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<?php
require dirname(__FILE__) . '/matroska.php';
// Header for single VPx keyframe
function vpxFrameHeader($size, $width, $height, $codecID) {
return "\x1A\x45\xDF\xA3\x9F\x42\x86\x81\x01\x42\xF7\x81\x01\x42\xF2\x81"
. "\x04\x42\xF3\x81\x08\x42\x82\x84\x77\x65\x62\x6D\x42\x87\x81\x02"
. "\x42\x85\x81\x02\x18\x53\x80\x67\x08" . pack('N', $size + 173) . "\x11\x4D\x9B"
. "\x74\xB8\x4D\xBB\x8B\x53\xAB\x84\x15\x49\xA9\x66\x53\xAC\x81\x3D"
. "\x4D\xBB\x8B\x53\xAB\x84\x16\x54\xAE\x6B\x53\xAC\x81\x58\x4D\xBB"
. "\x8B\x53\xAB\x84\x1C\x53\xBB\x6B\x53\xAC\x81\x85\x4D\xBB\x8B\x53"
. "\xAB\x84\x1F\x43\xB6\x75\x53\xAC\x81\x97\x15\x49\xA9\x66\x96\x2A"
. "\xD7\xB1\x83\x0F\x42\x40\x44\x89\x84\x41\x20\x00\x00\x4D\x80\x81"
. "\x66\x57\x41\x81\x66\x16\x54\xAE\x6B\xA8\xAE\xA6\xD7\x81\x01\x73"
. "\xC5\x81\x01\x83\x81\x01\x23\xE3\x83\x83\x98\x96\x80\x86\x85" . $codecID
. "\xE0\x8C\xB0\x84" . pack('N', $width) . "\xBA\x84" . pack('N', $height)
. "\x1C\x53\xBB\x6B\x8D\xBB\x8B\xB3\x81\x00\xB7\x86\xF7\x81"
. "\x01\xF1\x81\x97\x1F\x43\xB6\x75\x08" . pack('N', $size + 13) . "\xE7\x81\x00"
. "\xA3\x08" . pack('N', $size + 4) . "\x81\x00\x00\x80";
}
// Locate first VPx keyframe of track $trackNumber after timecode $skip
function firstVPxFrame($segment, $trackNumber, $skip=0) {
foreach($segment as $x1) {
if ($x1->name() == 'Cluster') {
$cluserTimecode = $x1->Get('Timecode');
foreach($x1 as $x2) {
$blockRaw = NULL;
if ($x2->name() == 'SimpleBlock') {
$blockRaw = $x2->value();
} elseif ($x2->name() == 'BlockGroup') {
$blockRaw = $x2->get('Block');
}
if (isset($blockRaw)) {
$block = new MatroskaBlock($blockRaw);
if ($block->trackNumber == $trackNumber) {
$frame = $block->frames[0];
if ($block->keyframe) {
if (!isset($cluserTimecode) || $cluserTimecode + $block->timecode >= $skip) {
return $frame;
} elseif (!isset($frame1)) {
$frame1 = $frame;
}
}
}
}
}
}
}
return isset($frame1) ? $frame1 : NULL;
}
function videoData($filename) {
$data = array();
// Open file
$fileHandle = fopen($filename, 'rb');
if (!$fileHandle) {
error_log('could not open file');
return $data;
}
try {
$root = readMatroska($fileHandle);
// Locate segment information and tracks
$segment = $root->get('Segment');
if (!isset($segment)) throw new Exception('missing Segment element');
// Get segment information
$info = $segment->get('Info');
if (isset($info)) {
$timecodeScale = $info->get('TimecodeScale');
$duration = $info->get('Duration');
if (isset($timecodeScale) && isset($duration)) {
$data['duration'] = 1e-9 * $timecodeScale * $duration;
}
}
// Locate video track
$tracks = $segment->get('Tracks');
if (!isset($tracks)) throw new Exception('missing Tracks element');
foreach($tracks as $trackEntry) {
if ($trackEntry->name() == 'TrackEntry' && $trackEntry->get('TrackType') == 1) {
$videoTrack = $trackEntry;
break;
}
}
if (!isset($videoTrack)) throw new Exception('no video track');
// Get track information
$videoAttr = $videoTrack->get('Video');
if (isset($videoAttr)) {
$pixelWidth = $videoAttr->get('PixelWidth');
$pixelHeight = $videoAttr->get('PixelHeight');
if ($pixelWidth == 0 || $pixelHeight == 0) {
error_log('bad PixelWidth/PixelHeight');
$pixelWidth = NULL;
$pixelHeight = NULL;
}
$data['width'] = $videoAttr->get('DisplayWidth', $pixelWidth);
$data['height'] = $videoAttr->get('DisplayHeight', $pixelHeight);
if ($data['width'] == 0 || $data['height'] == 0) {
error_log('bad DisplayWidth/DisplayHeight');
$data['width'] = $pixelWidth;
$data['height'] = $pixelHeight;
}
}
// Extract frame to use as thumbnail
$trackNumber = $videoTrack->get('TrackNumber');
if (!isset($trackNumber)) throw new Exception('missing track number');
$codecID = $videoTrack->get('CodecID');
if ($codecID != 'V_VP8' && $codecID != 'V_VP9') throw new Exception('codec is not VP8 or VP9');
if (!isset($pixelWidth) || !isset($pixelHeight)) throw new Exception('no width or height');
if (isset($data['duration']) && $data['duration'] >= 5) {
$skip = 1e9 / $timecodeScale;
} else {
$skip = 0;
}
$frame = firstVPxFrame($segment, $trackNumber, $skip);
if (!isset($frame)) throw new Exception('no keyframes');
$data['frame'] = vpxFrameHeader($frame->size(), $pixelWidth, $pixelHeight, $codecID) . $frame->readAll();
} catch (Exception $e) {
error_log($e->getMessage());
}
fclose($fileHandle);
return $data;
}
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