Add experiment bgsprite

Work in progress to generate ARF with stitched background image.

Change-Id: I2fea75bbe5ac6f713f53eb5825776dadfc1d98c5

av1/av1_cx.mk

@@ -21,6 +21,8 @@ AV1_CX_SRCS-yes += av1_cx_iface.c
 AV1_CX_SRCS-yes += encoder/av1_quantize.c
 AV1_CX_SRCS-yes += encoder/av1_quantize.h
 AV1_CX_SRCS-yes += encoder/bitstream.c
+AV1_CX_SRCS-$(CONFIG_BGSPRITE) += encoder/bgsprite.c
+AV1_CX_SRCS-$(CONFIG_BGSPRITE) += encoder/bgsprite.h
 AV1_CX_SRCS-yes += encoder/context_tree.c
 AV1_CX_SRCS-yes += encoder/context_tree.h
 AV1_CX_SRCS-yes += encoder/cost.h

av1/encoder/bgsprite.h

+/*
+ * Copyright (c) 2017, Alliance for Open Media. All rights reserved
+ *
+ * This source code is subject to the terms of the BSD 2 Clause License and
+ * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
+ * was not distributed with this source code in the LICENSE file, you can
+ * obtain it at www.aomedia.org/license/software. If the Alliance for Open
+ * Media Patent License 1.0 was not distributed with this source code in the
+ * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
+ */
+
+#ifndef AV1_ENCODER_BGSPRITE_H_
+#define AV1_ENCODER_BGSPRITE_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "av1/encoder/encoder.h"
+
+// Creates alternate reference frame staring from source image + frames up to
+// 'distance' past source frame.
+// Returns 0 on success and 1 on failure.
+int av1_background_sprite(AV1_COMP *cpi, int distance);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // AV1_ENCODER_BGSPRITE_H_

av1/encoder/encoder.c

@@ -31,6 +31,9 @@
 #include "av1/encoder/aq_cyclicrefresh.h"
 #include "av1/encoder/aq_variance.h"
 #include "av1/encoder/bitstream.h"
+#if CONFIG_BGSPRITE
+#include "av1/encoder/bgsprite.h"
+#endif  // CONFIG_BGSPRITE
 #if CONFIG_ANS
 #include "aom_dsp/buf_ans.h"
 #endif
@@ -5397,8 +5400,15 @@ int av1_get_compressed_data(AV1_COMP *cpi, unsigned int *frame_flags,
       cpi->alt_ref_source = source;
 
       if (oxcf->arnr_max_frames > 0) {
-        // Produce the filtered ARF frame.
+// Produce the filtered ARF frame.
+#if CONFIG_BGSPRITE
+        int bgsprite_ret = av1_background_sprite(cpi, arf_src_index);
+        if (bgsprite_ret != EXIT_SUCCESS) {
+          av1_temporal_filter(cpi, arf_src_index);
+        }
+#else
         av1_temporal_filter(cpi, arf_src_index);
+#endif  // CONFIG_BGSPRITE
         aom_extend_frame_borders(&cpi->alt_ref_buffer);
         force_src_buffer = &cpi->alt_ref_buffer;
       }

configure

@@ -324,6 +324,7 @@ EXPERIMENT_LIST="
     lgt
     sbl_symbol
     ncobmc_adapt_weight
+    bgsprite
 "
 CONFIG_LIST="
     dependency_tracking
@@ -537,6 +538,7 @@ post_process_cmdline() {
     enabled new_multisymbol && enable_feature ec_adapt
     enabled warped_motion && disable_feature ncobmc_adapt_weight
     enabled ncobmc_adapt_weight && enable_feature motion_var
+    enabled bgsprite && enable_feature global_motion
 
     if ! enabled delta_q && enabled ext_delta_q; then
       log_echo "ext_delta_q requires delta_q, so disabling ext_delta_q"