OneArtPlease: /* The Script Interpreter */

2011-02-15T16:35:38Z

‎The Script Interpreter

OneArtPlease at 16:34, 15 February 2011

2011-02-15T16:34:04Z

OneArtPlease: Created page with "= About = This PHP script allows to trigger timed events based on the current frame number. This means that all Elphel related parameters can be altered at a specific keyframe. ..."

2011-02-15T16:33:41Z

Created page with "= About = This PHP script allows to trigger timed events based on the current frame number. This means that all Elphel related parameters can be altered at a specific keyframe. ..."

New page

= About =

This PHP script allows to trigger timed events based on the current frame number. This means that all Elphel related parameters can be altered at a specific keyframe.

== Code ==

The application consists of 2 files: the interpreter and the script. The script contains a list of events and the time when these events should be triggered. The interpreter loads the script and makes sure that the events are executed at the correct time.

===The Script Interpreter===
<pre>
<?
echo "<pre>";

if (!isset($_GET['script'])) {
die ("error no script provided");
} else {
$scriptname = $_GET['script'];
}
</highlightSyntax>
$frame_count = 0;
$startframecount = elphel_get_P_value(ELPHEL_FRAME);
$starttime = date("U");

$fh = fopen($scriptname, 'r');
$script_file_content = fread($fh, filesize($scriptname));
fclose($fh);

$events = array();

$scriptlines = explode ("\n", $script_file_content);
$index = 0;
foreach ($scriptlines as $scriptline) {
if ((substr($scriptline, 0, 1) == "#") || (substr($scriptline, 0, 2) == "//") || ($scriptline == "")) {
continue;
} else {
$parts = explode (":", $scriptline);
$frame = $parts[0];
$command = $parts[1];
$events[$index]['frame'] = $frame;
$events[$index]['command'] = $command;
$index++;
}
}

foreach ($events as $event) {
echo "time: ".$event['frame']." code: ".$event['command']."\r\n";
}

$run = false;

echo "script starting<br>\r\n"; @flush();

$nextexecutionindex = 0;
while ($frame_count < $events[count($events)-1]['frame']) {
$frame_count = elphel_get_P_value(ELPHEL_FRAME) - $startframecount;
if ($currentframecount != $frame_count) {
echo "Frame: ".$frame_count."\r\n"; @flush();
if($frame_count == $events[$nextexecutionindex]['frame']) {
echo "executing command from script: ".$events[$nextexecutionindex]['command']."\r\n";
eval($events[$nextexecutionindex]['command']);
$nextexecutionindex++;
}
$currentframecount = $frame_count;
}
}

echo "script completed after: ".(date("U") - $starttime)." seconds<br>\r\n";@flush();

//print_r (get_defined_constants());
echo "</pre>";

?>
</pre>

===The Script==
<pre>
# Apertus Camera Script
# Syntax:
# <Framenumber>:<PHP code to execute>
# Framenumber must be increasing with lines or the interpreter will break
25:elphel_set_P_value(ELPHEL_EXPOS, 40000);
50:elphel_set_P_value(ELPHEL_EXPOS, 50000);
75:elphel_set_P_value(ELPHEL_EXPOS, 60000);
</pre>

Note that the script uses frame numbers so the actual time when the events are executed depends on the current frame-rate of the camera. If the above sample script is run with 25fps it will change exposure values after 1 second, 2 seconds and 3 seconds. The beginning (frame 0) is when the interpreter loads the script.

==Usage==
Simply run it by accessing:
http://192.168.0.9/interpreter.php?script=scriptfilename

[[Category:Development_Topics]]

@@ Line 9: / Line 9: @@
 ===The Script Interpreter===
 <pre>
- <?
+<?
 if (!isset($_GET['script'])) {
    die ("error no script provided");
@@ Line 66: / Line 64: @@
 echo "script completed after: ".(date("U") - $starttime)." seconds<br>\r\n";@flush();
 ?>
 </pre>

@@ Line 75: / Line 75: @@
 </pre>
-===The Script==
+===The Script===
 <pre>
 # Apertus Camera Script

TimeScript - Revision history

OneArtPlease: /* The Script Interpreter */

OneArtPlease at 16:34, 15 February 2011

OneArtPlease: Created page with "= About = This PHP script allows to trigger timed events based on the current frame number. This means that all Elphel related parameters can be altered at a specific keyframe. ..."