AC3 + external compressor?

[wumpi]

Scenario:
Casual holiday DV footage in stereo, with an additional stereo track for music in background

Question:
I usually apply only an EQ filter to remove some irritating noises (like the camera hiss) and a compressor to enhance voice dialogue (using Wavehammer for instance). Beside that, I leave audio untouched.

After editing, I encode my audio in .ac3. Now I ask, since the AC-3 encoder also comes with the dynamic range compressor, should I skip the first compressor (here Wavehammer)? :confused:

Help would be gladly appreciated!

[SomeJoe]

You could use either and get nearly the same effect. But here's some things to consider:

1. The external compressor may be more suitable for the material. If that compressor is specifically for voice/speech, it may do a better job than Dolby's "Speech" DRC profile, which I find to be fairly aggressive.

2. Using the external compressor means that the material will be compressed before it is encoded. Thus it will always play back with the compression effect applied. Dolby's compressors are applied during the decoding stage. So, the decoder has the option on whether to apply the compressor or not and how to apply it (granted, most decoders don't offer these options, but theoretically, the decoder could deliver uncompressed material from the encoded bitstream).

3. I wouldn't use both compressors together. You may get some strange artifacts. Pick one or the other.

[wumpi]

Cool, thank you SomeJoe! Before I will go and completely disable AC-3's metadata audio processing (move the dialog normalization to -31db and keep DRC to "none), I will have a look what effect it had on my already compressed material by switching Dolby's compressor on and off (on my father's Lexicon I think this is possible).

Cheers
Wumpi