protected function readContent()
 {
     $this->version = pReadInt8($this->mp4->readP);
     $this->flags = pReadInt24($this->mp4->readP);
     if ($this->version == 0) {
         $this->creationTime = pReadInt32($this->mp4->readP);
         $this->modificationTime = pReadInt32($this->mp4->readP);
         $this->trackId = pReadInt32($this->mp4->readP);
         $this->reserved1 = pReadInt32($this->mp4->readP);
         $this->duration = pReadInt32($this->mp4->readP);
     } else {
         $this->creationTime = pReadInt64($this->mp4->readP);
         $this->modificationTime = pReadInt64($this->mp4->readP);
         $this->trackId = pReadInt32($this->mp4->readP);
         $this->reserved1 = pReadInt32($this->mp4->readP);
         $this->duration = pReadInt64($this->mp4->readP);
     }
     $this->reserved2 = pReadInt32($this->mp4->readP);
     $this->reserved3 = pReadInt32($this->mp4->readP);
     $this->layer = pReadInt16($this->mp4->readP);
     $this->predefined = pReadInt16($this->mp4->readP);
     $this->volume = pReadSI16($this->mp4->readP);
     $this->reserved4 = pReadInt16($this->mp4->readP);
     for ($i = 0; $i < 9; $i++) {
         $this->matrix[] = pReadInt32($this->mp4->readP);
     }
     $this->width = pReadSI32($this->mp4->readP);
     $this->height = pReadSI32($this->mp4->readP);
 }
 protected function readContent()
 {
     $this->version = pReadInt8($this->mp4->readP);
     $this->flags = pReadInt24($this->mp4->readP);
     if ($this->version == 0) {
         $this->creationTime = pReadInt32($this->mp4->readP);
         $this->modificationTime = pReadInt32($this->mp4->readP);
         $this->timeScale = pReadInt32($this->mp4->readP);
         $this->duration = pReadInt32($this->mp4->readP);
     } else {
         $this->creationTime = pReadInt64($this->mp4->readP);
         $this->modificationTime = pReadInt64($this->mp4->readP);
         $this->timeScale = pReadInt32($this->mp4->readP);
         $this->duration = pReadInt64($this->mp4->readP);
     }
     $this->rate = pReadSI32($this->mp4->readP);
     $this->volume = pReadSI16($this->mp4->readP);
     $this->reserved1 = pReadInt16($this->mp4->readP);
     $this->reserved2 = pReadInt32($this->mp4->readP);
     $this->reserved3 = pReadInt32($this->mp4->readP);
     for ($i = 0; $i < 9; $i++) {
         $this->matrix[] = pReadInt32($this->mp4->readP);
     }
     for ($i = 0; $i < 6; $i++) {
         $this->predefined[] = pReadInt32($this->mp4->readP);
     }
     $this->nextTrackId = pReadInt32($this->mp4->readP);
 }