[FFmpeg-devel] [PATCH] avfilter/codecview/WIP: add QP support

[Clément Bœsch]

From: Clément Bœsch <clement at stupeflix.com>

---
I'm not sure I'm doing the correct thing here, but maybe that's just because my
samples aren't relevant.

TODO: doc
---
 libavfilter/vf_codecview.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/libavfilter/vf_codecview.c b/libavfilter/vf_codecview.c
index df45f55..5e1334e 100644
--- a/libavfilter/vf_codecview.c
+++ b/libavfilter/vf_codecview.c
@@ -27,7 +27,6 @@
  * libavcodec/mpegvideo.c.
  *
  * TODO: segmentation
- * TODO: quantization
  */
 
 #include "libavutil/imgutils.h"
@@ -43,11 +42,14 @@
 typedef struct {
     const AVClass *class;
     unsigned mv;
+    int hsub, vsub;
+    int qp;
 } CodecViewContext;
 
 #define OFFSET(x) offsetof(CodecViewContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 static const AVOption codecview_options[] = {
+    { "qp", NULL, OFFSET(qp), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, .flags = FLAGS },
     { "mv", "set motion vectors to visualize", OFFSET(mv), AV_OPT_TYPE_FLAGS, {.i64=0}, 0, INT_MAX, FLAGS, "mv" },
         {"pf", "forward predicted MVs of P-frames",  0, AV_OPT_TYPE_CONST, {.i64 = MV_P_FOR },  INT_MIN, INT_MAX, FLAGS, "mv"},
         {"bf", "forward predicted MVs of B-frames",  0, AV_OPT_TYPE_CONST, {.i64 = MV_B_FOR },  INT_MIN, INT_MAX, FLAGS, "mv"},
@@ -198,6 +200,31 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
     CodecViewContext *s = ctx->priv;
     AVFilterLink *outlink = ctx->outputs[0];
 
+    if (s->qp) {
+        int qstride, qp_type;
+        int8_t *qp_table = av_frame_get_qp_table(frame, &qstride, &qp_type);
+
+        if (qp_table) {
+            int x, y;
+            const int w = FF_CEIL_RSHIFT(frame->width,  s->hsub);
+            const int h = FF_CEIL_RSHIFT(frame->height, s->vsub);
+            uint8_t *pu = frame->data[1];
+            uint8_t *pv = frame->data[2];
+            const int lzu = frame->linesize[1];
+            const int lzv = frame->linesize[2];
+
+            for (y = 0; y < h; y++) {
+                for (x = 0; x < w; x++) {
+                    const int qp = ff_norm_qscale(qp_table[(y >> 3) * qstride + (x >> 3)], qp_type);
+                    pu[x] = pv[x] = qp;
+                }
+                pu += lzu;
+                pv += lzv;
+            }
+        }
+    }
+
+    if (s->mv) {
     AVFrameSideData *sd = av_frame_get_side_data(frame, AV_FRAME_DATA_MOTION_VECTORS);
     if (sd) {
         int i;
@@ -213,14 +240,28 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
                            100, 0, mv->source > 0);
         }
     }
+    }
+
     return ff_filter_frame(outlink, frame);
 }
 
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    CodecViewContext *s = ctx->priv;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
+
+    s->hsub = desc->log2_chroma_w;
+    s->vsub = desc->log2_chroma_h;
+    return 0;
+}
+
 static const AVFilterPad codecview_inputs[] = {
     {
         .name           = "default",
         .type           = AVMEDIA_TYPE_VIDEO,
         .filter_frame   = filter_frame,
+        .config_props   = config_input,
         .needs_writable = 1,
     },
     { NULL }
-- 
2.5.1