avfilter/buffersink: add support for alpha modes

4 files changed, 32 insertions, 2 deletions

diff --git a/doc/APIchanges b/doc/APIchanges
index 149ffc506e..9be59e7b8e 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2025-03-28
 
 API changes, most recent first:
 
+2025-09-xx - xxxxxxxxxx - lavfi 11.7.100 - buffersink.h
+  Add av_buffersink_get_alpha_mode().
+
 2025-09-xx - xxxxxxxxxx - lavc 62.15.100 - avcodec.h codec_par.h
   Add AVCodecContext.alpha_mode, AVCodecParameters.alpha_mode, and
   AV_CODEC_CONFIG_ALPHA_MODE.
diff --git a/libavfilter/buffersink.c b/libavfilter/buffersink.c
index 50a7da2756..f636d3728f 100644
--- a/libavfilter/buffersink.c
+++ b/libavfilter/buffersink.c
@@ -53,6 +53,8 @@ typedef struct BufferSinkContext {
     int color_spaces_size;
     enum AVColorRange *color_ranges;    ///< list of accepted color ranges
     int color_ranges_size;
+    enum AVColorRange *alpha_modes;     ///< list of accepted alpha modes
+    int alpha_modes_size;
 #endif
 
     enum AVPixelFormat *pixel_formats;
@@ -64,6 +66,9 @@ typedef struct BufferSinkContext {
     int                *colorranges;
     unsigned         nb_colorranges;
 
+    int                *alphamodes;
+    unsigned         nb_alphamodes;
+
     /* only used for audio */
 #if FF_API_BUFFERSINK_OPTS
     enum AVSampleFormat *sample_fmts;   ///< list of accepted sample formats
@@ -175,7 +180,7 @@ static av_cold int common_init(AVFilterContext *ctx)
         }
 
     if (ctx->input_pads[0].type == AVMEDIA_TYPE_VIDEO) {
-        if ((buf->pixel_fmts_size || buf->color_spaces_size || buf->color_ranges_size) &&
+        if ((buf->pixel_fmts_size || buf->color_spaces_size || buf->color_ranges_size || buf->alpha_modes_size) &&
             (buf->nb_pixel_formats || buf->nb_colorspaces || buf->nb_colorranges)) {
             av_log(ctx, AV_LOG_ERROR, "Cannot combine old and new format lists\n");
             return AVERROR(EINVAL);
@@ -184,6 +189,7 @@ static av_cold int common_init(AVFilterContext *ctx)
         CHECK_LIST_SIZE(pixel_fmts)
         CHECK_LIST_SIZE(color_spaces)
         CHECK_LIST_SIZE(color_ranges)
+        CHECK_LIST_SIZE(alpha_modes)
     } else {
         if ((buf->sample_fmts_size || buf->channel_layouts_str || buf->sample_rates_size) &&
             (buf->nb_sample_formats || buf->nb_samplerates || buf->nb_channel_layouts)) {
@@ -258,6 +264,7 @@ static int init_video(AVFilterContext *ctx)
     TERMINATE_ARRAY(pixel_formats, AV_PIX_FMT_NONE);
     TERMINATE_ARRAY(colorranges, -1);
     TERMINATE_ARRAY(colorspaces, -1);
+    TERMINATE_ARRAY(alphamodes, -1);
 
     return common_init(ctx);
 }
@@ -336,6 +343,7 @@ MAKE_AVFILTERLINK_ACCESSOR(int              , h                  )
 MAKE_AVFILTERLINK_ACCESSOR(AVRational       , sample_aspect_ratio)
 MAKE_AVFILTERLINK_ACCESSOR(enum AVColorSpace, colorspace)
 MAKE_AVFILTERLINK_ACCESSOR(enum AVColorRange, color_range)
+MAKE_AVFILTERLINK_ACCESSOR(enum AVAlphaMode , alpha_mode)
 
 MAKE_AVFILTERLINK_ACCESSOR(int              , sample_rate        )
 
@@ -409,6 +417,11 @@ static int vsink_query_formats(const AVFilterContext *ctx,
             if (ret < 0)
                 return ret;
         }
+        if (buf->nb_alphamodes) {
+            ret = ff_set_common_alpha_modes_from_list2(ctx, cfg_in, cfg_out, buf->alphamodes);
+            if (ret < 0)
+                return ret;
+        }
 #if FF_API_BUFFERSINK_OPTS
     } else {
     unsigned i;
@@ -438,6 +451,15 @@ static int vsink_query_formats(const AVFilterContext *ctx,
         if ((ret = ff_set_common_color_ranges2(ctx, cfg_in, cfg_out, formats)) < 0)
             return ret;
     }
+
+    if (buf->alpha_modes_size) {
+        AVFilterFormats *formats = NULL;
+        for (i = 0; i < NB_ITEMS(buf->alpha_modes); i++)
+            if ((ret = ff_add_format(&formats, buf->alpha_modes[i])) < 0)
+                return ret;
+        if ((ret = ff_set_common_alpha_modes2(ctx, cfg_in, cfg_out, formats)) < 0)
+            return ret;
+    }
     }
 #endif
 
@@ -509,6 +531,7 @@ static const AVOption buffersink_options[] = {
     { "pix_fmts", "set the supported pixel formats",    OFFSET(pixel_fmts),   AV_OPT_TYPE_BINARY, .flags = FLAGS | AV_OPT_FLAG_DEPRECATED },
     { "color_spaces", "set the supported color spaces", OFFSET(color_spaces), AV_OPT_TYPE_BINARY, .flags = FLAGS | AV_OPT_FLAG_DEPRECATED },
     { "color_ranges", "set the supported color ranges", OFFSET(color_ranges), AV_OPT_TYPE_BINARY, .flags = FLAGS | AV_OPT_FLAG_DEPRECATED },
+    { "alpha_modes", "set the supported alpha modes",   OFFSET(alpha_modes),  AV_OPT_TYPE_BINARY, .flags = FLAGS | AV_OPT_FLAG_DEPRECATED },
 #endif
 
     { "pixel_formats",  "array of supported pixel formats", OFFSET(pixel_formats),
@@ -517,6 +540,8 @@ static const AVOption buffersink_options[] = {
         AV_OPT_TYPE_INT | AV_OPT_TYPE_FLAG_ARRAY, .max = INT_MAX, .flags = FLAGS },
     { "colorranges",    "array of supported color ranges",  OFFSET(colorranges),
         AV_OPT_TYPE_INT | AV_OPT_TYPE_FLAG_ARRAY, .max = INT_MAX, .flags = FLAGS },
+    { "alphamodes",     "array of supported color ranges",  OFFSET(alphamodes),
+        AV_OPT_TYPE_INT | AV_OPT_TYPE_FLAG_ARRAY, .max = INT_MAX, .flags = FLAGS },
 
     { NULL },
 };
diff --git a/libavfilter/buffersink.h b/libavfilter/buffersink.h
index a8435eea8f..4e658a9795 100644
--- a/libavfilter/buffersink.h
+++ b/libavfilter/buffersink.h
@@ -58,6 +58,7 @@
  *  - pixel_formats (array of pixel formats),
  *  - colorspaces (array of int),
  *  - colorranges (array of int),
+ *  - alphamodes (array of int),
  *  - sample_formats (array of sample formats),
  *  - samplerates (array of int),
  *  - channel_layouts (array of channel layouts)
@@ -115,6 +116,7 @@ int              av_buffersink_get_h                   (const AVFilterContext *c
 AVRational       av_buffersink_get_sample_aspect_ratio (const AVFilterContext *ctx);
 enum AVColorSpace av_buffersink_get_colorspace         (const AVFilterContext *ctx);
 enum AVColorRange av_buffersink_get_color_range        (const AVFilterContext *ctx);
+enum AVAlphaMode  av_buffersink_get_alpha_mode         (const AVFilterContext *ctx);
 
 int              av_buffersink_get_channels            (const AVFilterContext *ctx);
 int              av_buffersink_get_ch_layout           (const AVFilterContext *ctx,
diff --git a/libavfilter/version.h b/libavfilter/version.h
index f191d98883..0050874108 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -31,7 +31,7 @@
 
 #include "version_major.h"
 
-#define LIBAVFILTER_VERSION_MINOR   6
+#define LIBAVFILTER_VERSION_MINOR   7
 #define LIBAVFILTER_VERSION_MICRO 100