command: read the diff if you want to know

DOCS/man/input.rst

@@ -1258,6 +1258,22 @@ Property list
     Returns ``yes`` if the demuxer is idle, which means the demuxer cache is
     filled to the requested amount, and is currently not reading more data.
 
+``demuxer-cache-state``
+    Various undocumented things. Some fields are documented:
+
+    ``demuxer-cache-state/seekable-start``, ``demuxer-cache-state/seekable-end``
+        Seekable range within demuxer cache. Unavailable if not possible.
+
+    When querying the property with the client API using ``MPV_FORMAT_NODE``,
+    or with Lua ``mp.get_property_native``, this will return a mpv_node with
+    the following contents:
+
+    ::
+
+        MPV_FORMAT_NODE_ARRAY
+            "seekable-start"    MPV_FORMAT_DOUBLE
+            "seekable-end"      MPV_FORMAT_DOUBLE
+
 ``demuxer-via-network``
     Returns ``yes`` if the stream demuxed via the main demuxer is most likely
     played via network. What constitutes "network" is not always clear, might

demux/demux.c

@@ -1931,6 +1931,7 @@ static int cached_demux_control(struct demux_internal *in, int cmd, void *arg)
         struct demux_ctrl_reader_state *r = arg;
         *r = (struct demux_ctrl_reader_state){
             .eof = in->last_eof,
+            .seekable = in->seekable_cache,
             .ts_start = MP_NOPTS_VALUE,
             .ts_min = MP_NOPTS_VALUE,
             .ts_max = MP_NOPTS_VALUE,

demux/demux.h

@@ -41,7 +41,7 @@ enum demux_ctrl {
 };
 
 struct demux_ctrl_reader_state {
-    bool eof, underrun, idle;
+    bool eof, underrun, idle, seekable;
     double ts_duration;
     double ts_reader; // approx. timerstamp of decoder position
     double ts_start; // approx. timestamp for the earliest packet buffered

options/m_property.h

@@ -200,6 +200,8 @@ struct m_sub_property {
     .type = {.type = CONF_TYPE_DOUBLE}, .value = {.double_ = (f)}
 #define SUB_PROP_FLAG(f) \
     .type = {.type = CONF_TYPE_FLAG}, .value = {.flag = (f)}
+#define SUB_PROP_PTS(f) \
+    .type = {.type = &m_option_type_time}, .value = {.double_ = (f)}
 
 int m_property_read_sub(const struct m_sub_property *props, int action, void *arg);
 

player/command.c

@@ -1716,6 +1716,41 @@ static int mp_property_demuxer_cache_idle(void *ctx, struct m_property *prop,
     return m_property_flag_ro(action, arg, s.idle);
 }
 
+static int mp_property_demuxer_cache_state(void *ctx, struct m_property *prop,
+                                           int action, void *arg)
+{
+    MPContext *mpctx = ctx;
+    if (!mpctx->demuxer)
+        return M_PROPERTY_UNAVAILABLE;
+
+    struct demux_ctrl_reader_state s;
+    if (demux_control(mpctx->demuxer, DEMUXER_CTRL_GET_READER_STATE, &s) < 1)
+        return M_PROPERTY_UNAVAILABLE;
+
+    bool seek_ok = s.ts_min != MP_NOPTS_VALUE &&
+                   s.ts_max != MP_NOPTS_VALUE &&
+                   s.seekable;
+
+    struct m_sub_property props[] = {
+        {"seekable-start",  SUB_PROP_PTS(s.ts_min),
+         .unavailable = !seek_ok},
+        {"seekable-end",    SUB_PROP_PTS(s.ts_max),
+         .unavailable = !seek_ok},
+        {"cache-start",     SUB_PROP_PTS(s.ts_start),
+         .unavailable = s.ts_start == MP_NOPTS_VALUE},
+        {"cache-end",       SUB_PROP_PTS(s.ts_max),
+         .unavailable = s.ts_max == MP_NOPTS_VALUE},
+        {"reader-pts",      SUB_PROP_PTS(s.ts_reader),
+         .unavailable = s.ts_reader == MP_NOPTS_VALUE},
+        {"eof",             SUB_PROP_FLAG(s.eof)},
+        {"underrun",        SUB_PROP_FLAG(s.underrun)},
+        {"idle",            SUB_PROP_FLAG(s.idle)},
+        {0}
+    };
+
+    return m_property_read_sub(props, action, arg);
+}
+
 static int mp_property_demuxer_start_time(void *ctx, struct m_property *prop,
                                           int action, void *arg)
 {
@@ -3937,6 +3972,7 @@ static const struct m_property mp_properties_base[] = {
     {"demuxer-cache-time", mp_property_demuxer_cache_time},
     {"demuxer-cache-idle", mp_property_demuxer_cache_idle},
     {"demuxer-start-time", mp_property_demuxer_start_time},
+    {"demuxer-cache-state", mp_property_demuxer_cache_state},
     {"cache-buffering-state", mp_property_cache_buffering},
     {"paused-for-cache", mp_property_paused_for_cache},
     {"demuxer-via-network", mp_property_demuxer_is_network},