Duplicate channel number

In a channel scan, channels with duplicate channel numbers now
get a suffix A, B etc to make them unique.
In DVB the broadcasters can define logical channel numbers;
this are usuallly numbers from 1 upwards.
In ATSC a channel number can be a major/minor number, e.g. 7_2.
An ATSC channel number can also be defined by the broadcaster
as a single number from 1 upwards, similar to DVB.
If there is nothing defined then the service ID of the channel
is used as channel number. A service ID is generally unique
within a network but especially on satellites it can happen that
thereare different channels with the same service id.
When receiving OTA signals via aerials/antenna's it can happen
that the same multiplex is received from different transmitters.
This will also lead to duplicate channel numbers.
It is now easier to recognize duplicate channels because they
are shown next to each other in the program guide and in
the mythtv-setup channel editor.

Refs #13472

(cherry picked from commit 405e049)
Signed-off-by: Klaas de Waal <kdewaal@mythtv.org>

mythtv/libs/libmythtv/channelscan/channelimporter.cpp

@@ -109,6 +109,16 @@ void ChannelImporter::Process(const ScanDTVTransportList &_transports,
     // Channels not found in scan but only in DB are returned in db_trans
     sourceid = transports[0].m_channels[0].m_sourceId;
     ScanDTVTransportList db_trans = GetDBTransports(sourceid, transports);
+    if (VERBOSE_LEVEL_CHECK(VB_CHANSCAN, LOG_ANY))
+    {
+        if (!db_trans.empty())
+        {
+            cout << endl;
+            cout << "Transport list of transports with channels in DB but not in scan (";
+            cout << db_trans.size() << "):" << endl;
+            cout << FormatTransports(db_trans).toLatin1().constData() << endl;
+        }
+    }
 
     // Make sure "Open Cable" channels are marked that way.
     FixUpOpenCable(transports);
@@ -414,6 +424,17 @@ void ChannelImporter::InsertChannels(
         }
     }
 
+    // Updated transports
+    if (VERBOSE_LEVEL_CHECK(VB_CHANSCAN, LOG_ANY))
+    {
+        if (!updated.empty())
+        {
+            cout << endl;
+            cout << "Transport list (updated) (" << updated.size() << "):" << endl;
+            cout << FormatTransports(updated).toLatin1().constData() << endl;
+        }
+    }
+
     // List what has been done with each channel
     if (!updated.empty())
     {
@@ -928,6 +949,8 @@ void ChannelImporter::CleanupDuplicates(ScanDTVTransportList &transports)
                 if (!found_same)
                     transports[i].m_channels.push_back(transports[j].m_channels[k]);
             }
+            LOG(VB_CHANSCAN, LOG_INFO, LOC +
+                QString("Duplicate transport ") + FormatTransport(transports[j]));
             ignore[j] = true;
         }
         no_dups.push_back(transports[i]);
@@ -1567,9 +1590,12 @@ int ChannelImporter::SimpleCountChannels(
 /**
  * \fn ChannelImporter::ComputeSuggestedChannelNum
  *
- * Compute a suggested channel number based on various aspects of the
- * channel information. Check to see if this channel number conflicts
- * with an existing channel number. If so, fall back to incrementing a
+ * Compute a suggested channel number that is unique in the video source.
+ * Check first to see if the existing channel number conflicts
+ * with an existing channel number. If so, try adding a suffix
+ * starting with 'A' to make the number unique while still being
+ * recognizable. For instance, the second "7-2" channel will be called "7-2A".
+ * If this fails then fall back to incrementing a
  * per-source number to find an unused value.
  *
  * \param chan       Info describing a channel
@@ -1580,64 +1606,33 @@ QString ChannelImporter::ComputeSuggestedChannelNum(
 {
     static QMutex          s_lastFreeLock;
     static QMap<uint,uint> s_lastFreeChanNumMap;
+    QString chanNum;
 
     // Suggest existing channel number if non-conflicting
     if (!ChannelUtil::IsConflicting(chan.m_chanNum, chan.m_sourceId))
         return chan.m_chanNum;
 
-    // ATSC major-minor channel number
-    QString channelFormat = "%1_%2";
-    QString chan_num = channelFormat
-        .arg(chan.m_atscMajorChannel)
-        .arg(chan.m_atscMinorChannel);
-    if (chan.m_atscMajorChannel)
-    {
-        if (!ChannelUtil::IsConflicting(chan_num, chan.m_sourceId))
-            return chan_num;
-    }
-
-    // DVB
-    if (chan.m_siStandard == "dvb")
+    // Add a suffix to make it unique
+    for (char suffix = 'A'; suffix <= 'Z'; ++suffix)
     {
-        // Service ID
-        chan_num = QString("%1").arg(chan.m_serviceId);
-        if (!ChannelUtil::IsConflicting(chan_num, chan.m_sourceId))
-            return chan_num;
-
-        // Frequency ID (channel) - Service ID
-        if (!chan.m_freqId.isEmpty())
-        {
-            chan_num = QString("%1-%2")
-                          .arg(chan.m_freqId)
-                          .arg(chan.m_serviceId);
-            if (!ChannelUtil::IsConflicting(chan_num, chan.m_sourceId))
-                return chan_num;
-        }
-
-        // Service ID - Network ID
-        chan_num = QString("%1-%2").arg(chan.m_serviceId).arg(chan.m_netId);
-        if (!ChannelUtil::IsConflicting(chan_num, chan.m_sourceId))
-            return chan_num;
-
-        // Service ID - Transport ID
-        chan_num = QString("%1-%2").arg(chan.m_serviceId).arg(chan.m_patTsId);
-        if (!ChannelUtil::IsConflicting(chan_num, chan.m_sourceId))
-            return chan_num;
+        chanNum = chan.m_chanNum + suffix;
+        if (!ChannelUtil::IsConflicting(chanNum, chan.m_sourceId))
+            return chanNum;
     }
 
     // Find unused channel number
     QMutexLocker locker(&s_lastFreeLock);
     uint last_free_chan_num = s_lastFreeChanNumMap[chan.m_sourceId];
     for (last_free_chan_num++; ; ++last_free_chan_num)
     {
-        chan_num = QString::number(last_free_chan_num);
-        if (!ChannelUtil::IsConflicting(chan_num, chan.m_sourceId))
+        chanNum = QString::number(last_free_chan_num);
+        if (!ChannelUtil::IsConflicting(chanNum, chan.m_sourceId))
             break;
     }
     // cppcheck-suppress unreadVariable
     s_lastFreeChanNumMap[chan.m_sourceId] = last_free_chan_num;
 
-    return chan_num;
+    return chanNum;
 }
 
 ChannelImporter::DeleteAction