... It's easier than that: use -snr <large negative number> with v0.5.3.....
I have no idea what a negative -snr value is doing. I had thought bringing in snr means giving the relevant min the chance to go lower than when not using snr. From this understanding any snr value has only the chance to make things more defensive compared to not using snr. Sure as we do use a snr value of 21 we will get lower bitrate when turning the -snr value down. However I wonder what makes your problem samples set go so low in bitrate. Guess there's a specific meaning of a negative snr value.
Anyway I'd prefer to use a higher -nts value of up to say 40 instead. It would give us the chance to keep the usual skew/snr combination and go extreme with noise threshold for learning about lossyWAV behavior.
I am beginning to feel that -snr is a bit of packing in the sausage. When I tried -3 -snr -215 (modified average = average - snr_value, i.e. average +215 in this case, effectively removing it from consideration) I got palatable results.
[edit] I would go further than saying palatable: 32.17MB / 362.8kbps on my 53 sample set. I've started a speculative 1496 track transcode - so far: 256 tracks, 2.20GB / 302kbps vs 6.43GB / 881kbps..... [/edit]
-nts amended as requested.
Now you can really cause awful results.......
Try: -3 -nts 48 -skew 0 -snr -215
This gave 9.504MB / 107.2kbps.
lossyWAV beta v0.5.4 attached. Superseded.[!--sizeo:1--][span style=\"font-size:8pt;line-height:100%\"][!--/sizeo--]lossyWAV beta v0.5.4 : WAV file bit depth reduction method by 2Bdecided.
Delphi implementation by Nick.C from a Matlab script, www.hydrogenaudio.org
Usage : lossyWAV <input wav file> <options>
Example : lossyWAV musicfile.wav
Quality Options:
-0 emulate script [2xFFT] (-cbs 1024 -nts 0.0 -skew 0 -snr -215
-spf 44444-44444-44444-44444-44444 -fft 10001)
-1 extreme quality [4xFFT] (-cbs 512 -nts -2.0 -skew 36 -snr 21
-spf 22224-22225-11235-11246-12358 -fft 11011)
-2 default quality [3xFFT] (-cbs 512 -nts +1.5 -skew 36 -snr 21
-spf 22224-22235-22346-12347-12358 -fft 10101)
-3 compact quality [2xFFT] (-cbs 512 -nts +6.0 -skew 36 -snr 21
-spf 22235-22236-22347-22358-2246C -fft 10001)
-o <folder> destination folder for the output file
-nts <n> set noise_threshold_shift to n dB (-48.0dB<=n<=+48.0dB)
(-ve values reduce bits to remove, +ve values increase)
-force forcibly over-write output file if it exists; default=off
Codec Options:
-wmalsl optimise internal settings for WMA Lossless codec; default=off
Advanced / System Options:
-snr <n> set minimum average signal to added noise ratio to n dB;
(-215.0dB<=n<=48.0dB) Increasing value reduces bits to remove.
-skew <n> skew fft analysis results by n dB (0.0db<=n<=48.0db) in the
frequency range 20Hz to 3.45kHz
-cbs <n> set codec block size to n samples (512<=n<=4608, n mod 32=0)
-fft <5xbin> select fft lengths to use in analysis, using binary switching,
from 64, 128, 256, 512 & 1024 samples, e.g. 01001 = 128,1024
-overlap enable conservative fft overlap method; default=off
-spf <5x5hex> manually input the 5 spreading functions as 5 x 5 characters;
These correspond to FFTs of 64, 128, 256, 512 & 1024 samples;
e.g. 22235-22236-22347-22358-2246C (Characters must be one of
1 to 9 and A to F (zero excluded).
-allowable select allowable number of clipping samples per codec block
before iterative clipping reduction; (0<=n<=64, default=0).
-clipping disable clipping prevention by iteration; default=off
-dither dither output using triangular dither; default=off
-quiet significantly reduce screen output
-nowarn suppress lossyWAV warnings
-detail enable detailled output mode
-below set process priority to below normal.
-low set process priority to low.
Special thanks:
David Robinson for the method itself and motivation to implement it in Delphi.
Dr. Jean Debord for the use of TPMAT036 uFFT & uTypes units for FFT analysis.
Halb27 @ www.hydrogenaudio.org for donation and maintenance of the wavIO unit.
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