Re: [Linphone-developers] oRTP and statistics

[Nicola Baldo]

Hi,

Eduardo Bezerra wrote:

>    I need to get the packet loss statistics from a RTP session. So, I am 
> using the  packet_loss variable
> from the report_block_init() function in the rtcp.c file. But sometimes 
> the variables gets a negative value.
> So, I need to know if packet_loss is the right variable to use. If it 
> is, I need to know why it is getting a negative
> value. Can anyone help me??

I actually don't remember how it's implemented in oRTP, but I remember 
that in RFC 1889 it is specified that the packet losses to be reported 
within RTCP (that's the variable you're using) can be negative:

[quote: RFC 1889]
   cumulative number of packets lost: 24 bits
        The total number of RTP data packets from source SSRC_n that
        have been lost since the beginning of reception. This number is
        defined to be the number of packets expected less the number of
        packets actually received, where the number of packets received
        includes any which are late or duplicates. Thus packets that
        arrive late are not counted as lost, and the loss may be
        negative if there are duplicates.
[/quote]

HTH

Nicola