[NORMATIVE] Add still image bit to seq header

BUG=aomedia:1708

Change-Id: Id8d7e4b025237f549c77ca1ef6435f81e415703a
diff --git a/av1/common/onyxc_int.h b/av1/common/onyxc_int.h
index 3c31ab2..831b8cf 100644
--- a/av1/common/onyxc_int.h
+++ b/av1/common/onyxc_int.h
@@ -193,7 +193,8 @@
   int force_integer_mv;            // 0 - Not to force. MV can be in 1/4 or 1/8
                                    // 1 - force to integer
                                    // 2 - adaptive
-  int monochrome;
+  int still_picture;               // Video is a single frame still picture
+  int monochrome;                  // Monochorme video
   int enable_filter_intra;         // enables/disables filterintra
   int enable_intra_edge_filter;    // enables/disables corner/edge/upsampling
   int enable_interintra_compound;  // enables/disables interintra_compound
diff --git a/av1/decoder/obu.c b/av1/decoder/obu.c
index cdf4983..e75f626 100644
--- a/av1/decoder/obu.c
+++ b/av1/decoder/obu.c
@@ -146,10 +146,14 @@
 
   cm->profile = av1_read_profile(rb);
 
+  SequenceHeader *seq_params = &cm->seq_params;
+
+  // Still picture or not
+  seq_params->still_picture = aom_rb_read_bit(rb);
+
   uint8_t operating_points_minus1_cnt = aom_rb_read_literal(rb, 5);
   pbi->common.enhancement_layers_cnt = operating_points_minus1_cnt + 1;
   int i;
-  SequenceHeader *seq_params = &cm->seq_params;
   for (i = 0; i < operating_points_minus1_cnt + 1; i++) {
     seq_params->operating_point_idc[i] = aom_rb_read_literal(rb, 12);
     seq_params->level[i] = aom_rb_read_literal(rb, 4);
diff --git a/av1/encoder/bitstream.c b/av1/encoder/bitstream.c
index 7c59568..83ca1a8 100644
--- a/av1/encoder/bitstream.c
+++ b/av1/encoder/bitstream.c
@@ -3328,6 +3328,9 @@
 
   write_profile(cm->profile, &wb);
 
+  // Still picture or not
+  aom_wb_write_bit(&wb, cm->seq_params.still_picture);
+
   uint8_t operating_points_minus1_cnt = enhancement_layers_cnt;
   aom_wb_write_literal(&wb, operating_points_minus1_cnt, 5);
   int i;
diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index c6539b5..4299346 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -891,6 +891,7 @@
 }
 
 void init_seq_coding_tools(SequenceHeader *seq, const AV1EncoderConfig *oxcf) {
+  seq->still_picture = 0;
   seq->force_screen_content_tools = 2;
   seq->force_integer_mv = 2;
   seq->order_hint_bits_minus1 = DEFAULT_EXPLICIT_ORDER_HINT_BITS - 1;