The VideoLAN Forums

Posted: **18 Aug 2011 16:06**

I have a list of about 90 channels multicasted in the network. When Itry to use SAP announcement instead of playlist in file, I get constantly refreshing playlist with items shuffling here and there. Search on this forum shows that the problem is not new, see viewtopic.php?f=2&t=88020&hilit=sap and viewtopic.php?f=14&t=74301

Looking into the code the problem is in modules/services_discovery/sap.c in function Run, specifically in this code:

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  /* Remove the annoucement, if the last announcement was 1 hour ago
             * or if the last packet emitted was 3 times the average time
             * between two packets */
            if( ( p_announce->i_period_trust > 5 && i_last_period > 3 * p_announce->i_period ) ||
                i_last_period > i_timeout )
            {
                RemoveAnnounce( p_sd, p_announce );
            }
            else ...

When I change part of the condition from

Code: Select all

i_last_period > 3 * p_announce->i_period

to

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i_last_period > 30 * p_announce->i_period

everything is fixed and SAP list is rock solid.
Can this number be configurable for those of us who hit this problem?

Posted: **18 Aug 2011 16:37**

Obviously no, they are not configurable. And I guess they shouldn't be. The values may be wrong though.

Posted: **18 Aug 2011 17:20**

I've added a code to show the values of dynamic timeout,

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            if( ( p_announce->i_period_trust > 5 && i_last_period > 3 * p_announce->i_period ) )
                msg_Dbg( p_sd, "hit the leg:  i_last_period %llu, i_period %llu", i_last_period, p_announce->i_period );

here is the output:

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sap debug: hit the leg:  i_last_period 5071153, i_period 1682680
sap debug: hit the leg:  i_last_period 5071243, i_period 1682680
sap debug: hit the leg:  i_last_period 5069620, i_period 1683637
sap debug: hit the leg:  i_last_period 5069692, i_period 1683637
sap debug: hit the leg:  i_last_period 5072075, i_period 1683018
sap debug: hit the leg:  i_last_period 5072146, i_period 1683018
sap debug: hit the leg:  i_last_period 5072124, i_period 1683007
sap debug: hit the leg:  i_last_period 5072226, i_period 1683007
sap debug: hit the leg:  i_last_period 5072120, i_period 1683002
sap debug: hit the leg:  i_last_period 5072292, i_period 1683002
sap debug: hit the leg:  i_last_period 5072167, i_period 1682998
sap debug: hit the leg:  i_last_period 5072238, i_period 1682998
sap debug: hit the leg:  i_last_period 5072138, i_period 1683014
sap debug: hit the leg:  i_last_period 5072211, i_period 1683014
sap debug: hit the leg:  i_last_period 5072154, i_period 1683000
sap debug: hit the leg:  i_last_period 5072226, i_period 1683000
sap debug: hit the leg:  i_last_period 5072140, i_period 1683008
sap debug: hit the leg:  i_last_period 5072212, i_period 1683008
sap debug: hit the leg:  i_last_period 5074245, i_period 1683192
sap debug: hit the leg:  i_last_period 5074318, i_period 1683192
sap debug: hit the leg:  i_last_period 5072145, i_period 1682720
sap debug: hit the leg:  i_last_period 5072217, i_period 1682720
sap debug: hit the leg:  i_last_period 5070211, i_period 1683813
sap debug: hit the leg:  i_last_period 5070295, i_period 1683813

minisapserver in my network runs with sap_delay=5, I think i_last_period shows exactly this value in usecs.
Not sure how this correlates...

Posted: **18 Aug 2011 17:44**

I don't really grasp the timeout logic in the SAP receiver either.

Posted: **18 Aug 2011 18:34**

All I can add for now is that if I change sap_delay for minisapserver then timeout values change accordingly.
for example with sap_delay=15 I've got i_last_period 14949523, i_period 4960453.
Have to find the logic here...

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