From 7dcca4b9ed571dd335c058f9bb860c1509de80ab Mon Sep 17 00:00:00 2001
From: Sergey Silkin <ssilkin@webrtc.org>
Date: Mon, 14 May 2018 18:25:06 +0200
Subject: [PATCH] Limit inter-layer prediction to key pictures.

This unconditionally limits usage of VP9 SVC inter-layer prediction to
frames of key picture.

Ideally we would like to let an application to configure SVC options.
But currently there is no API for this.

Bug: none
Change-Id: I21a84dafc946be122514d5b6bf327b65251f1115
Reviewed-on: https://webrtc-review.googlesource.com/76640
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23224}
---
 media/engine/webrtcvideoengine.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/media/engine/webrtcvideoengine.cc b/media/engine/webrtcvideoengine.cc
index 5932dbf048..a5ec5bc3e8 100644
--- a/media/engine/webrtcvideoengine.cc
+++ b/media/engine/webrtcvideoengine.cc
@@ -479,6 +479,9 @@ WebRtcVideoChannel::WebRtcVideoSendStream::ConfigureVideoEncoderSettings(
           num_spatial_layers, kConferenceMaxNumSpatialLayers);
       vp9_settings.numberOfTemporalLayers = std::min<unsigned char>(
           num_temporal_layers, kConferenceMaxNumTemporalLayers);
+
+      // Limit inter-layer prediction to key pictures.
+      vp9_settings.interLayerPred = webrtc::InterLayerPredMode::kOnKeyPic;
     }
 
     // VP9 denoising is disabled by default.