NBC HD sound

[iammike]

Does anybody know what the trick is to get the sound right on the NBC HD feeds on AMC18? There are 4 audio streams, but it seems like they are the separate channels of a 5.1 stream. One has primarily voices, but one or more of the others have the ambient noise. I've only been able to listen to one stream at a time. I'm using MT with the Sage TV network encoder to feed my Sage extender boxes.

I'm trying to figure it out before the game tomorrow, so I can watch the Superbowl on some master feed goodness.

 

[voomvoom]

Just change it till you find one that works. I have found that mostly the Commercials are on a different audio track from the regular program (usually?), unless the Commercial is in AC3 audio? I think that's what the difference in 2 may be, one is AC3 and another is stereo?

And, you may have to channel up or down and back to get it to work...?

 

[Lak7]

Usually Audio Channel 4 the center channel, and Audio Channel 2 for sound in Commercials.
If you can, use the audio from the Ku feeds on AMC1.

 

[iammike]

Just change it till you find one that works. I have found that mostly the Commercials are on a different audio track from the regular program (usually?), unless the Commercial is in AC3 audio? I think that's what the difference in 2 may be, one is AC3 and another is stereo?

And, you may have to channel up or down and back to get it to work...?

Thanks for the reply! That's pretty much what I've been doing. The trouble with football games is the stadium sounds are on one stream, and the announcers are on another. There must be a way of muxing the two together since the local NBC affiliate has all of the sound. I just haven't found it yet.

 

[iammike]

Usually Audio Channel 4 the center channel, and Audio Channel 2 for sound in Commercials.
If you can, use the audio from the Ku feeds on AMC1.

Thanks for the reply! I don't have a way to mux the KU and Cband feeds. I'll be watching through Sage. There might be a way to get the OTA sound though. Wish I new how the local stations did it. I think I'll post this on the Sage forums too. The interesting thing is that Sage sees all the streams, even though I can only select one at a time in MT. Unfortunately, they are separate on Sage too.

 

[Barry Erick]

If you are watching that AT a NBC station, this could be the problem. The Original NBC HD system, currently being replaced, has a problem in that they go from 2 ch to 5x1 and require stations to manually switch things to get it right. With the new system going in (we got ours last week), they are automatic and it works with Metadata and a Miranda box.

 

[iammike]

If you are watching that AT a NBC station, this could be the problem. The Original NBC HD system, currently being replaced, has a problem in that they go from 2 ch to 5x1 and require stations to manually switch things to get it right. With the new system going in (we got ours last week), they are automatic and it works with Metadata and a Miranda box.

I'm not at an NBC station, but I think the feeds on AMC18 are the ones the local affiliates use. I don't really know what a Miranda box is, but I'm guessing that it's somehow using the metadata to mux the multiple audio streams into one. Is that correct?

Don't suppose you know a way of doing the same job on the fly on a PC do you?

Thanks!
Mike

 

[Lak7]

Thanks for the reply! I don't have a way to mux the KU and Cband feeds. I'll be watching through Sage.

Do you have a Home Theater Receiver?
Usually there is an "A" and "B" speaker selection that can play 2 Audio inputs at the same time.

 

[iammike]

Do you have a Home Theater Receiver?
Usually there is an "A" and "B" speaker selection that can play 2 Audio inputs at the same time.

Hmmm, interesting thought. I could move the second extender out of the bedroom into the living room and tune it to the OTA broadcast. Not exactly a high-tech solution, but it would work. Thanks!

 

[Lak7]

The OTA will probably be 1 second or so behind the Sat feed.

I was thinking you could put a Primestar and STB on AMC1 and catch the sound from the 4:2:2 feeds and the BUD with Sage could be on AMC18 for Video.

 

[iammike]

The OTA will probably be 1 second or so behind the Sat feed.

I was thinking you could put a Primestar and STB on AMC1 and catch the sound from the 4:2:2 feeds and the BUD with Sage could be on AMC18 for Video.

I'll be watching through Sage. I usually pause games for a half hour or hour before I start watching so I can skip commercials. I'll have to manually sync the two extenders to get it to work anyway.

I'm not sure it's going to be worth the hassle though. It might be best to just watch OTA, or deal with the sound issues rather than trying to keep everything sync'd.

 

[Lak7]

Skip the Super Bowl commercials? That's why I watch it!

 

[iammike]

Skip the Super Bowl commercials? That's why I watch it!

Maybe I should skip through the game so I can get to the commercials!

 

[emuman100]

I'm guessing the way the affiliates do it, is they decode all the audio channels to PCM, input that into an AC3 encoder with the AES3 audio from the receivers, and output a AC3 5.1 stream. That, then gets multiplexed with the encoded MPEG2 video.

The MPEG4 video is decoded and output via HD-SDI into the MPEG2 HD encoder. The AC3 stream that they created then gets multiplexed, PSIP added, and sent to the ATSC modulator.

This is my guess, or at least how I'd do it.

 

[B.J.]

The OTA will probably be 1 second or so behind the Sat feed.
..

I'm curious why you say this. I've seldom seen much sync difference between OTA and raw sat feeds, and if you're looking at HD video from sat, and audio from a SD OTA feed, I'd expect the audio to come through first, just because I'd guess more processing time for the HD signal.

I was hoping to do something like this for the superbowl, but couldn't get it rigged up in time, plus something I previously had working on one of my receivers stopped working with new versions of firmware. Ie I was going to watch the video on my Coolsat 8100 along with a stadium noise audio stream, and was hoping to delay it by about 18 seconds to sync up with the Pittsburgh radio audio off Sirius radio. However I didn't test it out in time, and the darn Coolsat refused to pause and delay the video. I had tested this out with a previous version of Coolsat firmware, and it WORKED, but it didn't work sunday.
So instead, I went back to what I do with all the regular CBS feeds, ie I just feed OTA (or satellite) video via TSREADER to my Roku, and delayed that to sync with the Sirius audio (that wouldn't work for the NBC feed, since the Roku doesn't do mpeg4). Unfortunately the Sirius audio doesn't have much crowd noise, so it isn't quite as realistic as the TV audio. But I HATE those network sportscasters.
One other year, I fed audio into one TIVO, and video into another TIVO, that way I could sync it up perfectly, but that was only because I wasn't sure which would need delaying. I've since learned that Sirius audio is WAY behind.

 

[Lak7]

I'm curious why you say this.

Just my experience, nothing more than that. I can flip from the Main Feed to the OTA, it's about 1-2 seconds behind.

 

[boomer_106]

I've experienced the same delay issues that lak7 is talking about.

 

[B.J.]

The OTA will probably be 1 second or so behind the Sat feed.......

I'm curious why you say this. I've seldom seen much sync difference between OTA and raw sat feeds, and if you're looking at HD video from sat, and audio from a SD OTA feed, I'd expect the audio to come through first, just because I'd guess more processing time for the HD signal.
.........

Just my experience, nothing more than that. I can flip from the Main Feed to the OTA, it's about 1-2 seconds behind.

Thanks. I was curious about this, because if anything, I've observed the opposite, and a few years ago I had done an extensive study of the delays associated with 6 or 8 different ways of viewing TV. However then it occurred to me that MY observations have been using the OTA *ANALOG* signal, so I concluded that you must be using the OTA *DIGITAL ATSC* signal, so that receiver processing speeds would be involved. So I did a comparison to test this.
(1) OTA ANALOG.... analog receiver Fastest
(2) AMC-18 S2 MPEG4 digital less than 0.1 sec delay
(3) OTA ATSC... Samsung TV ~0.9 sec del
(4) OTA ATSC...Diamond 9000---> Samsung TV via HDMI ~1.1 sec delay
(5) OTA ATSC...Coolsat 8100-----> Samsung TV via HDMI ~1.2 sec delay
(6) OTA ATSC...Air2PC card-->TSREADER--->Roku--->Samsung TV via analog A/Component-V 2.8 sec delay.
(7) DirecTV local--->TIVO---> Samsung TV via A/V ~8.5 sec delay.

So my OTA digital results correspond to the 1 second offset you describe, and it also seems to suggest that the delays are due to the digital processing of the signal in our receivers. Ie I think it suggests that the local stations have receivers that have about the same processing time that our receivers do (maybe a tenth of a second faster), but when they re-encode the satellite signal and send it out ATSC, there must be nearly a second delay.

I did a similar comparison a while ago, back when I *THINK* the local stations still got their analog signal separate from the digital signal, but I forget what the results were. Too bad, because there just isn't enough data here to really pinpoint just where all the delays are. I'm also not sure just how many times the local channel processes the digital signal. I'm assuming that they process it once at the station, then probably re-encode it to send it to their transmitter site, and it's possible that there is decoding and re-encoding there too, I don't know.

Interesting topic.

 

[14karat]

So what you've found here is that nothing is as bad as the pizza pans?

 

[B.J.]

So what you've found here is that nothing is as bad as the pizza pans?

Well unless you're actually cooking Pizza.

Some additional data though. The above data was obtained with my local NBC station obviously. I then remembered that my local CBS station has both a HD and SD channel on the digital stream. I didn't look for a sat signal to compare, but I compared the HD and SD channels to my OTA analog signal. The HD channel was only about 1/10th second behind the analog, but the SD digital was about 2.5 seconds behind the analog SD, which I find as real confusing. I don't understand these delays at all, unless they are generating the analog signal from the HD digital, and the SD digital is coming from re-digitizing the analog??? Only thing that makes sense to me.