demux: export some debugging fields about low level demuxer behavior

Export them as explicitly undocumented debugging fields for the
"demuxer-cache-state" property.

Should be somewhat helpful to debug "wtf is the demuxer" doing
situations better, especially when seeking. It also becomes visible how
long the demuxer is blocked on an "old" seek when you keep seeking while
the first seek hasn't finished.

demux/demux.c

@@ -174,6 +174,11 @@ struct demux_internal {
     int seek_flags;             // flags for next seek (if seeking==true)
     double seek_pts;
 
+    // (fields for debugging)
+    double seeking_in_progress; // low level seek state
+    int low_level_seeks;        // number of started low level seeks
+    double demux_ts;            // last demuxed DTS or PTS
+
     double ts_offset;           // timestamp offset to apply to everything
 
     void (*run_fn)(void *);     // if non-NULL, function queued to be run on
@@ -1125,6 +1130,13 @@ void demux_add_packet(struct sh_stream *stream, demux_packet_t *dp)
     struct demux_internal *in = ds->in;
     pthread_mutex_lock(&in->lock);
 
+    double ts = dp->dts == MP_NOPTS_VALUE ? dp->pts : dp->dts;
+    if (dp->segmented)
+        ts = MP_PTS_MIN(ts, dp->end);
+
+    if (ts != MP_NOPTS_VALUE)
+        in->demux_ts = ts;
+
     struct demux_queue *queue = ds->queue;
 
     bool drop = !ds->selected || in->seeking;
@@ -1194,9 +1206,6 @@ void demux_add_packet(struct sh_stream *stream, demux_packet_t *dp)
     if (stream->type != STREAM_VIDEO && dp->pts == MP_NOPTS_VALUE)
         dp->pts = dp->dts;
 
-    double ts = dp->dts == MP_NOPTS_VALUE ? dp->pts : dp->dts;
-    if (dp->segmented)
-        ts = MP_PTS_MIN(ts, dp->end);
     if (ts != MP_NOPTS_VALUE && (ts > queue->last_ts || ts + 10 < queue->last_ts))
         queue->last_ts = ts;
     if (ds->base_ts == MP_NOPTS_VALUE)
@@ -1428,6 +1437,9 @@ static void execute_seek(struct demux_internal *in)
     int flags = in->seek_flags;
     double pts = in->seek_pts;
     in->seeking = false;
+    in->seeking_in_progress = pts;
+    in->demux_ts = MP_NOPTS_VALUE;
+    in->low_level_seeks += 1;
     in->initial_state = false;
 
     pthread_mutex_unlock(&in->lock);
@@ -1440,6 +1452,8 @@ static void execute_seek(struct demux_internal *in)
     MP_VERBOSE(in, "seek done\n");
 
     pthread_mutex_lock(&in->lock);
+
+    in->seeking_in_progress = MP_NOPTS_VALUE;
 }
 
 // Make demuxing progress. Return whether progress was made.
@@ -1999,6 +2013,8 @@ static struct demuxer *open_given_type(struct mpv_global *global,
         .max_bytes_bw = opts->max_bytes_bw,
         .initial_state = true,
         .highest_av_pts = MP_NOPTS_VALUE,
+        .seeking_in_progress = MP_NOPTS_VALUE,
+        .demux_ts = MP_NOPTS_VALUE,
     };
     pthread_mutex_init(&in->lock, NULL);
     pthread_cond_init(&in->wakeup, NULL);
@@ -2750,6 +2766,9 @@ static int cached_demux_control(struct demux_internal *in, int cmd, void *arg)
             .ts_duration = -1,
             .total_bytes = in->total_bytes,
             .fw_bytes = in->fw_bytes,
+            .seeking = in->seeking_in_progress,
+            .low_level_seeks = in->low_level_seeks,
+            .ts_last = in->demux_ts,
         };
         bool any_packets = false;
         for (int n = 0; n < in->num_streams; n++) {

demux/demux.h

@@ -53,6 +53,9 @@ struct demux_ctrl_reader_state {
     double ts_end; // approx. timestamp of end of buffered range
     int64_t total_bytes;
     int64_t fw_bytes;
+    double seeking; // current low level seek target, or NOPTS
+    int low_level_seeks; // number of started low level seeks
+    double ts_last; // approx. timestamp of demuxer position
     // Positions that can be seeked to without incurring the latency of a low
     // level seek.
     int num_seek_ranges;

player/command.c

@@ -1755,6 +1755,11 @@ static int mp_property_demuxer_cache_state(void *ctx, struct m_property *prop,
     node_map_add_flag(r, "idle", s.idle);
     node_map_add_int64(r, "total-bytes", s.total_bytes);
     node_map_add_int64(r, "fw-bytes", s.fw_bytes);
+    if (s.seeking != MP_NOPTS_VALUE)
+        node_map_add_double(r, "debug-seeking", s.seeking);
+    node_map_add_int64(r, "debug-low-level-seeks", s.low_level_seeks);
+    if (s.ts_last != MP_NOPTS_VALUE)
+        node_map_add_double(r, "debug-ts-last", s.ts_last);
 
     return M_PROPERTY_OK;
 }