diff --git a/source/app/InputStream.cpp b/source/app/InputStream.cpp
index 92d0553..2a5235a 100755
--- a/source/app/InputStream.cpp
+++ b/source/app/InputStream.cpp
@@ -71,6 +71,7 @@ QString InputStream::supportedReadFormats()
   formats = "*.yuv "  // Raw video
 #ifdef USE_FFMPEG
           "*.avi "   // Audio video interleaved
+          "*.mp4 "
           "*.wmv "// Windows media video
 #endif
       ;
@@ -94,6 +95,7 @@ QStringList InputStream::supportedReadFormatsList()
   formats << "Raw video (*.yuv)"
 #ifdef USE_FFMPEG
           << "Audio video interleaved (*.avi)"
+          << "MPEG4 (*.mp4)"
           << "Windows media video (*.wmv)"
 #endif
           ;
@@ -126,7 +128,8 @@ Bool InputStream::guessFormat( QString filename, UInt& rWidth, UInt& rHeight, In
       {
         resolutionString.remove( "_" );
         QStringList resolutionArgs = resolutionString.split( "x" );
-        qDebug( ) << "Found resolution = " << resolutionArgs;
+        qDebug( ) << "Found resolution = "
+                  << resolutionArgs;
         if( resolutionArgs.size() == 2 )
         {
           rWidth = resolutionArgs.at( 0 ).toUInt();
@@ -329,9 +332,9 @@ cv::Mat InputStream::getFrameCvMat()
 }
 #endif
 
-Void InputStream::seekInput( Int new_frame_num )
+Void InputStream::seekInput( UInt64 new_frame_num )
 {
-  if( new_frame_num < 0 || new_frame_num >= ( Int )m_uiTotalFrameNum )
+  if( new_frame_num < 0 || new_frame_num >= m_uiTotalFrameNum )
     return;
 #ifdef USE_FFMPEG
   if( m_cLibAvContext.getStatus() )
@@ -344,8 +347,8 @@ Void InputStream::seekInput( Int new_frame_num )
     UInt64 frame_bytes_input = m_ppcFrameBuffer[0]->getBytesPerFrame();
     UInt64 nbytes_seek = frame_bytes_input * new_frame_num;
     fseek( m_pFile, nbytes_seek, SEEK_SET );
-    m_iCurrFrameNum = new_frame_num - 1;
   }
+  m_iCurrFrameNum = new_frame_num - 1;
   readNextFrame();
   setNextFrame();
   readNextFrame();
diff --git a/source/app/InputStream.h b/source/app/InputStream.h
index 4b296e5..9485095 100755
--- a/source/app/InputStream.h
+++ b/source/app/InputStream.h
@@ -86,7 +86,7 @@ private:
   UInt m_uiWidth;
   UInt m_uiHeight;
   UInt m_uiFrameRate;
-  UInt m_uiTotalFrameNum;
+  UInt64 m_uiTotalFrameNum;
   Int m_iCurrFrameNum;
 
 public:
@@ -118,7 +118,7 @@ public:
   PlaYUVerFrame* getCurrFrame();
   PlaYUVerFrame* getCurrFrame( PlaYUVerFrame * );
 
-  Void seekInput( Int new_frame_num );
+  Void seekInput( UInt64 new_frame_num );
 
   Bool checkErrors( Int error_type );
 
diff --git a/source/app/SubWindowHandle.cpp b/source/app/SubWindowHandle.cpp
index d9716b9..a4db459 100644
--- a/source/app/SubWindowHandle.cpp
+++ b/source/app/SubWindowHandle.cpp
@@ -73,7 +73,7 @@ SubWindowHandle::~SubWindowHandle()
 Bool SubWindowHandle::loadFile( const QString &fileName )
 {
   UInt Width = 0, Height = 0, FrameRate = 30;
-  Int InputFormat = 0;
+  Int InputFormat = -1;
 
   if( m_pCurrStream->guessFormat( fileName, Width, Height, InputFormat, FrameRate ) )
   {
diff --git a/source/lib/ffmpeg/LibAvContextHandle.cpp b/source/lib/ffmpeg/LibAvContextHandle.cpp
index 8b4c6d0..807dcf7 100755
--- a/source/lib/ffmpeg/LibAvContextHandle.cpp
+++ b/source/lib/ffmpeg/LibAvContextHandle.cpp
@@ -102,7 +102,7 @@ Bool LibAvContextHandle::initAvFormat( char* filename, UInt& width, UInt& height
   /* register all formats and codecs */
   av_register_all();
 
-  if( width >= 0 && height >= 0 )
+  if( width > 0 && height > 0 )
   {
     Char aux_string[10];
     sprintf( aux_string, "%dx%d", width, height );
@@ -220,19 +220,19 @@ Bool LibAvContextHandle::initAvFormat( char* filename, UInt& width, UInt& height
 Bool LibAvContextHandle::decodeAvFormat()
 {
   Int got_frame;
-  int ret;
+  Bool bRet = false;
   /* read frames from the file */
 
-  if( av_read_frame( fmt_ctx, &pkt ) >= 0 )
+  while( av_read_frame( fmt_ctx, &pkt ) >= 0 && !bRet )
   {
     if( pkt.stream_index == video_stream_idx )
     {
       /* decode video frame */
-      ret = avcodec_decode_video2( video_dec_ctx, frame, &got_frame, &pkt );
+      Int ret = avcodec_decode_video2( video_dec_ctx, frame, &got_frame, &pkt );
       if( ret < 0 )
       {
         fprintf( stderr, "Error decoding video frame\n" );
-        return false;
+        return bRet;
       }
 
       if( got_frame )
@@ -242,13 +242,12 @@ Bool LibAvContextHandle::decodeAvFormat()
         av_image_copy( video_dst_data, video_dst_linesize, ( const uint8_t ** )( frame->data ), frame->linesize, video_dec_ctx->pix_fmt, video_dec_ctx->width,
             video_dec_ctx->height );
 
-        /* write to rawvideo file */
-        //fwrite( video_dst_data[0], 1, video_dst_bufsize, video_dst_file );
+        bRet = true;
       }
     }
     av_free_packet( &pkt );
   }
-
+  return bRet;
 //  /* flush cached frames */
 //  pkt.data = NULL;
 //  pkt.size = 0;
@@ -261,7 +260,7 @@ Bool LibAvContextHandle::decodeAvFormat()
   return true;
 }
 
-Void LibAvContextHandle::seekAvFormat( UInt frame_num )
+Void LibAvContextHandle::seekAvFormat( UInt64 frame_num )
 {
   av_seek_frame( fmt_ctx, video_stream_idx, frame_num, AVSEEK_FLAG_ANY );
 }
diff --git a/source/lib/ffmpeg/LibAvContextHandle.h b/source/lib/ffmpeg/LibAvContextHandle.h
index e8cb989..9fd15be 100755
--- a/source/lib/ffmpeg/LibAvContextHandle.h
+++ b/source/lib/ffmpeg/LibAvContextHandle.h
@@ -60,7 +60,7 @@ public:
   Void closeAvFormat();
   Bool decodeAvFormat();
 
-  Void seekAvFormat( UInt frame_num );
+  Void seekAvFormat( UInt64 frame_num );
 
   Bool getStatus()
   {