[FFmpeg-devel] [PATCH 3/3] h274: support a few more pixfmts

[Niklas Haas]

From: Niklas Haas <git at haasn.dev>

Based on extrapolating the intent of the SMPTE RDD 5-2006 spec, which
only provides the parameter adaptation code for yuv420p. I've deduced
that the change to `scale` has nothing to do with the reduction in grain
frequency and merely reflects the fact that chroma planes have half the
effective value range in typical integer encodings.

As such, with this change can support e.g. 4:4:4 yuv420p as well, in
which case we simply don't double the chroma grain frequencies.

Still no support for 10-bit, but at least this is something.

Signed-off-by: Niklas Haas <git at haasn.dev>
---
 libavcodec/h274.c | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/libavcodec/h274.c b/libavcodec/h274.c
index 265bd49ea1..e800351a3e 100644
--- a/libavcodec/h274.c
+++ b/libavcodec/h274.c
@@ -157,7 +157,8 @@ static av_always_inline void generate(int8_t *out, int out_stride,
                                       const uint8_t *in, int in_stride,
                                       H274FilmGrainDatabase *database,
                                       const AVFilmGrainH274Params *h274,
-                                      int c, int invert, int deblock,
+                                      int c, uint8_t xs, uint8_t ys,
+                                      int invert, int deblock,
                                       int y_offset, int x_offset)
 {
     const uint8_t shift = h274->log2_scale_factor + 6;
@@ -200,8 +201,8 @@ static av_always_inline void generate(int8_t *out, int out_stride,
 
     h = num_values > 1 ? h274->comp_model_value[c][s][1] : 8;
     v = num_values > 2 ? h274->comp_model_value[c][s][2] : h;
-    h = av_clip(h << (c > 0 ? 1 : 0), 2, 14) - 2;
-    v = av_clip(v << (c > 0 ? 1 : 0), 2, 14) - 2;
+    h = av_clip(h << xs, 2, 14) - 2;
+    v = av_clip(v << ys, 2, 14) - 2;
 
     init_slice(database, h, v);
     synth_grain_8x8_c(out, out_stride, scale, shift,
@@ -224,19 +225,34 @@ int ff_h274_apply_film_grain(AVFrame *out_frame, const AVFrame *in_frame,
                              const AVFilmGrainParams *params)
 {
     const AVFilmGrainH274Params *h274 = &params->codec.h274;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(out_frame->format);
     av_assert1(params->type == AV_FILM_GRAIN_PARAMS_H274);
     if (h274->model_id != 0)
         return AVERROR_PATCHWELCOME;
 
     av_assert1(out_frame->format == in_frame->format);
-    if (in_frame->format != AV_PIX_FMT_YUV420P)
+    switch (out_frame->format) {
+    case AV_PIX_FMT_YUV444P:
+    case AV_PIX_FMT_YUV440P:
+    case AV_PIX_FMT_YUV422P:
+    case AV_PIX_FMT_YUV420P:
+    case AV_PIX_FMT_YUV411P:
+    case AV_PIX_FMT_YUV410P:
+        // 8-bit YCbCr formats with varying subsampling
+        break;
+
+    default:
+        // TODO: support higher bit depth formats!
         return AVERROR_PATCHWELCOME;
+    }
 
     for (int c = 0; c < 3; c++) {
         static const uint8_t color_offset[3] = { 0, 85, 170 };
         uint32_t seed = Seed_LUT[(params->seed + color_offset[c]) % 256];
-        const int width = c > 0 ? AV_CEIL_RSHIFT(out_frame->width, 1) : out_frame->width;
-        const int height = c > 0 ? AV_CEIL_RSHIFT(out_frame->height, 1) : out_frame->height;
+        const uint8_t xs = c > 0 ? desc->log2_chroma_w : 0;
+        const uint8_t ys = c > 0 ? desc->log2_chroma_h : 0;
+        const int width = AV_CEIL_RSHIFT(out_frame->width, xs);
+        const int height = AV_CEIL_RSHIFT(out_frame->height, ys);
 
         uint8_t * const out = out_frame->data[c];
         const int out_stride = out_frame->linesize[c];
@@ -266,7 +282,7 @@ int ff_h274_apply_film_grain(AVFrame *out_frame, const AVFrame *in_frame,
                     for (int xx = 0; xx < 16 && x+xx < width; xx += 8) {
                         generate(grain + (y+yy) * grain_stride + (x+xx), grain_stride,
                                  in + (y+yy) * in_stride + (x+xx), in_stride,
-                                 database, h274, c, invert, (x+xx) > 0,
+                                 database, h274, c, xs, ys, invert, (x+xx) > 0,
                                  y_offset + yy, x_offset + xx);
                     }
                 }
-- 
2.35.1