This program creates an digital audio file on your computer that can be used to help calibrate a flutter meter. It cannot be used directly to measure flutter, but it does simulate a tape recorder that suffers from a known, well-defined percentage of sinusoidal speed modulation. The function generated is a sine wave whose instantaneous frequency is W + f sin (W t) 0 f where W is the carrier frequency, 0 f is the (radian) frequency deviation W is the flutter modulation frequency f t is time. Use of the software is illustrated below. This is a command line program. It asks you to enter various specifications about the audio file you want to produce. The output computer file format is Microsoft WAVE, monaural in 16-bit linear PCM. Most CD writer software products can translate and copy this onto a standard audio CD ROM, or you can play the file out on your computer's sound card. Steve Moshier November, 2003 $ ./flutterton Run the program File name ? test.wav Type in your desired output file name
Sample rate (44100.000) ? Hit enter to accept the value in parens 44100.000 Frequency ( 3000.000) ? This is the carrier frequency 3000.000 Amplitude (32767.000) ? Peak digital waveform amplitude 32767.000 Duration (sec) ( 10.000) ? Length of generated audio segment 10.000 Peak flutter percent ( 1.000) ? For RMS, use a value 1.414 times larger 1.000 Flutter frequency (Hz) ( 2.000) ? FM modulation frequency 2.000 Opened test.wav Chunk size = 882036 Output wave file header information Format chunk size = 16 Format tag is 1 = WAVE_FORMAT_PCM Microsoft Number of channels = 1 Sample rate = 44100 Average bytes per second = 88200 BlockAlign = 2 Sample size = 16 Data size = 882000 Files in this archive: test.wav Output audio produced by the above parameter settings flutter.exe DOS or Windows executable flutter.c The main program source code wav.c Parser and generator of Microsoft WAVE headers wav.h WAVE header data structure makefile Unix makefile script msvc6.zip Microsoft Visual C++ version 6 build scripts bcb5.zip Borland Code Builder version 5 build scripts
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Last update: 25 November 2003