1 Reply Latest reply on Oct 11, 2012 7:50 AM by irekslonina

    QoS of RTMFP - poor video quality, can't use whole bandwidth



      I am developing videocall application using RTMFP.

      I have encountered a problem that I can't use whole bandwidth of the connection.


      I got 4Mbit/512kbit, through VPN but the video is delivered at around 400-600kbps, delivering poor quality.

      When I switch to a HSDPA connection, which has potentially lower capabilities, the video looks much, much better. It is achieving up to 1.2Mbit (around maximum needed for my video settings).


      I am guessing that Flash is trying to determine some network parameter and makes the limit at some bandwidth. But what parameter is that? How I can tweak the connection to achieve better video quality?

      I can use the whole bandwidth (4Mbit) between same peers by using some testing software, like iperf.


      I am using Flash 11.4.402.278.


      I would be very glad for any hint.


      Best regards,

      Irek Slonina

        • 1. Re: QoS of RTMFP - poor video quality, can't use whole bandwidth
          irekslonina Level 1

          I have figured out that the main difference my connections is the available upload speed.

          My VPN has 512up, and HSDPA has 1024up.

          I wasn't thinking that it is such a difference, because I was sending only up to 250kb/s, using only 50% of the upload.


          To describe problem more briefly:

          static video takes around 450kB/s, when video is moving, it can take up to 800kB/s


          When I'm connected to the 512kbs upload wire, the receiving video is getting choppy when video is getting higher.

          I got bufferTime=0 to ensure minimum latency.


          Is there any relationship in available upload and download speed? Does the video receiving client is sending back some sort of info about what he gets?

          Can I alter this relationship somehow?