diff --git a/ci.c b/ci.c
index e4f43209..a788781b 100644
--- a/ci.c
+++ b/ci.c
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: ci.c 4.7 2017/03/18 15:20:27 kls Exp $
+ * $Id: ci.c 4.8 2017/03/23 14:30:56 kls Exp $
  */
 
 #include "ci.h"
@@ -2205,6 +2205,8 @@ void cCamSlot::BuildCaPmts(uint8_t CmdId, cCiCaPmtList &CaPmtList, cMtdMapper *M
                }
             }
         }
+     else if (CmdId == CPCI_NOT_SELECTED)
+        CaPmtList.Add(CmdId, 0, 0, 0, NULL);
      }
 }
 
@@ -2343,7 +2345,7 @@ void cCamSlot::AddChannel(const cChannel *Channel)
 
 #define QUERY_REPLY_WAIT  100 // ms to wait between checks for a reply
 
-bool cCamSlot::CanDecrypt(const cChannel *Channel)
+bool cCamSlot::CanDecrypt(const cChannel *Channel, cMtdMapper *MtdMapper)
 {
   if (Channel->Ca() < CA_ENCRYPTED_MIN)
      return true; // channel not encrypted
@@ -2361,6 +2363,8 @@ bool cCamSlot::CanDecrypt(const cChannel *Channel)
          CaPmt.AddPid(*Dpid, STREAM_TYPE_PRIVATE);
      for (const int *Spid = Channel->Spids(); *Spid; Spid++)
          CaPmt.AddPid(*Spid, STREAM_TYPE_PRIVATE);
+     if (MtdMapper)
+        CaPmt.MtdMapPids(MtdMapper);
      cas->SendPMT(&CaPmt);
      cTimeMs Timeout(QUERY_REPLY_TIMEOUT);
      do {
@@ -2385,7 +2389,11 @@ void cCamSlot::StartDecrypting(void)
 void cCamSlot::StopDecrypting(void)
 {
   cMutexLock MutexLock(&mutex);
-  caProgramList.Clear();
+  if (caProgramList.Count()) {
+     caProgramList.Clear();
+     if (!dynamic_cast<cMtdCamSlot *>(this))
+        SendCaPmt(CPCI_NOT_SELECTED);
+     }
 }
 
 bool cCamSlot::IsDecrypting(void)
diff --git a/ci.h b/ci.h
index 78d4087d..0e8253d9 100644
--- a/ci.h
+++ b/ci.h
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: ci.h 4.4 2017/03/19 10:48:14 kls Exp $
+ * $Id: ci.h 4.5 2017/03/23 14:23:33 kls Exp $
  */
 
 #ifndef __CI_H
@@ -314,7 +314,7 @@ public:
        ///< If the source or transponder of the channel are different than
        ///< what was given in a previous call to AddChannel(), any previously
        ///< added PIDs will be cleared.
-  virtual bool CanDecrypt(const cChannel *Channel);
+  virtual bool CanDecrypt(const cChannel *Channel, cMtdMapper *MtdMapper = NULL);
        ///< Returns true if there is a CAM in this slot that is able to decrypt
        ///< the given Channel (or at least claims to be able to do so).
        ///< Since the QUERY/REPLY mechanism for CAMs is pretty unreliable (some
@@ -325,11 +325,18 @@ public:
        ///< to the initial QUERY will perform this check at all. CAMs that never
        ///< replied to the initial QUERY are assumed not to be able to handle
        ///< more than one channel at a time.
+       ///< If MtdMapper is given, all SIDs and PIDs will be mapped accordingly.
   virtual void StartDecrypting(void);
-       ///< Triggers sending all currently active CA_PMT entries to the CAM,
-       ///< so that it will start decrypting.
+       ///< Sends all CA_PMT entries to the CAM that have been modified since the
+       ///< last call to this function. This includes CA_PMTs that have been
+       ///< added or activated, as well as ones that have been deactivated.
+       ///< StartDecrypting() will be called whenever a PID is activated or
+       ///< deactivated.
   virtual void StopDecrypting(void);
        ///< Clears the list of CA_PMT entries and tells the CAM to stop decrypting.
+       ///< Note that this function is only called when there are no more PIDs for
+       ///< the CAM to decrypt. There is no symmetry between StartDecrypting() and
+       ///< StopDecrypting().
   virtual bool IsDecrypting(void);
        ///< Returns true if the CAM in this slot is currently used for decrypting.
   virtual uchar *Decrypt(uchar *Data, int &Count);
diff --git a/device.c b/device.c
index b6a6ee10..6f3a155d 100644
--- a/device.c
+++ b/device.c
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: device.c 4.8 2017/03/18 15:45:53 kls Exp $
+ * $Id: device.c 4.9 2017/03/23 14:19:59 kls Exp $
  */
 
 #include "device.h"
@@ -320,8 +320,8 @@ cDevice *cDevice::GetDevice(const cChannel *Channel, int Priority, bool LiveView
       if (!NumUsableSlots)
          break; // no CAM necessary, so just one loop over the devices
       }
-  if (d && !Query) {
-     if (NeedsDetachReceivers)
+  if (d) {
+     if (!Query && NeedsDetachReceivers)
         d->DetachAllReceivers();
      if (s) {
         // Some of the following statements could probably be combined, but let's keep them
@@ -333,9 +333,11 @@ cDevice *cDevice::GetDevice(const cChannel *Channel, int Priority, bool LiveView
                  }
               else {
                  // device d has a CAM slot, but it's not the right one
-                 d->CamSlot()->Assign(NULL);
-                 s = s->MtdSpawn();
-                 s->Assign(d);
+                 if (!Query) {
+                    d->CamSlot()->Assign(NULL);
+                    s = s->MtdSpawn();
+                    s->Assign(d);
+                    }
                  }
               }
            else {
@@ -343,9 +345,10 @@ cDevice *cDevice::GetDevice(const cChannel *Channel, int Priority, bool LiveView
                  if (s->Device() != d) {
                     // CAM slot s is currently assigned to a different device than d
                     if (Priority > s->Priority()) {
-                       s->Device()->DetachAllReceivers();
-                       d->CamSlot()->Assign(NULL);
-                       s->Assign(d);
+                       if (!Query) {
+                          d->CamSlot()->Assign(NULL);
+                          s->Assign(d);
+                          }
                        }
                     else {
                        d = NULL;
@@ -359,8 +362,10 @@ cDevice *cDevice::GetDevice(const cChannel *Channel, int Priority, bool LiveView
               else {
                  if (s != d->CamSlot()) {
                     // device d has a CAM slot, but it's not the right one
-                    d->CamSlot()->Assign(NULL);
-                    s->Assign(d);
+                    if (!Query) {
+                       d->CamSlot()->Assign(NULL);
+                       s->Assign(d);
+                       }
                     }
                  else {
                     // device d already has a proper CAM slot, so nothing to do here
@@ -372,16 +377,20 @@ cDevice *cDevice::GetDevice(const cChannel *Channel, int Priority, bool LiveView
            // device d has no CAM slot, ...
            if (s->MtdActive()) {
               // ... so we assign s with MTD support
-              s = s->MtdSpawn();
-              s->Assign(d);
+              if (!Query) {
+                 s = s->MtdSpawn();
+                 s->Assign(d);
+                 }
               }
            else {
               // CAM slot s has no MTD support ...
               if (s->Device()) {
                  // ... but it is assigned to a different device, so we reassign it to d
                  if (Priority > s->Priority()) {
-                    s->Device()->DetachAllReceivers();
-                    s->Assign(d);
+                    if (!Query) {
+                       s->Device()->DetachAllReceivers();
+                       s->Assign(d);
+                       }
                     }
                  else {
                     d = NULL;
@@ -390,7 +399,8 @@ cDevice *cDevice::GetDevice(const cChannel *Channel, int Priority, bool LiveView
                  }
               else {
                  // ... and is not assigned to any device, so we just assign it to d
-                 s->Assign(d);
+                 if (!Query)
+                    s->Assign(d);
                  }
               }
            }
diff --git a/mtd.c b/mtd.c
index b3a6af96..a09f0162 100644
--- a/mtd.c
+++ b/mtd.c
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: mtd.c 1.3 2017/03/19 14:20:22 kls Exp $
+ * $Id: mtd.c 1.4 2017/03/23 14:34:53 kls Exp $
  */
 
 #include "mtd.h"
@@ -262,10 +262,9 @@ bool cMtdCamSlot::ProvidesCa(const int *CaSystemIds)
   return MasterSlot()->ProvidesCa(CaSystemIds);
 }
 
-bool cMtdCamSlot::CanDecrypt(const cChannel *Channel)
+bool cMtdCamSlot::CanDecrypt(const cChannel *Channel, cMtdMapper *MtdMapper)
 {
-  //TODO PID mapping?
-  return MasterSlot()->CanDecrypt(Channel);
+  return MasterSlot()->CanDecrypt(Channel, mtdMapper);
 }
 
 void cMtdCamSlot::StartDecrypting(void)
@@ -277,15 +276,12 @@ void cMtdCamSlot::StartDecrypting(void)
 void cMtdCamSlot::StopDecrypting(void)
 {
   cCamSlot::StopDecrypting();
+  if (!MasterSlot()->IsDecrypting())
+     MasterSlot()->StopDecrypting();
   mtdMapper->Clear();
   clearBuffer = true;
 }
 
-bool cMtdCamSlot::IsDecrypting(void)
-{
-  return cCamSlot::IsDecrypting();
-}
-
 uchar *cMtdCamSlot::Decrypt(uchar *Data, int &Count)
 {
   // Send data to CAM:
diff --git a/mtd.h b/mtd.h
index b9cf55ae..15d29b83 100644
--- a/mtd.h
+++ b/mtd.h
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: mtd.h 1.3 2017/03/19 13:32:48 kls Exp $
+ * $Id: mtd.h 1.4 2017/03/23 12:48:22 kls Exp $
  */
 
 #ifndef __MTD_H
@@ -166,10 +166,9 @@ public:
   cMtdMapper *MtdMapper(void) { return mtdMapper; }
   virtual bool RepliesToQuery(void);
   virtual bool ProvidesCa(const int *CaSystemIds);
-  virtual bool CanDecrypt(const cChannel *Channel);
+  virtual bool CanDecrypt(const cChannel *Channel, cMtdMapper *MtdMapper = NULL);
   virtual void StartDecrypting(void);
   virtual void StopDecrypting(void);
-  virtual bool IsDecrypting(void);
   virtual uchar *Decrypt(uchar *Data, int &Count);
   int PutData(const uchar *Data, int Count);
   int PutCat(const uchar *Data, int Count);