New HDTV Now New HR24 Crazies

Beerstalker said:

Are you sure this isn't just a DD 2.0/5.1 issue? When a channel sends out 2.0 as a 5.1 signal (5.1 signal with only sound encoded on the front left and right channels) there will be a big difference in sound since your center channel is no longer used for anything.

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This crossed my mind as well. But Dallas is a large market, and major net affils in even medium markets typically simulate 5.1 from 2.0 sources (using essentially a pro version of ProLogic IIx) so that they are sending 5.1 all of the time. This solves the problems of mutes at remap change points and the issue of audio collapsing to stereo on home rigs set up for 5.1.

But assume for the moment that they are not doing this. If so, the solution is to program your AVR to do it instead (default to ProLogic when 2.0 is sent, but pass true 5.1). That remaps 2.0 dialog (anything that has essentially equal volume in Ls and Rs) to Center, and sends a 90-degree phase shifted signal to Lr and Rr for sounds unequal in volume from Ls to Rs.

You can usually tell what they are doing if your AVR has a 5.1/DD indicator light. See if that goes on and off and tracks with the audio issue.

If we assume the problem is elsewhere, there seems to be no clear answer. I would post in the reception thread for your market on AVS Forums and see if others can verify this issue.

One thing it likely is not, is a native on-off situation. That deals with the metadata flags for pixel maps and what gear is responsible for rescaling, and it has no connection at all to the audio stream or its metadata.

And I think there is a pattern. There is always a pattern. You may just not have nailed down exactly what the pattern is yet. Unexplained science appears as magic, and undefined patterns appear as random. There is no true magic, and there is no true random.

<edit> just reread the original post, and it seems as if the OP is not using an AVR, but the audio in the TV only. That might explain why the issue appeared when the new TV got there. It also complicates troubleshooting or fixing the mapping issues, should that actually be the problem. Sounds like it might be time to either buy an AVR or start using an AVR as the audio center of this setup. See what AVS says first, and call the stations and ask them (Engineering dept) if they simulate 5.1 DD all the time.

It also could be something as simple as the speakers in the TV or in the stereo system wired out of phase. Always tie a knot in both ends of the positive for all speaker wires to keep them straight, and check that the woofer cone moves toward you (remove the speaker grille or use a flashlight) when you place a 9v battery across the amp end of the wire when connected only to the speaker (+ on positive). If the cone moves away from you, that speaker system or its wiring is out of phase. A 10-year old makes a great assistant for these tests, BTW.

TomCat said:

This crossed my mind as well. But Dallas is a large market, and major net affils in even medium markets typically simulate 5.1 from 2.0 sources (using essentially a pro version of ProLogic IIx) so that they are sending 5.1 all of the time. This solves the problems of mutes at remap change points and the issue of audio collapsing to stereo on home rigs set up for 5.1.

But assume for the moment that they are not doing this. If so, the solution is to program your AVR to do it instead (default to ProLogic when 2.0 is sent, but pass true 5.1). That remaps 2.0 dialog (anything that has essentially equal volume in Ls and Rs) to Center, and sends a 90-degree phase shifted signal to Lr and Rr for sounds unequal in volume from Ls to Rs.

You can usually tell what they are doing if your AVR has a 5.1/DD indicator light. See if that goes on and off and tracks with the audio issue.

If we assume the problem is elsewhere, there seems to be no clear answer. I would post in the reception thread for your market on AVS Forums and see if others can verify this issue.

One thing it likely is not, is a native on-off situation. That deals with the metadata flags for pixel maps and what gear is responsible for rescaling, and it has no connection at all to the audio stream or its metadata.

And I think there is a pattern. There is always a pattern. You may just not have nailed down exactly what the pattern is yet. Unexplained science appears as magic, and undefined patterns appear as random. There is no true magic, and there is no true random.

<edit> just reread the original post, and it seems as if the OP is not using an AVR, but the audio in the TV only. That might explain why the issue appeared when the new TV got there. It also complicates troubleshooting or fixing the mapping issues, should that actually be the problem. Sounds like it might be time to either buy an AVR or start using an AVR as the audio center of this setup. See what AVS says first, and call the stations and ask them (Engineering dept) if they simulate 5.1 DD all the time.

It also could be something as simple as the speakers in the TV or in the stereo system wired out of phase. Always tie a knot in both ends of the positive for all speaker wires to keep them straight, and check that the woofer cone moves toward you (remove the speaker grille or use a flashlight) when you place a 9v battery across the amp end of the wire when connected only to the speaker (+ on positive). If the cone moves away from you, that speaker system or its wiring is out of phase. A 10-year old makes a great assistant for these tests, BTW.

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I believe a bit more detailed explanation of the solution is due.

• Yes I have an AVR. A Denon AVR 987.

• All Infinity Alpha speakers, configured for 5.1, were examined for defects. None were found. All speaker connections are in phase.

• The HDMI connected to the Directv HR24-500 is routed into the Denon AVR. A master HDMI connects the Denon AVR to the Sony HDTV. Audio for all components (Directv Recvr, Panasonic Blu-Ray and Denon CD/SACD/DVD) is processed by the Denon AVR and routed to the Infinity speakers.

• No audio is emitted by the SONY HDTV. The Sony HDTV does not transfer audio to any external source.

• As I searched for a solution I talked with Denon, Directv and NBC & ABC Dallas affiliates.

• Both NBC & ABC affiliates broadcast commericals in either true 5.1 or simulated 5.1 thus AVR's should not switch to a different audio format during commericals.

• The ABC Engineer also has a Denon AVR and stated after connecting new equipment all components, including the power center should be powered down. The power center shoul be unplugged from the wall power outlet. This shutdown allows the Denon AVR, in particular, to reset. This reset solved the problem.

Thanks for your comments. The information was very interesting.

That's helpful, if not definitive.

It is best to put aside what is not likely causing the problem. We know it is both OTA through DTV and DVB/sat through DTV. Do we see the problem with OTA directly into your TV? How about when using headphones on the AVR?

What have you heard from AVS forums so far?

Your new info indicates that the Denon is at fault. While Denon makes kick-ass AVRs, they have a history of issues with HDMI. Be sure you are updated to the latest firmware.

If your TV can pass HDMI/5.1 to the line outputs, you might want to try connecting differently. Instead of connecting stuff to the Denon, connect through the TV first, and take a single output to the Denon, either HDMI or optical.

This actually has a lot of advantages. Modern FP TVs have inherent delay in the display, and they delay their audio to compensate for lipsync errors. If you connect around the display instead, you get no delay benefit, and must rely on the delay circuitry in the Denon.

This also allows you to switch all A/V sources using the TV remote, and all audio-only sources using the Denon remote, which is a lot more intuitive. It also opens up more inputs on the Denon.

Best of all, it might act as a workaround for this problem.

There is no real advantage to alleged video processing of digital video in an AVR anyway. PQ is locked in until you get to the TV in any case, and unless the AVR decodes and re-encodes, it won't be able to modify the PQ in any way, let alone improve it, and the last thing you want at consumer-level bit rates is another decode/re-encode stage, as at this bit rate it can only lead to large rounding errors and associated artifacts (which is why no consumer device actually processes HD video in the digital domain or converts it to the analog domain for processing--they may claim "100% digital processing", but that is really digital signal handling, not actual digital processing of the video information within the digital domain, which is impractical).

But many people have been fooled into thinking that their AVR can improve digital PQ by manufacturers who want to get you to believe just that. Unless binary math is performed on the coefficients representing each pixel, PQ will stay exactly the same as it was when it left the uplink or broadcast tower. And if math is done, it is nearly impossible, especially at a consumer level, to mount any sort of improvement without running the risk of actually making the PQ worse, which is why that isn't customarily done at the consumer level.

But what is customary is convincing potential buyers who are disadvantaged by not really understanding how this works, that there actually is some sort of digital magic at work. Sadly, there really isn't, regardless of what they typically seem to be claiming.

1953 said:

TO ALL,

You may not believe what I'm about to state but it is the truth. My wife even witnessed this weirder than weird event.

Just to see what would happen I went into the HR24's "Favorite Channels" section and unchecked Channels 5 & 5-1 (NBC Dallas) along with Channels 8 & 8-1 (ABC Dallas). All four channels were no longer listed in the GUIDE. While on another station I mistakenly pressed "5". Unbelievably Channel 5 appears! The same with Channel 8. Saddly the audio problem was still on Ch 5. I did not really check out Ch 8.

Now, you should know that we live on top of a hill and are in somewhat of a straight line with the Dallas TV towers that are about 10 miles west of us.

How could this happen and could it some how be associated audio problem?

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It is not associated at all.

The favorites list is just a list. It has nothing to do with what you can receive or what local market database the DVR is programmed for. If you have a channel 5 in your database and are in range of a channel 5, pressing 5 tunes you to that frequency if that is the physical frequency, and tunes you to the virtual frequency listed in the database if 5 is mapped from a different physical channel (which redirects the tuner to the real physical channel but displays the virtual channel, channel 5). That's the way its supposed to work. Deleting it from a list does not change what is in the database or what channel the tuner will go to when you press a channel number associated with that database.

"5", the SD version of 5-1, is also mapped in your DVR. Actually, all channels are mapped; you see 249 for Comedy Central, for instance, but that is a mapped number for a particular frequency slot on a particular transponder on a particular polarity of a particular satellite, and has nothing at all to do with the arbitrary number 249. The number is only there for you to be able to find it. 249 on DISH probably is mapped to an entirely different original service.

Here's an example of how mapping works.

DVB and ATSC use MPEG transport streams, which can carry multiple programs on a transponder or OTA channel. All of the packets from the different programs per TV channel or per transponder are jumbled together and interleaved into a single transport stream via a multiplexer. The way it keeps them straight is by mapping each elemental stream to a number, which is a similar sort of mapping system. It uses a PID, or program identifier, which is a 8-bit or single-byte unique code placed in the metadata of the header of the elemental stream's packets. For instance, the PID for the first (English) audio pair for the primary service in ATSC is 52 in base 10 (which has a 8-bit binary word, 00110100, representing it in the metadata). The multiplexer also creates and sends along a PMT, or program map table, which is sort of like a scorecard that lets the eventual decoder know which PIDs belong to what service.

Just like we know we can find Comedy Central if we tune the number 249 on DTV, the ATSC STB knows from consulting the PMT that it can find the audio track associated with the primary broadcast channel by parsing out PID 52 from the packet headers, and using that identifier to know which packets contain the audio track to associate with the video, which has its own PID of 49.

After reception and just before the local decoder (or HDD in a OTA DVR), the demux, once instructed to parse out that particular program (told by the user to go to channel "5.1" instead of "5.2" or "5.3", for instance), then sorts out all of the packets with a PID of 49 and reconstructs them into a bit stream that is sent to the decoder (or HDD), and sorts out all of the packets with a PID of 52 and interleaves those as well, discarding everything else in the main stream. Then the decoder reverses the encoding process, parses out and decodes each audio and video packet, and spits out the digital audio and video for a single program (what is on "5.1").

Here's an even simpler example.

In 1939(?) the OTA channel associated with the frequency 55.25 MHz (for the video carrier) or the band of 54 to 60 MHz, was mapped to the number 2, as part of standardization. When we select channel 2 on a recent analog TV, it doesn't tune to "2", it "consults the map"* and tunes to 55.25 MHz.

(*the old school version of "consulting the map" for older analog TVs was to physically insert a different particular tuning coil for each particular channel into the heterodyne circuitry changing the inductance and causing that particular RF frequency to convert to the fixed IF frequency. Channels above and below were filtered out using a bandpass filter, leaving just the tuned channel to eventually be demodulated to baseband audio and video. That's where the moniker "tuned" actually comes from. Significantly different technology, but the concept of mapping was very much the same.)

So the channel number is just a name; a pointer. A rose is a rose is a rose.

I still think you are having the issue I talked about earlier. You local channel is sending everything out as Dolby Digital 5.1 all of the time. However, when they are getting some content that is only available with stereo audio they are not using Pro-logic to simulate 5.1 from the stereo track. Instead they are just sending out the stereo audio on the front left and front right channels, and they are sending out blank signals with no sound to the center, surround left, surround right, and subwoofer channels.

Since this is still being reported to your AVR as a Dolby Digital 5.1 signal (which it is since it contains empty information for the other channels) your AVR just passes it through as it is. It does not try to use Pro-Logic 2 on the signal.

There is nothing you can do to fix this. You can choose to turn off dolby digital on your DirecTV receiver and just have it send out stereo sound to your AVR, and turn on Pro-Logic 2 on your AVR. This will get you surround sound, but it will be simulated surround sound and not as good as proper dedicated surround sound you would get using Dolby Digital.

You need to contact your local channels and talk to the sound engineers and explain to them that they are not handling stereo audio properly. Hopefully they will work with you to get it fixed. We have had the same issue with some of my local channels in the past.

Beerstalker said:

I still think you are having the issue I talked about earlier. You local channel is sending everything out as Dolby Digital 5.1 all of the time. However, when they are getting some content that is only available with stereo audio they are not using Pro-logic to simulate 5.1 from the stereo track. Instead they are just sending out the stereo audio on the front left and front right channels, and they are sending out blank signals with no sound to the center, surround left, surround right, and subwoofer channels.

Since this is still being reported to your AVR as a Dolby Digital 5.1 signal (which it is since it contains empty information for the other channels) your AVR just passes it through as it is. It does not try to use Pro-Logic 2 on the signal....

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Speaking as a Broadcast Engineer, I find this doubtful.

Virtually all of the equipment available for stations for the last 5-6 years that is used to either pass 5.1 or simulate 5.1 from 2.0 uses a Pro Logic IIx variety of simulation. The very reason they do this is to prevent the "2.0 collapse" issue in 5.1 setups, and to prevent muting at the switch points between 5.1 and 2.0 programs or events.

DFW is a pretty large market, and it would be highly unusual that two of the big 4 network stations would not use equipment of this caliber. sending the 5.1 flag to the consumers' DD decoders all of the time is nearly impossible to do without the equipment used to do that also truly sending all 6 channels.

But nothing is absolutely impossible. Odds are exceptionally low, but yes, two top-market crack Engineering staffs could have each done something to mess this up at two different stations in a single market. I'd bet heavily against that. Or, they are such a large market that they bought their gear early on and it is not as capable as modern gear or has some sort of setup flaw. Again, doubtful.

But this is why it is so important to check with other viewers in the area, either directly or using the reception forum at AVS. If you talk to the Chief at either station, tell them you suspect that it seems like you are not getting all 6 channels when they are simulating 5.1, and then you should have a direct answer. Ask if you are the only one complaining.

To really nail this down, get a free copy of TS Reader and watch the bit stream in PID 52. You can't parse out the 6 channels without a decoder, but you might be able to see a significant change when the audio changes from sounding good to sounding bad. If they are sending 4 of those channels with nothing but null bits, that should be discernable (the stream will probably be at 448 kbps and if there is no audio in 4 of those channels, It will be stuffed with lots of null bits to keep the rate at 448).