diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index fee760c56c..61ce24e3dd 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1236,6 +1236,7 @@ void *av_mallocz(unsigned int size);
 void av_free(void *ptr);
 void __av_freep(void **ptr);
 #define av_freep(p) __av_freep((void **)(p))
+void *av_fast_realloc(void *ptr, int *size, int min_size);
 /* for static data only */
 /* call av_free_static to release all staticaly allocated tables */
 void av_free_static(void);
diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
index 3e4610658c..1ac7366290 100644
--- a/libavcodec/h263dec.c
+++ b/libavcodec/h263dec.c
@@ -401,41 +401,19 @@ uint64_t time= rdtsc();
     if (buf_size == 0) {
         return 0;
     }
-    
+
     if(s->flags&CODEC_FLAG_TRUNCATED){
         int next;
-        ParseContext *pc= &s->parse_context;
         
-        pc->last_index= pc->index;
-
         if(s->codec_id==CODEC_ID_MPEG4){
             next= mpeg4_find_frame_end(s, buf, buf_size);
         }else{
             fprintf(stderr, "this codec doesnt support truncated bitstreams\n");
             return -1;
         }
-        if(next==-1){
-            if(buf_size + FF_INPUT_BUFFER_PADDING_SIZE + pc->index > pc->buffer_size){
-                pc->buffer_size= buf_size + pc->index + 10*1024;
-                pc->buffer= realloc(pc->buffer, pc->buffer_size);
-            }
-
-            memcpy(&pc->buffer[pc->index], buf, buf_size);
-            pc->index += buf_size;
+        
+        if( ff_combine_frame(s, next, &buf, &buf_size) < 0 )
             return buf_size;
-        }
-
-        if(pc->index){
-            if(next + FF_INPUT_BUFFER_PADDING_SIZE + pc->index > pc->buffer_size){
-                pc->buffer_size= next + pc->index + 10*1024;
-                pc->buffer= realloc(pc->buffer, pc->buffer_size);
-            }
-
-            memcpy(&pc->buffer[pc->index], buf, next + FF_INPUT_BUFFER_PADDING_SIZE );
-            pc->index = 0;
-            buf= pc->buffer;
-            buf_size= pc->last_index + next;
-        }
     }
 
 retry:
diff --git a/libavcodec/mem.c b/libavcodec/mem.c
index 0c876a851e..e59b25a223 100644
--- a/libavcodec/mem.c
+++ b/libavcodec/mem.c
@@ -71,6 +71,17 @@ void *av_malloc(unsigned int size)
     return ptr;
 }
 
+/**
+ * realloc which does nothing if the block is large enogh
+ */
+void *av_fast_realloc(void *ptr, int *size, int min_size){
+    if(min_size < *size) return ptr;
+    
+    *size= min_size + 10*1024;
+
+    return realloc(ptr, *size);
+}
+
 /* NOTE: ptr = NULL is explicetly allowed */
 void av_free(void *ptr)
 {
diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index c262191390..4d47dd4e0d 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -2627,6 +2627,35 @@ static void encode_mb(MpegEncContext *s, int motion_x, int motion_y)
 #endif
 }
 
+/**
+ * combines the (truncated) bitstream to a complete frame
+ * @returns -1 if no complete frame could be created
+ */
+int ff_combine_frame( MpegEncContext *s, int next, uint8_t **buf, int *buf_size){
+    ParseContext *pc= &s->parse_context;
+        
+    pc->last_index= pc->index;
+
+    if(next==-1){
+        pc->buffer= av_fast_realloc(pc->buffer, &pc->buffer_size, (*buf_size) + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);
+
+        memcpy(&pc->buffer[pc->index], *buf, *buf_size);
+        pc->index += *buf_size;
+        return -1;
+    }
+
+    if(pc->index){
+        pc->buffer= av_fast_realloc(pc->buffer, &pc->buffer_size, next + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);
+
+        memcpy(&pc->buffer[pc->index], *buf, next + FF_INPUT_BUFFER_PADDING_SIZE );
+        pc->index = 0;
+        *buf= pc->buffer;
+        *buf_size= pc->last_index + next;
+    }
+
+    return 0;
+}
+
 void ff_copy_bits(PutBitContext *pb, UINT8 *src, int length)
 {
     int bytes= length>>4;
diff --git a/libavcodec/mpegvideo.h b/libavcodec/mpegvideo.h
index 8408507071..7ecc6fd38c 100644
--- a/libavcodec/mpegvideo.h
+++ b/libavcodec/mpegvideo.h
@@ -604,6 +604,7 @@ void ff_draw_horiz_band(MpegEncContext *s);
 void ff_emulated_edge_mc(MpegEncContext *s, UINT8 *src, int linesize, int block_w, int block_h, 
                                     int src_x, int src_y, int w, int h);
 char ff_get_pict_type_char(int pict_type);
+int ff_combine_frame( MpegEncContext *s, int next, uint8_t **buf, int *buf_size);
 
 extern enum PixelFormat ff_yuv420p_list[2];