Re: [Linphone-developers] help in unit of RTT in RTCP parse

[address@hidden]

Hi,

I had the same problem, 
probably you forgot to apply the following patch
to the oRTP/src/rtcp.c file:


Index: oRTP/src/rtcp.c
===================================================================
RCS file: /cvsroot/linphone/linphone/oRTP/src/rtcp.c,v
retrieving revision 1.7
diff -u -r1.7 rtcp.c
--- oRTP/src/rtcp.c     4 Mar 2005 13:30:15 -0000       1.7
+++ oRTP/src/rtcp.c     13 Jun 2005 20:56:16 -0000
@@ -234,7 +234,7 @@
        b->cum_num_packet_lost=htonl((guint32)stream->stats.cum_packet_loss);
        b->interarrival_jitter=htonl((guint32) stream->jittctl.inter_jitter);
        b->ext_high_seq_num_rec=htonl(stream->hwrcv_extseq.one);
-       b->lsr=stream->last_rcv_SR_ts;
+       b->lsr=htonl(stream->last_rcv_SR_ts);
        b->delay_snc_last_sr=htonl(delay_snc_last_sr);
 }

Regards,
Andrea


> Da: julien thai <address@hidden>
> Data: Thu, 30 Jun 2005 11:11:46 +0200
> A: Nicola Baldo <address@hidden>
> Oggetto: Re: [Linphone-developers] help in unit of RTT in RTCP parse
>
> Hi Nicola,
> 
> Thank for your explanation.
> Actually, i also think that the unit of RTT is in seconds from
> your algorithm.
>  But when i made a test between two softphone via Proxy.
> I heard very well the voice, but RTT was about > 3000 ( if it's in
> seconds, i can't imagine) so i asked a question.
>  For RFC 1889 and RFC 3550, for RFC 3550, page 33, it recommend that
> unit of DLSR is in 1/ 65536 s. But it don't recommend the unit of LSR, can
> you show me where they indicate in RFC? Thank you so much.
>  JT
>   
> 
>  2005/6/28, Nicola Baldo <address@hidden>: 
> > 
> > julien thai wrote:
> > > I read rtcpparse, in function report_block_parse,
> > > you found that you calcule RTT ( actually, i spent one day to understand
> > > your algorithm, it's great )
> > 
> > The algorithm is actually defined within RFC 1889, it's a part of the
> > RTP standard. If you look on the above mentioned RFC, on page 28,
> > there's a pretty straightforward explanation on how it works.
> > 
> > 
> > > I think unit of RTT you calculed is microsecond.
> > > Can you confirme it?
> > 
> > Well, referring to the file rtcpparse.c, the 'delay_snc_last_sr' and
> > 'lsr' values are in units of 1/65536 seconds (that's the specification
> > in the RFC for the LSR and DLSR fields), the 'rcv_time' variable is also
> > calculated in the same units. So the value of the 'rtt' variable, after
> > the division by 65536, is in seconds.
> > 
> > Regards,
> > 
> > Nicola
> > 
> >
>