ao: rework audio output driver probing

Make the code a bit more uniform. Always build a "dummy" audio output
list before probing, which means that opening preferred devices and
pure auto-probing is done with the same code. We can drop the second
ao_init() call.

This also makes the next commit easier, which wants to selectively
fallback to ao_null. This could have been implemented by passing a
different requested audio output list (instead of reading it from
MPOptions), but I think it's better if this rather special feature
is handled internally in the AO code. This also makes sure the AO
code can handle its own options (such as the audio output list) in
a self-contained way.

1 files changed, 42 insertions, 38 deletions

diff --git a/audio/out/ao.c b/audio/out/ao.c
index 45dbbcf9c0..23c3987cb3 100644
--- a/audio/out/ao.c
+++ b/audio/out/ao.c
@@ -248,58 +248,62 @@ struct ao *ao_init_best(struct mpv_global *global,
     void *tmp = talloc_new(NULL);
     struct mp_log *log = mp_log_new(tmp, global->log, "ao");
     struct ao *ao = NULL;
-    struct m_obj_settings *ao_list = opts->audio_driver_list;
+    struct m_obj_settings *ao_list = NULL;
+    int ao_num = 0;
+
+    for (int n = 0; opts->audio_driver_list && opts->audio_driver_list[n].name; n++)
+        MP_TARRAY_APPEND(tmp, ao_list, ao_num, opts->audio_driver_list[n]);
 
     bool forced_dev = false;
     char *pref_ao, *pref_dev;
     split_ao_device(tmp, opts->audio_device, &pref_ao, &pref_dev);
-    if (!(ao_list && ao_list[0].name) && pref_ao) {
+    if (!ao_num && pref_ao) {
         // Reuse the autoselection code
-        ao_list = talloc_zero_array(tmp, struct m_obj_settings, 2);
-        ao_list[0].name = pref_ao;
+        MP_TARRAY_APPEND(tmp, ao_list, ao_num,
+            (struct m_obj_settings){.name = pref_ao});
         forced_dev = true;
     }
 
-    if (ao_list && ao_list[0].name) {
-        for (int n = 0; ao_list[n].name; n++) {
-            if (strlen(ao_list[n].name) == 0)
-                goto autoprobe;
-            mp_verbose(log, "Trying preferred audio driver '%s'\n",
-                       ao_list[n].name);
-            char *dev = NULL;
-            if (pref_ao && strcmp(ao_list[n].name, pref_ao) == 0)
-                dev = pref_dev;
-            if (dev)
-                mp_verbose(log, "Using preferred device '%s'\n", dev);
-            ao = ao_init(false, global, input_ctx, encode_lavc_ctx,
-                         samplerate, format, channels, dev,
-                         ao_list[n].name, ao_list[n].attribs);
-            if (ao)
-                goto done;
-            mp_err(log, "Failed to initialize audio driver '%s'\n",
-                   ao_list[n].name);
-            if (forced_dev) {
-                mp_err(log, "This audio driver/device was forced with the "
-                            "--audio-device option.\n"
-                            "Try unsetting it.\n");
-            }
+    bool autoprobe = ao_num == 0;
+
+    // Something like "--ao=a,b," means do autoprobing after a and b fail.
+    if (ao_num && strlen(ao_list[ao_num - 1].name) == 0) {
+        ao_num -= 1;
+        autoprobe = true;
+    }
+
+    if (autoprobe) {
+        for (int n = 0; audio_out_drivers[n]; n++) {
+            const struct ao_driver *driver = audio_out_drivers[n];
+            if (driver == &audio_out_null)
+                break;
+            MP_TARRAY_APPEND(tmp, ao_list, ao_num,
+                (struct m_obj_settings){.name = (char *)driver->name});
         }
-        goto done;
     }
 
-autoprobe: ;
-    // now try the rest...
-    for (int i = 0; audio_out_drivers[i]; i++) {
-        const struct ao_driver *driver = audio_out_drivers[i];
-        if (driver == &audio_out_null)
-            break;
-        ao = ao_init(true, global, input_ctx, encode_lavc_ctx, samplerate,
-                     format, channels, NULL, (char *)driver->name, NULL);
+    for (int n = 0; n < ao_num; n++) {
+        struct m_obj_settings *entry = &ao_list[n];
+        bool probing = n + 1 != ao_num;
+        mp_verbose(log, "Trying audio driver '%s'\n", entry->name);
+        char *dev = NULL;
+        if (pref_ao && pref_dev && strcmp(entry->name, pref_ao) == 0) {
+            dev = pref_dev;
+            mp_verbose(log, "Using preferred device '%s'\n", dev);
+        }
+        ao = ao_init(probing, global, input_ctx, encode_lavc_ctx,
+                     samplerate, format, channels, dev,
+                     entry->name, entry->attribs);
         if (ao)
-            goto done;
+            break;
+        if (!probing)
+            mp_err(log, "Failed to initialize audio driver '%s'\n", entry->name);
+        if (dev && forced_dev) {
+            mp_err(log, "This audio driver/device was forced with the "
+                        "--audio-device option.\nTry unsetting it.\n");
+        }
     }
 
-done:
     talloc_free(tmp);
     return ao;
 }