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aifcresample(1)						       aifcresample(1)

NAME    [Toc]    [Back]

     aifcresample - perform sampling rate conversion on	an AIFF-C file

SYNOPSIS    [Toc]    [Back]

     aifcresample [options] -rate rate infile.aifc outfile.aifc

OPTIONS    [Toc]    [Back]

     -rate rate
	   specifies the sampling rate for the output file outfile.aifc. The
	   value rate must be one of the following (sample frames per second):

	   8000	   11025    16000    22050    32000    44100	48000

	   The sampling	rate specified for the output file must	be different
	   from	the sampling rate of the input file.

     -dynamic decibels
	   specifies the minimum attenuation (in decibels) of the alias/image
	   artifacts generated by the sampling rate conversion.	 The loss in
	   dynamic range due to	the rate conversion process will be no worse
	   than	this value.

	   The value for decibels must be one of: 78, 96, or 120.  Default
	   value is 96.	A higher value for decibels gives higher quality rate

     -taper bandwidth
	   specifies the percentage of the final bandwidth tapered off.	 A
	   smaller percentage of tapered bandwidth corresponds to a greater
	   high	frequency content. Conversions to low sampling rates should
	   use higher values for bandwidth.

	   The value for bandwidth must	be chosen from:	1, 10, or 20. Default
	   value is 10.	A lower	value for bandwidth gives higher quality rate

	   causes the program to print out messages periodically which
	   indicate how	much of	the data in the	original file has been

									Page 1

aifcresample(1)						       aifcresample(1)

DESCRIPTION    [Toc]    [Back]

     aifcresample is a command-line program which reads	an AIFF-C (or AIFF)
     digital audio input file, converts	the audio data to new sampling rate,
     and writes	out a new AIFF-C file containing the resampled data.

     aifcresample uses high-quality rate conversion algorithms with linear
     phase filters to perform resampling between any two of the	following
     rates: 8000, 11025, 16000,	22050, 32000, 44100, 48000 sample frames per
     second (or	Hz).

     The speed of the rate conversion algorithm	depends	on the values
     specified for bandwidth, decibels,	and the	original and new sampling

     If	the input AIFF-C file parses correctly,	and the	output file is written
     with no errors, aifcresample returns 0. If	there is an error,
     aifcresample returns 1.

     The  AIFF-C file format specification is published	by Apple Computer Inc.

NOTES    [Toc]    [Back]

     Files converted using decibels set	to 96 and bandwidth set	to 10 will
     sound most	excellent.  For	the highest quality conversion algorithm,
     however, you can set decibels to 120 and bandwidth	to 1.  By decreasing
     decibels and increasing bandwidth,	you increase the speed of the rate
     conversion	at a loss of high frequency response.

     The following table shows the relationships between the bandwidth
     parameter,	and the	pass band ripple:

	       bandwidth      %	final	     passband
	       parameter bandwidth	ripple

	       20	 20%	   +/- 0.05   dB
	       10	 10%	   +/- 0.05   dB
		1	  1%	   +/- 0.0005 dB

BUGS    [Toc]    [Back]

     Due to convolution	remnants at the	beginning of the output	file's audio
     data, there may be	some inaccuracy	in rescaled loop points	or markers.
     The leading convolution remnant may displace some valid audio data	at the
     end of the	file. The magnitude of this inaccuracy depends on the rate

									Page 2

aifcresample(1)						       aifcresample(1)

     conversion	bandwidth parameters and input and output sampling rates.
     aifcresample simply multiplies existing loop points by the	ratio
     output/input sampling rate.

AUTHOR    [Toc]    [Back]

     Gints Klimanis and	Scott Porter, Silicon Graphics Inc.

SEE ALSO    [Toc]    [Back]

     playaifc(1), recordaifc(1),
     aifc2aiff(1), aifccompress(1), aifcdecompress(1),
     dmconvert(1), mediaconvert(1)
     AIFF-C File Format	Specification

									PPPPaaaaggggeeee 3333
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