HD PICTURE RUNNING DOLBY DIGITAL 5.1 OPTICAL OUTPUT WITH AUDO DROPOUTS

[jimfitzgerald]

Which part of the question can you not answer?  Is nobody here getting 8 channel sound via the HDMI out on the U-Verse stb?

Edit:  I guess it would only be 6 channel, not 8 channel with tv.

Message Edited by jimfitzgerald on 10-05-2008 04:18 PM

[jimfitzgerald]

What is the Cisco stb model number?

[randyl]

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jimfitzgerald wrote:

Which part of the question can you not answer?  Is nobody here getting 8 channel sound via the HDMI out on the U-Verse stb?  NO

Edit:  I guess it would only be 6 channel, not 8 channel with tv.

Message Edited by jimfitzgerald on 10-05-2008 04:18 PM

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       u have to use optical for 5.1 if its being sent on a hd channel..  aka 1002 1004 etc

       my take

       randy

[jimfitzgerald]

I don't think that is correct unless there is something strange about U-Verse or the Cisco stb they are using.  HDMI is fully capbably of passing the 5.1 signal to the receiver.  My Charter stb (Motorola) can't use HDMI because of the copyright protection.  I would hope the newer Cisco stb is fully capable.

Message Edited by jimfitzgerald on 10-05-2008 05:16 PM

[MrbWolf21]

Jimfitzgerald,

From all that I have gathered the AT&T Motorola or Cisco boxes STB/DVR HDMI outputs only support 2 channels down the HDMI port. Why this has been done is another AT&T miracle.

If you know anybody who as U-verse go and check it out. Also there maybe a AT&T retail store with U-verse up and running where you might be able to check it out. But, this solution might not work.

[randyl]

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jimfitzgerald wrote:
What is the Cisco stb model number?

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       model 330 and 430 (dvr)

Message Edited by randyl on 10-05-2008 08:27 PM

[jimfitzgerald]

Thanks.

[jimfitzgerald]

Does anyone know why the Cisco 430 DVR only supports 2-channel audio with HDMI on the U-Verse network?  I found the specifications for the stb and it is fully HDMI/HDCP capable.

[SomeJoe7777 ACE - Geek]

jimfitzgerald,

The Cisco 330 and 430, and the Motorola VIP 1200 and 1216 all support HDMI 1.3, and fully support many of the digital audio options in hardware (I think the maximum is 5.1 channels that the hardware on these boxes supports, even though HDMI is capable of transporting 7.1 channels by specification).

However, the software on the boxes right now only supports a 2.0 channel downmix over HDMI.  AT&T will have to update this software to allow the box to send 5.1 audio over HDMI.  One of the things they will need to put in is a selection in the system options menu for how to handle the audio.  For example, if the TV channel being watched has a 5.1 Dolby Digital audio stream, the user needs to be able to select whether to send the 5.1 Dolby Digital bitstream over the HDMI directly (where an AV receiver will decode it), or if they want the STB to decode the audio stream to 5.1 channel LPCM and send that over HDMI.  This might be very important if the user's HDMI device cannot decode anything but LPCM (which is true of some cheaper TVs).

Anyway, at this time you can use the following workarounds for the optical audio dropouts and 2.0 channel limitation on HDMI:

1. Use the optical audio output, and if dropouts occur, pause the live TV for about 10 seconds, then play.  When the stream is playing delayed from the DVR, the dropouts do not occur at all or occur much less often.  This only works on the DVR box.

2. Use the HDMI 2.0 channel output or the 2.0 RCA analog audio outputs, and put your receiver in Dolby Pro Logic II decoding mode.  The 2.0 channel output from the RCA analog outputs and the 2.0 channel output from HDMI are both Dolby Pro Logic matrix encoded, and you can get a 5.0 channel decode from this signal.  Your bass management settings in your AV receiver can route low frequencies to a subwoofer to give you low bass even though there is no dedicated LFE channel with a Dolby Pro Logic signal.

At some point, AT&T will probably update the software to support 5.1 audio over HDMI.  No word on when.

[MrbWolf21]

SomeJoe7777 ,

Question? 2 channel out to any Dolby Pro Logic decoder will not give you 5.0 but, 4.0 which is LCR & mono surrounds is this not correct?

Would like your take.

[SomeJoe7777 ACE - Geek]

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MrbWolf21 wrote:

SomeJoe7777 ,

Question? 2 channel out to any Dolby Pro Logic decoder will not give you 5.0 but, 4.0 which is LCR & mono surrounds is this not correct?

Would like your take.

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Dolby analog surround technologies break down as follows:

Dolby Pro Logic: Will take a 2.0 channel matrix-encoded signal and product a 4.0 channel output (front left, front right, front center, and rear mono surround).  "Dolby Pro Logic" is the consumer version of the theater system originally called Dolby Surround.

Dolby Pro Logic II: Will take any 2.0 channel signal (matrix-encoded or not, but matrix-encoded will work better) and produce a 5.0 channel output (front left, front right, front center, rear left, and rear right).  There is no dedicated LFE (.1) channel, all decoded 5.0 channels are full range.

Dolby Pro Logic IIx: Will take any 2.0 or 5.1 channel signal (matrix-encoded or not, but matrix-encoded will work better) and produce a 7.0 or 7.1 channel output (front left, front right, front center, surround left, surround right, back left, and back right). The LFE (.1) channel will be present if one was input or if the AV receiver's bass management routes low frequencies to a subwoofer, but the DPL IIx algorithm itself does not create an LFE channel.

Most modern AV receivers have a Pro Logic II or IIx decoder with proper bass management, so 5.1, 6.1 or 7.1 output is now the norm.

[jimfitzgerald]

Looks like my Onkyo 805 has three different codec's for converting 2 channel to 7.1 channel (or 5.1 if you don't have the rear surround speakers).  They are:

Dolby Pro Logic IIx

DTS NEO:6

Neural THX 7.1

There are lots of other options for converting 5.1 to 7.1 and a few options for handling 7.1 discreet channels:

Dolby Digital Plus

Dolby TrueHD

DTS-ES Discrete

DTS-HD High Resolution

DTS-HD Master Audio

These would only be available on Blu-ray DVD's, I suppose.

Message Edited by jimfitzgerald on 10-06-2008 07:23 PM

[SomeJoe7777 ACE - Geek]

The various audio formats from BD and their specifications:

Dolby Digital: Lossy compressed audio format.  Handles up to 5.1 channels.  Maximum bitrates: LaserDisc 384 kbps, DVD 448 kbps, BD 640 kbps.  Maximum sample rate/sample size: 48 kHz/16 bit.  Can be transported digitally on TosLink optical, S/PDIF coax, and HDMI.

Dolby Digital EX: Lossy compressed audio format.  Handles a 6th channel (rear center) using matrix encoding of the rear left and rear right channels.  Same bitrates, sample rates, and sample size as Dolby Digital.  Can be transported digitally on TosLink optical, S/PDIF coax, and HDMI.

Dolby Digital Plus: Lossy compressed audio format.  Can handle up to 7.1 channels discretely (not matrix encoded).  Maximum bitrate: 1.7 Mbps.  Maximum sample rate/sample size: 48 kHz/16 bit.  More advanced coding techniques improve fidelity for the same bitrate.  Backwards compatible with Dolby Digital (lossy compressed 5.1 channels only).  Can only be transported digitally on HDMI 1.3.

Dolby TrueHD: Lossless compressed audio format.  Can handle up to 7.1 discrete channels.  Maximum bitrate: 18 Mbps.  Maximum sample rate/sample size: 96 kHz/24 bit (7.1 configuration), 192 kHz/24 bit (5.1 configuration).  Backwards compatible with Dolby Digital (lossy compressed 5.1 channels only).  Can only be transported digitally on HDMI 1.3.

DTS: Lossy compressed audio format.  Handles up to 5.1 channels.  Maximum bitrate: 1.5 Mbps.  Maximum sample rate/sample size: 48 kHz/16 bit.  (A 96 kHz/24 bit version is also specified, but is generally regarded as useless since the maximum bitrate doesn't change.)  Can be transported digitally on TosLink optical, S/PDIF coax, and HDMI.

DTS-ES: Lossy compressed audio format.  Handles up to 6.1 channels.  Same maximum bitrate, sample rate, and sample size as DTS.  Comes in 2 versions - DTS-ES Matrix, where the 6th channel (rear center) is matrix-encoded on the rear left and rear right channels (same technique as Dolby Digital EX).  DTS-ES Discrete encodes the 6th channel in the bitstream instead of using matrix encoding.  Can be transported digitally on TosLink optical, S/PDIF coax, and HDMI.

DTS-HD High Resolution: Lossy compressed audio format.  Handles up to 7.1 discrete channels. Maximum bitrate: 6.0 Mbps.  Maximum sample rate/sample size: 96 kHz/24 bit. Backward compatible with DTS (lossy compressed 5.1 channels only).  Can only be transported digitally on HDMI 1.3.

DTS-HD Master Audio: Lossless compressed audio format.  Handles up to 7.1 discrete channels.  Maximum bitrate: 24.5 Mbps.  Maximum sample rate/sample size: 96 kHz/24 bit (7.1 configuration), 192 kHz/24 bit (5.1 configuration).  Backward compatible with DTS (lossy compressed 5.1 channels only).  Can only be transported digitally on HDMI 1.3.

Message Edited by SomeJoe7777 on 10-06-2008 10:07 PM

[MrbWolf21]

SomeJoe7777,

Any of these formats will put out 5 channels of sound from 2 channels but, unless the audio source is encoded 5.1 it will not decode in 5.1 discreetely. You are correct about Dolby TrueHD and DTS-HD Master Audio because they are based upon the original theatrical 6 or 8 track print masters which are not encoded for they are both mix downs from the original 6 or 8 dialog, sfx and music stems.

[SomeJoe7777 ACE - Geek]

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MrbWolf21 wrote:

Any of these formats will put out 5 channels of sound from 2 channels but, unless the audio source is encoded 5.1 it will not decode in 5.1 discreetely. You are correct about Dolby TrueHD and DTS-HD Master Audio because they are based upon the original theatrical 6 or 8 track print masters which are not encoded for they are both mix downs from the original 6 or 8 dialog, sfx and music stems.

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Not sure if you're speaking of the analog surround technologies or the digital multi-channel streams.  For the digital multi-channel streams (Dolby Digital family and DTS family), all channels are always encoded discretely, with the exception of the back center channel in Dolby Digital EX and DTS-ES Matrix.

For the analog surround technologies, the output channels are indeed 5 physically separate channels.  However, because they were transported at some point as a matrix-encoded signal, the separation between channels is nowhere near what you get when the transport was discrete all the way through.  For example, on U-Verse on an HD channel, the audio is coming in as a 5.1 discrete feed.  (Now, I won't get into whether those 5.1 channels are indeed discrete from the studio master or whether they've been themselves downmixed to some degree -- we won't know and can't really find out.)  If we use the optical audio output and decode the Dolby Digital stream, we get 5.1 discrete channels that are the same as what the network feed was.  If we use the 2.0 HDMI downmix or the 2.0 analog RCA outs and then use Dolby Pro Logic II to get 5.0/5.1 channels, the output channels are indeed physically separate but the logical separation of the soundstage between all of the speakers in the system is much reduced by comparision to a direct decode of the Dolby Digital stream.

In the strictest sense, even Dolby TrueHD and DTS-HD Master Audio are "downmixed" to some degree.  When the studio creates the master, there are many individual tracks that get recorded: The dialogue from boom mics, scene sound effects that are produced at the time the scene is shot, post-production sound effects, foley, music, etc.  All of those tracks get mixed to the 7.1 master.  The 5.1 masters can be created from a downmix of that or from the original tracks.

[MrbWolf21]

Analog is the old  2 channel Dolby Stereo matrixed. Even some of the 5.1 print masters are analog 6-track mag. The 5.1 6 track mags were then encoded through the Pro Dolby AC-3 encoder on the Dub stage for printing to the sound negative too be composited with the final feature print.

Now at the same time that they make this sound negative the studios also shoot on this negative DTS time code, SDDS and analog 2 channel Dolby SR for backup in case the digital fails.

Maybe we do not understanding each other. All features as you say have production audio such as original dialog and replacement ADR dialog for bad dialog from the location production. I think we both are saying that when the feature is mixed on the dub stage the units that are used are the dialog for mentioned and all of the SFX, foley, backgrounds and all music. These units come in to the stage in mono, stereo or six/eight track from the sound designers and music producers. These are then predubbed down to 6/8 track stems which are then mixed down to a final 6/8 track print master. This printer master is then dubbed downed to a Dolby SR 2 track for the analog optical track as the backup in case the digital tracks fail.

I do know that whether it be U-verse or any other media provider the audio source on that media is encoded AC-3 Dolby Stereo or Dolby Digital 5.1. There is no audio that is from the original 5.1/7.1 print masters on the HD video that is not encoded.

U-verse or any other media provider does not do the encoding they just pass it through to the consumers as they got it.

I think we are saying the same thing but using semantics to explain it.

Message Edited by MrbWolf21 on 10-07-2008 11:35 AM

[parkdoob]

Bottom line is, unfortunately, currently, if you want anything beyond two-channel audio your only options are:

  -- Use analog RCA stereo connectors, convert using a Pro-Logic or other setting on your receiver

  -- Use HDMI for audio (digital), convert PCM two-channel signal similar to the above (again: current Motorola setup only supports two-channel audio via HDMI, for whatever AT&T/Microsoft/Motorola implementation reason)

  -- Use TOSlink for audio (digital), and get discrete multi-channel audio signals as broadcast/received/recorded (though for me at least, fewer channels/programs seem to do this via Uverse than they did with Comcast)

I currently choose the TOSlink option, but it comes with various drawbacks that different users report to different degrees:

  -- split-second audio drops not present in actual programming (a rewind/replay will not repeat the error, and some users have reported such a replay seems to lessen the frequency of occurrences during particularly bad stretches)

  -- funny reversions to two-channel signals after accessing other features such as info screens and menus, not restored to the full multi-channel as broadcast until you pause/replay (essentially trick the thing into rethinking what format it is supposed to be sending; this is apparently related to the menu sound effects taking over the audio hardware, "flipping a switch" to a two-channel mode, and is not a problem if you turn those effects off)

I'm optimistic that both of these may be addressed by a soft update in the future.

My receiver tells me this setup, for reference, provides PCM audio for SD channels and a mix of two-channel Dolby Digital and surround DD signals (depending on channels/programming) on the HD channels.  Haven't seen any other formats come through (also different from Comcast in this respect)

Hope that's of use...

[ckellyne]

fyi...I was having the SAME problem with dropped audio ONLY when watching HD channels and figured out the solution and no more audio problems when viewing / listening to HD channels.  My system was installed October 31, 2008 and I had the tech out 3x and they couldn't fix it.  They thought it was my audio receiver system which I knew it was not since it worked fine with other services and on non-HD channels.  This is what I did to FIX the problem:

1. Select "Menu" with the remote

2. Scroll over to "Options"

3. Scroll over to "System Settings"

4. Select "System sound effects"

5. Select "Play sound effects" and then "Save"

Exit and I now listen to HD channels with NO audio drop whatsoever.  Yes, I hear a sound effect when I use the remote to view the Guide, or Info for a channel, etc. but that is no problem.  I'm not sure WHY this fixed it but there is obviously a bug and this is an EASY workaround to fix it.

[ckellyne]

fyi...I was having the SAME problem with dropped audio ONLY when watching HD channels and figured out the solution and no more audio problems when viewing / listening to HD channels.  My system was installed October 31, 2008 and I had the tech out 3x and they couldn't fix it.  They thought it was my audio receiver system which I knew it was not since it worked fine with other services and on non-HD channels.  This is what I did to FIX the problem:

1. Select "Menu" with the remote

2. Scroll over to "Options"

3. Scroll over to "System Settings"

4. Select "System sound effects"

5. Select "Play sound effects" and then "Save"

Exit and I now listen to HD channels with NO audio drop whatsoever.  Yes, I hear a sound effect when I use the remote to view the Guide, or Info for a channel, etc. but that is no problem.  I'm not sure WHY this fixed it but there is obviously a bug and this is an EASY workaround to fix it.

[SomeJoe7777 ACE - Geek]

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ckellyne wrote:

fyi...I was having the SAME problem with dropped audio ONLY when watching HD channels and figured out the solution and no more audio problems when viewing / listening to HD channels.  My system was installed October 31, 2008 and I had the tech out 3x and they couldn't fix it.  They thought it was my audio receiver system which I knew it was not since it worked fine with other services and on non-HD channels.  This is what I did to FIX the problem:

1. Select "Menu" with the remote

2. Scroll over to "Options"

3. Scroll over to "System Settings"

4. Select "System sound effects"

5. Select "Play sound effects" and then "Save"

Exit and I now listen to HD channels with NO audio drop whatsoever.  Yes, I hear a sound effect when I use the remote to view the Guide, or Info for a channel, etc. but that is no problem.  I'm not sure WHY this fixed it but there is obviously a bug and this is an EASY workaround to fix it.

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Unfortunately, this does not work correctly.  Please see my response here.