ffmpeg: explicitly handle sub2video subpicture initialization

Each time the sub2video structure is initialized, the sub2video
subpicture is initialized together with the first received heartbeat.
The heartbeat's PTS is utilized as the subpicture start time.

Additionally, add some documentation on the stages.

diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index e5fbd479a8836c992bb5857fbd6c8bb347a57634..aaaf24131449796c506f6ac27bdec1b3b15939a8 100644 (file)
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -237,7 +237,7 @@ static void sub2video_push_ref(InputStream *ist, int64_t pts)
     }
 }
 
-void sub2video_update(InputStream *ist, AVSubtitle *sub)
+void sub2video_update(InputStream *ist, int64_t heartbeat_pts, AVSubtitle *sub)
 {
     AVFrame *frame = ist->sub2video.frame;
     int8_t *dst;
@@ -254,7 +254,12 @@ void sub2video_update(InputStream *ist, AVSubtitle *sub)
                                  AV_TIME_BASE_Q, ist->st->time_base);
         num_rects = sub->num_rects;
     } else {
-        pts       = ist->sub2video.end_pts;
+        /* If we are initializing the system, utilize current heartbeat
+           PTS as the start time, and show until the following subpicture
+           is received. Otherwise, utilize the previous subpicture's end time
+           as the fall-back value. */
+        pts       = ist->sub2video.initialize ?
+                    heartbeat_pts : ist->sub2video.end_pts;
         end_pts   = INT64_MAX;
         num_rects = 0;
     }
@@ -269,6 +274,7 @@ void sub2video_update(InputStream *ist, AVSubtitle *sub)
         sub2video_copy_rect(dst, dst_linesize, frame->width, frame->height, sub->rects[i]);
     sub2video_push_ref(ist, pts);
     ist->sub2video.end_pts = end_pts;
+    ist->sub2video.initialize = 0;
 }
 
 static void sub2video_heartbeat(InputStream *ist, int64_t pts)
@@ -291,9 +297,11 @@ static void sub2video_heartbeat(InputStream *ist, int64_t pts)
         /* do not send the heartbeat frame if the subtitle is already ahead */
         if (pts2 <= ist2->sub2video.last_pts)
             continue;
-        if (pts2 >= ist2->sub2video.end_pts ||
-            (!ist2->sub2video.frame->data[0] && ist2->sub2video.end_pts < INT64_MAX))
-            sub2video_update(ist2, NULL);
+        if (pts2 >= ist2->sub2video.end_pts || ist2->sub2video.initialize)
+            /* if we have hit the end of the current displayed subpicture,
+               or if we need to initialize the system, update the
+               overlayed subpicture and its start/end times */
+            sub2video_update(ist2, pts2 + 1, NULL);
         for (j = 0, nb_reqs = 0; j < ist2->nb_filters; j++)
             nb_reqs += av_buffersrc_get_nb_failed_requests(ist2->filters[j]->filter);
         if (nb_reqs)
@@ -307,7 +315,7 @@ static void sub2video_flush(InputStream *ist)
     int ret;
 
     if (ist->sub2video.end_pts < INT64_MAX)
-        sub2video_update(ist, NULL);
+        sub2video_update(ist, INT64_MAX, NULL);
     for (i = 0; i < ist->nb_filters; i++) {
         ret = av_buffersrc_add_frame(ist->filters[i]->filter, NULL);
         if (ret != AVERROR_EOF && ret < 0)
@@ -2507,7 +2515,7 @@ static int transcode_subtitles(InputStream *ist, AVPacket *pkt, int *got_output,
         return ret;
 
     if (ist->sub2video.frame) {
-        sub2video_update(ist, &subtitle);
+        sub2video_update(ist, INT64_MIN, &subtitle);
     } else if (ist->nb_filters) {
         if (!ist->sub2video.sub_queue)
             ist->sub2video.sub_queue = av_fifo_alloc(8 * sizeof(AVSubtitle));

diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index c0b8eb599f5761a5e96745908b75d9de30764b9a..fbaae15377dd020364df939a15c7d649f38389e0 100644 (file)
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -348,6 +348,7 @@ typedef struct InputStream {
         AVFifoBuffer *sub_queue;    ///< queue of AVSubtitle* before filter init
         AVFrame *frame;
         int w, h;
+        unsigned int initialize; ///< marks if sub2video_update should force an initialization
     } sub2video;
 
     int dr1;
@@ -645,7 +646,7 @@ int filtergraph_is_simple(FilterGraph *fg);
 int init_simple_filtergraph(InputStream *ist, OutputStream *ost);
 int init_complex_filtergraph(FilterGraph *fg);
 
-void sub2video_update(InputStream *ist, AVSubtitle *sub);
+void sub2video_update(InputStream *ist, int64_t heartbeat_pts, AVSubtitle *sub);
 
 int ifilter_parameters_from_frame(InputFilter *ifilter, const AVFrame *frame);
 

diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
index 40cc4c191c6aaa8de7d1fa73d283b9893876adbb..b66faa50b53da687ef9e494201e5c22c08b7823f 100644 (file)
--- a/fftools/ffmpeg_filter.c
+++ b/fftools/ffmpeg_filter.c
@@ -740,6 +740,12 @@ static int sub2video_prepare(InputStream *ist, InputFilter *ifilter)
         return AVERROR(ENOMEM);
     ist->sub2video.last_pts = INT64_MIN;
     ist->sub2video.end_pts  = INT64_MIN;
+
+    /* sub2video structure has been (re-)initialized.
+       Mark it as such so that the system will be
+       initialized with the first received heartbeat. */
+    ist->sub2video.initialize = 1;
+
     return 0;
 }
 
@@ -1168,7 +1174,7 @@ int configure_filtergraph(FilterGraph *fg)
             while (av_fifo_size(ist->sub2video.sub_queue)) {
                 AVSubtitle tmp;
                 av_fifo_generic_read(ist->sub2video.sub_queue, &tmp, sizeof(tmp), NULL);
-                sub2video_update(ist, &tmp);
+                sub2video_update(ist, INT64_MIN, &tmp);
                 avsubtitle_free(&tmp);
             }
         }