ffmpeg-ebur128-reference.patch

diff --git a/libavfilter/f_ebur128.c b/libavfilter/f_ebur128.c
index c4b30b4926..7bbce7b1a5 100644
--- a/libavfilter/f_ebur128.c
+++ b/libavfilter/f_ebur128.c
@@ -111,6 +111,7 @@ typedef struct {
     struct rect gauge;              ///< rectangle for the gauge on the right
     AVFrame *outpicref;             ///< output picture reference, updated regularly
     int meter;                      ///< select a EBU mode between +9 and +18
+    int reference;                  ///< reference level in LUFS
     int scale_range;                ///< the range of LU values according to the meter
     int y_zero_lu;                  ///< the y value (pixel position) for 0 LU
     int *y_line_ref;                ///< y reference values for drawing the LU lines in the graph and the gauge
@@ -157,6 +158,7 @@ static const AVOption ebur128_options[] = {
     { "video", "set video output", OFFSET(do_video), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, V|F },
     { "size",  "set video size",   OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = "640x480"}, 0, 0, V|F },
     { "meter", "set scale meter (+9 to +18)",  OFFSET(meter), AV_OPT_TYPE_INT, {.i64 = 9}, 9, 18, V|F },
+    { "reference", "set reference level (-30 to 0)", OFFSET(reference), AV_OPT_TYPE_INT, {.i64 = -23}, -30, 0, V|F },
     { "framelog", "force frame logging level", OFFSET(loglevel), AV_OPT_TYPE_INT, {.i64 = -1},   INT_MIN, INT_MAX, A|V|F, "level" },
         { "info",    "information logging level", 0, AV_OPT_TYPE_CONST, {.i64 = AV_LOG_INFO},    INT_MIN, INT_MAX, A|V|F, "level" },
         { "verbose", "verbose logging level",     0, AV_OPT_TYPE_CONST, {.i64 = AV_LOG_VERBOSE}, INT_MIN, INT_MAX, A|V|F, "level" },
@@ -729,8 +731,8 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
                 int x, y, ret;
                 uint8_t *p;
 
-                const int y_loudness_lu_graph = lu_to_y(ebur128, loudness_3000 + 23);
-                const int y_loudness_lu_gauge = lu_to_y(ebur128, loudness_400  + 23);
+                const int y_loudness_lu_graph = lu_to_y(ebur128, loudness_3000 - ebur128->reference);
+                const int y_loudness_lu_gauge = lu_to_y(ebur128, loudness_400  - ebur128->reference);
 
                 /* draw the graph using the short-term loudness */
                 p = pic->data[0] + ebur128->graph.y*pic->linesize[0] + ebur128->graph.x*3;