some viewers Can't hear our audio

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rburleson
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some viewers Can't hear our audio

Post by rburleson » Fri Nov 02, 2012 9:35 am

Let me preface my question with a little information: We are a low power public TV Station terrestrial broadcast only, that just went on the air this summer.
We are broadcasting about 1000 watts and have a 366ft and cover about a 40 mile radius. Owned and operated by the Cheyenne and Arapaho Tribes of Oklahoma.
We are working on little to no budget and there is just me and one other guy that makes up the staff.
We have no engineer on staff and we have had several engineering issues and I am hopping I can get some help on this forum.
Currently, we are getting reports from some viewers that they are getting our picture just fine but that they cannot hear any audio but they can hear other stations just fine.
We have a TV here and we are picking it up just fine off the air.
I suspect either it is that fact that we are not transmitting Dolby Digital AC-3 audio but PCM only. OR maybe some of our viewers have older TV's with HD converter boxes that may be expecting AC-3 audio.
I am trying to get some feed back from our viewers but haven't had much luck in getting any useful feedback.
Have any of you guys run across this and what is the solution?
We are trying to get some money together to pay for the Dolby Digital AC-3 audio module for our Ensemble Designs Avenue.
Maybe that will get us there.
I was also wondering about standard broadcast settings for our International Datacasting/Tiernan Titan MPEG encoder.
If that wasn't set right maybe that would cause issue as well...
I am grasping at straws here. Help me out if you can.
Thanks guys!

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PID_Stop
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Re: some viewers Can't hear our audio

Post by PID_Stop » Fri Nov 02, 2012 11:06 am

rburleson wrote:Let me preface my question with a little information: We are a low power public TV Station terrestrial broadcast only, that just went on the air this summer.
We are broadcasting about 1000 watts and have a 366ft and cover about a 40 mile radius. Owned and operated by the Cheyenne and Arapaho Tribes of Oklahoma.
We are working on little to no budget and there is just me and one other guy that makes up the staff.
We have no engineer on staff and we have had several engineering issues and I am hopping I can get some help on this forum.
Currently, we are getting reports from some viewers that they are getting our picture just fine but that they cannot hear any audio but they can hear other stations just fine.
We have a TV here and we are picking it up just fine off the air.
I suspect either it is that fact that we are not transmitting Dolby Digital AC-3 audio but PCM only. OR maybe some of our viewers have older TV's with HD converter boxes that may be expecting AC-3 audio.
I am trying to get some feed back from our viewers but haven't had much luck in getting any useful feedback.
Have any of you guys run across this and what is the solution?
We are trying to get some money together to pay for the Dolby Digital AC-3 audio module for our Ensemble Designs Avenue.
Maybe that will get us there.
I was also wondering about standard broadcast settings for our International Datacasting/Tiernan Titan MPEG encoder.
If that wasn't set right maybe that would cause issue as well...
I am grasping at straws here. Help me out if you can.
Thanks guys!
Yes, the problem is indeed that you are not transmitting AC3. While AC3 is optional for things like satellite feeds and microwave links, it's mandatory for ATSC (over-the-air) broadcast. Without it, most TV sets won't be able to decode your audio.

-- Jeff

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NECRAT
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Re: some viewers Can't hear our audio

Post by NECRAT » Fri Nov 02, 2012 10:06 pm

PID_Stop wrote:
Yes, the problem is indeed that you are not transmitting AC3. While AC3 is optional for things like satellite feeds and microwave links, it's mandatory for ATSC (over-the-air) broadcast. Without it, most TV sets won't be able to decode your audio.

-- Jeff
+1 to what Jeff said.
Your MPEG encoder should be able to run AC-3 with any flavor of audio on the input, if you have it set to process/compression mode. If you have it set to passthrough and don't have an external AC3 source, i.e. a Dolby 569, then you will have problems.

Also are you using your Tandberg to generate PSIP? You know you're required to transmit a EIT and EPG, so while the Tandberg would be ok for a short term solution directly connected to the TX, you need to make sure you're muxing the entire PSIP standard.
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w4cl
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Re: some viewers Can't hear our audio

Post by w4cl » Sat Nov 03, 2012 11:39 am

I know the EPG is not require for an LP, yet. Not sure about the EIT. It may not be either.

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Re: some viewers Can't hear our audio

Post by Trip » Sun Nov 04, 2012 3:46 pm

Agreed on the AC3 audio.

All stations are required to broadcast static PSIP, but only full power and class A stations are required to broadcast dynamic PSIP (guide data).

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Re: some viewers Can't hear our audio

Post by NECRAT » Sun Nov 04, 2012 3:55 pm

w4cl wrote:I know the EPG is not require for an LP, yet. Not sure about the EIT. It may not be either.
I mis-read what he initially wrote, and thought it was a class A station. If it is just a LPTV, you're correct.
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Re: some viewers Can't hear our audio

Post by eadler » Wed Dec 19, 2012 11:00 am

You need main AC3 (usually flagged as English Complete-Main). Secondary-service AC3 service (often flagged as Spanish Complete-Main regardless of content but I'd flag it to match its content so long as that flag is not the same as the primary) is highly recommended (if you can do it) as a certain CECB (and the same code in some TVs with built-in tuners) will sometimes default to secondary audio (even if there is none present). Also, some CECBs and tuners/decoders (including but not limited to this same make/model) will allow viewers to select secondary audio even if none is present.
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rburleson
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Re: some viewers Can't hear our audio

Post by rburleson » Tue Jan 15, 2013 10:03 am

Ok guys... here is an update... We just installed AC-3 encoder and decoder cards on our Ensemble Designs Avenue 7660 card and we now have AC-3 audio.
However, The HD converter set top boxs are STILL not receiving our audio. I am pretty frustrated at this point.
Why can the STB HD converter pick up every station but ours?
Any other ideas?

I attached a pic of our Titan Encoder settings that the factory tech has already checked out. I don't know what else could be an issue.

Image
Image
Image
Image

Thanks for your help. Pl

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Re: some viewers Can't hear our audio

Post by PID_Stop » Tue Jan 15, 2013 10:30 am

I've had flaky problems with embedding the AC3 stream in the video... you might want to feed the AC3 directly from the Dolby encoder to an AES input on your Tiernan.

-- Jeff

rburleson
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Re: some viewers Can't hear our audio

Post by rburleson » Tue Jan 15, 2013 11:59 am

Jeff, I will try that to see if it will help. I will post results after I check it out.

rburleson
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Re: some viewers Can't hear our audio

Post by rburleson » Tue Jan 15, 2013 1:16 pm

Well Jeff the direct AES out of the AC-3 encoder to the AES in on the Tiernan Titan Encoder did not help.
Bummer.
Any other ideas?

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Re: some viewers Can't hear our audio

Post by PID_Stop » Tue Jan 15, 2013 1:47 pm

We use mainly Harris NetVX, Tandberg and Harmonic encoders... so the Tiernan is a bit foreign to me. Having said that... seeing "0" in the AC-3 stream number strikes me as a bit suspicious. This sounds like it ought to match the Dolby encoder's metadata program number... so what happens if you change that to "1" (which I would assume is what your Dolby encoder is set to generate)?

-- Jeff

rburleson
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Re: some viewers Can't hear our audio

Post by rburleson » Tue Jan 15, 2013 2:08 pm

Well.... the modern LCD TVs are not having any trouble getting the AC-3 audio. Just the Set Top converter boxes.

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Re: some viewers Can't hear our audio

Post by PID_Stop » Tue Jan 15, 2013 2:41 pm

Oh... I missed that detail. It sounds like a call to Ensemble Designs and/or Tiernan might be in your future... it has the feel of a compatibility problem. Somehow with all of the different combinations and models of equipment we've had over the years, that is one problem we haven't had.

Sorry...

-- Jeff

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Re: some viewers Can't hear our audio

Post by NECRAT » Tue Jan 15, 2013 7:36 pm

Try changing the compression type from AC-3 Pass-Through to AC-3 Compression or similar.
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