AC3 lowering volume of audio track

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AC3 lowering volume of audio track

Hi,

I have a 1 1/2 hour long concert that I compressed using compressor. The video seems to be jumpy or stutter. I compressed the video using MPEG2 at a bit rate of min 5.0 and max 7.4. I compressed the audio using AC3 and I also created an Aiff. I don't prefer AC3 because it lowered the volume of my audio track. When I simulated the DVD it looked great and then when I burned it using MPEG 2 and AIFF the video was jumpy. So, I think either it was my bit rate or the fact I did used an aiff file and not AC3. My two questions are:

1. is there anything I can do when compressing the audio using AC3 to not have the volume decrease?
2. is the bit rate to high or low and is that why the video is jumping?

I would appreciate any help with this.

Thank you.

Mac Pro, Mac OS X (10.4.11), using FCP 6

Posted on Nov 13, 2008 9:45 AM

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Answer 1

Nov 13, 2008 2:50 PM in response to Nel Shelby

1. To make sure the Dolby AC3 setting does not alter your audio with normalization or compression, you need to turn off dialog normalization and compression.

a) Click your audio setting and have a look at the Encoder tab in the Inspector window.
b) Under the Audio tab, change the Dialog Normalization from -27 to -31 to disable it
c) Click the Preprocessing tab and set the Compression Preset to None.
d) Deselect the Low-Pass Filter and DC Filter

Compressor User Manual -> Creating Dolby Digital Professional Output Files

Important: It is critical that you set the Dialog Normalization setting correctly if you intend to use any of the Compression Preset settings. The Compression Preset settings assume that the audio, after the dialogue has been normalized, is at the normal listening level of 31 dBFS. Levels that are consistently louder than that result in distorted sound and erratic levels.

If you do not know the sound level of the source file or for some other reason want to ensure the Dolby Digital Professional encoder does not affect your sound levels, enter –31 for the Dialog Normalization and choose None in the Compression Preset pop-up menu (located in the Preprocessing tab).

2. What is your source video format? What format did you did you convert to MPEG-2? Where are you watching this DVD? On your Mac? If so, what application?

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