HDTVs that pass through multi-channel PCM via optical. Or is Optical not capable of this? Since from what I hear Blu Ray players such as the PS3 are designed to be set to multi-channel PCM since you don't get secondary audio (commentary tracks, menu sounds) when set to bitstream. Apparently you can use bitstream(mix), but on the PS3 that is only available if you output sound via optical from the PS3 not if you use HDMI.

Does anyone have any insight or suggestions for me.
spidertaker23 is offline  
Sponsored Links
Advertisement
 
post #2 of 23 Old 08-23-2013, 12:42 PM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,617
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Liked: 57
Digital Audio for Consumers (ignoring expensive Pro-Audio Studio Equipments) is ONLY implemented as an SPDIF data stream, which can be output as IDENTICAL STREAMS via RCA Coax or TOSLINK Optical connectors at typically 1.41 Mbps (CD) to 2.3 Mbps (DVD) Stereo-PCM bit rates:
http://en.wikipedia.org/wiki/S/PDIF
http://www.epanorama.net/documents/audio/spdif.html

When outputting DD5.1 or DTS5.1 (incl 6 & 7 channel variants), the multiple audio streams must be COMPRESSED to fit wihin the range of the above "standard" data rates.

UNCOMPRESSED 5-channel PCM would require a max bit rate = 5-ch * 24-bits/sample * 48k samples/sec = 5.76 Mbps....8.06 Mbps for 7-channel. This is only found on very high speed cables, such as HDMI, with encryption to provide some sort of "protection" to thwart illegal copying of a pristine copy, as found on MOST SACD/DVD-Audio/Blu-Ray Players. [My Oppo Multi-Format Player is one of the exceptions, with ALL Hi-Rez formats output via the multiple Analog Audio RCA connectors.]

The Digital Audio (usually Optical) output on some HDTV's is intended to output the audio signal received via the internal OTA Tuner, which is ALWAYS Dolby Digital formal when transmitted, with either two or five channels occupied. So the HDTV outputs either DD2.0 or DD5.1 via it's Optical output....although there MIGHT be a few sets that have an option to convert it to Stereo-PCM. [And I think there may be VERY few HDTVs that will also "pass thru" the digital audio signals found on the HDTV's other inputs.]

Another important bottleneck: many times an HDTV is connected to the HDMI OUTPUT on an AVR. Since the HDTV is ONLY equipped with TWO speakers, it will tell the AVR that it needs a STEREO signal on the HDMI interface. On SOME AVR's, this ALSO forces the AVR to ONLY playback in STEREO...AAACCCKKKKK. To get around this problem, either connect HDTV to AVR via Component Video or insert some HDMI-to-DVI and DVI-to-HDMI Adapters on the interface so the AVR never sees the format request protocol....and connect RED/WHITE Stereo cables to HDTV.

I had a similar problem when they upgraded my Cable DVR firmware, which was connected directly to the HDTV via HDMI, which, of course, tells it to output a STEREO signal...which was now ALSO being forced on the Cable DVR's Optical output!!!! I got around it by changing to Component Video Cables instead of HDMI....problem solved...I can now playback Surround Sound via the AVR.
holl_ands is offline  
post #3 of 23 Old 08-23-2013, 01:04 PM - Thread Starter
Newbie
 
spidertaker23's Avatar
 
Join Date: Feb 2010
Location: Greendale, WI
Posts: 11
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thank you for the information! So basically there isn't enough bandwidth on an optical cable to do uncompressed 5.1/7.1 LPCM.

Who actually uses OTA anymore lol.

I guess I am trying to figure out what to do then?

If you want 5.1/7.1 LPCM audio you have to connect via HDMI to a AVR then connect HDMI to your tv.

I saw something about HDMI ARC. But, apparently that does the exact same thing that it does when outputting sound via optical! One would think that HDMI ARC would be able do everything that HDMI can.

Anyways, what is your suggestion on what I should do? Sounds like I am going to need a newer and better Soundbar, HTIB, or receiver and speakers if I want 5.1/7.1 LPCM for blu ray playback via my PS3. I am just trying to prepare too since when I buy a Xbox One or PS4 those both will have blu ray playback as well. Otherwise I am going to end up with 2 channel PCM for every one of my sources (ps3, xbox one, ps4) that has blu ray. And that's assuming the damn tv will even pass Dolby 5.1 for sources like my Direct TV and Xbox 360.

Kinda of a bummer there is no way to hook everything up to a HDTV and use the HDMI ports on the HDTV and use the tv as the HDMI switcher and output full quality HD sound to a receiver. Kinda makes how many HDMI ports your HDTV has irrelevant if you have to hook everything up to a AVR via HDMI in order to get full quality HD audio.

Please advise.
spidertaker23 is offline  
post #4 of 23 Old 08-23-2013, 04:10 PM
Advanced Member
 
Phil17108's Avatar
 
Join Date: Feb 2012
Location: Orange County California
Posts: 927
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 53
Quote:
Originally Posted by spidertaker23 View Post

Thank you for the information! So basically there isn't enough bandwidth on an optical cable to do uncompressed 5.1/7.1 LPCM.

Who actually uses OTA anymore lol.

I guess I am trying to figure out what to do then?

If you want 5.1/7.1 LPCM audio you have to connect via HDMI to a AVR then connect HDMI to your tv.

I saw something about HDMI ARC. But, apparently that does the exact same thing that it does when outputting sound via optical! One would think that HDMI ARC would be able do everything that HDMI can.

Anyways, what is your suggestion on what I should do? Sounds like I am going to need a newer and better Soundbar, HTIB, or receiver and speakers if I want 5.1/7.1 LPCM for blu ray playback via my PS3. I am just trying to prepare too since when I buy a Xbox One or PS4 those both will have blu ray playback as well. Otherwise I am going to end up with 2 channel PCM for every one of my sources (ps3, xbox one, ps4) that has blu ray. And that's assuming the damn tv will even pass Dolby 5.1 for sources like my Direct TV and Xbox 360.

Kinda of a bummer there is no way to hook everything up to a HDTV and use the HDMI ports on the HDTV and use the tv as the HDMI switcher and output full quality HD sound to a receiver. Kinda makes how many HDMI ports your HDTV has irrelevant if you have to hook everything up to a AVR via HDMI in order to get full quality HD audio.

Please advise.

Its a bummer alright. But this place can make it a little less painful http://www.accessories4less.com
You never had 5.1 anyway the Sony is 3.1
Phil17108 is offline  
post #5 of 23 Old 08-23-2013, 04:19 PM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,617
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Liked: 57
Sony HT-CT500 Sound Bar doesn't have any Rear/Surround Speaker outputs, so the BEST that it can do is to reproduce L/C/R as discrete sound sources....plus whatever "Synthetic Surround" mode you select (see pg 57), which will delay and sum the Rear/Surround DD signals into the Front L/R speakers....and fergit trying to think it's going to properly synthesize 6&7-channel signals:
http://www.docs.sony.com/release/specs/HTCT500_mksp.pdf
http://www.docs.sony.com/release/HTCT500_EN_ES_FR.pdf

Follow hookup instructions on pg 25 (Speakers), 30 (HDMI In) & 31 et.al. (NOT HDMI In) in the Sony HT-CT500 User Manual (can download from Sony Support if you can't find it). Since it was specifically designed to have a STEREO capable HDTV hooked up to the HDMI Output, it will do whatever it was designed to do as far as generating Synthetic Surround from a DD5.1/6.1/7.1 signal sources....so don't expect to hear a full Discrete Surround Speaker experience:
http://www.hometheaterhifi.com/volume_8_1/dolby-prologic2-3-2001.html
http://www.hometheaterhifi.com/volume_11_1/feature-prologic-iix-3-2004.html

You would need to replace the Sound Bar with a full 5.1 (or 7.1) AVR plus 2 (or 4) Surround Speakers for a much better Surround Sound experience.

BTW: Fibre Optic cable isn't the bottleneck...it can support very high data rates....it's an Interface STANDARDS issue.
holl_ands is offline  
post #6 of 23 Old 08-23-2013, 08:49 PM - Thread Starter
Newbie
 
spidertaker23's Avatar
 
Join Date: Feb 2010
Location: Greendale, WI
Posts: 11
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thanks for the information.

I tested my system tonight and compared what it sounds like when I output bitstream (mix) from optical (which outputs dolby digital 5.1) to my ct500 soundbar from my ps3 and compared it to what LPCM sounds like when the PS3 is hooked up through my ct500 with HDMI. I tested using the Blu Ray movie 300. When testing LPCM via HDMI I did turn on the LPCM audio track on the blu ray.

IMO, it sounds drastically better with LPCM via HDMI. Everything from volume, to bass, to clarity. I'm no audiophile, but LPCM via HDMI sounds much better imo. So it must help even though there is really only 3.1 actual channels.

I generally just use the Sony Sound Field "movie." I haven't used the other sound fields much, but to my ear movie sounds the best.

The reason I got a sound bar to begin with is because I have a kid and another kid on the way. I just can't have speakers with removable speaker grills and wires for kids to get into.

The thing that has me most confused is that most sound bars don't have HDMI switching at all. Alot of them just have one optical input. So they are obviously expecting you to route sound from your tv to the soundbar. For example this system:

http://store.vizio.com/home-theater/s4251wb4.html

In the case of the one above it's even more confusing since it has rear speakers. Basically, am I right that any system that doesn't have HDMI switching the best possible sound you are going to get out of it is 5.1 Dolby Digital?

In order to get LPCM 5.1/7.1 sound you have to have an AVR/HTIB/Sound Bar that has HDMI switching.

If that is the case is there any worthwhile Sound Bar/HTIB systems that are either 2.1/3.1 like I have ... or 5.1 like that vizio (since it wouldn't require running cables from the tv to the back of the room - since the rears connect to the sub) that actually have HDMI switching. The thing is that I am going to need at least 3 to 4 HDMI inputs.

It sounds like in order to get what I want I am going to have to buy a new system that has HDMI switching and supports 3d HDMI passthrough.

I heard around the net that Vizio is going to be making a 54" sound bar that has HDMI switching. If they include the wireless sub/rear speakers maybe this would be what I am looking for.

Are there any other systems on the market that would allow for rear speakers wirelessly kinda like the vizio system does? http://store.vizio.com/home-theater/s4251wb4.html but has HDMI switching.

I haven't looked at dedicated AVR's in awhile. Can you buy pre-packaged or piece meal systems where at least the back speakers are wireless?
spidertaker23 is offline  
post #7 of 23 Old 08-23-2013, 11:54 PM
Advanced Member
 
Phil17108's Avatar
 
Join Date: Feb 2012
Location: Orange County California
Posts: 927
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 53
spidertaker23

It sounds like in order to get what I want I am going to have to buy a new system that has HDMI switching and supports 3d HDMI passthrough.

I heard around the net that Vizio is going to be making a 54" sound bar that has HDMI switching. If they include the wireless sub/rear speakers maybe this would be what I am looking for.

Are there any other systems on the market that would allow for rear speakers wirelessly kinda like the vizio system does? http://store.vizio.com/home-theater/s4251wb4.html but has HDMI switching.

I haven't looked at dedicated AVR's in awhile. Can you buy pre-packaged or piece meal systems where at least the back speakers are wireless?


I use an Onkyo AVR with Polk speakers in the living room theater, and 2 Vizio soundbars in other places, and no kids. Yes I believe there are other sound bars will have a 5.1 setup but they cost a bunch more then the Vizio you expressed interest in. I have had good luck with Vizio products and recommend them for ease of setup and they sound good, to use.
There is another way to go with HDMI switching, and thats a separate switch like this.
http://www.monoprice.com/products/product.asp?c_id=101&cp_id=10110&cs_id=1011002&p_id=5557&seq=1&format=2
I have used a lot of Monoprice products and also believe they have good stuff and great service. As for pre packaged systems there are some really good ones out there and http://www.accessories4less.com has a number of Onkyo home theater systems plus a few from Denon. I have yet to see a home theater in a box that has wireless rears. I know there are some wireless systems out there but the prices oppressive for them.
Phil17108 is offline  
post #8 of 23 Old 08-24-2013, 06:03 AM - Thread Starter
Newbie
 
spidertaker23's Avatar
 
Join Date: Feb 2010
Location: Greendale, WI
Posts: 11
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thanks for the advice.

Looks like that www.accessories4less.com sells factory refurbished equipment. Does the equipment still come with the 1 year factory warranty or 90 days? Can you still buy extended warranties for the equipment from them or squaretrade or something?
spidertaker23 is offline  
post #9 of 23 Old 08-25-2013, 08:42 AM
Advanced Member
 
Phil17108's Avatar
 
Join Date: Feb 2012
Location: Orange County California
Posts: 927
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 53
Quote:
Originally Posted by spidertaker23 View Post

Thanks for the advice.

Looks like that www.accessories4less.com sells factory refurbished equipment. Does the equipment still come with the 1 year factory warranty or 90 days? Can you still buy extended warranties for the equipment from them or squaretrade or something?

I don't remember about the factory warranty , 90 days or a year but I bought an Onkyo and then when I registered with them I bought an extended warranty from Onkyo for not much money. I went to the web site and found the Onkyo warranty is one year from the factory and there are extended ones from New Leaf. I went with the Onkyo factory one. I'll bet you can get a Squaretrade warranty from Squaretrade.
Phil17108 is offline  
post #10 of 23 Old 09-02-2013, 07:42 PM
AVS Addicted Member
 
Tulpa's Avatar
 
Join Date: Jan 2007
Location: Los Angeles
Posts: 10,026
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 58
Quote:
Originally Posted by spidertaker23 View Post

Kinda of a bummer there is no way to hook everything up to a HDTV and use the HDMI ports on the HDTV and use the tv as the HDMI switcher and output full quality HD sound to a receiver. Kinda makes how many HDMI ports your HDTV has irrelevant if you have to hook everything up to a AVR via HDMI in order to get full quality HD audio.

Most people who don't have a receiver use the TV audio. No need to output any sound.

Those who use receivers tend to route it through there before the TV. The subset who use the TV for a switch but output to some kind of sound system is pretty small.
Quote:
Who actually uses OTA anymore lol.

You'd be surprised. smile.gif

Don't believe everything on the Interwebz! A duck's quack DOES echo!
Tulpa is offline  
post #11 of 23 Old 09-05-2013, 05:39 PM
Member
 
lclaman's Avatar
 
Join Date: Sep 2005
Posts: 26
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
I need advice for a related question (hope it's ok to post onto the tail of this thread rather than start a new one).

Until recently, I had the following setup, which worked great:
- Cable box HDMI out to the HDTV for video (& audio when I wanted to use the TV speakers)
- Cable box toslink out to the surround sound receiver (for when I wanted to use the surround sound system). This passed 5.1 audio to my receiver and played surround sound fine.

Last month, my 7 year old HDTV died, so I purchased a new one (Vizio E551i-A2). This HDTV does a lot more video processing than my old set, and thus when I hooked it up as before & used the receiver, I found the video lags the audio and thus I have the dreaded lipsync problem. Unfortunately, my received, also 7 years old, has no configurable audio delay, so I can't fix the problem that way.

One thing I've tried is connecting the HDTV's toslink out into the receiver (rather than going directly from the cable box to the receiver); in other words, it looks like:
Cable box ---hdmi--> HDTV ---toslink---> receiver
This setup solves the lipsync problem, but as the OP noted, it reduces the audio down to two channel pcm.

Do I have any alternatives other than buying a new receiver? e.g, is there something obvious I'm missing?
I tried to see if any sort of toslink-delay device exists (at a reasonable price point), but I couldn't find one.
One thought I had is the HDTV supports HDMI ARC for audio out, but my AVR does not have HDMI inputs. Would an HDMI to toslink splitter provide 5.1 over the toslink cable?
Any other suggestions?
lclaman is offline  
post #12 of 23 Old 09-05-2013, 06:24 PM
AVS Special Member
 
mikepier's Avatar
 
Join Date: Sep 2006
Location: Long Island and Upstate NY
Posts: 2,449
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 21
I have a Vizio 42" led that I just purchased this year, and it does pass through DD 5.1 through the optical out when watching on the STB or DVD player, so I'm surprised your tv does not do the same thing. Make sure your audio setting is set to Dolby Digital. Also my Vizio has a lip sync adjustment in the menu.
mikepier is offline  
post #13 of 23 Old 09-05-2013, 06:31 PM
Member
 
lclaman's Avatar
 
Join Date: Sep 2005
Posts: 26
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by mikepier View Post

Make sure your audio setting is set to Dolby Digital. Also my Vizio has a lip sync adjustment in the menu.
I tried flipping the audio setting on the Vizio between Dolby Digital & PCM, but regardless of the setting, it was outputting 2 channel PCM.
Lip sync adjustment in the menu didn't make a difference.

One more thing to note: When I use one of the TV's built-in sources (e.g, the build-in netflix client), I DO get 5.1 audio output on the toslink. It's only when I have the source as the cable set top box that it won't do 5.1
lclaman is offline  
post #14 of 23 Old 09-05-2013, 10:49 PM
Advanced Member
 
Phil17108's Avatar
 
Join Date: Feb 2012
Location: Orange County California
Posts: 927
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 53
Quote:
Originally Posted by lclaman View Post

I tried flipping the audio setting on the Vizio between Dolby Digital & PCM, but regardless of the setting, it was outputting 2 channel PCM.
Lip sync adjustment in the menu didn't make a difference.

One more thing to note: When I use one of the TV's built-in sources (e.g, the build-in netflix client), I DO get 5.1 audio output on the toslink. It's only when I have the source as the cable set top box that it won't do 5.1

Your Vizio is working just the way it's meant to. It outputs PCM with a sources from outside of the TV and 5.1 from the internal tuner or from one of the streaming services. Most TV work this way. I did have a Toshiba DLP that output 5.1 from the HDMI inputs. I have a 65 inch Vizio in the same spot now and do have a Toslink from it back to the AVR for just that.
Phil17108 is offline  
post #15 of 23 Old 09-06-2013, 08:29 AM
Member
 
xoned's Avatar
 
Join Date: Jul 2013
Location: Minnesota
Posts: 103
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by spidertaker23 View Post

I am considering buying a new HDTV. I am finding that alot of tvs won't pass anything other than 2 channel PCM via the optical port. Some will pass 5.1 dolby, but not multi-channel PCM. This is becoming increasingly frustrating in a world where most people want to hook everything up their HDTV that has 4 HDMI ports.

I have a PS3, Xbox 360, Wii, Direct TV Genie, and soon to be either a PS4 or Xbox One. I was considering buying a new 55" HDTV and connecting everything to my HDTV and then routing an optical cable to my sound bar. Right now I have a Sony HT-CT500 soundbar. This system has only 3 HDMI inputs and doesn't pass through 3D.

So when it comes down to it is there any HDTVs that pass through multi-channel PCM via optical. Or is Optical not capable of this? Since from what I hear Blu Ray players such as the PS3 are designed to be set to multi-channel PCM since you don't get secondary audio (commentary tracks, menu sounds) when set to bitstream. Apparently you can use bitstream(mix), but on the PS3 that is only available if you output sound via optical from the PS3 not if you use HDMI.

Does anyone have any insight or suggestions for me.

On certain models, LG for example, the DD pass through has been disabled by design due to lip sync issues. This option can be enabled by accessing the service menu. I'm not sure if this is true for other manufactures though.
xoned is offline  
post #16 of 23 Old 09-06-2013, 09:02 AM
AVS Special Member
 
Otto Pylot's Avatar
 
Join Date: May 2004
Location: San Jose, CA
Posts: 7,222
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 136 Post(s)
Liked: 239
Quote:
Originally Posted by spidertaker23 View Post


Who actually uses OTA anymore lol.

Quite a few of us. Especially if you live in an area with excellent OTA reception (like I do). Using the internal ATSC tuner, all network broadcasts are in clean 5.1 (when broadcast that way) via optical to the avr. All other sources (blu-ray, AppleTV2 etc) go thru the avr first. Using a Harmony remote, switching inputs is seamless and fast.
Otto Pylot is online now  
post #17 of 23 Old 09-06-2013, 04:32 PM
Member
 
lclaman's Avatar
 
Join Date: Sep 2005
Posts: 26
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Phil17108 View Post

I have a 65 inch Vizio in the same spot now and do have a Toslink from it back to the AVR for just that.
Not sure I follow you... are you saying you have the Vizio connected to the AVR using toslink? Per your post, doesn't that only give you two channels?
lclaman is offline  
post #18 of 23 Old 09-06-2013, 11:16 PM
Advanced Member
 
Phil17108's Avatar
 
Join Date: Feb 2012
Location: Orange County California
Posts: 927
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 53
Quote:
Originally Posted by lclaman View Post

Not sure I follow you... are you saying you have the Vizio connected to the AVR using toslink? Per your post, doesn't that only give you two channels?

The optical cable to the AVR is for off air or apps like Netflix, and have yet to use. That would send to the AVR what the incoming audio is from those sources be it 2 channel PCM or DD 5.1. My other sources, DirecTV DVR's and a Blu-Ray player use HDMI cables from them to the AVR, and a HDMI cable to the set. I get DD 5.1 from AVR and 2 channel audio to the TV, that I often use and headphones that connect to the analog audio out on the set. Just basic stuff.
Phil17108 is offline  
post #19 of 23 Old 09-07-2013, 06:21 AM
AVS Special Member
 
sneals2000's Avatar
 
Join Date: May 2003
Location: UK
Posts: 7,034
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 49 Post(s)
Liked: 46
Quote:
Originally Posted by holl_ands View Post

The Digital Audio (usually Optical) output on some HDTV's is intended to output the audio signal received via the internal OTA Tuner, which is ALWAYS Dolby Digital formal when transmitted, with either two or five channels occupied. So the HDTV outputs either DD2.0 or DD5.1 via it's Optical output....although there MIGHT be a few sets that have an option to convert it to Stereo-PCM. [And I think there may be VERY few HDTVs that will also "pass thru" the digital audio signals found on the HDTV's other inputs.]

This is only the case in some territories (North America definitely, probably other ATSC regions) and is far from universal everywhere.

In other parts of the world Dolby Digital isn't universal as the broadcast audio format, and in fact isn't that widespread as an audio signal on OTA Digital, and is not universal on satellite (and in some parts of the world, like the UK, integrated satellite receivers in TV sets are not unusual as our main network broadcasters are on satellite un-encrypted and free to receive just like OTA).

SD DVB satellite, cable and OTA broadcasts usually carry MP2 audio streams, sometimes accompanied by a Dolby Digital secondary stream. HD broadcasts on satellite are usually MP2 primary with a Dolby Digital secondary audio. HD broadcasts on terrestrial increasinly use AAC audio - though some do use Dolby. (AAC has advantages for audio description - as Dolby were late to the party with a suitable standard for this that supported "in receiver" mixing)

Taking the UK as an example :
SD OTA = MPEG2 Video, MP2 2.0 Audio
HD OTA = H264 Video, AAC 2.0/5.1 Audio
SD Satellite = MPEG2 Video, MP2 2.0 Audio, Small number of channels with DD 2.0/5.1 audio as secondary stream
HD Satellite = H264 Video, MP2 2.0 Audio AND 2.0/5.1 Dolby Digital Audio.

Whilst Dolby is widespread as a bitstreaming format, MP2 and AAC are far less supported (if at all) in amplifiers, so it is universal for most TVs here to offer PCM 2.0 output via Toslink/Coax as the default (with some offering the option to switch to Dolby bitstreamed rather than decoded PCM if a Dolby stream is selected)
sneals2000 is offline  
post #20 of 23 Old 09-07-2013, 07:28 AM
Member
 
lclaman's Avatar
 
Join Date: Sep 2005
Posts: 26
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
ok, so it's been established that my TV is working "as designed" in that it only sends two channel audio through the toslink to my AVR. If I want 5 channel, I must go directly from the cable box to the AVR. However, that brings me back to the video delay / lip sync problem mentioned in my earlier post. So how do I get around that? Must I purchase an entirely new AVR that has an audio delay function built in? Or do simpler (eg, cheaper) audio delay boxes exist that I could put inline? (e.g, cable box -> delay box -> AVR)
lclaman is offline  
post #21 of 23 Old 09-07-2013, 09:13 AM
AVS Special Member
 
Otto Pylot's Avatar
 
Join Date: May 2004
Location: San Jose, CA
Posts: 7,222
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 136 Post(s)
Liked: 239
^^^^^ probably a newer avr that has a lip sync feature would be the way to go. I don't know of any standalone audio delay devices that would work. It's usually handled by the avr. And to followup on a previous question, the only thing that an optical (toslink) cable can do is transmit 5.1 audio from the internal ATSC tuner or some SmartApps (depending on the app and tv mfr) to the avr. That's what I do for OTA and it works beautifully. The optical cable is limited to 5.1 or two-channel stereo though (you can't transmit lossless audio for example). Some tv's may allow you to send 5.1 audio thru optical via an external source but it's not very obvious which tv's do. So it really sounds like in your situation you could use a new avr to do what you want to do.
Otto Pylot is online now  
post #22 of 23 Old 09-07-2013, 12:40 PM
AVS Special Member
 
sneals2000's Avatar
 
Join Date: May 2003
Location: UK
Posts: 7,034
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 49 Post(s)
Liked: 46
There are some Toslink/Coax delays available for this purpose. Not sure how well they work with DD - and they aren't very cheap.

Quick google found these : http://www.felston.com/products.htm No idea if they are suitable or what they cost.
sneals2000 is offline  
post #23 of 23 Old 09-08-2013, 02:11 PM
Member
 
lclaman's Avatar
 
Join Date: Sep 2005
Posts: 26
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Well, after some more research and playing around, I am now able to have the TV output 5.1 over toslink (contrary, with all due respect, to the advice given earlier).

To review, my setup is Cable box --HDMI-->HDTV, then HDTV--toslink-->AVR. Initially, I was only getting 2 channel over the toslink. I found a posting here which suggested changing the cable box HDMI audio settings from 'auto' to 'passthough'. Once I made this change, I was able to get 5.1 on my AVR over the toslink!

I suspect what was happening is when the cable box is set to 'auto', the TV & cable box negotiate settings, and the TV says "I only need 2 channel", so that's all that was sent by the cable box. But when the setting is 'passthrough', the cable box sends whatever audio is on the channel. The TV then passes this over the toslink to the AVR directly with no downmixing.

Very happy to have figured this out, as I was just about to pull the trigger on a new AVR! Now I don't need to make that purchase!
xoned likes this.
lclaman is offline  
Reply HDTV Technical

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off