audio: add command/function to reload audio output

Anticipated use: simple solution for dealing with audio APIs which
request configuration changes via events.

DOCS/man/input.rst

@@ -544,7 +544,7 @@ Input Commands that are Possibly Subject to Change
 
 
 Undocumented commands: ``tv_last_channel`` (TV/DVB only), ``get_property`` (?),
-``vo_cmdline`` (experimental).
+``vo_cmdline`` (experimental), ``ao_reload`` (experimental/internal).
 
 Input Command Prefixes
 ----------------------

audio/out/ao.c

@@ -29,6 +29,7 @@
 #include "audio/format.h"
 #include "audio/audio.h"
 
+#include "input/input.h"
 #include "options/options.h"
 #include "options/m_config.h"
 #include "common/msg.h"
@@ -406,6 +407,13 @@ bool ao_chmap_sel_get_def(struct ao *ao, const struct mp_chmap_sel *s,
     return mp_chmap_sel_get_def(s, map, num);
 }
 
+// Request that the player core destroys and recreates the AO.
+void ao_request_reload(struct ao *ao)
+{
+    const char *cmd[] = {"ao_reload", NULL};
+    mp_input_run_cmd(ao->input_ctx, cmd);
+}
+
 // --- The following functions just return immutable information.
 
 void ao_get_format(struct ao *ao, struct mp_audio *format)

audio/out/internal.h

@@ -183,6 +183,8 @@ bool ao_chmap_sel_adjust(struct ao *ao, const struct mp_chmap_sel *s,
 bool ao_chmap_sel_get_def(struct ao *ao, const struct mp_chmap_sel *s,
                           struct mp_chmap *map, int num);
 
+void ao_request_reload(struct ao *ao);
+
 // Add a deep copy of e to the list.
 // Call from ao_driver->list_devs callback only.
 void ao_device_list_add(struct ao_device_list *list, struct ao *ao,

input/cmd_list.c

@@ -156,6 +156,7 @@ const struct mp_cmd_def mp_cmds[] = {
   { MP_CMD_DISCNAV, "discnav", { ARG_STRING } },
 
   { MP_CMD_AF, "af", { ARG_STRING, ARG_STRING } },
+  { MP_CMD_AO_RELOAD, "ao_reload", },
 
   { MP_CMD_VF, "vf", { ARG_STRING, ARG_STRING } },
 

input/cmd_list.h

@@ -80,6 +80,7 @@ enum mp_command_type {
 
     /// Audio Filter commands
     MP_CMD_AF,
+    MP_CMD_AO_RELOAD,
 
     /// Video filter commands
     MP_CMD_VF,

player/command.c

@@ -1454,6 +1454,18 @@ static int get_device_entry(int item, int action, void *arg, void *ctx)
     return m_property_read_sub(props, action, arg);
 }
 
+static void reload_audio_output(struct MPContext *mpctx)
+{
+    if (!mpctx->ao)
+        return;
+    ao_reset(mpctx->ao);
+    uninit_audio_out(mpctx);
+    // This normally recreates the AO, although there are situations when AO
+    // creation is delayed; for example if there are no audio packets around,
+    // and the audio format is yet unknown.
+    reinit_audio_chain(mpctx);
+}
+
 static int mp_property_audio_devices(void *ctx, struct m_property *prop,
                                      int action, void *arg)
 {
@@ -4233,6 +4245,10 @@ int run_command(MPContext *mpctx, mp_cmd_t *cmd)
         }
         break;
 
+    case MP_CMD_AO_RELOAD:
+        reload_audio_output(mpctx);
+        break;
+
     case MP_CMD_AF:
         return edit_filters_osd(mpctx, STREAM_AUDIO, cmd->args[0].v.s,
                                 cmd->args[1].v.s, msg_osd);