Bit-perfect AAC/MP3/etc decoding?, Is it an issue? Options

[mavere]

Sorry if this is easily answered elsewhere.

My question is that in a comparison of lossy-format decoders between, let's say, iTunes and Foobar and Winamp, will the output (edit: of a single source file) vary between decoding implementations?

Or is it that once a decoder follows a specified format, all output is equal assuming there are no bugs?

This post has been edited by mavere: Jan 5 2013, 00:51

[DVDdoug]

Unlike encoding, I believe all decoders are supposed to be the same.

The decoder has a lot simpler task of decoding & reconstructing a wavefrom from whatever data is present. The encoder has to decide what data to throw-away.

This post has been edited by DVDdoug: Jan 5 2013, 01:06

[Arnold B. Kruege...]

Unlike encoding, I believe all decoders are supposed to be the same.

The operation of decoders is generally well-known and well-defined.

Evens so, bit perfect can be tough because different hardware implements arithmetic with subtle differences and at the LSB level insignificant variations in things like order of operations can lead to tiny differences.