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Linux 2.6 - man page for dnoise (linux section 1)

DNOISE(1)			  The Canonical Csound Reference			DNOISE(1)

NAME
       dnoise - Reduces noise in a file. .

DESCRIPTION
       This is a noise reduction scheme using frequency-domain noise-gating.

SYNTAX
	   dnoise [flags] -i noise_ref_file  -o output_soundfile  input_soundfile

INITIALIZATION
       Dnoise specific flags:

       o   (no flag) input soundfile to be denoised

       o   -i fname input reference noise soundfile

       o   -o fname output soundfile

       o   -N fnum # of bandpass filters (default: 1024)

       o   -w fovlp filter overlap factor: {0,1,(2),3} DON'T USE -w AND -M

       o   -M awlen analysis window length (default: N-1 unless -w is specified)

       o   -L swlen synthesis window length (default: M)

       o   -D dfac decimation factor (default: M/8)

       o   -b btim begin time in noise reference soundfile (default: 0)

       o   -B smpst starting sample in noise reference soundfile (default: 0)

       o   -e etim end time in noise reference soundfile (default: end of file)

       o   -E smpend final sample in noise reference soundfile (default: end of file)

       o   -t thr threshold above noise reference in dB (default: 30)

       o   -S gfact sharpness of noise-gate turnoff, range: 1 to 5 (default: 1)

       o   -n numfrm number of FFT frames to average over (default: 5)

       o   -m mingain minimum gain of noise-gate when off in dB (default: -40)

       Soundfile format options:

       o   -A AIFF format output

       o   -W WAV format output

       o   -J IRCAM format output

       o   -h skip soundfile header (not valid for AIFF/WAV output)

       o   -8 8-bit unsigned char sound samples

       o   -c 8-bit signed_char sound samples

       o   -a alaw sound samples

       o   -u ulaw sound samples

       o   -s short_int sound samples

       o   -l long_int sound samples

       o   -f float sound samples. Floats also supported for WAV files. (New in Csound 3.47.)

       Additional options:

       o   -R verbose - print status info

       o   -H [N] print a heartbeat character at each soundfile write.

       o   -- fname output to log file fname

       o   -V verbose - print status info

	   Note
	   DNOISE also looks at the environment variable SFOUTYP to determine soundfile output
	   format.

	   The -i flag is used for a reference noise file (normally created from a short section
	   of the denoised file, where only noise is audible). The input soundfile to be denoised
	   can be given anywhere on the command line, without a flag.

PERFORMANCE
       This is a noise reduction scheme using frequency-domain noise-gating. This should work
       best in the case of high signal-to-noise with hiss-type noise.

       The algorithm is that suggested by Moorer & Berger in "Linear-Phase Bandsplitting: Theory
       and Applications" presented at the 76th Convention 1984 October 8-11 New York of the Audio
       Engineering Society (preprint #2132) except that it uses the Weighted Overlap-Add
       formulation for short-time Fourier analysis-synthesis in place of the recursive
       formulation suggested by Moorer & Berger. The gain in each frequency bin is computed
       independently according to

	   gain = g0 + (1-g0) * [avg / (avg + th*th*nref)] ^ sh

       where avg and nref are the mean squared signal and noise respectively for the bin in
       question. (This is slightly different than in Moorer & Berger.)

       The critical parameters th and g0 are specified in dB and internally converted to decimal
       values. The nref values are computed at the start of the program on the basis of a
       noise_soundfile (specified in the command line) which contains noise without signal.

       The avg values are computed over a rectangular window of m FFT frames looking both ahead
       and behind the current time. This corresponds to a temporal extent of m*D/R (which is
       typically (m*N/8)/R). The default settings of N, M, and D should be appropriate for most
       uses. A higher sample rate than 16 Khz might indicate a higher N.

CREDITS
       Author: Mark Dolson

       August 26, 1989

       Author: John ffitch

       December 30, 2000

       Updated by Rasmus Ekman on March 11, 2002.

AUTHORS
       Barry Vercoe
       MIT Media Lab

	   Author.

       Dan Ellis
       MIT Media Lab,
		 Cambridge
		 Massachussetts

	   Author.

COPYRIGHT
5.07					    06/23/2009					DNOISE(1)


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All times are GMT -4. The time now is 12:53 AM.

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