[FFmpeg-devel] libavfilter/vf_codecview: add block structure visualization

diff --git a/doc/filters.texi b/doc/filters.texi
index 84567dec16..db2c80b1e9 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -7285,6 +7285,9 @@  backward predicted MVs of B-frames
 @item qp
 Display quantization parameters using the chroma planes.
 
+@item bs
+Display block structure using the luma plane.
+
 @item mv_type, mvt
 Set motion vectors type to visualize. Includes MVs from all frames unless specified by @var{frame_type} option.
 
diff --git a/libavcodec/vp9.c b/libavcodec/vp9.c
index fd0bab14a2..e700def70e 100644
--- a/libavcodec/vp9.c
+++ b/libavcodec/vp9.c
@@ -1501,10 +1501,8 @@  static int vp9_export_enc_params(VP9Context *s, VP9Frame *frame)
     AVVideoEncParams *par;
     unsigned int tile, nb_blocks = 0;
 
-    if (s->s.h.segmentation.enabled) {
-        for (tile = 0; tile < s->active_tile_cols; tile++)
-            nb_blocks += s->td[tile].nb_block_structure;
-    }
+    for (tile = 0; tile < s->active_tile_cols; tile++)
+        nb_blocks += s->td[tile].nb_block_structure;
 
     par = av_video_enc_params_create_side_data(frame->tf.f,
         AV_VIDEO_ENC_PARAMS_VP9, nb_blocks);
@@ -1536,7 +1534,7 @@  static int vp9_export_enc_params(VP9Context *s, VP9Frame *frame)
                 b->w     = 1 << (3 + td->block_structure[block_tile].block_size_idx_x);
                 b->h     = 1 << (3 + td->block_structure[block_tile].block_size_idx_y);
 
-                if (s->s.h.segmentation.feat[seg_id].q_enabled) {
+                if (s->s.h.segmentation.enabled && s->s.h.segmentation.feat[seg_id].q_enabled) {
                     b->delta_qp = s->s.h.segmentation.feat[seg_id].q_val;
                     if (s->s.h.segmentation.absolute_vals)
                         b->delta_qp -= par->qp;
diff --git a/libavfilter/vf_codecview.c b/libavfilter/vf_codecview.c
index 331bfba777..db06625d70 100644
--- a/libavfilter/vf_codecview.c
+++ b/libavfilter/vf_codecview.c
@@ -34,6 +34,7 @@ 
 #include "libavutil/opt.h"
 #include "avfilter.h"
 #include "internal.h"
+#include "libavutil/video_enc_params.h"
 
 #define MV_P_FOR  (1<<0)
 #define MV_B_FOR  (1<<1)
@@ -51,6 +52,7 @@  typedef struct CodecViewContext {
     unsigned mv_type;
     int hsub, vsub;
     int qp;
+    int bs;
 } CodecViewContext;
 
 #define OFFSET(x) offsetof(CodecViewContext, x)
@@ -63,6 +65,7 @@  static const AVOption codecview_options[] = {
         CONST("bf", "forward predicted MVs of B-frames",  MV_B_FOR,  "mv"),
         CONST("bb", "backward predicted MVs of B-frames", MV_B_BACK, "mv"),
     { "qp", NULL, OFFSET(qp), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, .flags = FLAGS },
+    { "bs", "set block structure to visualize", OFFSET(bs), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, .flags = FLAGS },
     { "mv_type", "set motion vectors type", OFFSET(mv_type), AV_OPT_TYPE_FLAGS, {.i64=0}, 0, INT_MAX, FLAGS, "mv_type" },
     { "mvt",     "set motion vectors type", OFFSET(mv_type), AV_OPT_TYPE_FLAGS, {.i64=0}, 0, INT_MAX, FLAGS, "mv_type" },
         CONST("fp", "forward predicted MVs",  MV_TYPE_FOR,  "mv_type"),
@@ -212,6 +215,30 @@  static void draw_arrow(uint8_t *buf, int sx, int sy, int ex,
     draw_line(buf, sx, sy, ex, ey, w, h, stride, color);
 }
 
+static void draw_block_border(AVFrame *frame, AVVideoBlockParams *b)
+{
+    const int lzy = frame->linesize[0];
+    uint8_t *py = frame->data[0] + b->src_y * lzy;
+
+    for (int x = b->src_x; x < b->src_x + b->w; x++) {
+        if (x >= frame->width)
+            break;
+        py[x] = py[x] * 3 / 4;
+    }
+    for (int y = b->src_y; y < b->src_y + b->h; y++) {
+        if (y >= frame->height)
+            break;
+        py[b->src_x] = py[b->src_x] * 3 / 4;
+        py[b->src_x + b->w - 1] = py[b->src_x + b->w - 1] * 3 / 4;
+        py += lzy;
+    }
+    for (int x = b->src_x; x < b->src_x + b->w; x++) {
+        if (x >= frame->width)
+            break;
+        py[x] = py[x] * 3 / 4;
+    }
+}
+
 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
 {
     AVFilterContext *ctx = inlink->dst;
@@ -242,6 +269,20 @@  static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
         }
     }
 
+    if (s->bs) {
+        AVFrameSideData *sd = av_frame_get_side_data(frame, AV_FRAME_DATA_VIDEO_ENC_PARAMS);
+        if (sd) {
+            AVVideoEncParams *par = (AVVideoEncParams*)sd->data;
+
+            if (par->nb_blocks) {
+                for (int i = 0; i < par->nb_blocks; i++) {
+                    AVVideoBlockParams *b = av_video_enc_params_block(par, i);
+                    draw_block_border(frame, b);
+                }
+            }
+        }
+    }
+
     if (s->mv || s->mv_type) {
         AVFrameSideData *sd = av_frame_get_side_data(frame, AV_FRAME_DATA_MOTION_VECTORS);
         if (sd) {