[mythtv-commits] Ticket #13391: Incorrect "Timed out" message with DVB-T channelscan

[MythTV]

#13391: Incorrect "Timed out" message with DVB-T channelscan
-------------------------------------+-------------------------------------
     Reporter:  Klaas de Waal        |      Owner:  (none)
         Type:  Patch - Bug Fix      |     Status:  new
     Priority:  minor                |  Milestone:  needs_triage
    Component:  MythTV - Channel     |    Version:  Master Head
  Scanner                            |   Keywords:  DVB DVB-T NIT timeout
     Severity:  medium               |  channelscan
Ticket locked:  0                    |
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 A channelscan with mythtv-setup of the local DVB-T signal gives sometimes
 "Timed out" messages:

 {{{
 2019-01-26 23:33:07.357716 I  ChannelScanSM(/dev/dvb/adapter1/frontend0):
 Transport ID 2244 -- Timed out, 19 possible channels

 }}}
 The problem is that the "Timed out" messages are also given sometimes when
 a transport is scanned correct.\\

 The code for this is found in channelscan_sm.cpp, function
 ChannelScanSM::UpdateChannelInfo().\\
 The "Timed out" message depends on the following comparison:

 {{{
        if ((m_timer.elapsed() > (int)m_channelTimeout))

 }}}
 However, the scanning code allows for larger timeout times if there are
 DVB (or ATSC/MPEG) tables needed, as documented in lines 68-75 of
 channelscan_sm.cpp:

 {{{
 /// SDT's should be sent every 2 seconds and NIT's every
 /// 10 seconds, so lets wait at least 30 seconds, in
 /// case of bad transmitter or lost packets.
 const uint ChannelScanSM::kDVBTableTimeout  = 30 * 1000;
 /// No logic here, lets just wait at least 10 seconds.
 const uint ChannelScanSM::kATSCTableTimeout = 10 * 1000;
 /// No logic here, lets just wait at least 15 seconds.
 const uint ChannelScanSM::kMPEGTableTimeout = 15 * 1000;

 }}}
 In my DVB-T signal, Digitenne in The Netherlands, the NIT is repeated
 every 8 seconds. The value of m_channelTimeout is 7 seconds (see also
 ticket #13380) so this causes a "Timed out" message once in a while even
 when the scan is correct.\\

 The larger timeout values in case of DVB tables are implemented in
 function HasTimedOut() which is called from
 ChannelScanSM::HandleActiveScan to decide if the scan has timed out.\\
 The attached patch replaces the comparison with a call to this function:

 {{{
 @ -984,7 +984,7 @@ bool ChannelScanSM::UpdateChannelInfo(bool
 wait_until_complete)
          }

          SignalMonitor *sm = GetSignalMonitor();
 -        if ((m_timer.elapsed() > (int)m_channelTimeout))
 +        if (HasTimedOut())
          {
              msg_tr = (cchan_cnt) ?
                  QObject::tr("%1 possible channels").arg(cchan_cnt) :

 }}}

 This patch has been tested with the local DVB-T and DVB-C signals.

-- 
Ticket URL: <https://code.mythtv.org/trac/ticket/13391>
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