command: add load-input-conf

This can be used to auto reload the input configuration file, e.g. in
vim:

autocmd BufWritePost ~/.config/mpv/input.conf silent !echo load-input-conf %:p | socat - /tmp/mpvsocket

Partially fixes #6362.

Additionally this can be used as a replacement for deprecated input
sections if they are ever actually removed. For example, if you want to
define different bindings for images, you can load-input-conf an
input.conf for images, and load the original again when switching to a
video. Though currently you would have to redefine builtin bindings that
were overwritten with image ones in the default input.conf.

DOCS/interface-changes.rst

@@ -43,6 +43,7 @@ Interface changes
     - remove `--term-remaining-playtime` option
     - change fallback deinterlace to bwdif
     - add the command `load-config-file`
+    - add the command `load-input-conf`
  --- mpv 0.37.0 ---
     - `--save-position-on-quit` and its associated commands now store state files
       in %LOCALAPPDATA% instead of %APPDATA% directory by default on Windows.

DOCS/man/input.rst

@@ -1341,6 +1341,11 @@ Input Commands that are Possibly Subject to Change
     was already included, its previous options are not reset before it is
     reparsed.
 
+``load-input-conf <filename>``
+    Load an input configuration file, similar to the ``--input-conf`` option. If
+    the file was already included, its previous bindings are not reset before it
+    is reparsed.
+
 ``load-script <filename>``
     Load a script, similar to the ``--script`` option. Whether this waits for
     the script to finish initialization or not changed multiple times, and the

input/input.c

@@ -1395,6 +1395,14 @@ void mp_input_load_config(struct input_ctx *ictx)
     input_unlock(ictx);
 }
 
+bool mp_input_load_config_file(struct input_ctx *ictx, char *file)
+{
+    input_lock(ictx);
+    bool result = parse_config_file(ictx, file);
+    input_unlock(ictx);
+    return result;
+}
+
 static void clear_queue(struct cmd_queue *queue)
 {
     while (queue->first) {

input/input.h

@@ -178,8 +178,12 @@ struct input_ctx *mp_input_init(struct mpv_global *global,
                                 void (*wakeup_cb)(void *ctx),
                                 void *wakeup_ctx);
 
+// Load the configured input.conf files.
 void mp_input_load_config(struct input_ctx *ictx);
 
+// Load a specific input.conf file.
+bool mp_input_load_config_file(struct input_ctx *ictx, char *file);
+
 void mp_input_update_opts(struct input_ctx *ictx);
 
 void mp_input_uninit(struct input_ctx *ictx);

player/command.c

@@ -6288,6 +6288,15 @@ static void cmd_load_config_file(void *p)
     mp_notify_property(mpctx, "profile-list");
 }
 
+static void cmd_load_input_conf(void *p)
+{
+    struct mp_cmd_ctx *cmd = p;
+    struct MPContext *mpctx = cmd->mpctx;
+
+    char *config_file = cmd->args[0].v.s;
+    cmd->success = mp_input_load_config_file(mpctx->input, config_file);
+}
+
 static void cmd_load_script(void *p)
 {
     struct mp_cmd_ctx *cmd = p;
@@ -6827,6 +6836,8 @@ const struct mp_cmd_def mp_cmds[] = {
 
     { "load-config-file", cmd_load_config_file, {{"filename", OPT_STRING(v.s)}} },
 
+    { "load-input-conf", cmd_load_input_conf, {{"filename", OPT_STRING(v.s)}} },
+
     { "load-script", cmd_load_script, {{"filename", OPT_STRING(v.s)}} },
 
     { "dump-cache", cmd_dump_cache, { {"start", OPT_TIME(v.d),