[FFmpeg-devel] [PATCH] avfilter/vf_drawtext: add optional default value to metadata function

[Tobias Rapp]

Signed-off-by: Tobias Rapp <t.rapp at noa-archive.com>
---
 doc/filters.texi          | 7 ++++++-
 libavfilter/vf_drawtext.c | 4 +++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index 592fc24..3675b13 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -6499,7 +6499,12 @@ The time at which the filter is running, expressed in the local time zone.
 It can accept an argument: a strftime() format string.
 
 @item metadata
-Frame metadata. It must take one argument specifying metadata key.
+Frame metadata. Takes one or two arguments.
+
+The first argument is mandatory and specifyies the metadata key.
+
+The second argument is optional and specifies a default value, used when the
+metadata key is not found or empty.
 
 @item n, frame_num
 The frame number, starting from 0.
diff --git a/libavfilter/vf_drawtext.c b/libavfilter/vf_drawtext.c
index 1ef3ecb..6b9af5b 100644
--- a/libavfilter/vf_drawtext.c
+++ b/libavfilter/vf_drawtext.c
@@ -860,6 +860,8 @@ static int func_metadata(AVFilterContext *ctx, AVBPrint *bp,
 
     if (e && e->value)
         av_bprintf(bp, "%s", e->value);
+    else if (argc >= 2)
+        av_bprintf(bp, "%s", argv[1]);
     return 0;
 }
 
@@ -975,7 +977,7 @@ static const struct drawtext_function {
     { "localtime", 0, 1, 'L', func_strftime },
     { "frame_num", 0, 0, 0,   func_frame_num },
     { "n",         0, 0, 0,   func_frame_num },
-    { "metadata",  1, 1, 0,   func_metadata },
+    { "metadata",  1, 2, 0,   func_metadata },
 };
 
 static int eval_function(AVFilterContext *ctx, AVBPrint *bp, char *fct,
-- 
1.9.1