Add ml_var_partition experiment

Make partition decisions using machine learning models. The goal is to
achieve better coding quality than the variance-based parititioning
without much encoding speed loss.

To enable this experiment, use --enable-ml-var-partition for config.

When eanbled, the variance-based partitioning is replaced by this ML
based partitioing for speed 6 and above in real time mode(except low
resolution or high bit-depth).

Current coding gains(average PSNR):
                speed 6      speed 7      speed 8
rtc              2.04%        2.65%        3.90%
ytlivehr         3.11%        4.53%       11.57%
hdres(rtc mode)  5.10%

Further testing and tuning is needed to see if the speed and quality
tradeoff is reasonable.

Change-Id: I0da5a2fbc22c3261832b32920ee36d9b19d417af

1 files changed, 10 insertions, 5 deletions

diff --git a/vp9/encoder/vp9_speed_features.h b/vp9/encoder/vp9_speed_features.h
index 531df704c..acac39835 100644
--- a/vp9/encoder/vp9_speed_features.h
+++ b/vp9/encoder/vp9_speed_features.h
@@ -136,20 +136,25 @@ typedef enum {
 } INTERP_FILTER_MASK;
 
 typedef enum {
-  // Search partitions using RD/NONRD criterion
+  // Search partitions using RD/NONRD criterion.
   SEARCH_PARTITION,
 
-  // Always use a fixed size partition
+  // Always use a fixed size partition.
   FIXED_PARTITION,
 
   REFERENCE_PARTITION,
 
   // Use an arbitrary partitioning scheme based on source variance within
-  // a 64X64 SB
+  // a 64X64 SB.
   VAR_BASED_PARTITION,
 
-  // Use non-fixed partitions based on source variance
-  SOURCE_VAR_BASED_PARTITION
+  // Use non-fixed partitions based on source variance.
+  SOURCE_VAR_BASED_PARTITION,
+
+#if CONFIG_ML_VAR_PARTITION
+  // Make partition decisions with machine learning models.
+  ML_BASED_PARTITION
+#endif  // CONFIG_ML_VAR_PARTITION
 } PARTITION_SEARCH_TYPE;
 
 typedef enum {