5.1 Audio Fix Implementation – Your Feedback Needed

[RRM998]

I also agree -- right after I got the series priority option, I noticed that my screen was too bright. I reduced the brightness setting back to the same level I used with DTV and it is perfect on the HDnet test pattern.

[Frisky_Dingo]

I'm in San Antonio and was just watching "The Dark Knight" on HB02HD (Channel 1804) and I was still getting a large and very noticeable amount of audio drop outs throughout the whole movie.

I have a 5.1 surround setup with a Sony receiver, cable box is running into the receiver through HMDI and the receiver is also running through HDMI to the TV.

[wd0423]

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trparky wrote:

Is there a potential that this hardware change at the headends will fix possible picture/audio feed issues too?

Why I ask is that for some time now I've been experiencing issues in which the audio and video would freeze up for a second or two on Comedy Central HD.  SyFy HD has the issue too but not nearly as bad as Comedy Central HD.

I've had Tier-2 involved in which they said nothing was wrong with my line.  I even monitored my line stats during the hiccup and there were no corrected or uncorrected blocks, no dropped TCP/IP packets, etc.  Happens on both DVR and STB in both live and recorded mode.  Wiring in the house is all Ethernet.

So wait, you're saying that all new encoder hardware is needed at the uVerse video headends?  Yikes. *shudder* Can't imagine how much those boxes are.

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The fix were putting in place won't have an impact on AV freezing. However, we do have a technical team working to address that issue. We're actually replacing a component in our headend to address the 5.1 audio issue. Fortunately, the fix doesn't require an overhaul. To your point, that would get a little pricey! Thanks for your input.

[wd0423]

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ManuelM wrote:

I just tested it and the audio dropped once on CNN HD.

---

How long were you watching CNN HD? Our testing has shown the fix we're implementing will care for perhaps 85-95% of the audio drops we're seeing (actually hearing) on our test channels. (The actual percentage is probably higher, but I'd get myself into trouble with you folks if I got to cocky.) I wish there was a magic bullet that would totally eliminate audio problems. If there was, we would have loaded that puppy up and fired it off a long time ago! Seriously though, the change we're making is based on successful root cause analysis of a specific anomoly in our AV process chain that caused dropped audio at the output of our encoders. We do have a change coming in our next HD encoder software release that will provide an additional tool shown to effectively "conceal" audio drops caused by dropped packets. Depending on what actually caused your CNN HD audio drop, you won't hear it (or not hear it) once that tool is made available to us. 

[wd0423]

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chrisw wrote:

I can confirm that the HDMI black level issue is fixed. Last month I pulled up HDNET's calibration program and the black levels were spot on, and I didn't have to change a thing on my new HDTV - unlike when I tried a few months back.

I'm going to hit record while I review some channels, that way I can just rewind and see if the picture has problems that I haven't noticed at first and check for problems on the other TV as well. I think this would be a good idea for anyone who's testing.

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Thanks for the input chrisw. The kudos for this really need to go to SomeJoe7777. I took his analysis of the problem back to Microsoft last year who concurred he was right on the money. Like I've posted before, the willingness on your all's part to post your experiences and insights (and engage us directly when we can) does help us improve the product. The same thing is happening here with the 5.1 audio issue.

[wd0423]

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PJAndrews wrote:

Hi There - I am located in the Orange county, California market and I tested a few of the channels referenced in the list...I can say without hesitation that the audio drops are still present when the audio is set to surround sound.

PJ Andrews

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I've added this to our list. Thanks!

[wd0423]

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evansf1 wrote:

I have a Denon AVR-1609 connected via optical cable to the Motorola non-dvr box and an hdmi cable from the Motorola box to my Panasonic TC-P42G25.  I've recently noticed that on various HD Movie Channels (HBO's, Showtime's, Cinemax, etc) that the volume will randomly jump up to high levels for 1-2 minutes for no rhyme or reason.  And there are still audio drops although it happens less frequently.  I'm in CT.

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Now on our list as well. Thanks for the feedback!

[wd0423]

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ManuelM wrote:

So I'm not the only one in the Orange County area that still has problems. Audio drops on Comedy Central HD as well.

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Thanks ManuelM.

[wd0423]

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RRM998 wrote:

I also agree -- right after I got the series priority option, I noticed that my screen was too bright. I reduced the brightness setting back to the same level I used with DTV and it is perfect on the HDnet test pattern.

---

Thanks for the confirmation.

[wd0423]

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Frisky_Dingo wrote:

I'm in San Antonio and was just watching "The Dark Knight" on HB02HD (Channel 1804) and I was still getting a large and very noticeable amount of audio drop outs throughout the whole movie.

I have a 5.1 surround setup with a Sony receiver, cable box is running into the receiver through HMDI and the receiver is also running through HDMI to the TV.

---

Adding to the list. Thanks!

[wd0423]

The local HD Big Four channels have been upgraded in the following locations:

• St Louis
• Atlanta
• Cleveland
• Sacramento
• Milwaukee
• Houston (with the exception of the FOX station)
• Chicago

U-verse Operations has also completed upgrading the Indianapolis local "non-Big Four" HD channels. All local HD channels in Indianapolis should now be upgraded.

Regards,

[gbh62]

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wd0423 wrote:

The local HD Big Four channels have been upgraded in the following locations:

• St Louis
• Atlanta
• Cleveland
• Sacramento
• Milwaukee
• Houston (with the exception of the FOX station)
• Chicago

U-verse Operations has also completed upgrading the Indianapolis local "non-Big Four" HD channels. All local HD channels in Indianapolis should now be upgraded.

Regards,

---

Any idea when the Florida (Orlando) VHO will be upgraded?  Thanks.

[gbh62]

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wd0423 wrote:

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ManuelM wrote:

I just tested it and the audio dropped once on CNN HD.

---

How long were you watching CNN HD? Our testing has shown the fix we're implementing will care for perhaps 85-95% of the audio drops we're seeing (actually hearing) on our test channels. (The actual percentage is probably higher, but I'd get myself into trouble with you folks if I got to cocky.) I wish there was a magic bullet that would totally eliminate audio problems. If there was, we would have loaded that puppy up and fired it off a long time ago! Seriously though, the change we're making is based on successful root cause analysis of a specific anomoly in our AV process chain that caused dropped audio at the output of our encoders. We do have a change coming in our next HD encoder software release that will provide an additional tool shown to effectively "conceal" audio drops caused by dropped packets. Depending on what actually caused your CNN HD audio drop, you won't hear it (or not hear it) once that tool is made available to us. 

---

Hmmm?  So, if I understand this correctly, this "fix" really won't eliminate the problem? 

Is the real "root cause" of the problem actually an issue with the STB hardware or software that is economically infeasible for ATT to address until some "long in the future" time when a new STB rollout occurs?  And, you guys are really just trying to "mask" the issue in the VHO encoders, and maybe that's why people seem to be still having the isse, for the most part?

Excuse me for being a bit skeptical of this proposed fix, but it seems like DD5.1 has been done successfully by pretty much everyone else (cable, sat, etc).  What really went wrong 4 or 5 years ago when these STBs were selected?

Thanks.

[trparky]

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gbh62 wrote:

Excuse me for being a bit skeptical of this proposed fix, but it seems like DD5.1 has been done successfully by pretty much everyone else (cable, sat, etc).  What really went wrong 4 or 5 years ago when these STBs were selected?

---

Um... Microsoft?  LOL

In all seriousness I think it comes down to how digital audio receivers process the audio that is coming over the link.  You'd think that the better the receiver the better the chance that it would work.  I don't know.  I have a cheap Insignia surround sound receiver that's hooked up via the optical audio port and I have no issues.

From the little bit of research I've done I've come to the conclusion that the issue is because of some kind of issue with a chip inside the box and the Microsoft Media Room software.  I wouldn't be surprised if has something to do with the fact that there is a lack of processing capablity in the DVR box.  Last time I checked the processor in the box isn't exactly that beefy according to some of the chips you can find in say... a modern desktop.  A lowely Celeron would be able to run the software if they paired it with a specialized decoder chip to handle the decoding of the H.264 AVC encoded video stream.

[sailor397]

Does the Dallas VHO include Richardson, TX or are we on a separate VHO?

[TonyStark]

While it is always my favorite sport to blame MSFT also (especially since my laptop has been given me fits this week) it seems fairly clear this issue is an issue between their headend equipment and certain specific receivers.  When 5.1 audio is going through a typical STB to HDMI the audio is NOT processed by the STB.  That digital stream is just passed through to the digital HDMI output and on to the customers AV receiver.  Since many of the folks who reported this problem on receivers saw it on HDMI you can rule out processing problems in the STB.  If instead the behaviour we had seen was no audio drops on HDMI, but audio drops on STB's using analog audio outputs then one would suspect the STB.  Thus, the explanation given by AT&T makes sense to me. 

[SomeJoe7777 ACE - Geek]

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TonyStark wrote:

While it is always my favorite sport to blame MSFT also (especially since my laptop has been given me fits this week) it seems fairly clear this issue is an issue between their headend equipment and certain specific receivers.  When 5.1 audio is going through a typical STB to HDMI the audio is NOT processed by the STB.  That digital stream is just passed through to the digital HDMI output and on to the customers AV receiver.  Since many of the folks who reported this problem on receivers saw it on HDMI you can rule out processing problems in the STB.  If instead the behaviour we had seen was no audio drops on HDMI, but audio drops on STB's using analog audio outputs then one would suspect the STB.  Thus, the explanation given by AT&T makes sense to me. 

---

It's not just with specific receivers.  The digital audio was mistimed which was resulting in framing errors.  The framing errors reached all AV receivers, it's just that some of them hide the problem better than others.  Some receivers take 1/2 - 3/4 of a second to lock back onto the digital audio stream, resulting in a significant dropout.  Other receivers will simply lose one frame of Dolby Digital which is only 32 msec, and is barely audible.  A very few AV receivers, when one 32 msec frame is missing, will simply replay/duplicate the previous frame, and virtually no one can hear that.  (Indeed, I'll wager that this is the technique that he's talking about that will be implemented in the future).

Just because the digital audio is bitstreamed over HDMI or optical doesn't mean there is no processing in the STB.  In fact, there is a lot of buffering going on even though the audio itself is never decoded.  Since the problem is a timing issue, the buffers in the STB are absolutely in play here as a potential contributor to the problem.  Fortunately, a change at the headend looks like it was able to fix this without changing what's going on in the STB.

[trparky]

So what you're saying SomeJoe is that the blame can be put on both the headend equipment as well as the STBs?  What's going wrong in the STB?  Can it be fixed with a firmware upgrade?

[trparky]

When you say "framing error" do you mean that there's a sudden period of time in which there's no audio data?  That kind of seems strange and something that I'd think would be easy to spot in the data stream.  Look at the bitrate coming out of the encoder and see that every so often the bitrate drops more than it should, like some part of it is missing.

[wd0423]

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gbh62 wrote:

---

wd0423 wrote:

The local HD Big Four channels have been upgraded in the following locations:

• St Louis
• Atlanta
• Cleveland
• Sacramento
• Milwaukee
• Houston (with the exception of the FOX station)
• Chicago

U-verse Operations has also completed upgrading the Indianapolis local "non-Big Four" HD channels. All local HD channels in Indianapolis should now be upgraded.

Regards,

---

Any idea when the Florida (Orlando) VHO will be upgraded?  Thanks.

---

I don't have a specific date but U-verse Operations is working to have the local HD Big Four channels upgraded in all locations by the end of next week.

[wd0423]

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gbh62 wrote:

---

wd0423 wrote:

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ManuelM wrote:

I just tested it and the audio dropped once on CNN HD.

---

How long were you watching CNN HD? Our testing has shown the fix we're implementing will care for perhaps 85-95% of the audio drops we're seeing (actually hearing) on our test channels. (The actual percentage is probably higher, but I'd get myself into trouble with you folks if I got to cocky.) I wish there was a magic bullet that would totally eliminate audio problems. If there was, we would have loaded that puppy up and fired it off a long time ago! Seriously though, the change we're making is based on successful root cause analysis of a specific anomoly in our AV process chain that caused dropped audio at the output of our encoders. We do have a change coming in our next HD encoder software release that will provide an additional tool shown to effectively "conceal" audio drops caused by dropped packets. Depending on what actually caused your CNN HD audio drop, you won't hear it (or not hear it) once that tool is made available to us. 

---

Hmmm?  So, if I understand this correctly, this "fix" really won't eliminate the problem? 

Is the real "root cause" of the problem actually an issue with the STB hardware or software that is economically infeasible for ATT to address until some "long in the future" time when a new STB rollout occurs?  And, you guys are really just trying to "mask" the issue in the VHO encoders, and maybe that's why people seem to be still having the isse, for the most part?

Excuse me for being a bit skeptical of this proposed fix, but it seems like DD5.1 has been done successfully by pretty much everyone else (cable, sat, etc).  What really went wrong 4 or 5 years ago when these STBs were selected?

Thanks.

---

No MVPD can (truthfully) guarantee they can eliminate any and all audio impairements from their network; they're are too many factors outside of their control/influence. I can tell you that we're working hard to optimize our network and, at least in this particular case, the STB had nothing to do with the problem. Thanks for your input!

[trparky]

So you're saying that the problem is in the encoder.  What's actually going on?  Is the data just not there, as in it's missing in the data stream?  Or is it because the data is corrupted?

[wd0423]

---

trparky wrote:

---

gbh62 wrote:

Excuse me for being a bit skeptical of this proposed fix, but it seems like DD5.1 has been done successfully by pretty much everyone else (cable, sat, etc).  What really went wrong 4 or 5 years ago when these STBs were selected?

---

Um... Microsoft?  LOL

In all seriousness I think it comes down to how digital audio receivers process the audio that is coming over the link.  You'd think that the better the receiver the better the chance that it would work.  I don't know.  I have a cheap Insignia surround sound receiver that's hooked up via the optical audio port and I have no issues.

From the little bit of research I've done I've come to the conclusion that the issue is because of some kind of issue with a chip inside the box and the Microsoft Media Room software.  I wouldn't be surprised if has something to do with the fact that there is a lack of processing capablity in the DVR box.  Last time I checked the processor in the box isn't exactly that beefy according to some of the chips you can find in say... a modern desktop.  A lowely Celeron would be able to run the software if they paired it with a specialized decoder chip to handle the decoding of the H.264 AVC encoded video stream.

---

Your experience with your Insignia AVR speaks to some of the difficulting with fully characterizing this 5.1 audio issue. It's not an excuse, just the nature of the beast. 

[wd0423]

---

sailor397 wrote:

Does the Dallas VHO include Richardson, TX or are we on a separate VHO?

---

I beleive you're served out of the Dallas VHO. I'll try to get confirmation. If I'm wrong, I'll get back to you.

[wd0423]

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wd0423 wrote:

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sailor397 wrote:

Does the Dallas VHO include Richardson, TX or are we on a separate VHO?

---

I beleive you're served out of the Dallas VHO. I'll try to get confirmation. If I'm wrong, I'll get back to you.

---

Dallas and Richardson are served out of the same location.

[wd0423]

---

wd0423 wrote:

The local HD Big Four channels have been upgraded in the following locations:

• St Louis
• Atlanta
• Cleveland
• Sacramento
• Milwaukee
• Houston (with the exception of the FOX station)
• Chicago

U-verse Operations has also completed upgrading the Indianapolis local "non-Big Four" HD channels. All local HD channels in Indianapolis should now be upgraded.

Regards,

---

The following locations have also had their Big Four HD channels upgraded:

• Santa Clara
• Wallingford
• Hartford
• Miami
• West Palm Beach
• San Antonio

[viscountuk]

I was watching the tennis yesterday evening on ESPN2HD for about an hour and I counted at least 15 audio drop outs.  I rewound the footage to confirm that there was no issues with the video feed.

My set up is HDMI from DVR to my AV Receiver (Onkyo HT-RC160), and confirmed my DVR (Motorola VIP1225) is set to surround sound in the settings.

Although on the bright side the Syfy channel didn't exhibit any dropouts for the hour long show I was watching.

I am in the San Diego, CA area.

[SomeJoe7777 ACE - Geek]

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trparky wrote:

When you say "framing error" do you mean that there's a sudden period of time in which there's no audio data?  That kind of seems strange and something that I'd think would be easy to spot in the data stream.  Look at the bitrate coming out of the encoder and see that every so often the bitrate drops more than it should, like some part of it is missing.

---

Yes, that's correct.  If the encoded streams of the video and audio are not sharing a common time base, then one of them can get ahead of or behind the other one.  In this case, the audio stream is (was) approximately 0.04% slower than the video stream.  When the AV receiver runs out of data in its buffers, it has to wait for the next packet to arrive.  This is the framing error, and it results in a small period of time where there is no audio data to decode.

I was initially thinking that the point in the system where the audio and video were split apart and no longer sharing the same time base was in the STB.  According to wd0423, that actually was happening in the encoder unit at the head end, but the mechanics of the problem and the results are the same.

A similar problem occurs with consumer DV camcorders, see Adam Wilt's page on Locked and Unlocked Audio.

[dhascall ACE - Professor]

I see two identical threads.  Anyone else seeing this twice?

[ScottMac]

No, the data is there, but it's so far out from the timeline of the stream that the decoder drops the data, then re-synchronizes. 

My understanding is that it is happening farther up the stream (not in the AVR), and that the decoder that's doing the re-sync is still in the VIdeo Office i.e., two head-end devices have the problem, the result is carried downstream to the AVR, and it appears as blank DD audio (data is there, but the data is no audio).