#11705

diff --git a/mythtv/libs/libmythtv/avformatdecoder.cpp b/mythtv/libs/libmythtv/avformatdecoder.cpp
index 23dd0ca..6b9a863 100644
--- a/mythtv/libs/libmythtv/avformatdecoder.cpp
+++ b/mythtv/libs/libmythtv/avformatdecoder.cpp
@@ -695,6 +695,8 @@ void AvFormatDecoder::SeekReset(long long newKey, uint skipFrames,

     DecoderBase::SeekReset(newKey, skipFrames, doflush, discardFrames);

+    QMutexLocker locker(avcodeclock);
+
     if (doflush)
     {
         lastapts = 0;
@@ -871,8 +873,8 @@ extern "C" void HandleStreamChange(void *data)
         QString("streams_changed 0x%1 -- stream count %2")
             .arg((uint64_t)data,0,16).arg(cnt));

-    QMutexLocker locker(avcodeclock);
     decoder->SeekReset(0, 0, true, true);
+    QMutexLocker locker(avcodeclock);
     decoder->ScanStreams(false);
 }

@@ -887,8 +889,8 @@ extern "C" void HandleDVDStreamChange(void *data)
         QString("streams_changed 0x%1 -- stream count %2")
             .arg((uint64_t)data,0,16).arg(cnt));

-    QMutexLocker locker(avcodeclock);
     //decoder->SeekReset(0, 0, true, true);
+    QMutexLocker locker(avcodeclock);
     decoder->ScanStreams(true);
 }

@@ -4661,6 +4663,7 @@ bool AvFormatDecoder::GetFrame(DecodeType decodetype)
             }

             int retval = 0;
+            avcodeclock->lock();
             if (!ic || ((retval = ReadPacket(ic, pkt, storevideoframes)) < 0))
             {
                 if (retval == -EAGAIN)
@@ -4670,8 +4673,10 @@ bool AvFormatDecoder::GetFrame(DecodeType decodetype)
                 delete pkt;
                 errno = -retval;
                 LOG(VB_GENERAL, LOG_ERR, QString("decoding error") + ENO);
+                avcodeclock->unlock();
                 return false;
             }
+            avcodeclock->unlock();

             if (waitingForChange && pkt->pos >= readAdjust)
                 FileChanged();
diff --git a/mythtv/libs/libmythtv/nuppeldecoder.cpp b/mythtv/libs/libmythtv/nuppeldecoder.cpp
index 2f805a2..dd44c3e 100644
--- a/mythtv/libs/libmythtv/nuppeldecoder.cpp
+++ b/mythtv/libs/libmythtv/nuppeldecoder.cpp
@@ -1385,6 +1385,8 @@ void NuppelDecoder::SeekReset(long long newKey, uint skipFrames,
             .arg((doFlush) ? "do" : "don't")
             .arg((discardFrames) ? "do" : "don't"));

+    QMutexLocker locker(avcodeclock);
+
     DecoderBase::SeekReset(newKey, skipFrames, doFlush, discardFrames);

     if (mpa_vidcodec && doFlush)