GEOSATpro Can the microHD do 5.1 audio?

[Pepper]

I notice that the NBC mux channels on 103W Ku have four audio streams. Watching the Olympic ceremony, I noticed that they appear slightly different and wonder if by combining these, you could have a 5.1 audio. I have not found a way to do it.

It appears that stream 1 is front L+R and possibly low frequency; 3 is rear L+R; 2 has center and 4 appears to be a combined stereo. My observation might be wrong, and might not always be the way it's encoded. I'm still very new using this unit and it might not be doable, but perhaps a setting could be added somewhere so that you can choose which audio goes where?

It was nice to find a couple of streams that didn't contain the incessant commentary of Matt Lauer and friends, I guess those would be omitting the center channel.

 

[Jim S.]

Those feeds are always like that. There's no way to assemble a complete 5.1 stream unless you have three receivers and somehow get them in sync.

 

[Pepper]

I wouldn't put it past Brian to figure out a way to do it. All the streams are there; guess it depends whether the chipset supports decoding more than one simultaneously.

 

[Tron]

I would imagine that the recorded stream could be processed and the audio tracks merged into a 5.1 mix, although doing it in real time would require lots of equipment.

I wonder what the purpose of the separate tracks is? Perhaps to give affiliates control of the audio individually before being encoded into DD5.1...

 

[Pepper]

I don't think processing power is an issue. As we all know, it takes a lot more processor to do video than it does for audio. The box has been demonstrated to be able to record two video and audio channels, while decoding and watching a third live. So we know already it can handle three simultaneous audio streams. Drop one of those three video streams and you should have any required processor to mix the audio streams.

Just a theory.

 

[Magic Static]

Here's a thought. I think I'll run down to the local NBC affilliate and ask the engineers how they do it. This may shed some light on the process. To bad it isn't CBS, I already know those guys

 

[Panavision]

I remember when NBC SD existed on AMC1. All their video was squished from top to bottom. What would that have been for? You'd probably have to talk to a pretty high-ranking engineer before you get an explanation for the discrete audio channels. Maybe someone with C-band capabilities can share how the other big nets do their audio.

 

[Panavision]

Maybe the audio shows up differently on their Tandbergs/Ericssons than on our receivers. They probably use ASI to go from their receiver to some external audio processing.

 

[Pepper]

I was really hoping Brian might have noticed this by now and had something to say. (also the PM on an unrelated other subject).

 

[SatelliteAV]

Not sure what I could add since no one knows what the NBC audio mixes are and how the could be combined to produce a correct mix.

For starters... Could someone contribute how the 5.1 is assembled by the affiliates from these feeds and what equipment they use? Maybe this search for NBC mix information might get more exposure if moved to the main FTA area. Happy to look into a specialized application if it is possible.

 

[jdbob]

I'm pretty sure I saw a DD 5.1 stream on HD01 or HD02 on AMC-21. Most of PBS's shows are 2.0 of course so I was surprised to see it.

 

[Pepper]

I don't know the technical specifics of DD5.1-over-HDMI, but I specified what's contained in the individual streams in the first post. Does the box/chipset support decoding and processing multiple simultaneous streams?

I can't ask my local affiliate this question. As far as I can tell they are still stuck on stereo.

 

[SatelliteAV]

The microHD, like all DVB receivers receive many data streams from multiple PIDs and simultaneously decode, process and present.

I agree with an earlier post that it is likely that the affiliates use ASI to export the TS to specialized equipment to build the 5.1 by merging and timing the data carried on the different PIDs.

NBC method of distributing discrete audio on different PIDs is very unique if not proprietary. If someone researches this unique system and determines how the affiliates create the mix, we will determine if and how this might be accomplished with the microHD.

Then the question begs to be answered... to what extent should research and development be directed towards optimizing audio on only a few channels? Is this too niche of a solution?

First things first..... How do the affiliates process these audio feeds?

 

[jdbob]

I just checked and "Nature: White Falcon, White Wolf" on HD01 and "The War: When Things Get Tough" on HD02 and both are Dolby Digital 5.1. NBC is probably putting out weird stuff due to legacy systems and it doesn't seem like a good investment to try to work around their strange ways....

 

[SatelliteAV]

I just checked and "Nature: White Falcon, White Wolf" on HD01 and "The War: When Things Get Tough" on HD02 and both are Dolby Digital 5.1. NBC is probably putting out weird stuff due to legacy systems and it doesn't seem like a good investment to try to work around their strange ways....

Thank you for confirming that the microHD correctly handles 5.1 Dolby Digital transmissions that are encoded by the broadcaster.

 

[jdbob]

Thank you for confirming that the microHD correctly handles 5.1 Dolby Digital transmissions that are encoded by the broadcaster.

That's with Bitstream digital audio output on HDMI, I haven't tried it with LPCM to see what it does. I normally use bitstream and let the Audio/Video receiver do the decoding.

 

[rv1pop]

Cofirming, although I do not know what it means - NBC affiliate is using bitstream. Will not repeat what he called TS...

 

[Jim S.]

I always assumed that the audio streams on the NBC HD feeds were the same as the analog jacks on a PC sound card: left / right, left surround / right surround, and center / low frequency. I don't know what the fourth one on the channels that have four is, but someone here said it's a stereo mix. (Which would differ from the left / right pair because the left / right pair has NO trace of any dialog.)

 

[Tron]

I have noticed that the mix and content of the audio channels on 103W sometimes changes from program to program (for example, the Today show has a different mix than the Olympic coverage).

 

[SatelliteAV]

I have noticed that the mix and content of the audio channels on 103W sometimes changes from program to program (for example, the Today show has a different mix than the Olympic coverage).

That is my observation as well. Seems that the discrete audio mixes on the PIDs are not consistent as Pepper suggests.