video-decode: Allow reusing an old frame

3 files changed, 24 insertions, 11 deletions

diff --git a/src/advtime.c b/src/advtime.c
index 89af714..93a4057 100644
--- a/src/advtime.c
+++ b/src/advtime.c
@@ -9,6 +9,16 @@
 #include "video_decode.h"
 #include "util.h"
 
+static inline void
+pswap(void **p1, void **p2)
+{
+	void *tmp;
+
+	tmp = *p1;
+	*p1 = *p2;
+	*p2 = tmp;
+}
+
 /* print time in format: "hh:mm:ss.xxx" */
 static void
 print_time(int64_t msec) {
@@ -75,8 +85,7 @@ int
 main(int argc, char **argv)
 {
 	struct video_decode *vd;
-	struct video_frame *frame_a;
-	struct video_frame *frame_b;
+	struct video_frame *frame_a = NULL, *frame_b = NULL, *tmp;
 	int ret, ch;
 	int diff_flag = 0, average_flag = 0, frame_flag = 0, showcut_flag = 0;
 	int64_t timestamp = 0;
@@ -177,10 +186,10 @@ main(int argc, char **argv)
 		if (frame_flag || average_flag)
 			printf("\n");
 
-		video_decode_free_frame(&frame_a);
-		frame_a = frame_b;
+		pswap(&frame_a, &frame_b);
 	}
 
+	video_decode_free_frame(&frame_a);
 	video_decode_free_frame(&frame_b);
 	video_decode_uninit(&vd);
 	return EXIT_SUCCESS;
diff --git a/src/frame_to_pgm.c b/src/frame_to_pgm.c
index 36e9ac8..b878968 100644
--- a/src/frame_to_pgm.c
+++ b/src/frame_to_pgm.c
@@ -21,7 +21,7 @@ int
 main(int argc, char **argv)
 {
 	struct video_decode *vd;
-	struct video_frame *frame;
+	struct video_frame *frame = NULL;
 	int ret;
 	int64_t timestamp = 0;
 
diff --git a/src/video_decode.c b/src/video_decode.c
index 993fd14..e6748e0 100644
--- a/src/video_decode.c
+++ b/src/video_decode.c
@@ -97,9 +97,14 @@ video_decode_get_frame(struct video_decode *vd, struct video_frame **frame)
 	int decoded, got_picture;
 	int ret;
 
-	f = calloc(1, sizeof *f);
-	if (f == NULL)
-		return -1;
+	if (*frame != NULL) {
+		f = *frame;
+	} else  {
+		f = calloc(1, sizeof *f);
+		if (f == NULL)
+			return -1;
+		f->frame = avcodec_alloc_frame();
+	}
 
 	packet.data = NULL;
 	do {
@@ -122,8 +127,6 @@ video_decode_get_frame(struct video_decode *vd, struct video_frame **frame)
 		}
 	} while (packet.stream_index != vd->stream);
 
-	f->frame = avcodec_alloc_frame();
-
 	do {
 #if DEBUG
 		printf("packet.data: %p, packet.siz: %d, packet.strm_idx: %d\n",
@@ -150,7 +153,8 @@ video_decode_get_frame(struct video_decode *vd, struct video_frame **frame)
 	f->base.height = vd->codec_ctx->height;
 	f->base.stride = f->frame->linesize[0];
 
-	*frame = &f->base;
+	if (*frame == NULL)
+		*frame = &f->base;
 
 	return 1;
 }