player: minor fix/simplification of OSD time/duration handling

Always display the duration as "unknown" if the duration is known. Also
fix that at least demux_lavf reported unknown duration as 0 (fix by
setting the default to unknown in demux.c).

Remove the dumb _u formatter function, and use a different approach to
avoiding displaying "unknown" as playback time on playback start (set
last_seek_pts for that).

demux/demux.c

@@ -1937,6 +1937,7 @@ static struct demuxer *open_given_type(struct mpv_global *global,
         .is_network = stream->is_network,
         .access_references = opts->access_references,
         .events = DEMUX_EVENT_ALL,
+        .duration = -1,
     };
     demuxer->seekable = stream->seekable;
     if (demuxer->stream->underlying && !demuxer->stream->underlying->seekable)

player/command.c

@@ -837,7 +837,7 @@ static bool time_remaining(MPContext *mpctx, double *remaining)
     double len = get_time_length(mpctx);
     double playback = get_playback_time(mpctx);
 
-    if (playback == MP_NOPTS_VALUE)
+    if (playback == MP_NOPTS_VALUE || len <= 0)
         return false;
 
     *remaining = len - playback;

player/loadfile.c

@@ -1163,6 +1163,9 @@ static void play_current_file(struct MPContext *mpctx)
 
     reset_playback_state(mpctx);
 
+    // let get_current_time() show 0 as start time (before playback_pts is set)
+    mpctx->last_seek_pts = 0.0;
+
     mpctx->playing = mpctx->playlist->current;
     if (!mpctx->playing || !mpctx->playing->filename)
         goto terminate_playback;

player/osd.c

@@ -57,14 +57,6 @@ static void sadd_hhmmssff(char **buf, double time, bool fractions)
     talloc_free(s);
 }
 
-// If time unknown (MP_NOPTS_VALUE), use 0 instead.
-static void sadd_hhmmssff_u(char **buf, double time, bool fractions)
-{
-    if (time == MP_NOPTS_VALUE)
-        time = 0;
-    sadd_hhmmssff(buf, time, fractions);
-}
-
 static void sadd_percentage(char **buf, int percent) {
     if (percent >= 0)
         *buf = talloc_asprintf_append(*buf, " (%d%%)", percent);
@@ -207,13 +199,9 @@ static void term_osd_print_status_lazy(struct MPContext *mpctx)
     saddf(&line, ": ");
 
     // Playback position
-    sadd_hhmmssff_u(&line, get_playback_time(mpctx), mpctx->opts->osd_fractions);
-
-    double len = get_time_length(mpctx);
-    if (len >= 0) {
-        saddf(&line, " / ");
-        sadd_hhmmssff(&line, len, mpctx->opts->osd_fractions);
-    }
+    sadd_hhmmssff(&line, get_playback_time(mpctx), mpctx->opts->osd_fractions);
+    saddf(&line, " / ");
+    sadd_hhmmssff(&line, get_time_length(mpctx), mpctx->opts->osd_fractions);
 
     sadd_percentage(&line, get_percent_pos(mpctx));
 
@@ -442,15 +430,12 @@ static void sadd_osd_status(char **buffer, struct MPContext *mpctx, int level)
             *buffer = talloc_strdup_append(*buffer, text);
             talloc_free(text);
         } else {
-            sadd_hhmmssff_u(buffer, get_playback_time(mpctx), fractions);
+            sadd_hhmmssff(buffer, get_playback_time(mpctx), fractions);
 #if HAVE_GPL
             // Potentially GPL due to 8d190244d21a4d40bb9e8f7d51aa09ca1888de09.
             if (level == 3) {
-                double len = get_time_length(mpctx);
-                if (len >= 0) {
-                    saddf(buffer, " / ");
-                    sadd_hhmmssff(buffer, len, fractions);
-                }
+                saddf(buffer, " / ");
+                sadd_hhmmssff(buffer, get_time_length(mpctx), fractions);
                 sadd_percentage(buffer, get_percent_pos(mpctx));
             }
 #endif

player/playloop.c

@@ -438,11 +438,11 @@ void execute_queued_seek(struct MPContext *mpctx)
     }
 }
 
-// -1 if unknown
+// NOPTS (i.e. <0) if unknown
 double get_time_length(struct MPContext *mpctx)
 {
     struct demuxer *demuxer = mpctx->demuxer;
-    return demuxer ? demuxer->duration : -1;
+    return demuxer && demuxer->duration >= 0 ? demuxer->duration : MP_NOPTS_VALUE;
 }
 
 double get_current_time(struct MPContext *mpctx)