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Old 08 April 2012, 06:09 pm   #2
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Join Date: Jul 2004
Posts: 372

It is possible to encode 24-bit files. The resulting mpc file is a "lossy" file meant for playback and does not contain the amount of information that an uncompressed 24-bit stream can potentially contain.

The mpc file does not actually have "bits" (16-bit/24-bit, etc.) like an uncompressed file. Whether you get 16-bit or 24-bit decoding depends on the decoder, so when the player reports "16-bit mpc file" it actually means the decoder would give you a 16-bit stream, not that the file is actually a "16-bit file".

People don't set lossy format decoders to 24-bit since it would not offer any benefit compared to 16-bit with the lossy files. Lossy formats use "perceptual coding" and the only audible information that's left in the mpc file is that which you are able to perceive, and the rest is (crude explanation:) "thrown away" or "masked".
Although you hear no difference between the compressed file and the original, if you edit the compressed file, differences may be noticeable. For example, if you increase the volume by 40dB, you may hear artifacts that you wouldn't hear if you increased the uncompressed file's volume by 40dB. That's expected. The compressed stream is only suitable as a "final", "end-user" format and not meant to be altered.

Some tips:
In the case of a vinyl recording, the headroom is so low (amount of noise, crackle, etc.) that 24-bit does not enable you to preserve any more information than you would have been able to preserve with 16 bits of headroom. Merely the noise itself from the vinyl acts as a strong "dither" that makes 24-bit pointless.

I see you set the encoding quality to 10. You shouldn't do that, as it's a waste of space. Although quality 5 and 6 are very reliable (in being "transparent"), quality level 7 is the best balance between getting "assurance" that you get an artifacts-free stream and getting a file that doesn't waste a lot of space for no reason. In the extremely rare case that quality 7 does not sound identical to the original, higher quality settings would almost certainly not solve it either. Quality 10 is provided merely for completeness of the software.
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