[FFmpeg-devel] [PATCH] libavfilter/vf_subtitles: add options offset set subtitles time offset

[qq2225936589]

From: qq2225936589 <qq2225936589 at gmail.com>

---
 doc/filters.texi           | 3 +++
 libavfilter/vf_subtitles.c | 5 ++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index 0ef6f56d5d..5dee472837 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -16307,6 +16307,9 @@ useful if not UTF-8.
 @item stream_index, si
 Set subtitles stream index. @code{subtitles} filter only.
 
+ at item offset
+Set subtitles time offset. @code{subtitles} filter only.
+
 @item force_style
 Override default style or script info parameters of the subtitles. It accepts a
 string containing ASS style format @code{KEY=VALUE} couples separated by ",".
diff --git a/libavfilter/vf_subtitles.c b/libavfilter/vf_subtitles.c
index a7b02461f2..ba6f03e385 100644
--- a/libavfilter/vf_subtitles.c
+++ b/libavfilter/vf_subtitles.c
@@ -27,6 +27,7 @@
  * @see{http://www.matroska.org/technical/specs/subtitles/ssa.html}
  */
 
+#include <float.h>
 #include <ass/ass.h>
 
 #include "config.h"
@@ -52,6 +53,7 @@ typedef struct AssContext {
     char *filename;
     char *fontsdir;
     char *charenc;
+    float offset;
     char *force_style;
     int stream_index;
     int alpha;
@@ -266,6 +268,7 @@ static const AVOption subtitles_options[] = {
     {"charenc",      "set input character encoding", OFFSET(charenc),      AV_OPT_TYPE_STRING, {.str = NULL}, CHAR_MIN, CHAR_MAX, FLAGS},
     {"stream_index", "set stream index",             OFFSET(stream_index), AV_OPT_TYPE_INT,    { .i64 = -1 }, -1,       INT_MAX,  FLAGS},
     {"si",           "set stream index",             OFFSET(stream_index), AV_OPT_TYPE_INT,    { .i64 = -1 }, -1,       INT_MAX,  FLAGS},
+    {"offset",       "set subtitles time offset",    OFFSET(offset),       AV_OPT_TYPE_FLOAT,  { .dbl = 0.0}, -600.0,   600.0,    FLAGS},
     {"force_style",  "force subtitle style",         OFFSET(force_style),  AV_OPT_TYPE_STRING, {.str = NULL}, CHAR_MIN, CHAR_MAX, FLAGS},
     {NULL},
 };
@@ -458,7 +461,7 @@ static av_cold int init_subtitles(AVFilterContext *ctx)
                 av_log(ctx, AV_LOG_WARNING, "Error decoding: %s (ignored)\n",
                        av_err2str(ret));
             } else if (got_subtitle) {
-                const int64_t start_time = av_rescale_q(sub.pts, AV_TIME_BASE_Q, av_make_q(1, 1000));
+                const int64_t start_time = av_rescale_q(sub.pts, AV_TIME_BASE_Q, av_make_q(1, 1000)) + ass->offset*1000;
                 const int64_t duration   = sub.end_display_time;
                 for (i = 0; i < sub.num_rects; i++) {
                     char *ass_line = sub.rects[i]->ass;
-- 
2.13.0.windows.1