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Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?

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Glenn Camhi
Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 5:37:45 am

I've seen so much conflicting info, I'm hoping someone can help out with the right answers.

I've got a 5.1 mix and Lt/Rt mix from my sound mixer.

First question: Blu-ray via Toast Titanium.

I tried authoring 2 versions, one with the Lt/Rt mix, and one with the full 5.1 mix. The 5.1 Blu-ray sounds better, I'm hearing sounds that are lost in the Lt/Rt mix. But I'm not hearing any sounds at all through my surround speakers (which do work properly with commercial Blu-rays).

Wonder what I'm doing wrong? The Surround AIFF tracks sound good when exported from Final Cut Pro 7. I'm creating the AC3 in Compressor, mapping each of the 6 tracks using "Add Surround Sound," and under Settings I have Audio Coding Mode "3/2 (L, C, R,Ls, Rs)." Is this where the problem's likely occurring? Or in Toast?

Also, why would the Lt/Rt be burying some sounds? We didn't put anything solely in the surrounds, fwiw.

For Lt/Rt in FCP, should grouping be set to stereo or "dual mono" in Sequence settings?


Second question: Output for HDCAM SR

What should my settings be for the output file? Should I do the 6 5.1 tracks then Lt and Rt, for 8 tracks total? My mixer gave me the 5.1 tracks in this order: L, C, R, Ls, Rs, LFE. But I see this order more often: L, R, C, LFE, Ls, Rs. Does this matter, as long as I label the tape and include a slate in the video? Or is one preferable? This won't be for broadcast, just for theater screenings at festivals.

Thank you for any tips!


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Glenn Camhi
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 7:00:03 am

Never mind about sounds not coming through the surrounds. Someone helped solve that.

But could still use help on the rest.


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Mark Spano
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 2:43:22 pm

For your first question, I'd say something funky is happening in Toast. I've had success authoring Blu-ray with surround tracks straight out of Compressor. I'd try that.

The Lt/Rt mix is matrix encoded surround. It's taking 5 channels of discrete surround information and coding them into two, using phase manipulation and other processing. Things can get lost here, and it's generally regarded as an inferior substitute for a discrete surround mix. However, its only use should be for systems without surround playback capability. Are you decoding the signal? If not, it'll sound like a weird stereo mix with a bunch of things out of phase in the front channels, and nothing out the back.

Most of the time, if I'm authoring for Blu-ray, I dump the Lt/Rt. The player can handle making a decent downconvert of the surround track I author, and because I know it's inferior, I don't offer it as an option for people to mistakenly choose on a menu.

For your second question: the order should be L, R, C, LFE, LS, RS. This is what every broadcaster and projectionist is expecting. Any other order is annoying and doesn't conform with SMPTE standards. Put Lt/Rt (if you need them) on 7/8.



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Glenn Camhi
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 3:26:45 pm

Thank you very much for your help, Mark!

One other question then. I'm also delivering files soon which will be put on an HDCAM SR master. HDCAM and Digi Beta copies will be made as well, since those are the best formats that some festivals can project. Many festival theaters can't handle surround, and I have no clue if they can handle Pro Logic II. So, is it a mistake that the two mixes I was given are 5.1 and LtRt? Should I have gotten a straight basic stereo mix? I thought that's what LtRt functions as when projected at a place that can't handle surround. Not so much?


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Mark Spano
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 4:33:27 pm

You're correct. In venues and on tapes where there is not enough room or capability for discrete surround tracks, use the Lt/Rt provided. The encoding allows for the resulting two-channel matrix to be played on systems with or without decoding. That is one of the beauty points of Pro Logic encoding - playback is possible with or without decoding. If you are supplying a DVD or Blu-Ray, I strongly recommend only using the discrete surround mix, because the players have the downmixing capability by default. If they can use the surround, great, but a decent stereo downmix will come out of the L/R outputs regardless.



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Glenn Camhi
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 4:39:07 pm

Thanks again, Mark.

Great, that makes life easier. Now I just have to find out from my mixer why certain sounds are lost in the Lt/Rt mix, and why it eliminated pans.

And yep, on Blu-ray it'll just be the 5.1 mix. (Ultimately I won't be authoring the discs at home, I'll have it done properly. Just testing things for now.)


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Glenn Camhi
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 6:05:41 pm

Mixer solved those last two bits. Thanks again on the rest, Mark.


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Glenn Camhi
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 7:23:14 pm

One more question yet, re the Lt/Rt mix:

In Final Cut, should I set Audio Outputs in Sequence Settings to Stereo or Dual Mono? And should I export AIFFs? Assuming so, should I choose Channel Grouped or Stereo Mix under Congif?


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Mark Spano
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 7:31:25 pm

Assuming you're talking about the file you're delivering for tape output...

[Glenn Camhi] "In Final Cut, should I set Audio Outputs in Sequence Settings to Stereo or Dual Mono?"

Stereo is fine. Just make sure when you drop in the Lt/Rt mix to the sequence that it is hard panned left/right. If the mixer gave you separate Lt and Rt files, they will drop into the sequence panned center.

[Glenn Camhi] "And should I export AIFFs?"

I would avoid it. Your export should be the sequence, current settings, audio and video. That way whatever house you're giving it to to handle the tape layoff doesn't have to sync - they drop in the Quicktime file and layoff, audio and video locked from the moment it leaves your hands.

[Glenn Camhi] "Assuming so, should I choose Channel Grouped or Stereo Mix under Congif?"

Stereo Mix is fine, so is Channel Grouped, as long as you're exporting a Quicktime file.



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Glenn Camhi
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 7:46:15 pm

Ah, see, perhaps you should write the documentation for all this that I can't find anywhere. You're a great help.

So that makes sense, I just give the house the QT file. And the six 5.1 AIFFs, which they can connect to the video from that QT file as well. Right?

In the General tab of Sequence Settings, does it matter if Discrete Channels, Channel Grouped or Stereo Downmix is selected (for the Lt/Rt)?

Yeah, the hard panning was my problem before. I thought they were panned as a stereo pair, but they weren't. Doh!


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Mark Spano
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 10, 2011 at 8:18:25 pm

[Glenn Camhi] "I just give the house the QT file. And the six 5.1 AIFFs, which they can connect to the video from that QT file as well. Right?"

Right.

[Glenn Camhi] "In the General tab of Sequence Settings, does it matter if Discrete Channels, Channel Grouped or Stereo Downmix is selected (for the Lt/Rt)?"

For the Lt/Rt sequence, you should use either Channel Grouped or Stereo Downmix as both will preserve the stereo through to the Quicktime. I am not 100% on whether having Discrete Channels selected will pass stereo through to the QT - it might pass it as Dual Mono, in which case you have to worry about the next place making sure to pan (or set as discrete). FCP is weird when it comes to how it treats incoming audio sometimes. I'd stay stereo (Stereo Downmix) and make sure your pans are set before exporting.



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Glenn Camhi
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Oct 11, 2011 at 8:15:16 am

Grazie Mark! That exhausts my questions.

Sounds like they might want the Lt/Rt tracks separately as well, and just want to use the QT audio for verifying sync. Not sure, but I'll bring them too just in case.


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Glenn Camhi
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Nov 2, 2011 at 8:23:04 pm

Well, interesting. When an AC3 is made right off the QuickTime file, the LtRt mix sounds great whether played as straight stereo or decoded ProLogic II.

However, when an AC3 is made from an AIF file exported from Final Cut, it sounds lousy when played as straight stereo. Something happens in the export process from Final Cut that messes up the file.

Could it be some setting? I've set the tracks as a stereo pair in Sequence Settings / Audio Outputs, and tried both Stereo Downmix and Channel Grouped, and in the export AIFF options I've set it for Stereo Mix.


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Mark Spano
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Nov 2, 2011 at 8:48:45 pm

As long as the sequence setting is set for 2 Outputs, Stereo Monitoring, and the channels set to Channel Grouped (with A1 panned hard left and A2 panned hard right), then the sequence playback should be exactly what is in the Quicktime. I can't think of anything you'd have wrong there.



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Glenn Camhi
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Nov 2, 2011 at 8:54:56 pm

Thanks Mark. Weird, eh? Could Stereo Downmix have caused an issue? Maybe that's the version we've been testing most recently? I've tried both. (Though I thought Channel Grouped does a stereo downmix anyway with stereo pairs.)


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Mark Spano
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Nov 2, 2011 at 9:40:13 pm

I don't think it makes a difference there, since you've got just two tracks those two settings should come out identical...



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Glenn Camhi
Re: Settings for 5.1 and Lt/Rt, to HDCAM SR and Blu-ray?
on Nov 2, 2011 at 10:45:32 pm

Yeah, it is odd. Thanks for confirming.

Can't imagine what could be happening in the export of the AIFF file, but something is.


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