Cleaning up vp9_svc_layercontext.c

Change-Id: I7c94b02f621ccc1a738b0d52edf60e9012cfc014

vp9/encoder/vp9_svc_layercontext.c

@@ -15,13 +15,14 @@
 
 void vp9_init_layer_context(VP9_COMP *const cpi) {
   const VP9_CONFIG *const oxcf = &cpi->oxcf;
-  int temporal_layer = 0;
+  int layer;
+
   cpi->svc.spatial_layer_id = 0;
   cpi->svc.temporal_layer_id = 0;
-  for (temporal_layer = 0; temporal_layer < cpi->svc.number_temporal_layers;
-      ++temporal_layer) {
-    LAYER_CONTEXT *const lc = &cpi->svc.layer_context[temporal_layer];
+  for (layer = 0; layer < cpi->svc.number_temporal_layers; ++layer) {
+    LAYER_CONTEXT *const lc = &cpi->svc.layer_context[layer];
     RATE_CONTROL *const lrc = &lc->rc;
+
     lrc->avg_frame_qindex[INTER_FRAME] = q_trans[oxcf->worst_allowed_q];
     lrc->last_q[INTER_FRAME] = q_trans[oxcf->worst_allowed_q];
     lrc->ni_av_qi = q_trans[oxcf->worst_allowed_q];
@@ -35,11 +36,9 @@ void vp9_init_layer_context(VP9_COMP *const cpi) {
     lrc->decimation_factor = 0;
     lrc->rate_correction_factor = 1.0;
     lrc->key_frame_rate_correction_factor = 1.0;
-    lc->target_bandwidth = oxcf->ts_target_bitrate[temporal_layer] *
-        1000;
-    lrc->buffer_level =
-        vp9_rescale((int)(oxcf->starting_buffer_level),
-                    lc->target_bandwidth, 1000);
+    lc->target_bandwidth = oxcf->ts_target_bitrate[layer] * 1000;
+    lrc->buffer_level = vp9_rescale((int)(oxcf->starting_buffer_level),
+                                    lc->target_bandwidth, 1000);
     lrc->bits_off_target = lrc->buffer_level;
   }
 }
@@ -49,14 +48,14 @@ void vp9_update_layer_context_change_config(VP9_COMP *const cpi,
                                             const int target_bandwidth) {
   const VP9_CONFIG *const oxcf = &cpi->oxcf;
   const RATE_CONTROL *const rc = &cpi->rc;
-  int temporal_layer = 0;
+  int layer;
   float bitrate_alloc = 1.0;
-  for (temporal_layer = 0; temporal_layer < cpi->svc.number_temporal_layers;
-      ++temporal_layer) {
-    LAYER_CONTEXT *const lc = &cpi->svc.layer_context[temporal_layer];
+
+  for (layer = 0; layer < cpi->svc.number_temporal_layers; ++layer) {
+    LAYER_CONTEXT *const lc = &cpi->svc.layer_context[layer];
     RATE_CONTROL *const lrc = &lc->rc;
-    lc->target_bandwidth = oxcf->ts_target_bitrate[temporal_layer] * 1000;
-    bitrate_alloc = (float)lc->target_bandwidth / (float)target_bandwidth;
+    lc->target_bandwidth = oxcf->ts_target_bitrate[layer] * 1000;
+    bitrate_alloc = (float)lc->target_bandwidth / target_bandwidth;
     // Update buffer-related quantities.
     lc->starting_buffer_level =
         (int64_t)(oxcf->starting_buffer_level * bitrate_alloc);
@@ -67,7 +66,7 @@ void vp9_update_layer_context_change_config(VP9_COMP *const cpi,
     lrc->bits_off_target = MIN(lrc->bits_off_target, lc->maximum_buffer_size);
     lrc->buffer_level = MIN(lrc->buffer_level, lc->maximum_buffer_size);
     // Update framerate-related quantities.
-    lc->framerate = oxcf->framerate / oxcf->ts_rate_decimator[temporal_layer];
+    lc->framerate = oxcf->framerate / oxcf->ts_rate_decimator[layer];
     lrc->av_per_frame_bandwidth = (int)(lc->target_bandwidth / lc->framerate);
     lrc->max_frame_bandwidth = rc->max_frame_bandwidth;
     // Update qp-related quantities.
@@ -76,22 +75,27 @@ void vp9_update_layer_context_change_config(VP9_COMP *const cpi,
   }
 }
 
+static LAYER_CONTEXT *get_temporal_layer_context(SVC *svc) {
+  return &svc->layer_context[svc->temporal_layer_id];
+}
+
 void vp9_update_layer_framerate(VP9_COMP *const cpi) {
-  int temporal_layer = cpi->svc.temporal_layer_id;
+  const int layer = cpi->svc.temporal_layer_id;
   const VP9_CONFIG *const oxcf = &cpi->oxcf;
-  LAYER_CONTEXT *const lc = &cpi->svc.layer_context[temporal_layer];
+  LAYER_CONTEXT *const lc = get_temporal_layer_context(&cpi->svc);
   RATE_CONTROL *const lrc = &lc->rc;
-  lc->framerate = oxcf->framerate / oxcf->ts_rate_decimator[temporal_layer];
+
+  lc->framerate = oxcf->framerate / oxcf->ts_rate_decimator[layer];
   lrc->av_per_frame_bandwidth = (int)(lc->target_bandwidth / lc->framerate);
   lrc->max_frame_bandwidth = cpi->rc.max_frame_bandwidth;
   // Update the average layer frame size (non-cumulative per-frame-bw).
-  if (temporal_layer == 0) {
+  if (layer == 0) {
     lc->avg_frame_size = lrc->av_per_frame_bandwidth;
   } else {
-    double prev_layer_framerate = oxcf->framerate /
-        oxcf->ts_rate_decimator[temporal_layer - 1];
-    int prev_layer_target_bandwidth =
-        oxcf->ts_target_bitrate[temporal_layer - 1] * 1000;
+    const double prev_layer_framerate =
+        oxcf->framerate / oxcf->ts_rate_decimator[layer - 1];
+    const int prev_layer_target_bandwidth =
+        oxcf->ts_target_bitrate[layer - 1] * 1000;
     lc->avg_frame_size =
         (int)((lc->target_bandwidth - prev_layer_target_bandwidth) /
               (lc->framerate - prev_layer_framerate));
@@ -99,10 +103,10 @@ void vp9_update_layer_framerate(VP9_COMP *const cpi) {
 }
 
 void vp9_restore_layer_context(VP9_COMP *const cpi) {
-  int temporal_layer = cpi->svc.temporal_layer_id;
-  LAYER_CONTEXT *lc = &cpi->svc.layer_context[temporal_layer];
-  int frame_since_key = cpi->rc.frames_since_key;
-  int frame_to_key = cpi->rc.frames_to_key;
+  LAYER_CONTEXT *const lc = get_temporal_layer_context(&cpi->svc);
+  const int old_frame_since_key = cpi->rc.frames_since_key;
+  const int old_frame_to_key = cpi->rc.frames_to_key;
+
   cpi->rc = lc->rc;
   cpi->oxcf.target_bandwidth = lc->target_bandwidth;
   cpi->oxcf.starting_buffer_level = lc->starting_buffer_level;
@@ -111,17 +115,18 @@ void vp9_restore_layer_context(VP9_COMP *const cpi) {
   cpi->output_framerate = lc->framerate;
   // Reset the frames_since_key and frames_to_key counters to their values
   // before the layer restore. Keep these defined for the stream (not layer).
-  cpi->rc.frames_since_key = frame_since_key;
-  cpi->rc.frames_to_key = frame_to_key;
+  cpi->rc.frames_since_key = old_frame_since_key;
+  cpi->rc.frames_to_key = old_frame_to_key;
 }
 
 void vp9_save_layer_context(VP9_COMP *const cpi) {
-  int temporal_layer = cpi->svc.temporal_layer_id;
-  LAYER_CONTEXT *lc = &cpi->svc.layer_context[temporal_layer];
+  const VP9_CONFIG *const oxcf = &cpi->oxcf;
+  LAYER_CONTEXT *const lc = get_temporal_layer_context(&cpi->svc);
+
   lc->rc = cpi->rc;
-  lc->target_bandwidth = (int)cpi->oxcf.target_bandwidth;
-  lc->starting_buffer_level = cpi->oxcf.starting_buffer_level;
-  lc->optimal_buffer_level = cpi->oxcf.optimal_buffer_level;
-  lc->maximum_buffer_size = cpi->oxcf.maximum_buffer_size;
+  lc->target_bandwidth = (int)oxcf->target_bandwidth;
+  lc->starting_buffer_level = oxcf->starting_buffer_level;
+  lc->optimal_buffer_level = oxcf->optimal_buffer_level;
+  lc->maximum_buffer_size = oxcf->maximum_buffer_size;
   lc->framerate = cpi->output_framerate;
 }