I've started tinkering with the pieces of freedv, and I've found two
problems: The "Nc" number of channels parameter in fdmdv_demod does
not appear to be optional as shown on two rowetel web pages, and
fdmdv_demod is producing NUL bytes for output.
----- These commands appear to work:
$ cd ~/freedv-auto
$ svn info freetel-code | grep Revision
Revision: 1691
$ c2enc 1400 freetel-code/codec2/raw/morig.raw - | c2dec 1400 - - |
play -t raw -r 8000 -s -2 -
[ speech ]
$ fdmdv_get_test_bits - 2800 | fdmdv_mod - - | play -t raw -r 8000 -s
-2 -
[ 2.7 seconds of whirring noise ]
----- These commands do not appear to work:
This command is adapted from page: http://www.rowetel.com/blog/?page_id=2458
$ fdmdv_get_test_bits - 14000 | fdmdv_mod - - | fdmdv_demod - -
/tmp/demod_dump.txt | fdmdv_put_test_bits -
Error number of carriers must be btween 2 and 20
bits_per_fdmdv_frame: 28 bits_per_codec_frame: 56
bytes_per_codec_frame: 7
bits_per_fdmdv_frame: 28 bits_per_codec_frame: 56
bytes_per_codec_frame: 7
bits 0 errors 0 BER 0.0000
Note error "Error number of carriers must be btween 2 and 20" and also
typo in "between".
$ fdmdv_demod
usage: fdmdv_demod InputModemRawFile OutputBitFile [Nc] [OctaveDumpFile]
e.g fdmdv_demod hts1a_fdmdv.raw hts1a.c2
Number of carriers does not seem optional. Adding number of carriers:
$ fdmdv_get_test_bits - 14000 | fdmdv_mod - - | fdmdv_demod - - 14
/tmp/demod_dump.txt | fdmdv_put_test_bits -
bits_per_fdmdv_frame: 28 bits_per_codec_frame: 56
bytes_per_codec_frame: 7
bits_per_fdmdv_frame: 28 bits_per_codec_frame: 56
bytes_per_codec_frame: 7
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
bits 0 errors 0 BER 0.0000
Number of carriers error message goes away, but why is bit count 0 and not
14000?
There is no file /tmp/demod_dump.txt. Is 14 the right number of carriers?
$ fdmdv_get_test_bits - 14000 | fdmdv_mod - - | fdmdv_demod - - 14
/tmp/demod_dump.txt | od
bits_per_fdmdv_frame: 28 bits_per_codec_frame: 56
bytes_per_codec_frame: 7
0000000 000000 000000 000000 000000 000000 000000 000000 000000
*
0003320 000000 000000 000000 000000 000000 000000 000000
0003335
fdmdv_demod is producing NULs for output.
Brian
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