shithub: libvpx

Download patch

ref: b9be7a464f065c3700f937eea01d9298002b37eb
parent: 7288cdf79dd179d5bbf927db6240e3b9a4da412b
author: John Koleszar <jkoleszar@google.com>
date: Wed Sep 29 09:04:04 EDT 2010 

Fix loopfilter delta zero transitions

Loopfilter deltas are initialized to zero on keyframes in the decoder.
The values then persist from the previous frame unless an update bit
is set in the bitstream. This data is not included in the entropy
data saved by the 'refresh entropy' bit in the bitstream, so it is
effectively an additional contextual element beyond the 3 ref-frames
and the entropy data.

The encoder was treating this delta update bit as update-if-nonzero,
meaning that the value would be refreshed even if it hadn't changed,
and more significantly, if the correct value for the delta changed
to zero, the update wouldn't be sent, and the decoder would preserve
the last (presumably non-zero) value.

This patch updates the encoder to send an update only if the value
has changed from the previously transmitted value. It also forces the
value to be transmitted in error resilient mode, to account for lost
context in the event of lost frames.

Change-Id: I56671d5b42965d0166ac226765dbfce3e5301868


--- a/vp8/common/blockd.h
+++ b/vp8/common/blockd.h
@@ -262,9 +262,9 @@
     unsigned char mode_ref_lf_delta_update;
 
     // Delta values have the range +/- MAX_LOOP_FILTER
-    //char ref_lf_deltas[MAX_REF_LF_DELTAS];                      // 0 = Intra, Last, GF, ARF
-    //char mode_lf_deltas[MAX_MODE_LF_DELTAS];                            // 0 = BPRED, ZERO_MV, MV, SPLIT
+    signed char last_ref_lf_deltas[MAX_REF_LF_DELTAS];                // 0 = Intra, Last, GF, ARF
     signed char ref_lf_deltas[MAX_REF_LF_DELTAS];                     // 0 = Intra, Last, GF, ARF
+    signed char last_mode_lf_deltas[MAX_MODE_LF_DELTAS];                      // 0 = BPRED, ZERO_MV, MV, SPLIT
     signed char mode_lf_deltas[MAX_MODE_LF_DELTAS];                           // 0 = BPRED, ZERO_MV, MV, SPLIT
 
     // Distance of MB away from frame edges
--- a/vp8/encoder/bitstream.c
+++ b/vp8/encoder/bitstream.c
@@ -1490,9 +1490,11 @@
     if (xd->mode_ref_lf_delta_enabled)
     {
         // Do the deltas need to be updated
-        vp8_write_bit(bc, (xd->mode_ref_lf_delta_update) ? 1 : 0);
+        int send_update = xd->mode_ref_lf_delta_update
+                          || cpi->oxcf.error_resilient_mode;
 
-        if (xd->mode_ref_lf_delta_update)
+        vp8_write_bit(bc, send_update);
+        if (send_update)
         {
             int Data;
 
@@ -1502,8 +1504,10 @@
                 Data = xd->ref_lf_deltas[i];
 
                 // Frame level data
-                if (Data)
+                if (xd->ref_lf_deltas[i] != xd->last_ref_lf_deltas[i]
+                    || cpi->oxcf.error_resilient_mode)
                 {
+                    xd->last_ref_lf_deltas[i] = xd->ref_lf_deltas[i];
                     vp8_write_bit(bc, 1);
 
                     if (Data > 0)
@@ -1527,8 +1531,10 @@
             {
                 Data = xd->mode_lf_deltas[i];
 
-                if (Data)
+                if (xd->mode_lf_deltas[i] != xd->last_mode_lf_deltas[i]
+                    || cpi->oxcf.error_resilient_mode)
                 {
+                    xd->last_mode_lf_deltas[i] = xd->mode_lf_deltas[i];
                     vp8_write_bit(bc, 1);
 
                     if (Data > 0)
--- a/vp8/encoder/onyx_if.c
+++ b/vp8/encoder/onyx_if.c
@@ -272,6 +272,8 @@
     cpi->mb.e_mbd.mode_ref_lf_delta_update = 0;
     vpx_memset(cpi->mb.e_mbd.ref_lf_deltas, 0, sizeof(cpi->mb.e_mbd.ref_lf_deltas));
     vpx_memset(cpi->mb.e_mbd.mode_lf_deltas, 0, sizeof(cpi->mb.e_mbd.mode_lf_deltas));
+    vpx_memset(cpi->mb.e_mbd.last_ref_lf_deltas, 0, sizeof(cpi->mb.e_mbd.ref_lf_deltas));
+    vpx_memset(cpi->mb.e_mbd.last_mode_lf_deltas, 0, sizeof(cpi->mb.e_mbd.mode_lf_deltas));
 
     // jbb trial !
     mode_ref_lf_test_function(cpi);
@@ -4093,6 +4095,9 @@
     {
         int i;
 
+        // Reset the loop filter deltas and segmentation map
+        setup_features(cpi);
+
         // If segmentation is enabled force a map update for key frames
         if (cpi->mb.e_mbd.segmentation_enabled)
         {
@@ -4100,12 +4105,6 @@
             cpi->mb.e_mbd.update_mb_segmentation_data = 1;
         }
 
-        // If mode or reference frame based loop filter deltas are enabled then force an update for key frames.
-        if (cpi->mb.e_mbd.mode_ref_lf_delta_enabled)
-        {
-            cpi->mb.e_mbd.mode_ref_lf_delta_update = 1;
-        }
-
         // The alternate reference frame cannot be active for a key frame
         cpi->source_alt_ref_active = FALSE;
 
@@ -4527,17 +4526,14 @@
                 // Clear the Alt reference frame active flag when we have a key frame
                 cpi->source_alt_ref_active = FALSE;
 
+                // Reset the loop filter deltas and segmentation map
+                setup_features(cpi);
+
                 // If segmentation is enabled force a map update for key frames
                 if (cpi->mb.e_mbd.segmentation_enabled)
                 {
                     cpi->mb.e_mbd.update_mb_segmentation_map = 1;
                     cpi->mb.e_mbd.update_mb_segmentation_data = 1;
-                }
-
-                // If mode or reference frame based loop filter deltas are enabled then force an update for key frames.
-                if (cpi->mb.e_mbd.mode_ref_lf_delta_enabled)
-                {
-                    cpi->mb.e_mbd.mode_ref_lf_delta_update = 1;
                 }
 
                 vp8_restore_coding_context(cpi);