command: add better runtime filter toggling method

Basically, see the example in input.rst.

This is better than the "old" vf-toggle method, because it doesn't
require the user to duplicate the filter string in mpv.conf and
input.conf.

Some aspects of this changes are untested, so enjoy your alpha testing.

8 files changed, 100 insertions, 32 deletions

diff --git a/DOCS/man/af.rst b/DOCS/man/af.rst
index 040b44cd64..9dff18ebbe 100644
--- a/DOCS/man/af.rst
+++ b/DOCS/man/af.rst
@@ -4,8 +4,8 @@ AUDIO FILTERS
 Audio filters allow you to modify the audio stream and its properties. The
 syntax is:
 
-``--af=<filter1[=parameter1:parameter2:...],filter2,...>``
-    Setup a chain of audio filters.
+``--af=...``
+    Setup a chain of audio filters. See ``--vf`` for the syntax.
 
 .. note::
 
@@ -15,27 +15,8 @@ syntax is:
     wrapper, which gives you access to most of libavfilter's filters. This
     includes all filters that have been ported from MPlayer to libavfilter.
 
-You can also set defaults for each filter. The defaults are applied before the
-normal filter parameters.
-
-``--af-defaults=<filter1[=parameter1:parameter2:...],filter2,...>``
-    Set defaults for each filter.
-
-Audio filters are managed in lists. There are a few commands to manage the
-filter list:
-
-``--af-add=<filter1[,filter2,...]>``
-    Appends the filters given as arguments to the filter list.
-
-``--af-pre=<filter1[,filter2,...]>``
-    Prepends the filters given as arguments to the filter list.
-
-``--af-del=<index1[,index2,...]>``
-    Deletes the filters at the given indexes. Index numbers start at 0,
-    negative numbers address the end of the list (-1 is the last).
-
-``--af-clr``
-    Completely empties the filter list.
+See ``--vf`` group of options for info on how ``--af-defaults``, ``--af-add``,
+``--af-pre``, ``--af-del``, ``--af-clr``, and possibly others work.
 
 Available filters are:
 
diff --git a/DOCS/man/input.rst b/DOCS/man/input.rst
index 9e578867cf..d252bb93a1 100644
--- a/DOCS/man/input.rst
+++ b/DOCS/man/input.rst
@@ -452,6 +452,9 @@ Input Commands that are Possibly Subject to Change
         (If several filters are passed to the command, this is done for
         each filter.)
 
+        A special variant is combining this with labels, and using ``@name:!``
+        as filter entry. This toggles the enable/disable flag.
+
     del
         Remove the given filters from the video chain. Unlike in the other
         cases, the second parameter is a comma separated list of filter names
@@ -487,6 +490,16 @@ Input Commands that are Possibly Subject to Change
         - ``b vf set ""`` remove all video filters on ``b``
         - ``c vf toggle lavfi=gradfun`` toggle debanding on ``c``
 
+    .. admonition:: Example how to toggle disabled filters at runtime
+
+        - Add something ``vf-add=@deband:!lavfi=[gradfun]`` to ``mpv.conf``. The
+          ``@deband:`` is the label, and ``deband`` is an arbitrary, user-given
+          name for this filter entry. The ``!`` before the filter name disables
+          the filter by default. Everything after this is the normal filter name
+          and the filter parameters.
+        - Add ``a vf toggle @deband:!`` to ``input.conf``. This toggles the
+          "disabled" flag for the filter identified with ``deband``.
+
 ``cycle-values ["!reverse"] <property> "<value1>" "<value2>" ...``
     Cycle through a list of values. Each invocation of the command will set the
     given property to the next value in the list. The command maintains an
diff --git a/DOCS/man/vf.rst b/DOCS/man/vf.rst
index 9da20942f6..a3f7ee6dab 100644
--- a/DOCS/man/vf.rst
+++ b/DOCS/man/vf.rst
@@ -5,7 +5,37 @@ Video filters allow you to modify the video stream and its properties. The
 syntax is:
 
 ``--vf=<filter1[=parameter1:parameter2:...],filter2,...>``
-    Setup a chain of video filters.
+    Setup a chain of video filters. This consists on the filter name, and an
+    option list of parameters after ``=``. The parameters are separated by
+    ``:`` (not ``,``, as that starts a new filter entry).
+
+    Before the filter name, a label can be specified with ``@name:``, where
+    name is an arbitrary user-given name, which identifies the filter. This
+    is only needed if you want to toggle the filter at runtime.
+
+    A ``!`` before the filter name means the filter is enabled by default. It
+    will be skipped on filter creation. This is also useful for runtime filter
+    toggling.
+
+    See the ``vf`` command (and ``toggle`` sub-command) for further explanations
+    and examples.
+
+    The general filter entry syntax is:
+
+        ``["@"<label-name>":"] ["!"] <filter-name> [ "=" <filter-parameter-list> ]``
+
+    and the ``filter-parameter-list``:
+
+        ``<filter-parameter> | <filter-parameter> "," <filter-parameter-list>``
+
+    and ``filter-parameter``:
+
+        ``( <param-name> "=" <param-value> ) | <param-value>``
+
+    ``param-value`` can further be quoted in ``[`` / ``]`` in case the value
+    contains characters like ``,`` or ``=``. This is used in particular with
+    the ``lavfi`` filter, which uses a very similar syntax as mpv (MPlayer
+    historically) to specify filters and their parameters.
 
 You can also set defaults for each filter. The defaults are applied before the
 normal filter parameters.
diff --git a/audio/filter/af.c b/audio/filter/af.c
index 31f4e45614..84ee377136 100644
--- a/audio/filter/af.c
+++ b/audio/filter/af.c
@@ -78,6 +78,7 @@ static bool get_desc(struct m_obj_desc *dst, int index)
 const struct m_obj_list af_obj_list = {
     .get_desc = get_desc,
     .description = "audio filters",
+    .allow_disable_entries = true,
     .aliases = {
         {"force",     "format"},
         {0}
@@ -545,6 +546,8 @@ int af_init(struct af_stream *s)
         // Add all filters in the list (if there are any)
         struct m_obj_settings *list = s->opts->af_settings;
         for (int i = 0; list && list[i].name; i++) {
+            if (!list[i].enabled)
+                continue;
             struct af_instance *af =
                 af_prepend(s, s->last, list[i].name, list[i].attribs);
             if (!af) {
diff --git a/options/m_option.c b/options/m_option.c
index 7f30b73a9a..29bbcb17db 100644
--- a/options/m_option.c
+++ b/options/m_option.c
@@ -2590,6 +2590,7 @@ static void copy_obj_settings_list(const m_option_t *opt, void *dst,
     for (n = 0; s[n].name; n++) {
         d[n].name = talloc_strdup(NULL, s[n].name);
         d[n].label = talloc_strdup(NULL, s[n].label);
+        d[n].enabled = s[n].enabled;
         d[n].attribs = NULL;
         copy_str_list(NULL, &(d[n].attribs), &(s[n].attribs));
     }
@@ -2754,7 +2755,7 @@ exit:
 #define NAMECH "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-"
 
 // Parse one item, e.g. -vf a=b:c:d,e=f:g => parse a=b:c:d into "a" and "b:c:d"
-static int parse_obj_settings(struct mp_log *log, struct bstr opt,
+static int parse_obj_settings(struct mp_log *log, struct bstr opt, int op,
                               struct bstr *pstr, const struct m_obj_list *list,
                               m_obj_settings_t **_ret)
 {
@@ -2763,6 +2764,7 @@ static int parse_obj_settings(struct mp_log *log, struct bstr opt,
     struct m_obj_desc desc;
     bstr label = {0};
     bool nopos = list->disallow_positional_parameters;
+    bool enabled = true;
 
     if (bstr_eatstart0(pstr, "@")) {
         if (!bstr_split_tok(*pstr, ":", &label, pstr)) {
@@ -2771,9 +2773,14 @@ static int parse_obj_settings(struct mp_log *log, struct bstr opt,
         }
     }
 
+    if (list->allow_disable_entries && bstr_eatstart0(pstr, "!"))
+        enabled = false;
+
     bool has_param = false;
     int idx = bstrspn(*pstr, NAMECH);
     bstr str = bstr_splice(*pstr, 0, idx);
+    if (str.len == 0 && !enabled && label.len && op == OP_TOGGLE)
+        goto done; // "@labelname:!" is the special enable/disable toggle syntax
     *pstr = bstr_cut(*pstr, idx);
     // video filters use "=", VOs use ":"
     if (bstr_eatstart0(pstr, "=") || bstr_eatstart0(pstr, ":"))
@@ -2817,9 +2824,11 @@ static int parse_obj_settings(struct mp_log *log, struct bstr opt,
     if (!_ret)
         return 1;
 
+done: ;
     m_obj_settings_t item = {
         .name = bstrto0(NULL, str),
         .label = bstrdup0(NULL, label),
+        .enabled = enabled,
         .attribs = plist,
     };
     obj_settings_list_insert_at(_ret, -1, &item);
@@ -2964,7 +2973,7 @@ static int parse_obj_settings_list(struct mp_log *log, const m_option_t *opt,
         if (op == OP_DEL)
             r = parse_obj_settings_del(log, name, &param, dst, mark_del);
         if (r == 0) {
-            r = parse_obj_settings(log, name, &param, ol, dst ? &res : NULL);
+            r = parse_obj_settings(log, name, op, &param, ol, dst ? &res : NULL);
         }
         if (r < 0)
             return r;
@@ -3017,12 +3026,25 @@ static int parse_obj_settings_list(struct mp_log *log, const m_option_t *opt,
             talloc_free(res);
         } else if (op == OP_TOGGLE) {
             for (int n = 0; res && res[n].name; n++) {
-                int found = obj_settings_find_by_content(list, &res[n]);
-                if (found < 0) {
-                    obj_settings_list_insert_at(&list, -1, &res[n]);
-                } else {
-                    obj_settings_list_del_at(&list, found);
+                if (!res[n].enabled && !res[n].name[0]) {
+                    // Toggle enable/disable special case.
+                    int found =
+                        obj_settings_list_find_by_label0(list, res[n].label);
+                    if (found < 0) {
+                        mp_warn(log, "Option %.*s: Label %s not found\n",
+                                BSTR_P(name), res[n].label);
+                    } else {
+                        list[found].enabled = !list[found].enabled;
+                    }
                     obj_setting_free(&res[n]);
+                } else {
+                    int found = obj_settings_find_by_content(list, &res[n]);
+                    if (found < 0) {
+                        obj_settings_list_insert_at(&list, -1, &res[n]);
+                    } else {
+                        obj_settings_list_del_at(&list, found);
+                        obj_setting_free(&res[n]);
+                    }
                 }
             }
             talloc_free(res);
@@ -3073,6 +3095,8 @@ static char *print_obj_settings_list(const m_option_t *opt, const void *val)
         // Assume labels and names don't need escaping
         if (entry->label && entry->label[0])
             res = talloc_asprintf_append(res, "@%s:", entry->label);
+        if (!entry->enabled)
+            res = talloc_strdup_append(res, "!");
         res = talloc_strdup_append(res, entry->name);
         if (entry->attribs && entry->attribs[0]) {
             res = talloc_strdup_append(res, "=");
@@ -3111,6 +3135,10 @@ static int set_obj_settings_list(const m_option_t *opt, void *dst,
                 if (val->format != MPV_FORMAT_STRING)
                     goto error;
                 entry->label = talloc_strdup(NULL, val->u.string);
+            } else if (strcmp(key, "enabled") == 0) {
+                if (val->format != MPV_FORMAT_FLAG)
+                    goto error;
+                entry->enabled = val->u.flag;
             } else if (strcmp(key, "params") == 0) {
                 if (val->format != MPV_FORMAT_NODE_MAP)
                     goto error;
@@ -3176,6 +3204,9 @@ static int get_obj_settings_list(const m_option_t *opt, void *ta_parent,
         add_map_string(nentry, "name", entry->name);
         if (entry->label && entry->label[0])
             add_map_string(nentry, "label", entry->label);
+        struct mpv_node *enabled = add_map_entry(nentry, "enabled");
+        enabled->format = MPV_FORMAT_FLAG;
+        enabled->u.flag = entry->enabled;
         struct mpv_node *params = add_map_entry(nentry, "params");
         params->format = MPV_FORMAT_NODE_MAP;
         params->u.list = talloc_zero(ta_parent, struct mpv_node_list);
diff --git a/options/m_option.h b/options/m_option.h
index 8709d20bb2..f3a4e7bc1e 100644
--- a/options/m_option.h
+++ b/options/m_option.h
@@ -146,6 +146,8 @@ struct m_obj_list {
     // Allow unknown entries, for which a dummy entry is inserted, and whose
     // options are skipped and ignored.
     bool allow_unknown_entries;
+    // Allow syntax for disabling entries.
+    bool allow_disable_entries;
     // This helps with confusing error messages if unknown flag options are used.
     bool disallow_positional_parameters;
     // Each sub-item is backed by global options (for AOs and VOs).
@@ -162,6 +164,8 @@ typedef struct m_obj_settings {
     char *name;
     // Optional user-defined name.
     char *label;
+    // User enable flag.
+    bool enabled;
     // NULL terminated array of parameter/value pairs.
     char **attribs;
 } m_obj_settings_t;
diff --git a/player/command.c b/player/command.c
index 9050812fb3..28d331c97e 100644
--- a/player/command.c
+++ b/player/command.c
@@ -3449,7 +3449,10 @@ static char *print_obj_osd_list(struct m_obj_settings *list)
                                          list[n].attribs[i],
                                          list[n].attribs[i + 1]);
         }
-        res = talloc_asprintf_append(res, "]\n");
+        res = talloc_asprintf_append(res, "]");
+        if (!list[n].enabled)
+            res = talloc_strdup_append(res, " (disabled)");
+        res = talloc_strdup_append(res, "\n");
     }
     if (!res)
         res = talloc_strdup(NULL, "(empty)");
diff --git a/video/filter/vf.c b/video/filter/vf.c
index 94e6760603..5208c7f824 100644
--- a/video/filter/vf.c
+++ b/video/filter/vf.c
@@ -128,6 +128,7 @@ static bool get_desc(struct m_obj_desc *dst, int index)
 const struct m_obj_list vf_obj_list = {
     .get_desc = get_desc,
     .description = "video filters",
+    .allow_disable_entries = true,
 };
 
 // Try the cmd on each filter (starting with the first), and stop at the first
@@ -322,6 +323,8 @@ struct vf_instance *vf_append_filter(struct vf_chain *c, const char *name,
 int vf_append_filter_list(struct vf_chain *c, struct m_obj_settings *list)
 {
     for (int n = 0; list && list[n].name; n++) {
+        if (!list[n].enabled)
+            continue;
         struct vf_instance *vf =
             vf_append_filter(c, list[n].name, list[n].attribs);
         if (vf) {