RTP packet measurement module enabled VLC

• Descriptions

I've modified some codes of VLC to implement RTP packet measurement module.
The modified version make a log of RTP packet header into "rtp_packet_measurement_data" file,
which is created at the pwd directory when you starts VLC.
Then a simple parsing program which is in "vlc_source_root/modules/measurement/statistic.c" will
parse and analyse the log and print out those informations to console.

• the number of received RTP packets. Everytime that I get a RTP packet, I counted it.
   
• packet loss(%)
  After log all RTP packets, the "statistic program" sorts by the sequence number.
  Then packet loss is calculated like this :

total_number_of_packets = largest sequence number - smallest sequence number
packet_loss = recieved_packet_count / total_number_of_packets * 100 

• average jitter(in micro-seconds)
  Everytime the VLC get a RTP packet, it logs the time when the packet is received by using gettimeofday() function.
  I calculated the time, just like VLC streaming module via RTP like this :
  

recieved_time = current_time.tv_sec * 1000000 + current_time.tv_usec
recieved_time = recieved_time * 9 / 100
 

• variance of packet dis-order
  I defined the variance of packet dis-order like this :

When we compare the received order with the sorted RTP packet log by sequence number, the position difference is the degree of dis-order. I've sum up all the degree of dis-order, then average it. For example, if the recived RTP packet order is "5,2,3,4,1" and the sorted one is "1,2,3,4,5", then the degree of dis-order is "8", because "5" is apart from its expected posiont by "4" and "1" is also apart from its expected position by "4", so "8" in total. the average is "8/5" which is "1.6". So the variance of packet dis-order is "1.6" in this example.

• How to use it?
  I have developed and tested at Linux with X server enabled. In other OSes, help by yourself :D
   
1. Download the modified version of VLC here.
2. Install the required libraries by yourself.
3. Build it by using the "vlc_install.sh" script, which I created, in the source root directory.
4. Run the "vlc" with X server-enabled.
5. Get a RTP stream by using the command "vlc" as a client.
   Then, the RTP header log file, "rtp_packet_measurement_data", will be created at your running directory.
6. Stop VLC. Build the log file analysis tool, "vlc_source_root/modules/measurement/statistic.c".
   If you already build the tool, just run it with the "rtp_packet_measurement_data" file within same directory.
7. You will see the analysed informations on your console.

• Author Informations

Division of Computer Science,
Department of Electrical Engineering and Computer Science,
Korea Advanced Institute of Science and Technology (KAIST),
373-1 Guseong-dong, Yuseong-gu,
Daejeon,305-701
Republic of Korea
Email: dhhan@cosmos.kaist.ac.kr
Phone: +42-869-3554, Fax: +42-869-5554