Hi Ravi,
I'm afraid the sample data you've given is not detail enough, i.e:
beside the new sample to be added (=91) and the mean (=95), could you
give a bit more detail on pj_math_stat instance fields values (at
least samples number/'n' and mean residu/'mean_res_') right before the
overflow happens.
Or if you could give a simple snippet code to reproduce the problem,
something like:
#define PJ_HAS_FLOATING_POINT 0
#include <pj/math.h>
int main() {
pj_math_stat ms;
pj_math_stat_init(&ms);
ms.mean_res_ = 0;
ms.mean = 95;
ms.n = 1000;
pj_math_stat_update(&ms, 91);
}
Regards,
nanang
2008/7/23 Ravi Inder Singh <raviinder at gmail.com>:
> Hi Benny,
> I don't have floating points so compiled off PJ_HAS_FLOATING_POINT & val(
> Jitter ) = 91 & mean = (95), so its simply taking integer values of delta.
> Its comes to be -4.
> Did i done something wrong please let me know ?
>
> Regards,
> Ravi Inder Singh
>
> On Tue, Jul 22, 2008 at 5:35 PM, Benny Prijono <bennylp at pjsip.org> wrote:
>>
>> On Tue, Jul 22, 2008 at 12:41 PM, Ravi Inder Singh <raviinder at gmail.com>
>> wrote:
>>>
>>> Hi all,
>>> Inside fuction pj_math_stat_update,calling from pjmedia_rtcp_xr_rx_rtp
>>> is leading to overflow in mean calculation, as jitter value is less than
>>> mean value & delta comes out to be in minus value.
>>>
>>> delta = val - stat->mean; {leads to minus value, coz while setting we
>>> make it divide by 16 in this code
>>>
>>> #if defined(PJMEDIA_HAS_RTCP_XR) && (PJMEDIA_HAS_RTCP_XR != 0)
>>> pjmedia_rtcp_xr_rx_rtp(&sess->xr_session, seq,
>>> 0, /* lost */
>>> 0, /* dup */
>>> discarded, /* discard */
>>> (sess->jitter >> 4), /* jitter */
>>> -1, 0); /* toh */
>>> #endif
>>>
>>> }
>>> This all leads to some overflow value in int variable, leading wrong
>>> results.
>>
>> Minus value in delta variable is perfectly fine, and unless you give
>> negative "val" value, the "fmean_" and "mean" variable will never have
>> negative value.
>>
>> Do you have sample data to prove your observation?
>>
>> Cheers
>> Benny
>>
>>
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>
>
>
> --
> Thanks & Regards,
> Ravi Inder Singh
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