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Topic: Downmixing options in AC3 Machine (Read 3279 times) previous topic - next topic
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Downmixing options in AC3 Machine

Can anyone explain what each of the Azid Downmix Levels options in AC3 Machine do? What should I set them to if I just want to keep the exact same settings as the original 5.1 AC3 (taken straight off the DVD) but just at a lower bitrate?

Also, how low can I encode the AC3 in 5.1 without the quality getting too bad (ie keeping quality roughly equivalent to say a 128 abr mp3 in lame or to a q2 vorbis file?). Is 256 reasonable?

Would I be better off using AAC instead (I'm doing this to use as the sound in a DivX movie)?

Downmixing options in AC3 Machine

Reply #1
Quote
Originally posted by The Belgain
Also, how low can I encode the AC3 in 5.1 without the quality getting too bad (ie keeping quality roughly equivalent to say a 128 abr mp3 in lame or to a q2 vorbis file?). Is 256 reasonable?


If you want high quality AC3 encoding, you will probably need a commercial AC3 encoder, like SonicFoundry's SoftEncode and Surcode Dolby Digital. And I think a 5.1 AC3 at 256kbps will sound quite worse than a MP3 at 128kbps (Although a stereo AC3 should sound better)

Quote
Would I be better off using AAC instead (I'm doing this to use as the sound in a DivX movie)?


Yes, but, unfortunately, there are no good AAC DirectShow filters yet.

Regards;

Roberto.

Downmixing options in AC3 Machine

Reply #2
Quote
Originally posted by The Belgain
Can anyone explain what each of the Azid Downmix Levels options in AC3 Machine do? What should I set them to if I just want to keep the exact same settings as the original 5.1 AC3 (taken straight off the DVD) but just at a lower bitrate?
[/b]simply select "5.1".

Quote
Would I be better off using AAC instead (I'm doing this to use as the sound in a DivX movie)?
quality of AacEnc is most probably better, but encoding to aac will prevent you from being able to play your movie thru spdif.

 
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