Re: [LAD] new lossless/lossy audio compressor

bad luck mate, it's always good to see people willing to give something a go
though :)

porl

On 01/08/07, Gregory Alan Hildstrom <hildstromoo@email-addr-hidden> wrote:
>
> Hello again. I discovered a disappointing, to me, bug in
> j2kaudio/libjasper today while I was
> working on 32-bit audio support.
>
> My previous holy-grail-looking lossless audio compression test results
> were incorrect. I was
> passing rate=1 to the JasPer JPEG 2000 encoder, which was not performing
> lossless compression, but
> slightly lossy compression. I actually do not know what it was doing
> because the behavior I was
> getting is somewhat undocumented. I could not differentiate the quality by
> ear; everything sounded
> perfect to me. I only discovered this when I had to do sample by sample
> checks for accuracy and I
> found that they were very close, but not exactly the same. The results
> matched exactly when I left
> rate= out of the encoder options entirely, but the resulting file size
> increased. I will post a
> question to the jasper email list to find out what rate=1 should be doing
> and why it does not
> match omitting the rate.
>
> The new lossless results from my test song are:
> la - 65.5%
> ofr - 66.3%
> ma - 66.9%
> lpac - 69%
> flac - 70.2%
> shorten - 75.2%
> j2kaudio - 76.6% (dead last)
> bzip2 - 96.7%
> gzip - 97.1%
>
> Thank you again for all of your feedback and input. I apologize for
> getting anyone's hopes up and
> for not performing a sample-by-sample check at the integer level sooner.
>
> For now, I think I have proved and improved the concept, but I conclude
> that even though it
> outperforms file compressors, other lossless and lossy audio compressors
> are superior for audio
> data.
>
> Updated tables and information:
> http://geocities.com/hildstrom/projects/j2kaudio
>
> Thanks. -Greg
>
> Gregory Alan Hildstrom
> Secure Systems Engineer - Trusted Computer Solutions
> trustedcs.com
> ghildstrom@email-addr-hidden
> Software Engineer - Hildstrom Engineering
> geocities.com/hildstrom
> hildstrom@email-addr-hidden
> Mobile:(210)413-6082
> Fax:(210)599-0469
> Office:(210)340-3151x117
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>

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Received on Wed Aug 15 04:15:09 2007