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Allow automatic resync, and use of current timezone
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@simonhyde
simonhyde committed Jan 20, 2018
1 parent a22cbfc commit 9708804
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Showing 2 changed files with 108 additions and 16 deletions.
6 changes: 6 additions & 0 deletions jltcgen.1
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Original file line number Diff line number Diff line change
Expand Up @@ -21,9 +21,15 @@ display this help and exit
\fB\-g\fR, \fB\-\-volume\fR float
set output level in dBFS default \fB\-18db\fR
.TP
\fB\-l\fR, \fB\-\-localtime\fR
automatically generated timecode in the currently configured timezone, instead of UTC
.TP
\fB\-m\fR, \fB\-\-timezone\fR tz
set timezone in minutes\-west of UTC
.TP
\fB\-r\fR, \fB\-\-auto-resync\fR
automatically re\-sync and re\-start the feed if it gets more than 100ms out of sync with the local clock. a check is performed once every 30 seconds.
.TP
\fB\-t\fR, \fB\-\-timecode\fR time
specify start\-time/timecode [[[HH:]MM:]SS:]FF
.TP
Expand Down
118 changes: 102 additions & 16 deletions jltcgen.c
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,8 @@ int showdrift = 0; // set by signal handler
int sync_initialized =0;
double sync_offset_ms = 0;
int reinit=1;
int local_time=0;
int tzoff = 0;// time-zone in minuteswest

/* options */
int fps_num = 25;
Expand All @@ -67,8 +69,34 @@ enum LTC_TV_STANDARD ltc_tv = LTC_TV_625_50;
int sync_now =1; // set to 1 to start timecode at date('now')
float volume_dbfs = -18.0;

int auto_resync = 0; //Set to 1 to autmoatically resync if we drift out

void set_encoder_time(double usec, long int date, int tz_minuteswest, int fps_num, int fps_den, int print);
void cleanup(int sig);
void resync(int sig);

//Borrowed from https://stackoverflow.com/questions/32424125/c-code-to-get-local-time-offset-in-minutes-relative-to-utc
int tz_offset_minutes(time_t t) {
struct tm local;
struct tm utc;
#ifdef WIN32
local = *localtime(&t);
utc = *gmtime (&t);
#else
if (!localtime_r(&t, &local) || !gmtime_r(&t, &utc))
return 0;
#endif
int diff = (local.tm_hour - utc.tm_hour) * 60 + (local.tm_min - utc.tm_min);

int delta_day = local.tm_mday - utc.tm_mday;
if ((delta_day == 1) || (delta_day < -1)) {
diff += 24 * 60;
} else if ((delta_day == -1) || (delta_day > 1)) {
diff -= 24 * 60;
}
return diff;
}


int process (jack_nframes_t nframes, void *arg) {
jack_default_audio_sample_t *out = jack_port_get_buffer (j_output_port, nframes);
Expand All @@ -83,24 +111,32 @@ int process (jack_nframes_t nframes, void *arg) {
double sync_usec;
struct timespec t;
my_clock_gettime(&t);
sync_usec = (t.tv_sec%86400)*1000000.0 + (t.tv_nsec/1000.0);
//This used to round to the nearest day here, but it messes up timezone adjustment...There should still be enough range in a double to cover >230 years from 1970
sync_usec = t.tv_sec*1000000.0 + (t.tv_nsec/1000.0);

if (sync_now) {
time_t now = t.tv_sec;
time_t now;
long int sync_date = 0;

sync_usec += nframes*1000000.0/(double)j_samplerate; // start next callback
sync_offset_ms= nframes*1000.0 / (double) j_samplerate;
sync_usec += 1000000.0 * ltc_frame_alignment(j_samplerate * fps_den / (double) fps_num, ltc_tv) / j_samplerate;
if(local_time)
{
tzoff = tz_offset_minutes((time_t)(sync_usec/1000000.0));
sync_usec += (double)tzoff * 60000000.0;
}
now = (time_t)(sync_usec/1000000.0);
#ifdef WIN32
struct tm *gm = gmtime (&now);
sync_date = gm->tm_mday*10000 + gm->tm_mon*100 + gm->tm_year;
sync_date = gm->tm_mday*10000 + (gm->tm_mon+1)*100 + (gm->tm_year%100);
#else
struct tm gm;
if (gmtime_r(&now, &gm))
sync_date = gm.tm_mday*10000 + gm.tm_mon*100 + gm.tm_year;
sync_date = gm.tm_mday*10000 + (gm.tm_mon+1)*100 + (gm.tm_year%100);
#endif

sync_usec += nframes*1000000.0/(double)j_samplerate; // start next callback
sync_offset_ms= nframes*1000.0 / (double) j_samplerate;
sync_usec += 1000000.0 * ltc_frame_alignment(j_samplerate * fps_den / (double) fps_num, ltc_tv) / j_samplerate;
set_encoder_time(sync_usec, sync_date, 0, fps_num, fps_den, 0);
sync_usec = fmod(sync_usec, 86400000000.0);
set_encoder_time(sync_usec, sync_date, tzoff, fps_num, fps_den, 0);
#if 1 // align fractional-frame msec with jack-period
int frame = (int)floor(((long long int)floor(sync_usec)%1000000)*(double)fps_num/(double)fps_den/1000000.0);
double foff= 1000000.0*(frame*(double)fps_den/(double)fps_num) - ((long long int)floor(sync_usec)%1000000);
Expand Down Expand Up @@ -216,6 +252,9 @@ void main_loop(void) {
pthread_mutex_lock (&ltc_thread_lock);
int last_underruns=0;
active=1;
int dst_was=-99;

time_t last_time_block = 0;

while(active==1) {
if (!sync_initialized) {
Expand All @@ -241,8 +280,11 @@ void main_loop(void) {
printf("audio ringbuffer underrun (%d)\n", underruns);
}

if (showdrift) {
showdrift=0;
time_t cur_time = 0;
if(auto_resync)
cur_time = time(NULL);
time_t time_block = 0;
if ((auto_resync && ((time_block = cur_time/30) != last_time_block)) || showdrift) {
SMPTETimecode stime;
int bo = jack_ringbuffer_read_space (j_rb)/sizeof(jack_default_audio_sample_t);
LTCFrame lf;
Expand All @@ -254,14 +296,45 @@ void main_loop(void) {
struct timespec t;
my_clock_gettime(&t);
double usec = (t.tv_sec%86400)*1000000.0 + (t.tv_nsec/1000.0);
printf("drift: %+.1f ltc-frames (off: %+.2f ms | lat:%d as)\n",(us-usec)*fps_num/1000000.0/fps_den, (us-usec)/1000.0, j_latency);
ltc_encoder_get_timecode(encoder, &stime);
printf("TC: %02d/%02d/%02d (DD/MM/YY) %02d:%02d:%02d:%02d %s\n",
//Add timezone, we're adding an extra day here to ensure the number is always positive after a negative timzone is added
usec = fmod(usec + 86400000000.0 + (double)tzoff * 60000000.0,86400000000.0);
double drift = us - usec;
if(auto_resync)
{
int dst = -99;
//DST can't change if we're in UTC, so only check if we're not.
if(local_time)
{
#ifdef WIN32
struct tm *local = localtime(&cur_time);
dst = local->tm_isdst;
#else
struct tm local;
if(localtime_r(&cur_time,&local))
dst = local.tm_isdst;
#endif
}
if(dst != dst_was || ((drift > 100000.0) || (drift < -100000.0)))
{
resync(SIGHUP);
//Show the drift twice (hopefully before and after the resync)
showdrift=2;
}
dst_was = dst;
}
if(showdrift > 0)
{
printf("drift: %+.1f ltc-frames (off: %+.2f ms | lat:%d as)\n",drift*fps_num/1000000.0/fps_den, drift/1000.0, j_latency);
ltc_encoder_get_timecode(encoder, &stime);
printf("TC: %02d/%02d/%02d (DD/MM/YY) %02d:%02d:%02d:%02d %s\n",
stime.days,stime.months,stime.years,
stime.hours,stime.mins,stime.secs,stime.frame,
stime.timezone
);
showdrift--;
}
}
last_time_block = time_block;

const int precache = 8192;
while (jack_ringbuffer_read_space (j_rb) < (precache * sizeof(jack_default_audio_sample_t))) {
Expand Down Expand Up @@ -303,6 +376,8 @@ static struct option const long_options[] =
{"minuteswest", required_argument, 0, 'm'},
{"wait", required_argument, 0, 'w'},
{"timecode", required_argument, 0, 't'},
{"auto-resync", no_argument, 0, 'r'},
{"localtime", no_argument, 0, 'l'},
{NULL, 0, NULL, 0}
};

Expand All @@ -315,7 +390,9 @@ static void usage (int status) {
" -f, --fps fps set frame-rate NUM[/DEN][ndf|df] default: 25/1ndf \n"
" -h, --help display this help and exit\n"
" -g, --volume float set output level in dBFS default -18db\n"
" -l, --localtime when using current time, do it in local TZ (not UTC)\n"
" -m, --timezone tz set timezone in minutes-west of UTC\n"
" -r, --auto-resync automatically resync if drift is more than 100ms\n"
" -t, --timecode time specify start-time/timecode [[[HH:]MM:]SS:]FF\n"
" -w, --wait wait for a key-stroke before starting.\n"
" -V, --version print version information and exit\n"
Expand Down Expand Up @@ -369,7 +446,6 @@ int main (int argc, char **argv) {
program_name = argv[0];
long long int msec = 0;// start timecode in ms from 00:00:00.00
long int date = 0;// bcd: 201012 = 20 Oct 2012
long int tzoff = 0;// time-zone in minuteswest
int wait_for_key = 0;

while ((c = getopt_long (argc, argv,
Expand All @@ -381,7 +457,9 @@ int main (int argc, char **argv) {
"z:" /* timezone */
"m:" /* timezone */
"w" /* wait */
"V", /* version */
"V" /* version */
"l" /* local time */
"r", /* auto-resync */
long_options, (int *) 0)) != EOF)
{
switch (c) {
Expand Down Expand Up @@ -444,6 +522,14 @@ int main (int argc, char **argv) {
}
break;

case 'r':
auto_resync=1;
break;

case 'l':
local_time=1;
break;

default:
usage (EXIT_FAILURE);
}
Expand Down

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