PHP从FLV文件获取视频预览图的方法

<?php

　　// references http://www.longtailvideo.com/support/forum/Modules/12661/External-PHP-with-FFmpeg-using-readfile-

　　// generate a preview image from an FLV file on-the-fly, or to save

　　// call with: ffmpeg_image.php?file=video.flv&time=00:00:05&browser=true

　　// call with: ffmpeg_image.php?file=video.flv&percent=75.3&browser=true

　　// no time defaults to "00:00:01" (one second), no browser defaults to "true"

　　$videofile = (isset($_GET['file'])) ? strval($_GET['file']) : 'video.flv';

　　$image = substr($videofile, 0, strlen($videofile) - 4);

　　$time = (isset($_GET['time'])) ? strval($_GET['time']) : '00:00:01';

　　// debug ("  File: ", $videofile);

　　// debug (" Image: ", $image);

　　// debug ("  Time: ", $time);

　　// check time format

　　if (!preg_match('/\d\d:\d\d:\d\d/', $time))

　　{

　　$time = "00:00:00";

　　}

　　if (isset($_GET['percent']))

　　{

　　$percent = $_GET['percent'];

　　// debug (" Percent: ", $percent);

　　ob_start();

　　exec("/usr/bin/ffmpeg -i \"". $videofile . "\" 2>&1");

　　$duration = ob_get_contents();

　　ob_end_clean();

　　// debug ("Duration: ", $duration);

　　preg_match('/Duration: (.*?),/', $duration, $matches);

　　$duration = $matches[1];

　　// debug ("Duration: ", $duration);

　　$duration_array = split(':', $duration);

　　$duration = $duration_array[0] * 3600 + $duration_array[1] * 60 + $duration_array[2];

　　$time = $duration * $percent / 100;

　　// debug (" Time: ", $time);

　　$time = intval($time/3600) . ":" . intval(($time-(intval($time/3600)*3600))/60) . ":" . sprintf("%01.3f", ($time-(intval($time/60)*60)));

　　// debug (" Time: ", $time);

　　}

　　$browser = (isset($_GET['browser'])) ? strval($_GET['browser']) : 'true';

　　// debug (" Browser: ", $browser);

　　if ($browser == "true")

　　{

　　header('Content-Type: image/png');

　　exec("/usr/bin/ffmpeg -vcodec png -i \"" . $videofile . "\" -ss " . $time . " -vframes 1 -f image2 -");

　　//header('Content-Type: image/jpeg');

　　//exec("/usr/bin/ffmpeg -vcodec mjpeg -i \"" . $videofile . "\" -ss " . $time . " -vframes 1 -f image2 -");

　　}

　　else

　　{

　　exec("/usr/bin/ffmpeg -vcodec png -i \"" . $videofile . "\" -ss " . $time . " -vframes 1 -f image2 \"" . $image . "\"%d.png");

　　//exec("/usr/bin/ffmpeg -vcodec mjpeg -i \"" . $videofile . "\" -ss " . $time . " -vframes 1 -f image2 \"" . $image . "\"%d.jpg");

　　}

　　?>