[FFmpeg-devel] [PATCH v3 5/9] avutil/film_grain_params: add av_film_grain_params_select()

[Niklas Haas]

From: Niklas Haas <git at haasn.dev>

Common utility function that can be used by all codecs to select the
right (any valid) film grain parameter set. In particular, this is
useful for AFGS1, which has support for multiple parameters.

However, it also performs parameter validation for H274.
---
 doc/APIchanges                |  3 ++
 libavutil/film_grain_params.c | 57 +++++++++++++++++++++++++++++++++++
 libavutil/film_grain_params.h |  7 +++++
 libavutil/version.h           |  2 +-
 4 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/doc/APIchanges b/doc/APIchanges
index 5a192b600af..34245c8b708 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2024-03-07
 
 API changes, most recent first:
 
+2024-03-08 - xxxxxxxxxx - lavu 59.3.100 - film_grain_params.h
+  Add av_film_grain_params_select().
+
 2024-03-08 - xxxxxxxxxx - lavu 59.2.100 - film_grain_params.h
   Add AVFilmGrainAOMParams.color_range, color_primaries, color_trc,
   color_space, width, height, subx, suby and bit_depth.
diff --git a/libavutil/film_grain_params.c b/libavutil/film_grain_params.c
index 930d23c7fe9..8c80adc66a7 100644
--- a/libavutil/film_grain_params.c
+++ b/libavutil/film_grain_params.c
@@ -17,6 +17,7 @@
  */
 
 #include "film_grain_params.h"
+#include "pixdesc.h"
 
 AVFilmGrainParams *av_film_grain_params_alloc(size_t *size)
 {
@@ -40,3 +41,59 @@ AVFilmGrainParams *av_film_grain_params_create_side_data(AVFrame *frame)
 
     return (AVFilmGrainParams *)side_data->data;
 }
+
+const AVFilmGrainParams *av_film_grain_params_select(const AVFrame *frame)
+{
+    const AVFilmGrainParams *fgp, *best = NULL;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(frame->format);
+    const AVFilmGrainAOMParams *aom;
+    const AVFilmGrainH274Params *h274;
+    if (!desc)
+        return NULL;
+
+#define CHECK(a, b, unspec)                                     \
+    do {                                                        \
+        if ((a) != (unspec) && (b) != (unspec) && (a) != (b))   \
+            continue;                                           \
+    } while (0)
+
+    for (int i = 0; i < frame->nb_side_data; i++) {
+        if (frame->side_data[i]->type != AV_FRAME_DATA_FILM_GRAIN_PARAMS)
+            continue;
+        fgp = (const AVFilmGrainParams*)frame->side_data[i]->data;
+        switch (fgp->type) {
+        case AV_FILM_GRAIN_PARAMS_NONE:
+            continue;
+        case AV_FILM_GRAIN_PARAMS_AV1:
+            aom = &fgp->codec.aom;
+            if (aom->subx != desc->log2_chroma_w || aom->suby != desc->log2_chroma_h)
+                continue;
+            CHECK(aom->bit_depth,       desc->comp[0].depth, 0);
+            CHECK(aom->width,           frame->width, 0);
+            CHECK(aom->height,          frame->height, 0);
+            CHECK(aom->color_range,     frame->color_range,     AVCOL_RANGE_UNSPECIFIED);
+            CHECK(aom->color_primaries, frame->color_primaries, AVCOL_PRI_UNSPECIFIED);
+            CHECK(aom->color_trc,       frame->color_trc,       AVCOL_TRC_UNSPECIFIED);
+            CHECK(aom->color_space,     frame->colorspace,      AVCOL_SPC_UNSPECIFIED);
+
+            if (!best ||
+                best->codec.aom.width < aom->width ||
+                best->codec.aom.height < aom->height)
+                best = fgp;
+            break;
+        case AV_FILM_GRAIN_PARAMS_H274:
+            h274 = &fgp->codec.h274;
+            /* There are no YUV formats with different bit depth per component,
+             * so just check both against the first component for simplicity */
+            CHECK(h274->bit_depth_luma,   desc->comp[0].depth, 0);
+            CHECK(h274->bit_depth_chroma, desc->comp[0].depth, 0);
+            CHECK(h274->color_range,      frame->color_range,     AVCOL_RANGE_UNSPECIFIED);
+            CHECK(h274->color_primaries,  frame->color_primaries, AVCOL_PRI_UNSPECIFIED);
+            CHECK(h274->color_trc,        frame->color_trc,       AVCOL_TRC_UNSPECIFIED);
+            CHECK(h274->color_space,      frame->colorspace,      AVCOL_SPC_UNSPECIFIED);
+            return fgp; /* H274 can't have multiple resolutions */
+        }
+    }
+
+    return best;
+}
diff --git a/libavutil/film_grain_params.h b/libavutil/film_grain_params.h
index 17fefeb06c3..75c020ceb92 100644
--- a/libavutil/film_grain_params.h
+++ b/libavutil/film_grain_params.h
@@ -272,4 +272,11 @@ AVFilmGrainParams *av_film_grain_params_alloc(size_t *size);
  */
 AVFilmGrainParams *av_film_grain_params_create_side_data(AVFrame *frame);
 
+/**
+ * Select the most appropriate film grain parameters set for the frame,
+ * taking into account the frame's format, resolution and video signal
+ * characteristics.
+ */
+const AVFilmGrainParams *av_film_grain_params_select(const AVFrame *frame);
+
 #endif /* AVUTIL_FILM_GRAIN_PARAMS_H */
diff --git a/libavutil/version.h b/libavutil/version.h
index 57cad02ec0a..5027b025be4 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  59
-#define LIBAVUTIL_VERSION_MINOR   2
+#define LIBAVUTIL_VERSION_MINOR   3
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
-- 
2.44.0