opus - Jun 2014 - encode/decode with Opus

?Hi to everybody.
I have data in a buffer. when i encode it and decode it i does not obtain the
same data. i think encode(decode(data)) = decode(encode(data)) = data.
I also try it with trivial example in opus boundle downloded on the official
website. My probleme is that how can i write two function myencode and mydecode
such as myencode(mydecode(data)) = mydecode(myencode(data)) = data?
Thank 
Best regards

Dott. Didier J. Nkalla Ehawe
Tel: 3287016325
Master student in software engineering?
Polytechnic University of Turin, Italy
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On 1 June 2014 21:39, Didier Nkalla <didnkallaehawe at yahoo.fr>
wrote:
>
>  Hi to everybody.
> I have data in a buffer. when i encode it and decode it i does not obtain
> the same data. i think encode(decode(data)) = decode(encode(data)) = data.
> I also try it with trivial example in opus boundle downloded on the
official
> website. My probleme is that how can i write two function myencode and
> mydecode such as myencode(mydecode(data)) = mydecode(myencode(data)) =
data?
Hi,

Neither of these identities is true. Opus is a lossy perceptual
encoding, this means
decode(encode(data)) != data
As information is discarded. (It also means that simple measures such
as sum of square difference do not tell you how similar the two
streams will sound to a listener.)

encode(decode(data)) != decode(encode(data))
Assumes the two operations commute, which they don't. The encode
operation reduces the data to a representation using a variety of
encodings, I sounds like you are expecting it to be a simple operation
like a Fourier transform, which it isn't, even if it was, information
is discarded (again, lossy) and the encoded data is additionally
compressed I'm not sure there are any non-trivial compression
algorithms where the encode and decode can commute like that.

-- 
imalone
http://ibmalone.blogspot.co.uk