lavfi/select: add support for concatdec_select option

This option can be used to select useful frames from an ffconcat file which is
using inpoints and outpoints but where the source files are not intra frame
only.

Reviewed-by: Stefano Sabatini <stefasab@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>

1 files changed, 27 insertions, 0 deletions

diff --git a/libavfilter/f_select.c b/libavfilter/f_select.c
index 2b926e1e14..52f474eb93 100644
--- a/libavfilter/f_select.c
+++ b/libavfilter/f_select.c
@@ -82,6 +82,8 @@ static const char *const var_names[] = {
 
     "scene",
 
+    "concatdec_select",  ///< frame is within the interval set by the concat demuxer
+
     NULL
 };
 
@@ -132,6 +134,8 @@ enum var_name {
 
     VAR_SCENE,
 
+    VAR_CONCATDEC_SELECT,
+
     VAR_VARS_NB
 };
 
@@ -278,6 +282,28 @@ static double get_scene_score(AVFilterContext *ctx, AVFrame *frame)
     return ret;
 }
 
+static double get_concatdec_select(AVFrame *frame, int64_t pts)
+{
+    AVDictionary *metadata = av_frame_get_metadata(frame);
+    AVDictionaryEntry *start_time_entry = av_dict_get(metadata, "lavf.concatdec.start_time", NULL, 0);
+    AVDictionaryEntry *duration_entry = av_dict_get(metadata, "lavf.concatdec.duration", NULL, 0);
+    if (start_time_entry) {
+        int64_t start_time = strtoll(start_time_entry->value, NULL, 10);
+        if (pts >= start_time) {
+            if (duration_entry) {
+              int64_t duration = strtoll(duration_entry->value, NULL, 10);
+              if (pts < start_time + duration)
+                  return -1;
+              else
+                  return 0;
+            }
+            return -1;
+        }
+        return 0;
+    }
+    return NAN;
+}
+
 #define D2TS(d)  (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
 #define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
 
@@ -297,6 +323,7 @@ static void select_frame(AVFilterContext *ctx, AVFrame *frame)
     select->var_values[VAR_T  ] = TS2D(frame->pts) * av_q2d(inlink->time_base);
     select->var_values[VAR_POS] = av_frame_get_pkt_pos(frame) == -1 ? NAN : av_frame_get_pkt_pos(frame);
     select->var_values[VAR_KEY] = frame->key_frame;
+    select->var_values[VAR_CONCATDEC_SELECT] = get_concatdec_select(frame, av_rescale_q(frame->pts, inlink->time_base, AV_TIME_BASE_Q));
 
     switch (inlink->type) {
     case AVMEDIA_TYPE_AUDIO: