video: reset filters on seek

Drop queued frames on seek. Reset the internal state of some filters
that seem to need it as well: at least vf_divtc still produced some
frames using the previous PTS.

This fixes weird behavior with some filters on seeking. In particular,
this could lead to A/V desync or apparent lockups due to the PTS of
filtered frames being too far away from audio PTS.

This commit does only the minimally required work to fix these PTS
related issues. Some filters have state dependent on previously filtered
frames, and these are not automatically reset with this commit (even
vf_divtc and vf_softpulldown reset the PTS info only). Filters that
actually require a full reset can implement VFCTRL_SEEK_RESET.

1 files changed, 7 insertions, 0 deletions

diff --git a/video/filter/vf.c b/video/filter/vf.c
index 93088953dc..a4b78ab5ab 100644
--- a/video/filter/vf.c
+++ b/video/filter/vf.c
@@ -401,6 +401,13 @@ static void vf_forget_frames(struct vf_instance *vf)
     vf->num_out_queued = 0;
 }
 
+void vf_chain_seek_reset(struct vf_instance *vf)
+{
+    vf->control(vf, VFCTRL_SEEK_RESET, NULL);
+    for (struct vf_instance *cur = vf; cur; cur = cur->next)
+        vf_forget_frames(cur);
+}
+
 int vf_config_wrapper(struct vf_instance *vf,
                       int width, int height, int d_width, int d_height,
                       unsigned int flags, unsigned int outfmt)