How to remove SID frame from RTP Jitter calculation ?

asked 2017-12-14 10:24:37 +0000

pixxav gravatar image

updated 2017-12-14 19:40:10 +0000

Hi everyone,

I'm using wireshark to analyse a VOLTE call. SIP frames are decoded, RTP is properly decoded as AMR (using AMR dynamic payload type = 104 and AMR coding = BW-efficient). Wireshark is able to find all the RTP streams and show the different statistics for each packet (jitter, delay, etc).

My issue is that AMR packets are sent with two possible intervals within the same Volte call, as displayed in the "FT bits":

  • every 40ms (*) (voice : AMR-WB 12.65 kbit/s)
  • or every 160ms (SID : AMR-WB SID (Comfort Noise Frame)

(*) : this interval can also be only 20ms depending on phone and radio network settings.

Unfortunately that's polluting the way the jitter is calculated. It would be great if the jitter could be computed twice : one jitter for voice frames , and one jitter for SID frames, depending on the FT bits.

I am going to do it manually, but that's quite painful... Anyone knows of a better way , please ?

Thanks a lot, PX

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