Commit 799b0625bb for ffmpeg

commit 799b0625bbf2f7b8d363db4cd782a45ed3348f9b
Author: Kacper Michajłow <kasper93@gmail.com>
Date:   Wed Sep 30 19:18:25 2026 +0200

    avfilter/vaapi_vpp: assume untagged input is sited like the output

    VA-API leaves the meaning of an unknown chroma siting to the driver, so an
    untagged input with a tagged output was converted from the driver's own
    default. Take the input location from the output instead, so that nothing
    is converted.

    Signed-off-by: Kacper Michajłow <kasper93@gmail.com>

diff --git a/libavfilter/vaapi_vpp.c b/libavfilter/vaapi_vpp.c
index cb855cc281..1676820061 100644
--- a/libavfilter/vaapi_vpp.c
+++ b/libavfilter/vaapi_vpp.c
@@ -463,10 +463,6 @@ static int vaapi_vpp_colour_properties(AVFilterContext *avctx,
         .chroma_sample_location = input_frame->chroma_location,
     };

-    vaapi_vpp_fill_colour_properties(avctx, &input_props,
-                                     caps.input_color_standards,
-                                     caps.num_input_color_standards);
-
     output_props = (VAAPIColourProperties) {
         .colorspace = vaapi_vpp_frame_is_rgb(output_frame)
                 ? AVCOL_SPC_RGB : output_frame->colorspace,
@@ -475,6 +471,14 @@ static int vaapi_vpp_colour_properties(AVFilterContext *avctx,
         .color_range            = output_frame->color_range,
         .chroma_sample_location = output_frame->chroma_location,
     };
+
+    // Input without a chroma location is assumed to be sited like the output.
+    if (input_props.chroma_sample_location == AVCHROMA_LOC_UNSPECIFIED)
+        input_props.chroma_sample_location = output_props.chroma_sample_location;
+
+    vaapi_vpp_fill_colour_properties(avctx, &input_props,
+                                     caps.input_color_standards,
+                                     caps.num_input_color_standards);
     vaapi_vpp_fill_colour_properties(avctx, &output_props,
                                      caps.output_color_standards,
                                      caps.num_output_color_standards);