h264: Lower bound check for slice offsets
[ffmpeg.git] / libavcodec / h264.c
index 9cc32e9..7a81a71 100644 (file)
@@ -3840,8 +3840,8 @@ static int decode_slice_header(H264Context *h, H264Context *h0)
         get_se_golomb(&h->gb); /* slice_qs_delta */
 
     h->deblocking_filter     = 1;
-    h->slice_alpha_c0_offset = 52;
-    h->slice_beta_offset     = 52;
+    h->slice_alpha_c0_offset = 0;
+    h->slice_beta_offset     = 0;
     if (h->pps.deblocking_filter_parameters_present) {
         tmp = get_ue_golomb_31(&h->gb);
         if (tmp > 2) {
@@ -3854,10 +3854,12 @@ static int decode_slice_header(H264Context *h, H264Context *h0)
             h->deblocking_filter ^= 1;  // 1<->0
 
         if (h->deblocking_filter) {
-            h->slice_alpha_c0_offset += get_se_golomb(&h->gb) << 1;
-            h->slice_beta_offset     += get_se_golomb(&h->gb) << 1;
-            if (h->slice_alpha_c0_offset > 104U ||
-                h->slice_beta_offset     > 104U) {
+            h->slice_alpha_c0_offset = get_se_golomb(&h->gb) * 2;
+            h->slice_beta_offset     = get_se_golomb(&h->gb) * 2;
+            if (h->slice_alpha_c0_offset >  12 ||
+                h->slice_alpha_c0_offset < -12 ||
+                h->slice_beta_offset >  12     ||
+                h->slice_beta_offset < -12) {
                 av_log(h->avctx, AV_LOG_ERROR,
                        "deblocking filter parameters %d %d out of range\n",
                        h->slice_alpha_c0_offset, h->slice_beta_offset);
@@ -3894,7 +3896,7 @@ static int decode_slice_header(H264Context *h, H264Context *h0)
             }
         }
     }
-    h->qp_thresh = 15 + 52 -
+    h->qp_thresh = 15 +
                    FFMIN(h->slice_alpha_c0_offset, h->slice_beta_offset) -
                    FFMAX3(0,
                           h->pps.chroma_qp_index_offset[0],
@@ -3956,7 +3958,7 @@ static int decode_slice_header(H264Context *h, H264Context *h0)
                h->ref_count[0], h->ref_count[1],
                h->qscale,
                h->deblocking_filter,
-               h->slice_alpha_c0_offset / 2 - 26, h->slice_beta_offset / 2 - 26,
+               h->slice_alpha_c0_offset, h->slice_beta_offset,
                h->use_weight,
                h->use_weight == 1 && h->use_weight_chroma ? "c" : "",
                h->slice_type == AV_PICTURE_TYPE_B ? (h->direct_spatial_mv_pred ? "SPAT" : "TEMP") : "");