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minimodem: --volume sets tx amplitude

This commit is contained in:
Kamal Mostafa 2012-08-25 00:32:11 -07:00
parent 501ee25c7d
commit 762a3ea788
4 changed files with 35 additions and 10 deletions
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5
src/minimodem.1.in
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@ -73,6 +73,11 @@ encode or decode an audio file (extension sets audio format)
.TP
.B \-b, \-\-bandwidth {rx_bandwidth}
.TP
.B \-v, \-\-volume {tx_amplitude or 'E'}
Sets the generated signal amplitude (default is 1.0). As a special case
useful for testing, the value 'E' sets the amplitude to the very small value
FLT_EPSILON. (This option applies to \-\-tx mode only).
.TP
.B \-M, \-\-mark {mark_freq}
.TP
.B \-S, \-\-space {space_freq}

19
src/minimodem.c
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@ -26,6 +26,7 @@
#include <string.h>
#include <ctype.h>
#include <math.h>
#include <float.h>
#include <assert.h>
#include <signal.h>
#include <sys/time.h>
@ -257,7 +258,7 @@ benchmarks()
// enable the sine wave LUT
simpleaudio_tone_init(1024);
simpleaudio_tone_init(1024, 1.0);
sa_out = simpleaudio_open_stream(backend, SA_STREAM_PLAYBACK,
SA_SAMPLE_FORMAT_S16, sample_rate, 1,
@ -277,7 +278,7 @@ benchmarks()
// disable the sine wave LUT
simpleaudio_tone_init(0);
simpleaudio_tone_init(0, 1.0);
sa_out = simpleaudio_open_stream(backend, SA_STREAM_PLAYBACK,
SA_SAMPLE_FORMAT_S16, sample_rate, 1,
@ -328,6 +329,7 @@ usage()
" -5, --baudot Baudot 5-N-1\n"
" -f, --file {filename.flac}\n"
" -b, --bandwidth {rx_bandwidth}\n"
" -v, --volume {amplitude or 'E'}\n"
" -M, --mark {mark_freq}\n"
" -S, --space {space_freq}\n"
" -T, --txstopbits {m.n}\n"
@ -382,6 +384,7 @@ main( int argc, char*argv[] )
unsigned int sample_rate = 48000;
unsigned int nchannels = 1; // FIXME: only works with one channel
float tx_amplitude = 1.0;
unsigned int tx_sin_table_len = 4096;
/* validate the default system audio mechanism */
@ -424,6 +427,7 @@ main( int argc, char*argv[] )
{ "baudot", 0, 0, '5' },
{ "file", 1, 0, 'f' },
{ "bandwidth", 1, 0, 'b' },
{ "volume", 1, 0, 'v' },
{ "mark", 1, 0, 'M' },
{ "space", 1, 0, 'S' },
{ "txstopbits", 1, 0, 'T' },
@ -435,7 +439,7 @@ main( int argc, char*argv[] )
{ "benchmarks", 0, 0, MINIMODEM_OPT_BENCHMARKS },
{ 0 }
};
c = getopt_long(argc, argv, "Vtrc:l:a85f:b:M:S:T:qAR:",
c = getopt_long(argc, argv, "Vtrc:l:a85f:b:v:M:S:T:qAR:",
long_options, &option_index);
if ( c == -1 )
break;
@ -475,6 +479,13 @@ main( int argc, char*argv[] )
band_width = atof(optarg);
assert( band_width != 0 );
break;
case 'v':
if ( optarg[0] == 'E' )
tx_amplitude = FLT_EPSILON;
else
tx_amplitude = atof(optarg);
assert( tx_amplitude > 0.0 );
break;
case 'M':
bfsk_mark_f = atoi(optarg);
assert( bfsk_mark_f > 0 );
@ -642,7 +653,7 @@ main( int argc, char*argv[] )
*/
if ( TX_mode ) {
simpleaudio_tone_init(tx_sin_table_len);
simpleaudio_tone_init(tx_sin_table_len, tx_amplitude);
int tx_interactive = 0;
if ( ! stream_name ) {

19
src/simple-tone-generator.c
View File

@ -27,14 +27,17 @@
static float tone_mag = 1.0;
static unsigned int sin_table_len;
static short *sin_table_short;
static float *sin_table_float;
void
simpleaudio_tone_init( unsigned int new_sin_table_len )
simpleaudio_tone_init( unsigned int new_sin_table_len, float mag )
{
sin_table_len = new_sin_table_len;
tone_mag = mag;
if ( sin_table_len != 0 ) {
sin_table_short = realloc(sin_table_short, sin_table_len * sizeof(short));
@ -45,10 +48,13 @@ simpleaudio_tone_init( unsigned int new_sin_table_len )
}
unsigned int i;
unsigned short mag_s = 32767.0 * tone_mag + 0.5f;
if ( mag_s < 2 ) // "short epsilon"
mag_s = 2;
for ( i=0; i<sin_table_len; i++ )
sin_table_short[i] = 32767 * sin(M_PI*2.0*(float)i/sin_table_len);
sin_table_short[i] = mag_s * sin(M_PI*2.0*(float)i/sin_table_len);
for ( i=0; i<sin_table_len; i++ )
sin_table_float[i] = sinf(M_PI*2.0*(float)i/sin_table_len);
sin_table_float[i] = tone_mag * sinf(M_PI*2.0*(float)i/sin_table_len);
} else {
if ( sin_table_short ) {
@ -122,7 +128,7 @@ simpleaudio_tone(simpleaudio *sa_out, float tone_freq, size_t nsamples_dur)
float_buf[i] = sin_lu_float(SINE_PHASE_TURNS);
} else {
for ( i=0; i<nsamples_dur; i++ )
float_buf[i] = sinf(SINE_PHASE_RADIANS);
float_buf[i] = tone_mag * sinf(SINE_PHASE_RADIANS);
}
}
break;
@ -134,8 +140,11 @@ simpleaudio_tone(simpleaudio *sa_out, float tone_freq, size_t nsamples_dur)
for ( i=0; i<nsamples_dur; i++ )
short_buf[i] = sin_lu_short(SINE_PHASE_TURNS);
} else {
unsigned short mag_s = 32767.0 * tone_mag + 0.5f;
if ( mag_s < 2 ) // "short epsilon"
mag_s = 2;
for ( i=0; i<nsamples_dur; i++ )
short_buf[i] = 32767 * sinf(SINE_PHASE_RADIANS);
short_buf[i] = mag_s * sinf(SINE_PHASE_RADIANS);
}
break;
}

2
src/simpleaudio.h
View File

@ -96,6 +96,6 @@ void
simpleaudio_tone(simpleaudio *sa_out, float tone_freq, size_t nsamples_dur);
void
simpleaudio_tone_init( unsigned int new_sin_table_len );
simpleaudio_tone_init( unsigned int new_sin_table_len, float mag );
#endif