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Compressor reducing 5.1 to stereo?

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Jeffrey Ellis
Compressor reducing 5.1 to stereo?
on Aug 4, 2010 at 10:49:12 pm

I exported my tracks for a 5.1 project out of FCP successfully, but when I add a new surround sound in Compressor, drag in each of the channels, and then apply the Dolby Professional 5.1 preset to it, well, you see the results below. The first set are the originals, the second, the exports from FCP, the third, the resulting .ac3 file.



Can someone tell me what I'm doing wrong?


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Michael Gissing
Re: Compressor reducing 5.1 to stereo?
on Aug 4, 2010 at 11:43:57 pm

An ac3 file is a data stream which contains the 5.1 in a stereo file. I have no idea what you have dropped into the FCP timeline, but it isn't an ac3 file.

An ac3 file is just pure data so it looks like full level unmodulated noise. If you listen to it it sounds like pure noise at high level so I don't recommend you try to play it through speakers.

You don't need the audio to be in FCP to make an ac3 file with Compressor. It can encode directly from multi channel wavs or mono wavs or aifs. Can you explain better your settings and what the third output files actually are.


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Jeremy Garchow
Re: Compressor reducing 5.1 to stereo?
on Aug 4, 2010 at 11:52:35 pm

Everything that MIchael says AND if exporting from FCP (like the multichannel mix you have there) you export your timeline broken it into 6 discrete channels (you know how to do that, right?) as a channel grouped aif file. That will make 6 aif files. You then add those as the surround.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 12:19:35 am

Yes, that's exactly what I did. And yes, that is an .ac3 file, dragged into the timeline:



So here's my workflow:

My Sequence settings are for 6 channels, all set to 0 db (I had left them at the defaults, but changed them when all this din't work to see if it would help), all set to Dual Mono.

I then set each audio channel from 1-6 in the timeline. I then exported the tracks you see as the first set in the timeline as Audio as Aiff, using 48k, 16-bit, Channel Grouped. I got the resulting files which I then checked by importing and placing them on the timeline as well (This is the second set in the timeline).

I then open Compressor, and select Add Surround Sound. I add all the 6 exported .aif's into the window to their corresponding channels, and click ok. I then drag the Dolby Digital Professional 5.1 preset onto the source, and click submit. I then drag the resulting .ac3 into fcp to check the audio, and that is the third set in the timeline.


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Michael Gissing
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 12:28:55 am

[Jeffrey Ellis] "I then drag the resulting .ac3 into fcp to check the audio, and that is the third set in the timeline."

Makes no sense. The third file has six channels and the two channels with waveforms are showing the same basic waveform as the 5.1 channels. An ac3 file should be stereo and have nothing but data so a squared waveform at full level.


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Jeremy Garchow
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 12:30:49 am

What Michael says. the dolby decoder at the other end will decode and route the 5.1 The ac3 file is not going to show you the 6 discrete channels as they aren't encoded as such.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 12:58:45 am

Oh.

Ok, but then why, when I actually burn the file to blu-ray, am I not hearing any of the other channels?


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 12:57:58 am

Michael--

I'm sorry, but I am telling you exactly the steps that i've taken. I'm not trying to hide some weird procedure, or anything else you may think I'm leaving out. I've even tried it 3 times now, just to be sure.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 1:00:03 am

Is there another way to test if the information is actually there aside from that?


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Michael Gissing
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 1:01:09 am

What happens when you author the DVD with that ac3 file? Does it play back OK?

I have no idea why an ac3 file would reimport into FCP looking like that but the bottom line is, is there a problem with your DVD playback using the Compressor file?


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Michael Gissing
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 1:02:26 am

Ah, so there is a playback problem. What are your Compressor settings.


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Jeremy Garchow
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 1:03:06 am

in Compressor, you assigned the channels, correct? It woudl take 6 clicks to do this, not just dropping a preset on a file.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 1:08:14 am

Here are exactly the steps I'm taking:



Select the preset:



Drag onto the source:



Swear to g*d.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 1:21:36 am

Can I maybe send one of you guys my six channel files and see what happens on your end?


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Michael Gissing
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 1:38:41 am

[Jeffrey Ellis] "Can I maybe send one of you guys my six channel files and see what happens on your end?"

How long is the aif file?


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Jeremy Garchow
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 1:53:46 am

Are you sure your bluray player and receiver are setup properly?

How are you authoring the bluray? Is it really a blueray or DVD?


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 2:04:12 am

It's being done in Toast from one .avc, and the one .ac3 with matching names. The video is definitely blu-ray, and the .ac3 is the file in question.

I've checked all the settings in my blu-ray player, and tested with another surround blu-ray which plays successfully.


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Jeremy Garchow
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 2:06:44 am

[Jeffrey Ellis] "and tested with another surround blu-ray which plays successfully."

That was burned in toast?


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 2:10:21 am

Right.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 2:14:38 am

Here's how it shows up in Toast.



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Jeremy Garchow
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 2:15:44 am

The reason I ask is that Toast can reencode and do weird things when you don't want it to.

From your screen grabs, it looks like you have setup everything correctly in Compressor.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 2:20:59 am

Thanks.

Could one of you maybe look at my files and test them. I' m lost here.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 2:01:07 am

Hi, Michael--

Here's all six tracks. It's about 300 MB.

http://dhnet.us/images/6_Channel_Audio.zip


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Michael Gissing
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 2:26:10 am

[Jeffrey Ellis] "Here's all six tracks. It's about 300 MB."

I am downloading now and will have a look.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 2:28:09 am

Thanks :)


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Michael Gissing
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 6:55:45 am

Jeffrey, I made an ac3 file using compressor and it was 40meg. It loads into DVDSP but I didn't burn a disk to test the playback on my hifi . The weirdness is importing the ac3 back into FCP which attempts to unpack the ac3 and it creates six channels but plays the audio like a stereo fold down so i am getting the same as you. However, that doesn't mean it didn't encode properly.

If your ac3 isn't working on the bluray, try burning it to a regular DVD using DVDSP to test it. If you want my ac3 file I can upload it you yousendit if you want to send me your email details, but I suspect there is nothing wrong with yours.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 7:26:00 am

Hi, Michael--

That would be great, thank you.

I don't know how to PM here. so my email is rlinsurf2001 at dhnet dot us.

Thanks again.


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Michael Gissing
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 8:56:01 am

Notification to download sent.


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Jeremy Garchow
Re: Compressor reducing 5.1 to stereo?
on Aug 5, 2010 at 12:20:10 pm

I got the exact same results.


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Jeffrey Ellis
Re: Compressor reducing 5.1 to stereo?
on Aug 6, 2010 at 4:18:08 am

Hi, Michael--

I used your version and miraculously, this time it all just worked. So thank you again :)

I noticed you suggested I use DVDSP to burn this to a DVD. Can you tell me how to do that, so that it will auto-play, no menus?


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