protected function writeContent()
 {
     pWriteInt8($this->mp4->writeP, $this->version);
     pWriteInt24($this->mp4->writeP, $this->flags);
     if ($this->version == 0) {
         pWriteInt32($this->mp4->writeP, $this->creationTime);
         pWriteInt32($this->mp4->writeP, $this->modificationTime);
         pWriteInt32($this->mp4->writeP, $this->trackId);
         pWriteInt32($this->mp4->writeP, $this->reserved1);
         pWriteInt32($this->mp4->writeP, $this->duration);
     } else {
         pWriteInt64($this->mp4->writeP, $this->creationTime);
         pWriteInt32($this->mp4->writeP, $this->modificationTime);
         pWriteInt32($this->mp4->writeP, $this->trackId);
         pWriteInt32($this->mp4->writeP, $this->reserved1);
         pWriteInt64($this->mp4->writeP, $this->duration);
     }
     pWriteInt32($this->mp4->writeP, $this->reserved2);
     pWriteInt32($this->mp4->writeP, $this->reserved3);
     pWriteInt16($this->mp4->writeP, $this->layer);
     pWriteInt16($this->mp4->writeP, $this->predefined);
     pWriteSI16($this->mp4->writeP, $this->volume);
     pWriteInt16($this->mp4->writeP, $this->reserved4);
     for ($i = 0; $i < 9; $i++) {
         pWriteInt32($this->mp4->writeP, $this->matrix[$i]);
     }
     pWriteSI32($this->mp4->writeP, $this->width);
     pWriteSI32($this->mp4->writeP, $this->height);
 }
 protected function writeContent()
 {
     pWriteInt8($this->mp4->writeP, $this->version);
     pWriteInt24($this->mp4->writeP, $this->flags);
     if ($this->version == 0) {
         pWriteInt32($this->mp4->writeP, $this->creationTime);
         pWriteInt32($this->mp4->writeP, $this->modificationTime);
         pWriteInt32($this->mp4->writeP, $this->timeScale);
         pWriteInt32($this->mp4->writeP, $this->duration);
     } else {
         pWriteInt64($this->mp4->writeP, $this->creationTime);
         pWriteInt32($this->mp4->writeP, $this->modificationTime);
         pWriteInt64($this->mp4->writeP, $this->timeScale);
         pWriteInt64($this->mp4->writeP, $this->duration);
     }
     pWriteSI32($this->mp4->writeP, $this->rate);
     pWriteSI16($this->mp4->writeP, $this->volume);
     pWriteInt16($this->mp4->writeP, $this->reserved1);
     pWriteInt32($this->mp4->writeP, $this->reserved2);
     pWriteInt32($this->mp4->writeP, $this->reserved3);
     for ($i = 0; $i < 9; $i++) {
         pWriteInt32($this->mp4->writeP, $this->matrix[$i]);
     }
     for ($i = 0; $i < 6; $i++) {
         pWriteInt32($this->mp4->writeP, $this->predefined[$i]);
     }
     pWriteInt32($this->mp4->writeP, $this->nextTrackId);
 }