Bug#567397: unixcw: CW output tone is "ringy" on some audio devices
For some audio devices (soundcards) the Morse code 800 Hz output tone generated by cwlib is "ringy" (sounds as if it is being modulated by another tone).
The 'cwlib' library tries to set the DSP sample rate to 8192 Hz and the fragment size to 2^7 == 128. On audio devices where a different fragment size is returned for that rate, the audio output sounds "ringy":
$ echo T | CWLIB_DEBUG=0x4 cw -w 4 2>&1 | grep fragment
cw: dsp fragment size not set, 131
(For audio devices which accept that fragment size and rate, the "fragment size not set" line will not appear and the tone will sound fine).