7 Replies Latest reply: Apr 26, 2011 10:06 PM by attar RSS

    A question about Jitter Buff ?

    attar
      My application use jmf to send RTP audio data, but now I meet a question that sometimes the audio is not hear clearly and I get this packet with wireshark. If I use Jitter Buff 500MS, then I can here audio clearly, but with default config 50MS, the data drop by jitter buff at least >99%, why? How can I improve this ?
        • 1. Re: A question about Jitter Buff ?
          captfoss
          user11007219 wrote:
          the data drop by jitter buff at least >99%, why?
          RTP is designed for real-time streams, so maintaining real-time status is more important than quality...
          How can I improve this ?
          Well, you can make the internet less sucky about losing / delaying packets... transmit the RTP packets over TCP instead of UDP... or do the thing that you're already doing and increase the "Jitter Buf" to 500MS.
          • 2. Re: A question about Jitter Buff ?
            attar
            3q, I found if I start transmit RTP data before the last datasource did not stop, then I can not get the clear voice. Is it the problem?
            • 3. Re: A question about Jitter Buff ?
              captfoss
              user11007219 wrote:
              3q, I found if I start transmit RTP data before the last datasource did not stop, then I can not get the clear voice. Is it the problem?
              I have no idea what you just said...
              • 4. Re: A question about Jitter Buff ?
                attar
                "Well, you can make the internet less sucky about losing / delaying packets... transmit the RTP packets over TCP instead of UDP... or do the thing that you're already doing and increase the "Jitter Buf" to 500MS."

                How to increase the "Jitter Buff" with JMF?RTPManager?
                • 5. Re: A question about Jitter Buff ?
                  captfoss
                  attar wrote:
                  How to increase the "Jitter Buff" with JMF? RTPManager?
                  How the hell should I know, you said you'd already done it!

                  There is an example of changing around the capture and render buffers...
                  http://classic-web.archive.org/web/20071022054231/http://java.sun.com/products/java-media/jmf/2.1.1/solutions/AudioBufferControl.html

                  Additionally, there are a number of other "controls" you can get on your processor
                  http://download.oracle.com/docs/cd/E17802_01/j2se/javase/technologies/desktop/media/jmf/2.1.1/apidocs/javax/media/Control.html

                  I don't see anything specifically setup to allow you to change the jitter buffer size... only control I see that has any affect on RTP is the PacketSizeControl, which you could use. Smaller packets = more jitter, if I recall correctly.
                  • 6. Re: A question about Jitter Buff ?
                    attar
                    captfoss

                    I can not open the page "http://classic-web.archive.org/web/20071022054231/http://java.sun.com/products/java-media/jmf/2.1.1/solutions/AudioBufferControl.html", could you paste it here? 3Q~~
                    • 7. Re: A question about Jitter Buff ?
                      attar
                      Hi, captfoss:
                      I found the article about AudioBuffer, I fellow the step and add buff in my player(it is uesed to play audio from cilent-side rtp data) and datasource(it is uesed to get the micphone voice to transmit to cilent-side as rtp data), but it dose not worked...
                      so, could you have anothor solution?
                      3q