[FFmpeg-devel] [PATCH v2 01/13] vf_libplacebo: add support for specifying a LUT for the input

[Lynne <dev@lynne.ee>]

This makes it possible to apply Adobe .cube files to inputs.
---
 doc/filters.texi            | 30 ++++++++++++++++++++++++++++++
 libavfilter/vf_libplacebo.c | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+)

diff --git a/doc/filters.texi b/doc/filters.texi
index ed2956fe75..13add0ff01 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -16321,6 +16321,36 @@ Render frames with rounded corners. The value, given as a float ranging from
 square to fully circular. In other words, it gives the radius divided by half
 the smaller side length. Defaults to @code{0.0}.
 
+@item lut
+Specifies a custom LUT (in Adobe .cube format) to apply to the colors
+as part of color conversion. The exact interpretation depends on the value
+of @option{lut_type}.
+
+@item lut_type
+Controls the interpretation of color values fed to and from the LUT
+specified as @option{lut}. Valid values are:
+
+@table @samp
+@item auto
+Chooses the interpretation of the LUT automatically from tagged
+metadata, and otherwise falls back to @samp{native}. (Default)
+
+@item native
+Applied to raw image contents in its native RGB colorspace (non-linear
+light), before conversion to the output color space.
+
+@item normalized
+Applied to the normalized RGB image contents, in linear light, before
+conversion to the output color space.
+
+@item conversion
+Fully replaces the conversion from the image color space to the output
+color space. If such a LUT is present, it has the highest priority, and
+overrides any ICC profiles, as well as options related to tone mapping
+and output colorimetry (@option{color_primaries}, @option{color_trc}).
+
+@end table
+
 @item extra_opts
 Pass extra libplacebo internal configuration options. These can be specified
 as a list of @var{key}=@var{value} pairs separated by ':'. The following example
diff --git a/libavfilter/vf_libplacebo.c b/libavfilter/vf_libplacebo.c
index 475030c80d..cbdbe3e665 100644
--- a/libavfilter/vf_libplacebo.c
+++ b/libavfilter/vf_libplacebo.c
@@ -159,6 +159,7 @@ typedef struct LibplaceboContext {
     pl_vulkan vulkan;
     pl_gpu gpu;
     pl_tex tex[4];
+    struct pl_custom_lut *lut;
 
     /* input state */
     LibplaceboInput *inputs;
@@ -184,6 +185,8 @@ typedef struct LibplaceboContext {
     AVExpr *pos_x_pexpr, *pos_y_pexpr, *pos_w_pexpr, *pos_h_pexpr;
     float pad_crop_ratio;
     float corner_rounding;
+    char *lut_filename;
+    enum pl_lut_type lut_type;
     int force_original_aspect_ratio;
     int force_divisible_by;
     int reset_sar;
@@ -371,6 +374,26 @@ static int find_scaler(AVFilterContext *avctx,
     return AVERROR(EINVAL);
 }
 
+static int parse_custom_lut(LibplaceboContext *s)
+{
+    int ret;
+    uint8_t *lutbuf;
+    size_t lutbuf_size;
+
+    if ((ret = av_file_map(s->lut_filename, &lutbuf, &lutbuf_size, 0, s)) < 0) {
+        av_log(s, AV_LOG_ERROR,
+               "The LUT file '%s' could not be read: %s\n",
+               s->lut_filename, av_err2str(ret));
+        return ret;
+    }
+
+    s->lut = pl_lut_parse_cube(s->log, lutbuf, lutbuf_size);
+    av_file_unmap(lutbuf, lutbuf_size);
+    if (!s->lut)
+        return AVERROR(EINVAL);
+    return 0;
+}
+
 static int update_settings(AVFilterContext *ctx)
 {
     int err = 0;
@@ -729,6 +752,9 @@ static int init_vulkan(AVFilterContext *avctx, const AVVulkanDeviceContext *hwct
         RET(parse_shader(avctx, buf, buf_len));
     }
 
+    if (s->lut_filename)
+        RET(parse_custom_lut(s));
+
     /* Initialize inputs */
     s->inputs = av_calloc(s->nb_inputs, sizeof(*s->inputs));
     if (!s->inputs)
@@ -757,6 +783,7 @@ static void libplacebo_uninit(AVFilterContext *avctx)
         av_freep(&s->inputs);
     }
 
+    pl_lut_free(&s->lut);
 #if PL_API_VER >= 351
     pl_cache_destroy(&s->cache);
 #endif
@@ -1005,6 +1032,8 @@ static bool map_frame(pl_gpu gpu, pl_tex *tex,
         .tex        = tex,
         .map_dovi   = s->apply_dovi,
     ));
+    out->lut = s->lut;
+    out->lut_type = s->lut_type;
 
     if (!s->apply_filmgrain)
         out->film_grain.type = PL_FILM_GRAIN_NONE;
@@ -1406,6 +1435,13 @@ static const AVOption libplacebo_options[] = {
     { "pad_crop_ratio", "ratio between padding and cropping when normalizing SAR (0=pad, 1=crop)", OFFSET(pad_crop_ratio), AV_OPT_TYPE_FLOAT, {.dbl=0.0}, 0.0, 1.0, DYNAMIC },
     { "fillcolor", "Background fill color", OFFSET(fillcolor), AV_OPT_TYPE_COLOR, {.str = "black@0"}, .flags = DYNAMIC },
     { "corner_rounding", "Corner rounding radius", OFFSET(corner_rounding), AV_OPT_TYPE_FLOAT, {.dbl = 0.0}, 0.0, 1.0, .flags = DYNAMIC },
+    { "lut", "Path to custom LUT file to apply", OFFSET(lut_filename), AV_OPT_TYPE_STRING, { .str = NULL }, .flags = STATIC },
+    { "lut_type", "Application mode of the custom LUT", OFFSET(lut_type), AV_OPT_TYPE_INT, { .i64 = PL_LUT_UNKNOWN }, 0, PL_LUT_CONVERSION, STATIC, .unit = "lut_type" },
+        { "auto",  NULL, 0, AV_OPT_TYPE_CONST, {.i64 = PL_LUT_UNKNOWN }, 0, 0, STATIC, .unit = "lut_type" },
+        { "native", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = PL_LUT_NATIVE }, 0, 0, STATIC, .unit = "lut_type" },
+        { "normalized", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = PL_LUT_NORMALIZED }, 0, 0, STATIC, .unit = "lut_type" },
+        { "conversion", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = PL_LUT_CONVERSION }, 0, 0, STATIC, .unit = "lut_type" },
+
     { "extra_opts", "Pass extra libplacebo-specific options using a :-separated list of key=value pairs", OFFSET(extra_opts), AV_OPT_TYPE_DICT, .flags = DYNAMIC },
 #if PL_API_VER >= 351
     { "shader_cache",  "Set shader cache path", OFFSET(shader_cache), AV_OPT_TYPE_STRING, {.str = NULL}, .flags = STATIC },
-- 
2.50.0
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