Fix to VP8 external RC for dynamic update of layers

On change/update of rc_cfg: when number of temporal
layers change call vp8_reset_temporal_layer_change(),
which in turn will call vp8_init_temporal_layer_context()
only for the new layers.

Bug:b/249644737

Change-Id: Ib20d746c7eacd10b78806ca6a5362c750d9ca0b3

vp8/encoder/onyx_if.c

@@ -328,8 +328,8 @@ void vp8_init_temporal_layer_context(VP8_COMP *cpi, VP8_CONFIG *oxcf,
 // for any "new" layers. For "existing" layers, let them inherit the parameters
 // from the previous layer state (at the same layer #). In future we may want
 // to better map the previous layer state(s) to the "new" ones.
-static void reset_temporal_layer_change(VP8_COMP *cpi, VP8_CONFIG *oxcf,
-                                        const int prev_num_layers) {
+void vp8_reset_temporal_layer_change(VP8_COMP *cpi, VP8_CONFIG *oxcf,
+                                     const int prev_num_layers) {
   int i;
   double prev_layer_framerate = 0;
   const int curr_num_layers = cpi->oxcf.number_of_layers;
@@ -1643,7 +1643,7 @@ void vp8_change_config(VP8_COMP *cpi, VP8_CONFIG *oxcf) {
       cpi->temporal_layer_id = 0;
     }
     cpi->temporal_pattern_counter = 0;
-    reset_temporal_layer_change(cpi, oxcf, prev_number_of_layers);
+    vp8_reset_temporal_layer_change(cpi, oxcf, prev_number_of_layers);
   }
 
   if (!cpi->initial_width) {

vp8/encoder/onyx_int.h

@@ -713,6 +713,8 @@ void vp8_initialize_enc(void);
 
 void vp8_alloc_compressor_data(VP8_COMP *cpi);
 int vp8_reverse_trans(int x);
+void vp8_reset_temporal_layer_change(VP8_COMP *cpi, VP8_CONFIG *oxcf,
+                                     const int prev_num_layers);
 void vp8_init_temporal_layer_context(VP8_COMP *cpi, VP8_CONFIG *oxcf,
                                      const int layer,
                                      double prev_layer_framerate);

vp8/vp8_ratectrl_rtc.cc

@@ -92,6 +92,7 @@ void VP8RateControlRTC::UpdateRateControl(
     const VP8RateControlRtcConfig &rc_cfg) {
   VP8_COMMON *cm = &cpi_->common;
   VP8_CONFIG *oxcf = &cpi_->oxcf;
+  const unsigned int prev_number_of_layers = oxcf->number_of_layers;
   vpx_clear_system_state();
   cm->Width = rc_cfg.width;
   cm->Height = rc_cfg.height;
@@ -124,17 +125,33 @@ void VP8RateControlRTC::UpdateRateControl(
         static_cast<int>(cpi_->output_framerate);
   }
 
-  if (oxcf->number_of_layers > 1) {
+  if (oxcf->number_of_layers > 1 || prev_number_of_layers > 1) {
     memcpy(oxcf->target_bitrate, rc_cfg.layer_target_bitrate,
            sizeof(rc_cfg.layer_target_bitrate));
     memcpy(oxcf->rate_decimator, rc_cfg.ts_rate_decimator,
            sizeof(rc_cfg.ts_rate_decimator));
-    oxcf->periodicity = 2;
+    if (cm->current_video_frame == 0) {
+      double prev_layer_framerate = 0;
+      for (unsigned int i = 0; i < oxcf->number_of_layers; ++i) {
+        vp8_init_temporal_layer_context(cpi_, oxcf, i, prev_layer_framerate);
+        prev_layer_framerate = cpi_->output_framerate / oxcf->rate_decimator[i];
+      }
+    } else if (oxcf->number_of_layers != prev_number_of_layers) {
+      // The number of temporal layers has changed, so reset/initialize the
+      // temporal layer context for the new layer configuration: this means
+      // calling vp8_reset_temporal_layer_change() below.
+
+      // Start at the base of the pattern cycle, so set the layer id to 0 and
+      // reset the temporal pattern counter.
+      // TODO(marpan/jianj): don't think lines 148-151 are needed (user controls
+      // the layer_id) so remove.
+      if (cpi_->temporal_layer_id > 0) {
+        cpi_->temporal_layer_id = 0;
+      }
+      cpi_->temporal_pattern_counter = 0;
 
-    double prev_layer_framerate = 0;
-    for (unsigned int i = 0; i < oxcf->number_of_layers; ++i) {
-      vp8_init_temporal_layer_context(cpi_, oxcf, i, prev_layer_framerate);
-      prev_layer_framerate = cpi_->output_framerate / oxcf->rate_decimator[i];
+      vp8_reset_temporal_layer_change(cpi_, oxcf,
+                                      static_cast<int>(prev_number_of_layers));
     }
   }