function http_stream_file($file_path) {
    if (!file_exists($file_path)) {
      throw new Exception('The file did not exist');
    }
    if (($file_size = filesize($file_path)) === false) {
      throw new Exception('Unable to get filesize.');
    }
  
  // Define start and end of stream
  $start = 0;
  $end = $file_size - 1; // Minus 1 (Byte ranges are zero-indexed)
  
  // Attempt to Open file for (r) reading (b=binary safe)
  if (($fp = @fopen($file_path, 'rb')) == false) {
    throw new Exception('Unable to open file.');
  }
  
  
  // -----------------------
  // Handle "range" requests
  // -----------------------
  // A Range request is sent when a client requests a specific part of a file
  // such as when using the video controls or when a download is resumed.
  // We need to handle range requests in order to send back the requested part of a file.
  
  // Determine if the "range" Request Header was set
  if (isset($_SERVER['HTTP_RANGE'])) {
  
    // Parse the range header
    if (preg_match('|=([0-9]+)-([0-9]+)$|', $_SERVER['HTTP_RANGE'], $matches)) {
      $start = $matches["1"];
      $end = $matches["2"] - 1;
    } elseif (preg_match('|=([0-9]+)-?$|', $_SERVER['HTTP_RANGE'], $matches)) {
      $start = $matches["1"];
    }
  
    // Make sure we are not out of range
    if (($start > $end) || ($start > $file_size) || ($end > $file_size) || ($end <= $start)) {
      http_response_code(416);
      exit();
    }
  
    // Position the file pointer at the requested range
    fseek($fp, $start);
  
    // Respond with 206 Partial Content
    http_response_code(206);
  
    // A "content-range" response header should only be sent if the "range" header was used in the request
      $response_headers['content-range'] = 'bytes ' . $start . '-' . $end . '/' . $file_size;
  } else {
    // If the range header is not used, respond with a 200 code and start sending some content
    http_response_code(200);
  }
  
  // Tell the client we support range-requests
  $response_headers['accept-ranges'] = 'bytes';
  // Set the content length to whatever remains
  $response_headers['content-length'] = ($file_size - $start);
  
  // ---------------------
  // Send the file headers
  // ---------------------
  // Send the "last-modified" response header
  // and compare with the "if-modified-since" request header (if present)
  
  if (($timestamp = filemtime($file_path)) !== false) {
    $response_headers['last-modified'] = gmdate("D, d M Y H:i:s", $timestamp) . ' GMT';
    if ((isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) && ($_SERVER['HTTP_IF_MODIFIED_SINCE'] == $response_headers['last-modified'])) {
      http_response_code(304); // Not Modified
      exit();
    }
  }
  
  // Set HTTP response headers
  $response_headers['content-type'] = 'video/mp4';

  foreach ($response_headers as $header => $value) {
    header($header . ': ' . $value);
  }
  
  // ---------------------
  // Start the file output
  // ---------------------
  $buffer = 8192;
  while (!feof($fp) && ($pointer = ftell($fp)) <= $end) {
  
    // If next $buffer will pass $end,
    // calculate remaining size
    if ($pointer + $buffer > $end) {
      $buffer = $end - $pointer + 1;
    }
    echo @fread($fp, $buffer);
      flush();
    }
    fclose($fp);
    exit();
  }

http_stream_file('some-video-file.mp4');