client API: add chapter change event

Also works for mpv_observe_property() on the "chapter" property.

DOCS/man/en/lua.rst

@@ -533,3 +533,6 @@ List of events
 
 ``metadata-update``
     Metadata (like file tags) was updated.
+
+``chapter-change``
+    The current chapter possibly changed.

libmpv/client.h

@@ -913,7 +913,11 @@ typedef enum mpv_event_id {
      * Event sent due to mpv_observe_property().
      * See also mpv_event and mpv_event_property.
      */
-    MPV_EVENT_PROPERTY_CHANGE   = 22
+    MPV_EVENT_PROPERTY_CHANGE   = 22,
+    /**
+     * Happens when the current chapter changes.
+     */
+    MPV_EVENT_CHAPTER_CHANGE = 23
 } mpv_event_id;
 
 /**

player/client.c

@@ -1317,6 +1317,7 @@ static const char *event_table[] = {
     [MPV_EVENT_SEEK] = "seek",
     [MPV_EVENT_PLAYBACK_RESTART] = "playback-restart",
     [MPV_EVENT_PROPERTY_CHANGE] = "property-change",
+    [MPV_EVENT_CHAPTER_CHANGE] = "chapter-change",
 };
 
 const char *mpv_event_name(mpv_event_id event)

player/command.c

@@ -2443,6 +2443,7 @@ const char **mp_event_property_change[] = {
     E(MPV_EVENT_AUDIO_RECONFIG, "audio-format", "audio-codec", "audio-bitrate",
       "samplerate", "channels", "audio"),
     E(MPV_EVENT_METADATA_UPDATE, "metadata"),
+    E(MPV_EVENT_CHAPTER_CHANGE, "chapter", "chapter-metadata"),
 };
 #undef E
 

player/core.h

@@ -276,6 +276,8 @@ typedef struct MPContext {
     // Video PTS, or audio PTS if video has ended.
     double playback_pts;
 
+    int last_chapter;
+
     // History of video frames timestamps that were queued in the VO
     // This includes even skipped frames during hr-seek
     double vo_pts_history_pts[MAX_NUM_VO_PTS];

player/loadfile.c

@@ -1333,6 +1333,7 @@ goto_reopen_demuxer: ;
     mpctx->paused = false;
     mpctx->paused_for_cache = false;
     mpctx->eof_reached = false;
+    mpctx->last_chapter = -2;
     mpctx->seek = (struct seek_params){ 0 };
 
     // If there's a timeline force an absolute seek to initialize state

player/main.c

@@ -310,6 +310,7 @@ struct MPContext *mp_create(void)
     struct MPContext *mpctx = talloc(NULL, MPContext);
     *mpctx = (struct MPContext){
         .last_dvb_step = 1,
+        .last_chapter = -2,
         .term_osd_contents = talloc_strdup(mpctx, ""),
         .osd_progbar = { .type = -1 },
         .playlist = talloc_struct(mpctx, struct playlist, {0}),

player/playloop.c

@@ -845,6 +845,15 @@ static void handle_keep_open(struct MPContext *mpctx)
     }
 }
 
+static void handle_chapter_change(struct MPContext *mpctx)
+{
+    int chapter = get_current_chapter(mpctx);
+    if (chapter != mpctx->last_chapter) {
+        mpctx->last_chapter = chapter;
+        mp_notify(mpctx, MPV_EVENT_CHAPTER_CHANGE, NULL);
+    }
+}
+
 // Execute a forceful refresh of the VO window, if it hasn't had a valid frame
 // for a while. The problem is that a VO with no valid frame (vo->hasframe==0)
 // doesn't redraw video and doesn't OSD interaction. So screw it, hard.
@@ -1295,6 +1304,8 @@ void run_playloop(struct MPContext *mpctx)
 
     handle_keep_open(mpctx);
 
+    handle_chapter_change(mpctx);
+
     handle_force_window(mpctx, false);
 
     execute_queued_seek(mpctx);