code: public void write(IoBuffer buffer) {
          // FLV
          buffer.put(signature);
          // version
          buffer.put(version);
          // flags
          buffer.put((byte) (FLV_HEADER_FLAG_HAS_AUDIO * (flagAudio ? 1 : 0) + FLV_HEADER_FLAG_HAS_VIDEO * (flagVideo ? 1 : 0)));
          // data offset
          buffer.putInt(9);
          // previous tag size 0 (this is the "first" tag)
          buffer.putInt(0);
          buffer.flip();
      }
docs: Writes the FLVHeader to IoBuffer.
  
  @param buffer
  IoBuffer to write