media/gpu/vaapi/vp9Encoder: Correct |layer_target_bitrate| value

libvpx::VP9RateControlRtcConfig::layer_target_bitrate must be
set in an accumulative manner, but originally Vp9Encoder sets
the bitrate of each layer independently. This CL fixes the
wrong settlement.

Bug: b:169219904, 1030199
Test: appr.tc/?vrc=vp9&vsc=vp9
Change-Id: I27787d2ce43394ff5b032562a21425da4654e772
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2434416
Commit-Queue: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Jeffrey Kardatzke <jkardatzke@google.com>
Reviewed-by: Miguel Casas <mcasas@chromium.org>
Auto-Submit: Hirokazu Honda <hiroh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812586}

media/gpu/vaapi/vp9_encoder.cc

@@ -127,8 +127,7 @@ libvpx::VP9RateControlRtcConfig CreateRateControlConfig(
   rc_cfg.min_quantizer =
       QindexToQuantizer(encode_params.scaling_settings.min_qp);
   // libvpx::VP9RateControlRtcConfig is kbps.
-  rc_cfg.target_bandwidth = base::checked_cast<int64_t>(
-      encode_params.bitrate_allocation.GetSumBps() / 1000.0);
+  rc_cfg.target_bandwidth = encode_params.bitrate_allocation.GetSumBps() / 1000;
   // These default values come from
   // //third_party/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc.
   rc_cfg.buf_initial_sz = 500;
@@ -146,11 +145,12 @@ libvpx::VP9RateControlRtcConfig CreateRateControlConfig(
   rc_cfg.scaling_factor_den[0] = 1;
   // Fill temporal layers variables.
   rc_cfg.ts_number_layers = num_temporal_layers;
+  int bitrate_sum = 0;
   for (size_t ti = 0; ti < num_temporal_layers; ti++) {
     rc_cfg.max_quantizers[ti] = rc_cfg.max_quantizer;
     rc_cfg.min_quantizers[ti] = rc_cfg.min_quantizer;
-    rc_cfg.layer_target_bitrate[ti] = base::checked_cast<int>(
-        bitrate_allocation.GetBitrateBps(0, ti) / 1000.0);
+    bitrate_sum += bitrate_allocation.GetBitrateBps(0, ti);
+    rc_cfg.layer_target_bitrate[ti] = bitrate_sum / 1000;
     rc_cfg.ts_rate_decimator[ti] = 1u << (num_temporal_layers - ti - 1);
   }
   return rc_cfg;

media/gpu/vaapi/vp9_encoder_unittest.cc

@@ -139,19 +139,17 @@ MATCHER_P4(MatchRtcConfigWithRates,
            framerate,
            num_temporal_layers,
            "") {
-  if (arg.target_bandwidth !=
-      static_cast<int64_t>(bitrate_allocation.GetSumBps() / 1000.0)) {
+  if (arg.target_bandwidth != bitrate_allocation.GetSumBps() / 1000)
     return false;
-  }
 
   if (arg.framerate != static_cast<double>(framerate))
     return false;
 
+  int bitrate_sum = 0;
   for (size_t i = 0; i < num_temporal_layers; i++) {
-    if (arg.layer_target_bitrate[i] !=
-        static_cast<int>(bitrate_allocation.GetBitrateBps(0, i) / 1000.0)) {
+    bitrate_sum += bitrate_allocation.GetBitrateBps(0, i);
+    if (arg.layer_target_bitrate[i] != bitrate_sum / 1000)
       return false;
-    }
     if (arg.ts_rate_decimator[i] != (1 << (num_temporal_layers - i - 1)))
       return false;
   }