Make sure that seq params are changed only once

Ensure with a check that sequence level coding tools flags
cannot be changed after the frist legitimate av1_pack_bitstream()
call that writes the sequence header.

Change-Id: I9cee8ace9b584e8bc6d81e0ebf3a1c891c93cd37

av1/encoder/encoder.c

diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index fa692e8..a50b1a7 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -2384,9 +2384,10 @@
   cm->allow_filter_intra = 1;
 
   // Init sequence level coding tools
-  // TODO(debargha): This should not be called after the first key frame.
-  // Need to add a check for that.
-  init_seq_coding_tools(&cm->seq_params, oxcf);
+  // This should not be called after the first key frame.
+  if (!cpi->seq_params_locked) {
+    init_seq_coding_tools(&cm->seq_params, oxcf);
+  }
 }
 
 AV1_COMP *av1_create_compressor(AV1EncoderConfig *oxcf,
@@ -2428,6 +2429,7 @@
   av1_rc_init(&cpi->oxcf, oxcf->pass, &cpi->rc);
 
   cm->current_video_frame = 0;
+  cpi->seq_params_locked = 0;
   cpi->partition_search_skippable_frame = 0;
   cpi->tile_data = NULL;
   cpi->last_show_frame_buf_idx = INVALID_IDX;
@@ -4156,7 +4158,7 @@
   }
 }
 
-static void encode_without_recode_loop(AV1_COMP *cpi) {
+static int encode_without_recode_loop(AV1_COMP *cpi) {
   AV1_COMMON *const cm = &cpi->common;
   int q = 0, bottom_index = 0, top_index = 0;  // Dummy variables.
 
@@ -4217,6 +4219,7 @@
   // seen in the last encoder iteration.
   // update_base_skip_probs(cpi);
   aom_clear_system_state();
+  return AOM_CODEC_OK;
 }
 
 static int encode_with_recode_loop(AV1_COMP *cpi, size_t *size, uint8_t *dest) {
@@ -4778,6 +4781,8 @@
     if (av1_pack_bitstream(cpi, dest, size) != AOM_CODEC_OK)
       return AOM_CODEC_ERROR;
 
+    cpi->seq_params_locked = 1;
+
     // Set up frame to show to get ready for stats collection.
     cm->frame_to_show = get_frame_new_buffer(cm);
 
@@ -4858,8 +4863,6 @@
   cm->single_tile_decoding = cpi->oxcf.single_tile_decoding;
   if (cm->large_scale_tile) cm->seq_params.frame_id_numbers_present_flag = 0;
 
-  cm->seq_params.monochrome = oxcf->monochrome;
-
   // For 1 pass CBR, check if we are dropping this frame.
   // Never drop on key frame.
   if (oxcf->pass == 0 && oxcf->rc_mode == AOM_CBR &&
@@ -4927,7 +4930,7 @@
 #endif  // CONFIG_CDF_UPDATE_MODE
 
   if (cpi->sf.recode_loop == DISALLOW_RECODE) {
-    encode_without_recode_loop(cpi);
+    if (encode_without_recode_loop(cpi) != AOM_CODEC_OK) return AOM_CODEC_ERROR;
   } else {
     if (encode_with_recode_loop(cpi, size, dest) != AOM_CODEC_OK)
       return AOM_CODEC_ERROR;
@@ -4999,6 +5002,8 @@
   if (av1_pack_bitstream(cpi, dest, size) != AOM_CODEC_OK)
     return AOM_CODEC_ERROR;
 
+  cpi->seq_params_locked = 1;
+
   if (skip_adapt) return AOM_CODEC_OK;
 
   if (cm->seq_params.frame_id_numbers_present_flag) {

av1/encoder/encoder.h

diff --git a/av1/encoder/encoder.h b/av1/encoder/encoder.h
index ec6350d..a53976d 100644
--- a/av1/encoder/encoder.h
+++ b/av1/encoder/encoder.h
@@ -562,6 +562,11 @@
   int resize_buffer_underflow;
   int resize_count;
 
+  // Sequence parameters have been transmitted already and locked
+  // or not. Once locked av1_change_config cannot change the seq
+  // parameters.
+  int seq_params_locked;
+
   // VARIANCE_AQ segment map refresh
   int vaq_refresh;