code: public void processPacketAESF8(RawPacket pkt) {
  		// 11 bytes of the RTP header are the 11 bytes of the iv
  		// the first byte of the RTP header is not used.
  		ByteBuffer buf = pkt.getBuffer();
  		buf.compact();
  		buf.get(ivStore, 0, 12);
  		ivStore[0] = 0;
  
  		// set the ROC in network order into IV
  		ivStore[12] = (byte) (this.roc >> 24);
  		ivStore[13] = (byte) (this.roc >> 16);
  		ivStore[14] = (byte) (this.roc >> 8);
  		ivStore[15] = (byte) this.roc;
  
  		final int payloadOffset = pkt.getHeaderLength();
  		final int payloadLength = pkt.getPayloadLength();
  
  		SRTPCipherF8.process(cipher, pkt.getBuffer(), payloadOffset, payloadLength, ivStore, cipherF8);
  	}
docs: Perform F8 Mode AES encryption / decryption
  
  @param pkt
  the RTP packet to be encrypted / decrypted