I received some Tektronix documents regarding various Dolby/audio information. I'm gong to upload to the files section if the attachement doesn't come through in this post. Time to get my nerd on.
---In avid-l2@yahoogroups.com, <bogdan_grigorescu@...> wrote :
It could very well be discrete 5.1 (+ metadata) as the source at the headend - but I now see what you meant by E in context.
B.
From: "Mark Spano cutandcover@... [Avid-L2]" <Avid-L2@yahoogroups.com>
To: "Avid-L2@yahoogroups.com" <Avid-L2@yahoogroups.com>
Sent: Tuesday, January 27, 2015 12:03 PM
Subject: Re: [Avid-L2] OTish: Dolby Digital 5.1 vs PCM Center channel Matrix Errors on OTA signals in L.A.?
I think I was saying the stream coming from OTA (not OVER OTA) is Dolby E. It's E at the head end, then gets packed into OTA as regular Dolby AC3. But yeah, doesn't change the explanation. I was just pointing out how E is the container at the programmer's end, and if it has 5.1 +2 buckets to put audio channels in, it will always have those buckets, no matter how many they decide to fill.
On Tue, Jan 27, 2015 at 2:44 PM, Bogdan Grigorescu bogdan_grigorescu@... [Avid-L2] <Avid-L2@yahoogroups.com> wrote:
For the acurracy's sake there is no DolbyE over cable, satellite or OTA - only DolbyD a.k.a DolbyAC3.The other thing worth mentioning is that the majority of receivers have different surround modes, where they remap/remix incoming decoded streams to match the number of speakers - including creation of phantom channels to fill up the listening space - which can also be a factor in what John's experiencing.cheers,BG
From: "Mark Spano cutandcover@... [Avid-L2]" <Avid-L2@yahoogroups.com>
To: "Avid-L2@yahoogroups.com" <Avid-L2@yahoogroups.com>
Sent: Tuesday, January 27, 2015 9:40 AM
Subject: Re: [Avid-L2] OTish: Dolby Digital 5.1 vs PCM Center channel Matrix Errors on OTA signals in L.A.?
Ideally, I would leave the TV set to Auto, let your receiver decode the stream, and anything that's true surround will come out that way, and anything that's not will come out its appropriate channels. Then we can talk about how most promo and many commercials' post budgets do not accommodate for surround mixing.Job is correct here. The stream coming from OTA is Dolby E. That provides up to 5.1+2 channels of audio. Much of primetime programming is 5.1, so that's getting passed through the E stream. However, most of the commercials and promos are not mixed for 5.1, so the two channels (stereo) get encoded into the same E stream and passed through, coming out in stereo (no center channel or surround) from your receiver (since the receiver never has to switch decoding modes).When you switch the TV into PCM, you're telling the TV to decode the E stream into two channels of PCM (likely a 5.1 downmix to Pro-Logic). Then your receiver is now decoding Pro Logic into LCRS, and performs that decode on everything. That decode is done in time and phase domains, so it's just math (not discrete) - therefore, something that is not surround can come out sounding like surround if the mix has certain time and phase relationships. An easy point to make here is that Pro Logic decoding always takes whatever is common phase and common level in L/R speakers and puts it out C channel. So if there's a stereo mix that has dialogue mixed into the phantom center, the Pro Logic decoder will attempt to isolate this and put it out the center channel speaker.On Tue, Jan 27, 2015 at 2:55 AM, 'Job ter Burg (L2B)' Job_L2@... [Avid-L2] <Avid-L2@yahoogroups.com> wrote:You're confusing Dolby Digital encoding and actual channel use.
If you create a stereo mix, you end up with an L and an R channel. You can create a 5.1 DD signal from that with just the L and R channels addressed.
My bet is that some of those commercials were simply mixed in stereo, and do not use C, Lfe Ls or Rs.
J
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