forked from sox_ng/sox_ng
2d3812aa78
This is the hard fork, allowing old sox and sox_ng to coexist on the same system. Any distro wishing to switch to sox_ng just needs to make symlinks from the old file names to the new. This also removes the Debian-specific files rather than trying to update them, as Debian uses its own version of them.
40 lines
1.6 KiB
Bash
Executable file
40 lines
1.6 KiB
Bash
Executable file
#!/bin/sh
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# Thanks to Reynir H. Stefánsson for the original version of this script.
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# In marine radio, a Mayday emergency call is transmitted preceded by a
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# 30-second alert sound. The alert sound comprises two audio tones at
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# 1300Hz and 2100Hz alternating at a rate of 4Hz. This script shows how SoX
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# can be used to construct an audio file containing the alert sound.
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# This is a `Bourne shell' (sh) script but it should be simple to translate
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# this to another scripting language if you do not have access to sh.
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# If you run this script, you may want to hit Ctrl-C fairly soon after the
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# alert tone starts playing---it's not a pleasant sound!
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# The synth effect is used to generate each of the tones; "-e mu-law -r 8000"
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# selects u-law 8kHz sampling-rate audio (i.e. relatively low fidelity,
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# suitable for the marine radio transmission channel); each tone is
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# generated at a length of 0.25 seconds to give the required 4Hz
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# alternation.
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# Note the use of `raw' as the intermediary file format; a self-describing
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# (header) format would just get in the way here. The self-describing
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# header is added only at the final stage.
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# ---------------------------------------------------------------------------
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SOX=../src/sox_ng
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rm -f 2tones.ul # Make sure we append to a file that's initially empty
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for freq in 1300 2100; do
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$SOX -e mu-law -r 8000 -n -t raw - synth 0.25 sine $freq gain -3 >> 2tones.ul
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done
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$SOX -c 1 -r 8000 2tones.ul alert.au repeat - trim 0 30
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# Repeat to fill 30 seconds and add a file header
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rm 2tones.ul # Tidy up intermediate file
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$SOX alert.au -d
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