[Live-devel] Does live555 RTSP client support RTP AMR frames redundant?

changchun.zhang at tektronix.com changchun.zhang at tektronix.com
Fri Jan 22 01:21:20 PST 2010


Hi Experts,

I am not sure if the live555 support redundant AMR frames in RTP streams. I don't see such code in the live555 lib. So if the SDP contains max-red >0, how does the RTSP client react such RTP stream?

Attach is the description on max-red in SDP described in RFC4867, section 8:
max-red: The maximum duration in milliseconds that elapses between
               the primary (first) transmission of a frame and any
               redundant transmission that the sender will use.  This
               parameter allows a receiver to have a bounded delay when
               redundancy is used.  Allowed values are between 0 (no
               redundancy will be used) and 65535.  If the parameter is
               omitted, no limitation on the use of redundancy is
               present.
and the example in section 3.7.1 figure 1:
  --+--------+--------+--------+--------+--------+--------+--------+--
     | f(n-2) | f(n-1) |  f(n)  | f(n+1) | f(n+2) | f(n+3) | f(n+4) |
   --+--------+--------+--------+--------+--------+--------+--------+--

     <---- p(n-1) ---->
              <----- p(n) ----->
                       <---- p(n+1) ---->
                                <---- p(n+2) ---->
                                         <---- p(n+3) ---->
                                                  <---- p(n+4) ---->

              Figure 1: An example of redundant transmission


Zhang, Changchun  | NM | CDC | Tektronix Communications | +86 21 38960464 | changchun.zhang at tektronix.com<mailto:zhang.changchun at tektronix.com>

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