EXT_DELTA_Q: make segment and SB deltas add.

As per spec, if delta quant is signalled at the superblock
and at the segment level both should be allowed and the
deltas should be summed to get the correct quant.

BUG=aomedia:897

Change-Id: Ia07265c944c9969befa16f194e02bf4e7a8dd142

av1/decoder/decodeframe.c

@@ -4014,6 +4014,8 @@ static size_t read_uncompressed_header(AV1Decoder *pbi,
   setup_segmentation(cm, rb);
 
   {
+    int delta_q_allowed = 1;
+#if !CONFIG_EXT_DELTA_Q
     struct segmentation *const seg = &cm->seg;
     int segment_quantizer_active = 0;
     for (i = 0; i < MAX_SEGMENTS; i++) {
@@ -4021,6 +4023,8 @@ static size_t read_uncompressed_header(AV1Decoder *pbi,
         segment_quantizer_active = 1;
       }
     }
+    delta_q_allowed = !segment_quantizer_active;
+#endif
 
     cm->delta_q_res = 1;
 #if CONFIG_EXT_DELTA_Q
@@ -4030,7 +4034,7 @@ static size_t read_uncompressed_header(AV1Decoder *pbi,
     cm->delta_lf_multi = 0;
 #endif  // CONFIG_LOOPFILTER_LEVEL
 #endif
-    if (segment_quantizer_active == 0 && cm->base_qindex > 0) {
+    if (delta_q_allowed == 1 && cm->base_qindex > 0) {
       cm->delta_q_present_flag = aom_rb_read_bit(rb);
     } else {
       cm->delta_q_present_flag = 0;
@@ -4039,7 +4043,6 @@ static size_t read_uncompressed_header(AV1Decoder *pbi,
       xd->prev_qindex = cm->base_qindex;
       cm->delta_q_res = 1 << aom_rb_read_literal(rb, 2);
 #if CONFIG_EXT_DELTA_Q
-      assert(!segment_quantizer_active);
       cm->delta_lf_present_flag = aom_rb_read_bit(rb);
       if (cm->delta_lf_present_flag) {
         xd->prev_delta_lf_from_base = 0;

av1/encoder/bitstream.c

@@ -4488,6 +4488,8 @@ static void write_uncompressed_header_frame(AV1_COMP *cpi,
   encode_quantization(cm, wb);
   encode_segmentation(cm, xd, wb);
   {
+    int delta_q_allowed = 1;
+#if !CONFIG_EXT_DELTA_Q
     int i;
     struct segmentation *const seg = &cm->seg;
     int segment_quantizer_active = 0;
@@ -4496,15 +4498,18 @@ static void write_uncompressed_header_frame(AV1_COMP *cpi,
         segment_quantizer_active = 1;
       }
     }
+    delta_q_allowed = !segment_quantizer_active;
+#endif
 
     if (cm->delta_q_present_flag) assert(cm->base_qindex > 0);
-    if (segment_quantizer_active == 0 && cm->base_qindex > 0) {
+    // Segment quantizer and delta_q both allowed if CONFIG_EXT_DELTA_Q
+    if (delta_q_allowed == 1 && cm->base_qindex > 0) {
       aom_wb_write_bit(wb, cm->delta_q_present_flag);
       if (cm->delta_q_present_flag) {
         aom_wb_write_literal(wb, OD_ILOG_NZ(cm->delta_q_res) - 1, 2);
         xd->prev_qindex = cm->base_qindex;
 #if CONFIG_EXT_DELTA_Q
-        assert(seg->abs_delta == SEGMENT_DELTADATA);
+        assert(cm->seg.abs_delta == SEGMENT_DELTADATA);
         aom_wb_write_bit(wb, cm->delta_lf_present_flag);
         if (cm->delta_lf_present_flag) {
           aom_wb_write_literal(wb, OD_ILOG_NZ(cm->delta_lf_res) - 1, 2);
@@ -4821,6 +4826,8 @@ static void write_uncompressed_header_obu(AV1_COMP *cpi,
   encode_quantization(cm, wb);
   encode_segmentation(cm, xd, wb);
   {
+    int delta_q_allowed = 1;
+#if !CONFIG_EXT_DELTA_Q
     int i;
     struct segmentation *const seg = &cm->seg;
     int segment_quantizer_active = 0;
@@ -4829,10 +4836,12 @@ static void write_uncompressed_header_obu(AV1_COMP *cpi,
         segment_quantizer_active = 1;
       }
     }
+    delta_q_allowed = !segment_quantizer_active;
+#endif
 
     if (cm->delta_q_present_flag)
-      assert(segment_quantizer_active == 0 && cm->base_qindex > 0);
-    if (segment_quantizer_active == 0 && cm->base_qindex > 0) {
+      assert(delta_q_allowed == 1 && cm->base_qindex > 0);
+    if (delta_q_allowed == 1 && cm->base_qindex > 0) {
       aom_wb_write_bit(wb, cm->delta_q_present_flag);
       if (cm->delta_q_present_flag) {
         aom_wb_write_literal(wb, OD_ILOG_NZ(cm->delta_q_res) - 1, 2);