fftools/ffmpeg_filter: buffer sub2video heartbeat frames like other frames

Otherwise they'd be silently ignored if received by the filtering thread
before the filtergraph can be initialized, which would make the output
dependent on the order in which frames from different inputs arrive.

fftools/ffmpeg_filter.c

@@ -1769,6 +1769,8 @@ static int graph_is_meta(AVFilterGraph *graph)
     return 1;
 }
 
+static int sub2video_frame(InputFilter *ifilter, AVFrame *frame);
+
 static int configure_filtergraph(FilterGraph *fg, const FilterGraphThread *fgt)
 {
     FilterGraphPriv *fgp = fgp_from_fg(fg);
@@ -1880,7 +1882,7 @@ static int configure_filtergraph(FilterGraph *fg, const FilterGraphThread *fgt)
         AVFrame *tmp;
         while (av_fifo_read(ifp->frame_queue, &tmp, 1) >= 0) {
             if (ifp->type_src == AVMEDIA_TYPE_SUBTITLE) {
-                sub2video_update(ifp, INT64_MIN, (const AVSubtitle*)tmp->buf[0]->data);
+                sub2video_frame(&ifp->ifilter, tmp);
             } else {
                 ret = av_buffersrc_add_frame(ifp->filter, tmp);
             }
@@ -2475,9 +2477,6 @@ static void sub2video_heartbeat(InputFilter *ifilter, int64_t pts, AVRational tb
     InputFilterPriv *ifp = ifp_from_ifilter(ifilter);
     int64_t pts2;
 
-    if (!ifilter->graph->graph)
-        return;
-
     /* subtitles seem to be usually muxed ahead of other streams;
        if not, subtracting a larger time here is necessary */
     pts2 = av_rescale_q(pts, tb, ifp->time_base) - 1;
@@ -2495,18 +2494,38 @@ static void sub2video_heartbeat(InputFilter *ifilter, int64_t pts, AVRational tb
         sub2video_push_ref(ifp, pts2);
 }
 
-static int sub2video_frame(InputFilter *ifilter, const AVFrame *frame)
+static int sub2video_frame(InputFilter *ifilter, AVFrame *frame)
 {
     InputFilterPriv *ifp = ifp_from_ifilter(ifilter);
     int ret;
 
+    if (!ifilter->graph->graph) {
+        AVFrame *tmp;
+
+        if (!frame)
+            return 0;
+
+        tmp = av_frame_alloc();
+        if (!tmp)
+            return AVERROR(ENOMEM);
+
+        av_frame_move_ref(tmp, frame);
+
+        ret = av_fifo_write(ifp->frame_queue, &tmp, 1);
+        if (ret < 0) {
+            av_frame_free(&tmp);
+            return ret;
+        }
+
+        return 0;
+    }
+
     // heartbeat frame
     if (frame && !frame->buf[0]) {
         sub2video_heartbeat(ifilter, frame->pts, frame->time_base);
         return 0;
     }
 
-    if (ifilter->graph->graph) {
         if (!frame) {
             if (ifp->sub2video.end_pts < INT64_MAX)
                 sub2video_update(ifp, INT64_MAX, NULL);
@@ -2518,18 +2537,6 @@ static int sub2video_frame(InputFilter *ifilter, const AVFrame *frame)
         ifp->height = frame->height ? frame->height : ifp->height;
 
         sub2video_update(ifp, INT64_MIN, (const AVSubtitle*)frame->buf[0]->data);
-    } else if (frame) {
-        AVFrame *tmp = av_frame_clone(frame);
-
-        if (!tmp)
-            return AVERROR(ENOMEM);
-
-        ret = av_fifo_write(ifp->frame_queue, &tmp, 1);
-        if (ret < 0) {
-            av_frame_free(&tmp);
-            return ret;
-        }
-    }
 
     return 0;
 }