aboutsummaryrefslogtreecommitdiff
path: root/scripts/encode_smpte.pl
diff options
context:
space:
mode:
Diffstat (limited to 'scripts/encode_smpte.pl')
-rwxr-xr-xscripts/encode_smpte.pl181
1 files changed, 181 insertions, 0 deletions
diff --git a/scripts/encode_smpte.pl b/scripts/encode_smpte.pl
new file mode 100755
index 0000000..de8f427
--- /dev/null
+++ b/scripts/encode_smpte.pl
@@ -0,0 +1,181 @@
1#!/usr/bin/perl --
2#
3#http://en.wikipedia.org/wiki/SMPTE_time_code
4sub bitnum {
5 my ($val,$bit)=@_;
6 while (1==1) {
7 if ($bit<=0) {
8 return $val % 2;
9 }
10 $val=int($val/2);
11 $bit--;
12 }
13}
14my $lastframe=-1;
15my @smpteword;
16
17my $prevbitnum=-1;
18my $prevhalfbit=-1;
19my $prevoutval=0;
20sub smpte_modulate {
21 my ($currbitval,$bitnum,$halfbit)=@_;
22 if (($bitnum!=$prevbitnum) || (($halfbit!=$prevhalfbit) && ($currbitval==1)))
23 {
24 $prevoutval=1-$prevoutval;
25 }
26 $prevbitnum=$bitnum;
27 $prevhalfbit=$halfbit;
28 return $prevoutval;
29}
30
31sub smpte_timecodebit {
32 my ($insamplerate,$framerate,$nondrop,$insamnum)=@_;
33 my $samnum=$insamnum;
34 my $samplerate=$insamplerate;
35 if ($insamplerate!=48000)
36 {
37 $samplerate=48000;
38 $samnum=$insamnum*(48000/$insamplerate);
39 }
40 my $sampleinsecond=$samnum % $samplerate;
41 my $currentsecond=($samnum-$sampleinsecond)/$samplerate;
42 my $currenthour=int($currentsecond/3600);
43 $currentsecond-=3600*$currenthour;
44 my $currentminute=int($currentsecond/60);
45 $currentsecond-=60*$currentminute;
46 my $bitsperframe=80;
47 my $bitspersecond=$bitsperframe*$framerate;
48 my $samplesperbit=$samplerate/$bitspersecond;
49 my $samplesperframe=$samplerate/$framerate;
50 my $currentframe=int($sampleinsecond/$samplesperframe);
51 my $sampleinframe=$sampleinsecond-($currentframe*$samplesperframe);
52 my $bitinframe=int($sampleinframe/$samplesperbit);
53 my $subbit=int($sampleinframe-($bitinframe*$samplesperbit));
54 my $halfbit=($samplesperbit/2);
55
56 my $frameunits=($currentframe%10);
57 my $frametens=int(($currentframe-$frameunits)/10);
58
59 my $secondsunits=($currentsecond%10);
60 my $secondstems=int(($currentsecond-$secondunits)/10);
61
62 my $minuteunits=($currentminute%10);
63 my $minutetens=int(($currentminute-$minuteunits)/10);
64
65 my $hourunits=($currenthour%10);
66 my $hourtens=int(($currenthour-$hourunits)/10);
67
68 $smpteword[0]=bitnum($frameunits,0);
69 $smpteword[1]=bitnum($frameunits,1);
70 $smpteword[2]=bitnum($frameunits,2);
71 $smpteword[3]=bitnum($frameunits,3);
72 $smpteword[4]=0;
73 $smpteword[5]=0;
74 $smpteword[6]=0;
75 $smpteword[7]=0;
76 $smpteword[8]=bitnum($frametens,0);
77 $smpteword[9]=bitnum($frametens,1);
78 $smpteword[10]=0;
79 $smpteword[11]=0;
80 $smpteword[12]=0;
81 $smpteword[13]=0;
82 $smpteword[14]=0;
83 $smpteword[15]=0;
84 $smpteword[16]=bitnum($secondsunits,0);
85 $smpteword[17]=bitnum($secondsunits,1);
86 $smpteword[18]=bitnum($secondsunits,2);
87 $smpteword[19]=bitnum($secondsunits,3);
88 $smpteword[20]=0;
89 $smpteword[21]=0;
90 $smpteword[22]=0;
91 $smpteword[23]=0;
92 $smpteword[24]=bitnum($secondstens,0);
93 $smpteword[25]=bitnum($secondstens,1);
94 $smpteword[26]=bitnum($secondstens,2);
95 $smpteword[27]=0; #biphasemark, fill in later
96 $smpteword[28]=0;
97 $smpteword[29]=0;
98 $smpteword[30]=0;
99 $smpteword[31]=0;
100 $smpteword[32]=bitnum($minuteunits,0);
101 $smpteword[33]=bitnum($minuteunits,1);
102 $smpteword[34]=bitnum($minuteunits,2);
103 $smpteword[35]=bitnum($minuteunits,3);
104 $smpteword[36]=0;
105 $smpteword[37]=0;
106 $smpteword[38]=0;
107 $smpteword[39]=0;
108 $smpteword[40]=bitnum($minutetens,0);
109 $smpteword[41]=bitnum($minutetens,1);
110 $smpteword[42]=bitnum($minutetens,2);
111 $smpteword[43]=0; # binary group flag bit
112 $smpteword[44]=0;
113 $smpteword[45]=0;
114 $smpteword[46]=0;
115 $smpteword[47]=0;
116 $smpteword[48]=bitnum($hourunits,0);
117 $smpteword[49]=bitnum($hourunits,1);
118 $smpteword[50]=bitnum($hourunits,2);
119 $smpteword[51]=bitnum($hourunits,3);
120 $smpteword[52]=0;
121 $smpteword[53]=0;
122 $smpteword[54]=0;
123 $smpteword[55]=0;
124 $smpteword[56]=bitnum($hourtens,0);
125 $smpteword[57]=bitnum($hourtens,1);
126 $smpteword[58]=0; # reserved, must be 0
127 $smpteword[59]=0; # binary group flag bit
128 $smpteword[60]=0;
129 $smpteword[61]=0;
130 $smpteword[62]=0;
131 $smpteword[63]=0;
132
133 # sync word follows
134 $smpteword[64]=0;
135 $smpteword[65]=0;
136 $smpteword[66]=1;
137 $smpteword[67]=1;
138 $smpteword[68]=1;
139 $smpteword[69]=1;
140 $smpteword[70]=1;
141 $smpteword[71]=1;
142 $smpteword[72]=1;
143 $smpteword[73]=1;
144 $smpteword[74]=1;
145 $smpteword[75]=1;
146 $smpteword[76]=1;
147 $smpteword[77]=1;
148 $smpteword[78]=0;
149 $smpteword[79]=1;
150 my $parity=0;
151 for ($i=0;$i<=79;$i++) {
152 $parity+=$smpteword[$i];
153 }
154 $smpteword[27]=$parity & 1;
155
156 return $smpteword[$bitinframe];
157 # Enable this to also perform bit modulation:
158 # ###########################
159 if ($subbit<$halfbit) {
160 return smpte_modulate($smpteword[$bitinframe],$bitinframe,0);
161 }
162 return smpte_modulate($smpteword[$bitinframe],$bitinframe,1);
163 ##################################
164 # or only use this to return the raw SMPTE bits.
165}
166
167my $i;
168my $samplerate=48000;
169my $framerate=30;
170$startsam=0; #($samplerate/$framerate);
171my $nondrop=true;
172for ($samnum=$startsam;$samnum<1500000;$samnum+=10) {
173 $x=smpte_timecodebit($samplerate,$framerate,$nondrop,$samnum);
174 if ($x==0) {
175 print "0"; #chr(0);
176 } else {
177 print "1"; #chr(255);
178 }
179
180}
181
© 2015 Mike Crute