player: don't display zero duration for files with unknown duration

On OSD/terminal, just don't display the duration if unavailable.

Make the "length" property unavailable if duration is unavailable.

player/command.c

@@ -485,9 +485,9 @@ static int mp_property_length(void *ctx, struct m_property *prop,
                               int action, void *arg)
 {
     MPContext *mpctx = ctx;
-    double len;
+    double len = get_time_length(mpctx);
 
-    if ((len = get_time_length(mpctx)) <= 0)
+    if (len < 0)
         return M_PROPERTY_UNAVAILABLE;
 
     return property_time(action, arg, len);
@@ -605,7 +605,7 @@ static bool time_remaining(MPContext *mpctx, double *remaining)
 
     *remaining = len - playback;
 
-    return len > 0;
+    return len >= 0;
 }
 
 static int mp_property_remaining(void *ctx, struct m_property *prop,
@@ -2234,10 +2234,12 @@ static int get_frame_count(struct MPContext *mpctx)
         return 0;
     if (!mpctx->d_video)
         return 0;
+    double len = get_time_length(mpctx);
+    double fps = mpctx->d_video->fps;
+    if (len < 0 || fps <= 0)
+        return 0;
 
-    int frame_count = (int)(get_time_length(mpctx) * mpctx->d_video->fps);
-
-    return frame_count;
+    return len * fps;
 }
 
 static int mp_property_frame_number(void *ctx, struct m_property *prop,

player/misc.c

@@ -65,12 +65,12 @@ double rel_time_to_abs(struct MPContext *mpctx, struct m_rel_time t)
         if (t.pos >= 0) {
             return start + t.pos;
         } else {
-            if (length != 0)
+            if (length >= 0)
                 return MPMAX(start + length + t.pos, 0.0);
         }
         break;
     case REL_TIME_PERCENT:
-        if (length != 0)
+        if (length >= 0)
             return start + length * (t.pos / 100.0);
         break;
     case REL_TIME_CHAPTER:

player/osd.c

@@ -408,8 +408,11 @@ static void sadd_osd_status(char **buffer, struct MPContext *mpctx, int level)
         } else {
             sadd_hhmmssff(buffer, get_playback_time(mpctx), fractions);
             if (level == 3) {
-                saddf(buffer, " / ");
-                sadd_hhmmssff(buffer, get_time_length(mpctx), fractions);
+                double len = get_time_length(mpctx);
+                if (len >= 0) {
+                    saddf(buffer, " / ");
+                    sadd_hhmmssff(buffer, len, fractions);
+                }
                 sadd_percentage(buffer, get_percent_pos(mpctx));
             }
         }

player/playloop.c

@@ -196,7 +196,7 @@ static int mp_seek(MPContext *mpctx, struct seek_params seek,
         mpctx->last_chapter_seek = -2;
     if (seek.type == MPSEEK_FACTOR && !mpctx->demuxer->ts_resets_possible) {
         double len = get_time_length(mpctx);
-        if (len > 0) {
+        if (len >= 0) {
             seek.amount = seek.amount * len + get_start_time(mpctx);
             seek.type = MPSEEK_ABSOLUTE;
         }
@@ -359,11 +359,12 @@ void execute_queued_seek(struct MPContext *mpctx)
     }
 }
 
+// -1 if unknown
 double get_time_length(struct MPContext *mpctx)
 {
     struct demuxer *demuxer = mpctx->demuxer;
     if (!demuxer)
-        return 0;
+        return -1;
 
     if (mpctx->timeline)
         return mpctx->timeline[mpctx->num_timeline_parts].start;
@@ -372,8 +373,7 @@ double get_time_length(struct MPContext *mpctx)
     if (len >= 0)
         return len;
 
-    // Unknown
-    return 0;
+    return -1; // unknown
 }
 
 /* If there are timestamps from stream level then use those (for example
@@ -410,8 +410,8 @@ double get_current_pos_ratio(struct MPContext *mpctx, bool use_range)
     if (use_range) {
         double startpos = rel_time_to_abs(mpctx, mpctx->opts->play_start);
         double endpos = get_play_end_pts(mpctx);
-        if (endpos == MP_NOPTS_VALUE || endpos > start + len)
-            endpos = start + len;
+        if (endpos == MP_NOPTS_VALUE || endpos > start + MPMAX(0, len))
+            endpos = start + MPMAX(0, len);
         if (startpos == MP_NOPTS_VALUE || startpos < start)
             startpos = start;
         if (endpos < startpos)
@@ -420,7 +420,7 @@ double get_current_pos_ratio(struct MPContext *mpctx, bool use_range)
         len = endpos - startpos;
     }
     double pos = get_current_time(mpctx);
-    if (len > 0 && !demuxer->ts_resets_possible) {
+    if (len >= 0 && !demuxer->ts_resets_possible) {
         ans = MPCLAMP((pos - start) / len, 0, 1);
     } else {
         int64_t size;