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IRIX Base Documentation 1998 November
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IRIX 6.5.2 Base Documentation November 1998.img
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catman
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cat1
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dmedia
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aifcresample.z
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aifcresample
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Text File
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1998-10-30
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6KB
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199 lines
aaaaiiiiffffccccrrrreeeessssaaaammmmpppplllleeee((((1111)))) aaaaiiiiffffccccrrrreeeessssaaaammmmpppplllleeee((((1111))))
NNNNAAAAMMMMEEEE
aifcresample - perform sampling rate conversion on an AIFF-C file
SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
aifcresample [options] -rate rate infile.aifc outfile.aifc
OOOOPPPPTTTTIIIIOOOONNNNSSSS
----rrrraaaatttteeee _r_a_t_e
specifies the sampling rate for the output file _o_u_t_f_i_l_e._a_i_f_c. The
value _r_a_t_e must be one of the following (sample frames per second):
8888000000000000 11111111000022225555 11116666000000000000 22222222000055550000 33332222000000000000 44444444111100000000 44448888000000000000
The sampling rate specified for the output file must be different
from the sampling rate of the input file.
----ddddyyyynnnnaaaammmmiiiicccc _d_e_c_i_b_e_l_s
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 _d_e_c_i_b_e_l_s must be one of: 77778888, 99996666, or 111122220000. Default
value is 99996666. A higher value for _d_e_c_i_b_e_l_s gives higher quality rate
conversion.
----ttttaaaappppeeeerrrr _b_a_n_d_w_i_d_t_h
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 _b_a_n_d_w_i_d_t_h.
The value for _b_a_n_d_w_i_d_t_h must be chosen from: 1111, 11110000, or 22220000. Default
value is 11110000. A lower value for _b_a_n_d_w_i_d_t_h gives higher quality rate
conversion.
----vvvveeeerrrrbbbboooosssseeee
causes the program to print out messages periodically which
indicate how much of the data in the original file has been
converted.
PPPPaaaaggggeeee 1111
aaaaiiiiffffccccrrrreeeessssaaaammmmpppplllleeee((((1111)))) aaaaiiiiffffccccrrrreeeessssaaaammmmpppplllleeee((((1111))))
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
_a_i_f_c_r_e_s_a_m_p_l_e 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.
_a_i_f_c_r_e_s_a_m_p_l_e 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 _b_a_n_d_w_i_d_t_h, _d_e_c_i_b_e_l_s, and the original and new sampling
rates.
If the input AIFF-C file parses correctly, and the output file is written
with no errors, _a_i_f_c_r_e_s_a_m_p_l_e returns 0. If there is an error,
_a_i_f_c_r_e_s_a_m_p_l_e returns 1.
The AIFF-C file format specification is published by Apple Computer Inc.
NNNNOOOOTTTTEEEESSSS
Files converted using _d_e_c_i_b_e_l_s set to 96 and _b_a_n_d_w_i_d_t_h set to 10 will
sound most excellent. For the highest quality conversion algorithm,
however, you can set _d_e_c_i_b_e_l_s to 120 and _b_a_n_d_w_i_d_t_h to 1. By decreasing
_d_e_c_i_b_e_l_s and increasing _b_a_n_d_w_i_d_t_h, you increase the speed of the rate
conversion at a loss of high frequency response.
The following table shows the relationships between the _b_a_n_d_w_i_d_t_h
parameter, and the pass band ripple:
bandwidth % final passband
parameter bandwidth ripple
tapered
20 20% +/- 0.05 dB
10 10% +/- 0.05 dB
1 1% +/- 0.0005 dB
BBBBUUUUGGGGSSSS
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
PPPPaaaaggggeeee 2222
aaaaiiiiffffccccrrrreeeessssaaaammmmpppplllleeee((((1111)))) aaaaiiiiffffccccrrrreeeessssaaaammmmpppplllleeee((((1111))))
conversion bandwidth parameters and input and output sampling rates.
aifcresample simply multiplies existing loop points by the ratio
output/input sampling rate.
AAAAUUUUTTTTHHHHOOOORRRR
Gints Klimanis and Scott Porter, Silicon Graphics Inc.
SSSSEEEEEEEE AAAALLLLSSSSOOOO
playaifc(1), recordaifc(1),
aifc2aiff(1), aifccompress(1), aifcdecompress(1),
dmconvert(1), mediaconvert(1)
AIFF-C File Format Specification
PPPPaaaaggggeeee 3333