[LAD] Ardour session archiver (Was: new lossless/lossy audio compressor)

Paul Davis paul at linuxaudiosystems.com
Wed Aug 1 18:09:34 UTC 2007

On Wed, 2007-08-01 at 10:45 -0700, Gregory Alan Hildstrom wrote:
> I got 32-bit true lossless j2kaudio transcoding working today. I compared it against wavpack and
> wavpack seems far superior in terms of speed and compression for 32-bit floating point data. I
> created the test files with audacity, which only uses float values from +1 to -1, so I am not sure
> if it actually uses the full 32-bits, but it is still good enough for a meaningful test.
> Here are the compressed size % for the worst case that I tested:
> 32bWN.wav 44.1kHz/32b/10ch
> 60sec 10 channels of white noise
> 105840152B
> j2kaudio 91.06
> wavpack 82.32
> tar czf (gzip) 92.29
> tar cjf (bz2) 93.24
> The full test tables are here:
> http://geocities.com/hildstrom/projects/j2kaudio/
> Are there any wav/audio programs out there that use the full float range of 3.4e+/-38? It seems to
> me that this larger range would use more of the 32 bits.

all of them :)

the idea is that 0 ... +1 maps to the nominal range of the D/A converter
(-inf dB ... 0dbFS), leaving the rest of the range to span larger and
smaller values without clipping.

as fons explained recently, you could agree on a different convention
for this, and say that 0 ... 2^23-1 mapped to the physical range, but
you don't gain anything in so doing.


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