Base screenshare layers on TemporalReferences.

webrtc/modules/video_coding/codecs/vp8/default_temporal_layers.cc

Index: webrtc/modules/video_coding/codecs/vp8/default_temporal_layers.cc
diff --git a/webrtc/modules/video_coding/codecs/vp8/default_temporal_layers.cc b/webrtc/modules/video_coding/codecs/vp8/default_temporal_layers.cc
index 2af8f41cd71d5798a14c83e4674f3974cea00f39..f0f385c625c5fee458b4f3071558e55905a9a292 100644
--- a/webrtc/modules/video_coding/codecs/vp8/default_temporal_layers.cc
+++ b/webrtc/modules/video_coding/codecs/vp8/default_temporal_layers.cc
@@ -45,7 +45,8 @@ TemporalReferences::TemporalReferences(TemporalBufferUsage last,
                                        TemporalBufferUsage arf,
                                        bool layer_sync,
                                        bool freeze_entropy)
-    : reference_last((last & kReference) != 0),
+    : drop_frame(last == kNone && golden == kNone && arf == kNone),
+      reference_last((last & kReference) != 0),
       update_last((last & kUpdate) != 0),
       reference_golden((golden & kReference) != 0),
       update_golden((golden & kUpdate) != 0),
@@ -246,14 +247,19 @@ bool DefaultTemporalLayers::UpdateConfiguration(vpx_codec_enc_cfg_t* cfg) {
   return true;
 }
 
-int DefaultTemporalLayers::EncodeFlags(uint32_t timestamp) {
+// TODO(pbos): Name method so that it's obvious that it updates state.

[sprang_webrtc, 2017/03/26 12:20:08]

Not sure "get" makes it obvious state is changed either. Maybe
UpdateLayerConfig() or NextLayerConfig() or something along those lines?

[pbos-webrtc, 2017/03/27 16:31:07]

I like update. Thanks.

+TemporalReferences DefaultTemporalLayers::GetLayerConfig(uint32_t timestamp) {
   RTC_DCHECK_GT(num_layers_, 0);
   RTC_DCHECK_LT(0, temporal_pattern_.size());
+  return temporal_pattern_[++pattern_idx_ % temporal_pattern_.size()];
+}
+
+int TemporalLayers::EncodeFlags(uint32_t timestamp) {
+  TemporalReferences references = GetLayerConfig(timestamp);
+  if (references.drop_frame)
+    return -1;
+
   int flags = 0;
-  // TODO(pbos): Move pattern-update out of EncodeFlags. It's not obvious that
-  // EncodeFlags() is non-const.
-  const TemporalReferences& references =
-      temporal_pattern_[++pattern_idx_ % temporal_pattern_.size()];
 
   if (!references.reference_last)
     flags |= VP8_EFLAG_NO_REF_LAST;
@@ -274,7 +280,7 @@ int DefaultTemporalLayers::EncodeFlags(uint32_t timestamp) {
 }
 
 void DefaultTemporalLayers::PopulateCodecSpecific(
-    bool base_layer_sync,
+    bool frame_is_keyframe,
     CodecSpecificInfoVP8* vp8_info,
     uint32_t timestamp) {
   RTC_DCHECK_GT(num_layers_, 0);
@@ -284,7 +290,7 @@ void DefaultTemporalLayers::PopulateCodecSpecific(
     vp8_info->layerSync = false;
     vp8_info->tl0PicIdx = kNoTl0PicIdx;
   } else {
-    if (base_layer_sync) {
+    if (frame_is_keyframe) {
       vp8_info->temporalIdx = 0;
       vp8_info->layerSync = true;
     } else {
@@ -303,7 +309,7 @@ void DefaultTemporalLayers::PopulateCodecSpecific(
       timestamp_ = timestamp;
       tl0_pic_idx_++;
     }
-    last_base_layer_sync_ = base_layer_sync;
+    last_base_layer_sync_ = frame_is_keyframe;
     vp8_info->tl0PicIdx = tl0_pic_idx_;
   }
 }