FORUMS: list search recent posts

Defaulting to a stereo mix plus subwoofer

COW Forums : Compression Techniques

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Rick Peters
Defaulting to a stereo mix plus subwoofer
on Sep 13, 2010 at 3:20:13 pm

Please forgive the elementary question here ...

I have an HD video shot of a rock band, with a terrific stereo WAV remix, that I am burning to SD discs. I have synced up the remix and output as a QT movie (huge file). I ran it through Compressor to get it down to 720X480, and am reasonably satisfied with the video portion. Audio, not so much.

I would like it as a default to play back in a true stereo mix, with the subwoofer active, on whatever system it happens to be played on.

To accomplish that, I set Compressor to do the following, but while I achieved the goal of a Dolby Digital stereo mix, with subwoofer active, I also got a file with pretty severe compression and breathing, even though compression is set to "none" inside of Compressor. Can anyone suggest a fix? (The audio on the raw QT files sounds perfect, it's previewing within DVD Studio Pro where I noticed the compression.)


Description: 2.0 Dolby Digital audio at 192kbps
File Extension: ac3
Estimated file size: 192.26 MB/hour of source
Audio Encoder
Format: AC3
Sample Rate: 48.000kHz
Channels: 6
Bits Per Sample: 16
Target System: DVD Video
Data Rate: 448 kbps
Compression Preset: None
Audio Coding Mode: 3/2 (L, C, R, Ls, Rs)
BitStream Mode: Complete Main
Center Mix Level: -3dB
Surround Mix Level: -3dB
Dolby Surround Mode: None
LFE Exists: Yes
Dialog Normalization: -31 dbFS
Copyright Exists: Yes
Original Content: Yes
Audio Production Information Exists: No
RF Overmodulation Protection: Off
Channel Bandwidth Lowpass Filter: Off
DC Highpass Filter: Off
LFE Channel Lowpass Filter: On
3dB Attenuation: Off
phase 90: Off
Deemphasis: Off
Dynamic Range
Soften Above: -30.300
Noise Threshold: -100.000
Master Gain: 0.000


Return to posts index

Mark Spano
Re: Defaulting to a stereo mix plus subwoofer
on Sep 17, 2010 at 10:45:00 pm

OK, so you have a stereo mix source file - why are you compressing to AC3 in 5.1? That seems like it might at least be a potential cause of your problem. Tell Compressor you want a Stereo AC3 file, highest bit rate it will allow. Then, also go into your preset in Compressor and under the Filters tab, sub tab Audio, uncheck anything that's checked. I say this because it seems you might have a limiter engaged there judging by this info above:

"Dynamic Range
Soften Above: -30.300
Noise Threshold: -100.000
Master Gain: 0.000"


With this setting, keeping as you have set dialog normalization to -31, you won't get most of the other things to choose as options (and this is good). No 5.1 stuff, no LFE, nothing else. You should get an AC3 that is a pretty close to perfect representation of the stereo mix you started with.

Now about this:

"I would like it as a default to play back in a true stereo mix, with the subwoofer active, on whatever system it happens to be played on."

Well, you have *no* control over how the sub is set up on anyone's system if you have a stereo mix. Some people have their bass management set up to automatically engage the sub and pass frequencies from the stereo mix that are below 120 Hz to it. Some just don't. You can't control it at all. If you want to have slightly more control, you will have to remix it to 2.1 (L, R, Sub). That's a pain, and probably not worth the effort, since even then, you still don't have control over how someone's playback system will interpret 2.1 signals.

You have to just go with the best thing you can make. A stereo mix, properly encoded. Using the above tweaks to your preset should make this happen.



Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]