Description: Make LibAvLogCallback thread safe
 FFmpeg requires the av_log callback to be threadsafe, but was not because it
 used the global "Previous" variable.
 .
 Fix by adding a QMutex and QMutexLocker to the function. Also use vsnprintf
 here to avoid any chance of a buffer overflow.
Author: James Cowgill <jcowgill@debian.org>
---
This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
--- a/src/ffDiaporama/engine/cDeviceModelDef.cpp
+++ b/src/ffDiaporama/engine/cDeviceModelDef.cpp
@@ -430,6 +430,7 @@ QString AllowMusicExtensions="wav#aac#ad
 
 //====================================================================================================================
 QString Previous;
+QMutex  LibAvLogMutex;
 int     LastLibAvMessageLevel=0;
 
 void LibAVLogCallback(void * /*ptr*/, int level, const char *fmt, va_list vargs) {
@@ -439,12 +440,14 @@ void LibAVLogCallback(void * /*ptr*/, in
 
     char    Buf[16384*10];
     int     MessageLevel=0;
-    vsprintf(Buf,fmt,vargs);
+    vsnprintf(Buf,sizeof(Buf),fmt,vargs);
     while ((strlen(Buf)>0)&&(Buf[strlen(Buf)-1]==32)) Buf[strlen(Buf)-1]=0;
     if (strlen(Buf)>0) {
         char    End=Buf[strlen(Buf)-1];
         QString DisplayMsg;
 
+        QMutexLocker locker(&LibAvLogMutex);
+
         if ((End==10)||(End==13)) {
             while ((strlen(Buf)>0)&&((Buf[strlen(Buf)-1]==10)||(Buf[strlen(Buf)-1]==13))) Buf[strlen(Buf)-1]=0;
             DisplayMsg=QString("LIBAV: ")+Previous+QString(Buf);