options: add --hr-seek-framedrop option

This allows disabling of decoder framedrop during hr-seek.

It's basically another useless option, but it will help exploring
whether this framedropping really makes seeking faster, or whether
disabling it helps with precise seeking (especially frame backstepping).

DOCS/man/en/input.rst

@@ -110,7 +110,8 @@ List of Input Commands
     see the ``--hr-seek-demuxer-offset`` option). Video filters or other video
     postprocessing that modifies timing of frames (e.g. deinterlacing) should
     usually work, but might make backstepping silently behave incorrectly in
-    corner cases.
+    corner cases. Using ``--hr-seek-framedrop=no`` should help, although it
+    might make precise seeking slower.
 
     This does not work with audio-only playback.
 

DOCS/man/en/options.rst

@@ -1078,6 +1078,15 @@ OPTIONS
     the earlier demuxer position and the real target may be unnecessarily
     decoded.
 
+``--hr-seek-framedrop=<yes|no>``
+    Allow the video decoder to drop frames during seek, if these frames are
+    before the seek target. If this is enabled, precise seeking can be faster,
+    but if you're using video filters which modify timestamps or add new
+    frames, it can lead to precise seeking skipping the target frame. This
+    e.g. can break frame backstepping when deinterlacing is enabled.
+
+    Default: ``yes``
+
 ``--http-header-fields=<field1,field2>``
     Set custom HTTP fields when accessing HTTP stream.
 

options/options.c

@@ -578,6 +578,7 @@ const m_option_t mp_opts[] = {
     OPT_CHOICE("hr-seek", hr_seek, 0,
                ({"no", -1}, {"absolute", 0}, {"always", 1}, {"yes", 1})),
     OPT_FLOATRANGE("hr-seek-demuxer-offset", hr_seek_demuxer_offset, 0, -9, 99),
+    OPT_FLAG("hr-seek-framedrop", hr_seek_framedrop, 0),
     OPT_CHOICE_OR_INT("autosync", autosync, 0, 0, 10000,
                       ({"no", -1})),
 
@@ -685,6 +686,7 @@ const struct MPOpts mp_default_opts = {
     .ordered_chapters = 1,
     .chapter_merge_threshold = 100,
     .chapter_seek_threshold = 5.0,
+    .hr_seek_framedrop = 1,
     .load_config = 1,
     .position_resume = 1,
     .stream_cache_min_percent = 20.0,

options/options.h

@@ -121,6 +121,7 @@ typedef struct MPOpts {
     int initial_audio_sync;
     int hr_seek;
     float hr_seek_demuxer_offset;
+    int hr_seek_framedrop;
     float audio_delay;
     float default_max_pts_correction;
     int autosync;

player/video.c

@@ -318,7 +318,8 @@ static int decode_image(struct MPContext *mpctx)
     if (pkt && pkt->pts != MP_NOPTS_VALUE)
         pkt->pts += mpctx->video_offset;
     if ((pkt && pkt->pts >= mpctx->hrseek_pts - .005) ||
-        d_video->has_broken_packet_pts)
+        d_video->has_broken_packet_pts ||
+        !mpctx->opts->hr_seek_framedrop)
     {
         mpctx->hrseek_framedrop = false;
     }