lavfi/movie: flush decoder frames on EOF

movie currently forwards EOF (or begins looping) immediately upon
reaching the last packet in the input stream, which can leave frames in
the decoder. This change first tries to read any remaining packets from
the decoder before forwarding EOF.
Signed-off-by: Steven Robertson <steven@strobe.cc>
Signed-off-by: Stefano Sabatini <stefasab@gmail.com>

libavfilter/src_movie.c

@@ -42,6 +42,12 @@
 #include "internal.h"
 #include "video.h"
 
+typedef enum {
+    STATE_DECODING,
+    STATE_FLUSHING,
+    STATE_DONE,
+} MovieState;
+
 typedef struct {
     /* common A/V fields */
     const AVClass *class;
@@ -54,7 +60,7 @@ typedef struct {
 
     AVFormatContext *format_ctx;
     AVCodecContext *codec_ctx;
-    int is_done;
+    MovieState state;
     AVFrame *frame;   ///< video frame to store the decoded images in
 
     /* video-only fields */
@@ -236,13 +242,14 @@ static int movie_get_frame(AVFilterLink *outlink)
 {
     MovieContext *movie = outlink->src->priv;
     AVPacket pkt;
-    int ret, frame_decoded;
+    int ret = 0, frame_decoded;
     AVStream *st = movie->format_ctx->streams[movie->stream_index];
 
-    if (movie->is_done == 1)
+    if (movie->state == STATE_DONE)
         return 0;
 
     while (1) {
+        if (movie->state == STATE_DECODING) {
         ret = av_read_frame(movie->format_ctx, &pkt);
         if (ret == AVERROR_EOF) {
             int64_t timestamp;
@@ -251,20 +258,19 @@ static int movie_get_frame(AVFilterLink *outlink)
                 if (movie->format_ctx->start_time != AV_NOPTS_VALUE)
                     timestamp += movie->format_ctx->start_time;
                 if (av_seek_frame(movie->format_ctx, -1, timestamp, AVSEEK_FLAG_BACKWARD) < 0) {
-                    movie->is_done = 1;
-                    break;
+                    movie->state = STATE_FLUSHING;
                 } else if (movie->loop_count>1)
                     movie->loop_count--;
                 continue;
             } else {
-                movie->is_done = 1;
-                break;
+                movie->state = STATE_FLUSHING;
             }
         } else if (ret < 0)
             break;
+        }
 
         // Is this a packet from the video stream?
-        if (pkt.stream_index == movie->stream_index) {
+        if (pkt.stream_index == movie->stream_index || movie->state == STATE_FLUSHING) {
             avcodec_decode_video2(movie->codec_ctx, movie->frame, &frame_decoded, &pkt);
 
             if (frame_decoded) {
@@ -295,6 +301,10 @@ static int movie_get_frame(AVFilterLink *outlink)
                 av_free_packet(&pkt);
 
                 return 0;
+            } else if (movie->state == STATE_FLUSHING) {
+                movie->state = STATE_DONE;
+                av_free_packet(&pkt);
+                return AVERROR_EOF;
             }
         }
         // Free the packet that was allocated by av_read_frame
@@ -310,7 +320,7 @@ static int movie_request_frame(AVFilterLink *outlink)
     MovieContext *movie = outlink->src->priv;
     int ret;
 
-    if (movie->is_done)
+    if (movie->state == STATE_DONE)
         return AVERROR_EOF;
     if ((ret = movie_get_frame(outlink)) < 0)
         return ret;
@@ -391,7 +401,7 @@ static int amovie_get_samples(AVFilterLink *outlink)
     AVPacket pkt;
     int ret, got_frame = 0;
 
-    if (!movie->pkt.size && movie->is_done == 1)
+    if (!movie->pkt.size && movie->state == STATE_DONE)
         return AVERROR_EOF;
 
     /* check for another frame, in case the previous one was completely consumed */
@@ -408,7 +418,7 @@ static int amovie_get_samples(AVFilterLink *outlink)
         }
 
         if (ret == AVERROR_EOF) {
-            movie->is_done = 1;
+            movie->state = STATE_DONE;
             return ret;
         }
     }
@@ -451,7 +461,7 @@ static int amovie_request_frame(AVFilterLink *outlink)
     MovieContext *movie = outlink->src->priv;
     int ret;
 
-    if (movie->is_done)
+    if (movie->state == STATE_DONE)
         return AVERROR_EOF;
     do {
         if ((ret = amovie_get_samples(outlink)) < 0)