Add simple version of activity masking.

This uses MB variance to change the RDO weight for mode decision
 and quantization.
Activity is normalized against the average for the frame, which is
 currently tracked using feed-forward statistics.
This could also be used to adjust the quantizer for the entire
 frame, but that requires more extensive rate control changes.
This does not yet attempt to adapt the quantizer within the frame,
 but the signaling cost means that will likely only be useful at
 very high rates.

Change-Id: I26cd7c755cac3ff33cfe0688b1da50b2b87b9c93

diff --git a/vp8/encoder/block.h b/vp8/encoder/block.h
index ffb8890..fc65618 100644 (file)
--- a/vp8/encoder/block.h
+++ b/vp8/encoder/block.h
@@ -81,6 +81,7 @@ typedef struct
     int errthresh;
     int rddiv;
     int rdmult;
+    INT64 activity_sum;
 
     int mvcosts[2][MVvals+1];
     int *mvcost[2];

diff --git a/vp8/encoder/encodeframe.c b/vp8/encoder/encodeframe.c
index efbe236..b0a3c47 100644 (file)
--- a/vp8/encoder/encodeframe.c
+++ b/vp8/encoder/encodeframe.c
@@ -369,6 +369,62 @@ void vp8cx_frame_init_quantizer(VP8_COMP *cpi)
 }
 
 
+/* activity_avg must be positive, or flat regions could get a zero weight
+ *  (infinite lambda), which confounds analysis.
+ * This also avoids the need for divide by zero checks in
+ *  vp8_activity_masking().
+ */
+#define VP8_ACTIVITY_AVG_MIN (64)
+
+/* This is used as a reference when computing the source variance for the
+ *  purposes of activity masking.
+ * Eventually this should be replaced by custom no-reference routines,
+ *  which will be faster.
+ */
+static const unsigned char VP8_VAR_OFFS[16]=
+{
+    128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128
+};
+
+unsigned int vp8_activity_masking(VP8_COMP *cpi, MACROBLOCK *x)
+{
+    unsigned int act;
+    unsigned int sse;
+    int sum;
+    unsigned int a;
+    unsigned int b;
+    unsigned int d;
+    /* TODO: This could also be done over smaller areas (8x8), but that would
+     *  require extensive changes elsewhere, as lambda is assumed to be fixed
+     *  over an entire MB in most of the code.
+     * Another option is to compute four 8x8 variances, and pick a single
+     *  lambda using a non-linear combination (e.g., the smallest, or second
+     *  smallest, etc.).
+     */
+    VARIANCE_INVOKE(&cpi->rtcd.variance, get16x16var)(x->src.y_buffer,
+     x->src.y_stride, VP8_VAR_OFFS, 0, &sse, &sum);
+    /* This requires a full 32 bits of precision. */
+    act = (sse<<8) - sum*sum;
+    /* Drop 4 to give us some headroom to work with. */
+    act = (act + 8) >> 4;
+    /* If the region is flat, lower the activity some more. */
+    if (act < 8<<12)
+        act = act < 5<<12 ? act : 5<<12;
+    /* TODO: For non-flat regions, edge regions should receive less masking
+     *  than textured regions, but identifying edge regions quickly and
+     *  reliably enough is still a subject of experimentation.
+     * This will be most noticable near edges with a complex shape (e.g.,
+     *  text), but the 4x4 transform size should make this less of a problem
+     *  than it would be for an 8x8 transform.
+     */
+    /* Apply the masking to the RD multiplier. */
+    a = act + 4*cpi->activity_avg;
+    b = 4*act + cpi->activity_avg;
+    x->rdmult = (unsigned int)(((INT64)x->rdmult*b + (a>>1))/a);
+    return act;
+}
+
+
 
 static
 void encode_mb_row(VP8_COMP *cpi,
@@ -380,6 +436,7 @@ void encode_mb_row(VP8_COMP *cpi,
                    int *segment_counts,
                    int *totalrate)
 {
+    INT64 activity_sum = 0;
     int i;
     int recon_yoffset, recon_uvoffset;
     int mb_col;
@@ -431,6 +488,11 @@ void encode_mb_row(VP8_COMP *cpi,
         xd->dst.v_buffer = cm->yv12_fb[dst_fb_idx].v_buffer + recon_uvoffset;
         xd->left_available = (mb_col != 0);
 
+        x->rddiv = cpi->RDDIV;
+        x->rdmult = cpi->RDMULT;
+
+        activity_sum += vp8_activity_masking(cpi, x);
+
         // Is segmentation enabled
         // MB level adjutment to quantizer
         if (xd->segmentation_enabled)
@@ -537,6 +599,7 @@ void encode_mb_row(VP8_COMP *cpi,
     // this is to account for the border
     xd->mode_info_context++;
     x->partition_info++;
+    x->activity_sum += activity_sum;
 }
 
 
@@ -653,8 +716,7 @@ void vp8_encode_frame(VP8_COMP *cpi)
 
     vp8_setup_block_ptrs(x);
 
-    x->rddiv = cpi->RDDIV;
-    x->rdmult = cpi->RDMULT;
+    x->activity_sum = 0;
 
 #if 0
     // Experimental rd code
@@ -709,11 +771,12 @@ void vp8_encode_frame(VP8_COMP *cpi)
         else
         {
 #if CONFIG_MULTITHREAD
+            int i;
+
             vp8cx_init_mbrthread_data(cpi, x, cpi->mb_row_ei, 1,  cpi->encoding_thread_count);
 
             for (mb_row = 0; mb_row < cm->mb_rows; mb_row += (cpi->encoding_thread_count + 1))
             {
-                int i;
                 cpi->current_mb_col_main = -1;
 
                 for (i = 0; i < cpi->encoding_thread_count; i++)
@@ -791,6 +854,11 @@ void vp8_encode_frame(VP8_COMP *cpi)
                 totalrate += cpi->mb_row_ei[i].totalrate;
             }
 
+            for (i = 0; i < cpi->encoding_thread_count; i++)
+            {
+                x->activity_sum += cpi->mb_row_ei[i].mb.activity_sum;
+            }
+
 #endif
 
         }
@@ -926,6 +994,14 @@ void vp8_encode_frame(VP8_COMP *cpi)
     cpi->last_frame_distortion = cpi->frame_distortion;
 #endif
 
+    /* Update the average activity for the next frame.
+     * This is feed-forward for now; it could also be saved in two-pass, or
+     *  done during lookahead when that is eventually added.
+     */
+    cpi->activity_avg = (unsigned int )(x->activity_sum/cpi->common.MBs);
+    if (cpi->activity_avg < VP8_ACTIVITY_AVG_MIN)
+        cpi->activity_avg = VP8_ACTIVITY_AVG_MIN;
+
 }
 void vp8_setup_block_ptrs(MACROBLOCK *x)
 {

diff --git a/vp8/encoder/encodeintra.c b/vp8/encoder/encodeintra.c
index af80857..820b85b 100644 (file)
--- a/vp8/encoder/encodeintra.c
+++ b/vp8/encoder/encodeintra.c
@@ -109,7 +109,7 @@ void vp8_encode_intra16x16mby(const VP8_ENCODER_RTCD *rtcd, MACROBLOCK *x)
 
 #if !(CONFIG_REALTIME_ONLY)
 #if 1
-    if (x->optimize && x->rddiv > 1)
+    if (x->optimize)
         vp8_optimize_mby(x, rtcd);
 
 #endif

diff --git a/vp8/encoder/encodemb.c b/vp8/encoder/encodemb.c
index 63cdf3c..a37188b 100644 (file)
--- a/vp8/encoder/encodemb.c
+++ b/vp8/encoder/encodemb.c
@@ -662,7 +662,7 @@ void vp8_encode_inter16x16(const VP8_ENCODER_RTCD *rtcd, MACROBLOCK *x)
     vp8_quantize_mb(x);
 
 #if !(CONFIG_REALTIME_ONLY)
-    if (x->optimize && x->rddiv > 1)
+    if (x->optimize)
     {
         vp8_optimize_mb(x, rtcd);
         vp8_find_mb_skip_coef(x);

diff --git a/vp8/encoder/ethreading.c b/vp8/encoder/ethreading.c
index 962e741..3646375 100644 (file)
--- a/vp8/encoder/ethreading.c
+++ b/vp8/encoder/ethreading.c
@@ -61,6 +61,7 @@ THREAD_FUNCTION thread_encoding_proc(void *p_data)
                     int recon_y_stride = cm->yv12_fb[ref_fb_idx].y_stride;
                     int recon_uv_stride = cm->yv12_fb[ref_fb_idx].uv_stride;
                     volatile int *last_row_current_mb_col;
+                    INT64 activity_sum = 0;
 
                     if (ithread > 0)
                         last_row_current_mb_col = &cpi->mb_row_ei[ithread-1].current_mb_col;
@@ -111,6 +112,11 @@ THREAD_FUNCTION thread_encoding_proc(void *p_data)
                         xd->dst.v_buffer = cm->yv12_fb[dst_fb_idx].v_buffer + recon_uvoffset;
                         xd->left_available = (mb_col != 0);
 
+                        x->rddiv = cpi->RDDIV;
+                        x->rdmult = cpi->RDMULT;
+
+                        activity_sum += vp8_activity_masking(cpi, x);
+
                         // Is segmentation enabled
                         // MB level adjutment to quantizer
                         if (xd->segmentation_enabled)
@@ -197,6 +203,7 @@ THREAD_FUNCTION thread_encoding_proc(void *p_data)
                     // this is to account for the border
                     xd->mode_info_context++;
                     x->partition_info++;
+                    x->activity_sum += activity_sum;
 
                     x->src.y_buffer += 16 * x->src.y_stride * (cpi->encoding_thread_count + 1) - 16 * cm->mb_cols;
                     x->src.u_buffer +=  8 * x->src.uv_stride * (cpi->encoding_thread_count + 1) - 8 * cm->mb_cols;
@@ -240,8 +247,6 @@ static void setup_mbby_copy(MACROBLOCK *mbdst, MACROBLOCK *mbsrc)
     z->sadperbit16      = x->sadperbit16;
     z->sadperbit4       = x->sadperbit4;
     z->errthresh        = x->errthresh;
-    z->rddiv            = x->rddiv;
-    z->rdmult           = x->rdmult;
 
     /*
     z->mv_col_min    = x->mv_col_min;
@@ -392,8 +397,7 @@ void vp8cx_init_mbrthread_data(VP8_COMP *cpi,
 
         vp8_setup_block_ptrs(mb);
 
-        mb->rddiv = cpi->RDDIV;
-        mb->rdmult = cpi->RDMULT;
+        mb->activity_sum = 0;
 
         mbd->left_context = &cm->left_context;
         mb->mvc = cm->fc.mvc;

diff --git a/vp8/encoder/onyx_if.c b/vp8/encoder/onyx_if.c
index 34af6ea..08c7ad4 100644 (file)
--- a/vp8/encoder/onyx_if.c
+++ b/vp8/encoder/onyx_if.c
@@ -2187,6 +2187,8 @@ VP8_PTR vp8_create_compressor(VP8_CONFIG *oxcf)
     init_context_counters();
 #endif
 
+    /*Initialize the feed-forward activity masking.*/
+    cpi->activity_avg = 90<<12;
 
     cpi->frames_since_key = 8;        // Give a sensible default for the first frame.
     cpi->key_frame_frequency = cpi->oxcf.key_freq;

diff --git a/vp8/encoder/onyx_int.h b/vp8/encoder/onyx_int.h
index cb768c0..3f2d920 100644 (file)
--- a/vp8/encoder/onyx_int.h
+++ b/vp8/encoder/onyx_int.h
@@ -308,6 +308,7 @@ typedef struct
     int mvcostmultiplier;
     int subseqblockweight;
     int errthresh;
+    unsigned int activity_avg;
 
     int RDMULT;
     int RDDIV ;
@@ -659,6 +660,8 @@ void vp8_encode_frame(VP8_COMP *cpi);
 
 void vp8_pack_bitstream(VP8_COMP *cpi, unsigned char *dest, unsigned long *size);
 
+unsigned int vp8_activity_masking(VP8_COMP *cpi, MACROBLOCK *x);
+
 int rd_cost_intra_mb(MACROBLOCKD *x);
 
 void vp8_tokenize_mb(VP8_COMP *, MACROBLOCKD *, TOKENEXTRA **);