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, 2 insertions, 0 deletions

diff --git a/video/filter/vf.h b/video/filter/vf.h
index 2a6fc5a41e..4398abebc7 100644
--- a/video/filter/vf.h
+++ b/video/filter/vf.h
@@ -86,6 +86,7 @@ typedef struct vf_seteq {
     int value;
 } vf_equalizer_t;
 
+#define VFCTRL_SEEK_RESET 1 // reset on picture and PTS discontinuities
 #define VFCTRL_QUERY_MAX_PP_LEVEL 4 // query max postprocessing level (if any)
 #define VFCTRL_SET_PP_LEVEL 5       // set postprocessing level
 #define VFCTRL_SET_EQUALIZER 6 // set color options (brightness,contrast etc)
@@ -109,6 +110,7 @@ void vf_add_output_frame(struct vf_instance *vf, struct mp_image *img);
 
 int vf_filter_frame(struct vf_instance *vf, struct mp_image *img);
 struct mp_image *vf_chain_output_queued_frame(struct vf_instance *vf);
+void vf_chain_seek_reset(struct vf_instance *vf);
 
 vf_instance_t *vf_open_plugin(struct MPOpts *opts,
         const vf_info_t * const *filter_list, vf_instance_t *next,