Re: [MP3 ENCODER] cwlimit (was: very lowand very high-quality settings)
| OdesÃlatel: Gabriel Bouvigne <[EMAIL PROTECTED]> | | > lame -m m -h -b32 --voice --lowpass 8 --lowpass-width 1 | > --highpass 0.054 --highpass-width 0.04 --cwlimit 7 | > --resample 22.05 --noshort a.wav a.mp3 | > | > NOTES: | > cwlimit=lowpass minus lowpass-width (kHz) | | Did you played a lot with cwlimit? Could you please share your results about | it? Not as much. But if you use really high bitrates about 160 or 192kbps, then you will get better results with higher cwlimit value , such as 11 (by default 8.3... kHz). If you need low bitrate, then set cwlimit as shown, because you do not need to calculate tonality over rejected (or partially rejected) frequencies. If you want to remove highs due low bitrate, then use empiric highpass filter set to 0.6/lowpass (kHz), all at -10dB. eg., 6kHz lowpass will have 0.6/6=0.1 kHz highpass. (it is not my empiric, this is from cca 40yrs old book about acoustics) And here LAME values: --lowpass 6.4 --lowpass-width 1 --highpass 0.06 --highpass-width 0.1 Note that highpass values above 54Hz are very well, because they spare first sfb that dataspace should be used for other bands. -3dB point is at highpass munis highpass-width, or lowpass plus lowpass-width -10dB point you will get at (not measured, only speculation, dont know what filters in lame works exactly) highpass minus highpass-width/3 or lowpass plus lowpass-witdh/3 If you dont apply highpass, then encoded output will sound with very boom basses and speech is masked by strong bass. Regards Jaroslav Lukesh -- note: (Bill) Gates to Hell! -- MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
Re: [MP3 ENCODER] cwlimit (was: very lowand very high-quality settings)
> lame -m m -h -b32 --voice --lowpass 8 --lowpass-width 1 > --highpass 0.054 --highpass-width 0.04 --cwlimit 7 > --resample 22.05 --noshort a.wav a.mp3 > > NOTES: > cwlimit=lowpass minus lowpass-width (kHz) Did you played a lot with cwlimit? Could you please share your results about it? Regards, -- Gabriel Bouvigne - France [EMAIL PROTECTED] icq: 12138873 MP3' Tech: www.mp3-tech.org -- MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
[MP3 ENCODER] --cwlimit
What increases sound quality? A low or a high --cwlimit? On VBR a high cwlimit decreases bit rate: Bytes cwlimit 226680 1.mp3 226363 2.mp3 225346 3.mp3 224456 4.mp3 223568 5.mp3 222578 6.mp3 221636 7.mp3 220538 8.mp3 220019 9.mp3 218395 10.mp3 216210 11.mp3 214796 12.mp3 213288 13.mp3 212497 14.mp3 212236 15.mp3 212132 16.mp3 212180 17.mp3 212181 18.mp3 and higher -- Frank Klemm -- MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
Re: [MP3 ENCODER] --cwlimit option
> > > The tonality is used for the spreading function. The more noiselike > > a signal, the more masking it generates. > > Isn't it the other way around? More tonal -> more masking? > > Ciao, > > Segher > If you believe the psymodels in the ISO docs, it appears that more noise like -> more masking. In the ISO formulas (both mp3 and aac), a pure noise signal will have a spreading function 23db stronger than a pure tonal signal. (for AAC, it is 12db stronger) Mark -- MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
Re: [MP3 ENCODER] --cwlimit option
> The tonality is used for the spreading function. The more noiselike > a signal, the more masking it generates. Isn't it the other way around? More tonal -> more masking? Ciao, Segher -- MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
Re: [MP3 ENCODER] --cwlimit option
> > What really does the cwlimit option do/change? That is one thing I am > clueless on. > > -- LAME uses a formula (from the ISO docs) to estimate the tonality of each frequency band. It computes this up to N khz, where N is specified by "--cwlimit N" (default=9khz). Above 9khz, a default tonality value is used. The tonality is used for the spreading function. The more noiselike a signal, the more masking it generates. Mark -- MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
[MP3 ENCODER] --cwlimit option
What really does the cwlimit option do/change? That is one thing I am clueless on. -- MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
RE: [MP3 ENCODER] cwlimit?
> From: Robert Hegemann [mailto:[EMAIL PROTECTED]]
>
> The unpredictability measure is used by the tonality
> function and controls the masking level within
> scalefactor bands. (masking capabilities vary if the
> sound is more tonal or atonal)
Has anyone experimented with different unpredictability measures? That debug
text I posted from the FhG coder suggests that they provide several
different options, at least internally ("euclidian distance", "peak filter",
fast versions of each of those, and a hybrid of the two.
-- Mat.
--
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Re: [MP3 ENCODER] cwlimit?
Ross wrote: > Can someone please explain this option please. > > Thanks, > Ross. The option --cwlimit limits the unpredictability measure computation. Above that frequency, a default value will be used. In the previous versions it was computed up to a fixed index. This fixed index had the drawback, that at a sampling frequency of 16 kHz the unpredictability measure was computed up to 3 kHz only. The default value is now a frequency of 8.9 kHz for all sampling frequencies, but it can be set with this option. The unpredictability measure is used by the tonality function and controls the masking level within scalefactor bands. (masking capabilities vary if the sound is more tonal or atonal) Robert PS: For a deeper view, take a look at psymodel.c -- MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
[MP3 ENCODER] cwlimit?
Can someone please explain this option please. Thanks, Ross. -- MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
