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Old 18th May 2007, 21:41   #16  |  Link
madshi
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Join Date: Sep 2006
Posts: 9,140
Quote:
Originally Posted by tebasuna51 View Post
For what 16 bit?

BitDepth have no sense with encoded audio in frequency domain.
In the document 'Digital Audio Compression Standard (AC-3, E-AC-3) Revision B' say:
"8.2.1.1 Input Word Length
The AC-3 encoder accepts audio in the form of PCM words. The internal dynamic range of AC-3 allows input wordlengths of up to 24 bits to be useful."

Then if a input of 24 bits is appropriate for ac3 encoder also the output can be 24 bits.

Edit: and Aften accept 24 bits input without problem.
You are correct - but only when talking about (E-)AC3. Things are totally different with TrueHD. TrueHD is a lossless codec. That means, it takes 16bit, 20bit or 24bit input data and does *NOT* convert that into frequency domain (doing that wouldn't be lossless), but simply compresses the audio data similar to how ZIP works. So if you feed e.g. a 16bit track into the TrueHD encoder and if you then feed the encoded data into a TrueHD decoder, you should get a perfect 1:1 copy of the original data out of the decoder.
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