Cody Boone Ferguson
8eafe398e2
This commit also adds the faq.html and bugs.html file that should have been committed with 2013. The reason the faq.md is updated with only the version update (backdated to yesterday) is because the version was not updated with the previous update.
143 lines
3.3 KiB
Markdown
143 lines
3.3 KiB
Markdown
## To build:
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``` <!---sh-->
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make
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```
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There is an alternate version that will theoretically work with Windows
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compilers (if anything in Windows works :-) ). See the [Alternate
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code](#alternate-code) section below.
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### Bugs and (Mis)features:
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The current status of this entry is:
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> **STATUS: known bug - please help us fix**
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For more detailed information see [2014/vik in bugs.html](../../bugs.html#2014_vik).
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## To use:
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``` <!---sh-->
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echo foo | ./prog > audio_file.raw
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echo foo | ./prog | mplayer -demuxer rawaudio -
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```
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## Try:
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``` <!---sh-->
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./try.sh
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```
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## Alternate code:
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The alternate code, [prog.alt.c](%%REPO_URL%%/2014/vik/prog.alt.c), is based on the author's
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instructions on how to get it to work with Windows.
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### Alternate build:
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``` <!---sh-->
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make alt
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```
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### Alternate use:
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Use `prog.alt` as you would `prog` above as well as below.
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## Judges' remarks:
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This program sets a new tone for obfuscation. But do you understand
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what it says about obfuscation? Perhaps:
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``` <!---sh-->
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./prog < prog.c > prog.raw
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```
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might speak to your coding style? If not, then perhaps:
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``` <!---sh-->
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./prog < README.md | mplayer -demuxer rawaudio -
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```
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might help? :-)
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## Author's remarks:
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### Remarks
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This program converts ASCII text to Morse audio file and vice versa. As far as
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I can tell, there are at least six chocolate references in this program.
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This program can convert text to Morse to a raw 44.1kHz stereo audio file.
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Via streaming to `mplayer(1)`, you can listen to the Morse audio.
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Don't forget the last '`-`' as it makes `mplayer(1)` read from `stdin`.
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## Convert audio file with Morse signals to text
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``` <!---sh-->
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./prog e < audio_file.raw
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```
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or alternatively pass a .wav file as input.
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The preferred input format 44.1kHz stereo, but it does a decent job on mono
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input and different frequencies as well.
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### Portability
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The program is portable to most platforms. The only system dependency is that
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the program relies on writing binary data to `stdout`.
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Microsoft compilers add a carriage return to newlines, and to compile the
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program with this platform, the following line can be added to `main()` before
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any code in order for the program to run correctly:
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``` <!---c-->
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_setmode(_fileno(stdout), 0x8000);
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```
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**NOTE**: see the [Alternate code](#alternate-code) for this.
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### Known Issues
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The program uses a quite simple algorithm for detecting tone on and off events
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in the Morse signal. Hence the program does not work well with noisy input
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signals. I have tested it with several samples of man made Morse recordings as
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well as computer generated ones.
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Generally, any recording from ham radio transmissions does not decode due to
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noise and echoes. Other man made recordings may decode, but some characters
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can be incorrect due to too big variation in length of tones and pauses.
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However I found some man made recordings on that decode reasonable well.
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If a recording doesn't decode, you could try to pre-process the input with a
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narrow bandpass filter on the frequency of the transmission.
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<!--
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Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
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You are free to share and adapt this file under the terms of this license:
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Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
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For more information, see:
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https://creativecommons.org/licenses/by-sa/4.0/
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-->
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