diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index 713fda7421..fe3bac0eae 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -3783,8 +3783,10 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
                         buf[buf_index + 2] == 1)
                         break;
 
-                if (buf_index + 3 >= buf_size)
+                if (buf_index + 3 >= buf_size) {
+                    buf_index = buf_size;
                     break;
+                }
 
                 buf_index += 3;
                 if (buf_index >= next_avc)
diff --git a/libavcodec/mpeg12.c b/libavcodec/mpeg12.c
index 2cf65e11c9..1d3d40d9b8 100644
--- a/libavcodec/mpeg12.c
+++ b/libavcodec/mpeg12.c
@@ -2241,7 +2241,7 @@ int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size,
 }
 
 static int decode_chunks(AVCodecContext *avctx,
-                         AVFrame *picture, int *data_size,
+                         AVFrame *picture, int *got_output,
                          const uint8_t *buf, int buf_size)
 {
     Mpeg1Context *s = avctx->priv_data;
@@ -2272,7 +2272,7 @@ static int decode_chunks(AVCodecContext *avctx,
 
                 if (slice_end(avctx, picture)) {
                     if (s2->last_picture_ptr || s2->low_delay) //FIXME merge with the stuff in mpeg_decode_slice
-                        *data_size = sizeof(AVPicture);
+                        *got_output = 1;
                 }
             }
             s2->pict_type = 0;
@@ -2509,7 +2509,7 @@ static int decode_chunks(AVCodecContext *avctx,
 }
 
 static int mpeg_decode_frame(AVCodecContext *avctx,
-                             void *data, int *data_size,
+                             void *data, int *got_output,
                              AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
@@ -2525,7 +2525,7 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
             *picture = s2->next_picture_ptr->f;
             s2->next_picture_ptr = NULL;
 
-            *data_size = sizeof(AVFrame);
+            *got_output = 1;
         }
         return buf_size;
     }
@@ -2546,17 +2546,17 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
     s->slice_count = 0;
 
     if (avctx->extradata && !s->parsed_extra) {
-        int ret = decode_chunks(avctx, picture, data_size, avctx->extradata, avctx->extradata_size);
-        if(*data_size) {
+        int ret = decode_chunks(avctx, picture, got_output, avctx->extradata, avctx->extradata_size);
+        if(*got_output) {
             av_log(avctx, AV_LOG_ERROR, "picture in extradata\n");
-            *data_size = 0;
+            *got_output = 0;
         }
         s->parsed_extra = 1;
         if (ret < 0 && (avctx->err_recognition & AV_EF_EXPLODE))
             return ret;
     }
 
-    return decode_chunks(avctx, picture, data_size, buf, buf_size);
+    return decode_chunks(avctx, picture, got_output, buf, buf_size);
 }