clean up frame extraction code

11 years ago · 14ac1b562d
2 changed files with 105 additions and 18 deletions
--- a/matroska.php
+++ b/matroska.php
@ -9,6 +9,7 @@ class EBMLElementType {
 // Information needed to parse all possible element types in a document
 class EBMLElementTypeList {
    private $_els;
+    private $_ids;

    public function __construct($filename) {
        $lines = file($filename);
@ -27,6 +28,7 @@ class EBMLElementTypeList {
                }
            }
            $this->_els[$id] = $t;
+            $this->_ids[strtoupper($t->name)] = $id;
        }
    }

@ -39,6 +41,12 @@ class EBMLElementTypeList {
        return $this->_els[$id]->name;
    }

+    public function id($name) {
+        $name = strtoupper($name);
+        if (!isset($this->_ids[$name])) return NULL;
+        return $this->_ids[$name];
+    }
+
    public function datatype($id) {
        if ($id == 'root') return 'container';
        if (!isset($this->_els[$id])) return 'binary';
@ -379,7 +387,7 @@ class EBMLElementList extends EBMLElement implements Iterator {
        foreach ($this as $element) {
            $iElement++;
            if ($iElement > self::$MAX_ELEMENTS) throw new Exception('not supported: too many elements');
-            if ($element->name() == $name) {
+            if (strtoupper($element->name()) == strtoupper($name)) {
                return $element->value();
            }
        }
@ -488,3 +496,27 @@ function readMatroska($fileHandle) {
    }
    return $root;
 }
+
+function encodeVarInt($n) {
+    $data = '';
+    $flag = 0x80;
+    while ($n >= $flag) {
+        if ($flag == 0) {
+            throw new Exception('not supported: number too large');
+        }
+        $data = chr($n & 0xFF) . $data;
+        $n = $n >> 8;
+        $flag = $flag >> 1;
+    }
+    $data = chr($n | $flag) . $data;
+    return $data;
+}
+
+function encodeElementName($name) {
+    global $EBML_ELEMENTS;
+    return encodeVarInt($EBML_ELEMENTS->id($name));
+}
+
+function encodeElement($name, $content) {
+    return encodeElementName($name) . encodeVarInt(strlen($content)) . $content;
+}
--- a/videodata.php
+++ b/videodata.php
@ -1,22 +1,77 @@
 <?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', $size + 4) . "\x81\x00\x00\x80";
+// Make video from single VPx keyframe
+function muxVPxFrame($width, $height, $codecID, $data) {
+    $size = strlen($data);
+    $lenSeekHead = 61;
+    $lenCues = 18;
+    $ebml = encodeElement('EBML',
+        encodeElement('EBMLVersion', "\x01")
+        . encodeElement('EBMLReadVersion', "\x01")
+        . encodeElement('EBMLMaxIDLength', "\x04")
+        . encodeElement('EBMLMaxSizeLength', "\x08")
+        . encodeElement('DocType', "webm")
+        . encodeElement('DocTypeVersion', "\x02")
+        . encodeElement('DocTypeReadVersion', "\x02")
+    );
+    $info = encodeElement('Info',
+        encodeElement('TimecodeScale', "\x0F\x42\x40")
+        . encodeElement('Duration', "\x41\x20\x00\x00")
+        . encodeElement('MuxingApp', 'f')
+        . encodeElement('WritingApp', 'f')
+    );
+    $tracks = encodeElement('Tracks',
+        encodeElement('TrackEntry',
+            encodeElement('TrackNumber', "\x01")
+            . encodeElement('TrackUID', "\x01")
+            . encodeElement('TrackType', "\x01")
+            . encodeElement('DefaultDuration', "\x98\x96\x80")
+            . encodeElement('CodecID', $codecID)
+            . encodeElement('Video',
+                encodeElement('PixelWidth', pack('N', $width))
+                . encodeElement('PixelHeight', pack('N', $height))
+            )
+        )
+    );
+    $cues = encodeElement('Cues',
+        encodeElement('CuePoint',
+            encodeElement('CueTime', "\x00")
+            . encodeElement('CueTrackPositions',
+                encodeElement('CueTrack', "\x01")
+                . encodeElement('CueClusterPosition', chr($lenSeekHead + strlen($info) + strlen($tracks) + $lenCues))
+            )
+        )
+    );
+    $seekHead = encodeElement('SeekHead',
+        encodeElement('Seek',
+            encodeElement('SeekID', encodeElementName('Info'))
+            . encodeElement('SeekPosition', chr($lenSeekHead))
+        )
+        . encodeElement('Seek',
+            encodeElement('SeekID', encodeElementName('Tracks'))
+            . encodeElement('SeekPosition', chr($lenSeekHead + strlen($info)))
+        )
+        . encodeElement('Seek',
+            encodeElement('SeekID', encodeElementName('Cues'))
+            . encodeElement('SeekPosition', chr($lenSeekHead + strlen($info) + strlen($tracks)))
+        )
+        . encodeElement('Seek',
+            encodeElement('SeekID', encodeElementName('Cluster'))
+            . encodeElement('SeekPosition', chr($lenSeekHead + strlen($info) + strlen($tracks) + $lenCues))
+        )
+    );
+    $cluster = "\x1F\x43\xB6\x75\x08" . pack('N', $size + 13) . (
+    //. encodeElement('Cluster',
+        encodeElement('Timecode', "\x00")
+        . "\xA3\x08" . pack('N', $size + 4) . ("\x81\x00\x00\x80" . $data)
+        //. encodeElement('SimpleBlock', "\x81\x00\x00\x80" . $data)
+    );
+    $segment = "\x18\x53\x80\x67\x08" . pack('N', $size + 173) . (
+    // . encodeElement('Segment',
+        $seekHead . $info . $tracks . $cues . $cluster
+    );
+    return $ebml . $segment;
 }

 // Locate first VPx keyframe of track $trackNumber after timecode $skip
@ -120,7 +175,7 @@ function videoData($filename) {
        }
        $frame = firstVPxFrame($segment, $trackNumber, $skip);
        if (!isset($frame)) throw new Exception('no keyframes');
-        $data['frame'] = vpxFrameHeader($frame->size(), $pixelWidth, $pixelHeight, $codecID) . $frame->readAll();
+        $data['frame'] = muxVPxFrame($pixelWidth, $pixelHeight, $codecID, $frame->readAll());

    } catch (Exception $e) {
        error_log($e->getMessage());