lavu/raw_color_params: add Panasonic RW2 parameters

The as-shot white balance of RW2 files, as red and blue multipliers
relative to green. The files carry no camera matrix.

doc/APIchanges

@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2026-06-23.
 
 API changes, most recent first:
 
+2026-10-xx - xxxxxxxxxx - lavu 61.13.100 - raw_color_params.h
+  Add AV_RAW_COLOR_PARAMS_RW2 and AVRW2RawColorParams.
+
 2026-10-xx - xxxxxxxxxx - lavc 63.18.100 - codec_id.h
   Add AV_CODEC_ID_RW2.
 

libavutil/raw_color_params.h

@@ -35,6 +35,12 @@ enum AVRawColorParamsType {
      * (codec.prores_raw).
      */
     AV_RAW_COLOR_PARAMS_PRORES_RAW,
+
+    /**
+     * The union is valid when interpreted as AVRW2RawColorParams
+     * (codec.rw2).
+     */
+    AV_RAW_COLOR_PARAMS_RW2,
 };
 
 /**
@@ -80,6 +86,29 @@ typedef struct AVProResRawColorParams {
     AVRational gain;
 } AVProResRawColorParams;
 
+/**
+ * Panasonic RW2 as-shot white balance, from the file's WB level tags.
+ *
+ * The file carries no camera matrix. After white balance and debayering,
+ * camera RGB needs a profile for the camera model, which the EXIF side data
+ * names.
+ *
+ * @note The struct must be allocated as part of AVRawColorParams using
+ *       av_raw_color_params_alloc(). Its size is not a part of the public ABI.
+ */
+typedef struct AVRW2RawColorParams {
+    /**
+     * White balance multiplier for the red channel, applied pre-debayer.
+     */
+    AVRational wb_red;
+
+    /**
+     * White balance multiplier for the blue channel, applied pre-debayer.
+     * The green channel is implicitly 1.0.
+     */
+    AVRational wb_blue;
+} AVRW2RawColorParams;
+
 /**
  * Per-frame color information for a RAW camera codec. Carried as side data of
  * type AV_FRAME_DATA_RAW_COLOR_PARAMS.
@@ -125,6 +154,7 @@ typedef struct AVRawColorParams {
      */
     union {
         AVProResRawColorParams prores_raw;
+        AVRW2RawColorParams rw2;
     } codec;
 } AVRawColorParams;
 

libavutil/version.h

@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  61
-#define LIBAVUTIL_VERSION_MINOR  12
+#define LIBAVUTIL_VERSION_MINOR  13
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \