audio: output human-readable channel layouts too

This gets you the "logical" channel layout, instead of the exact thing
we're sending to the AO. (Tired of the cryptic shit ALSA gives me.)

DOCS/interface-changes.rst

@@ -20,6 +20,7 @@ Interface changes
 ::
 
  --- mpv 0.10.0 will be released ---
+    - add audio-params/channel-count and ``audio-params-out/channel-count props.
     - add af volume replaygain-fallback suboption
     - add video-params/stereo-in property
     - add "keypress", "keydown", and "keyup" commands

DOCS/man/input.rst

@@ -1181,6 +1181,11 @@ Property list
         The channel layout as a string. This is similar to what the
         ``--audio-channels`` accepts.
 
+    ``audio-params/hr-channels``
+        As ``channels``, but instead of the possibly cryptic actual layout
+        sent to the audio device, return a hopefully more human readable form.
+        (Usually only ``audio-out-params/hr-channels`` makes sense.)
+
     ``audio-params/channel-count``
         Number of audio channels. This is redundant to the ``channels`` field
         described above.
@@ -1197,6 +1202,7 @@ Property list
                 "samplerate"        MPV_FORMAT_INT64
                 "channels"          MPV_FORMAT_STRING
                 "channel-count"     MPV_FORMAT_INT64
+                "hr-channels"       MPV_FORMAT_STRING
 
 ``audio-out-params``
     Same as ``audio-params``, but the format of the data written to the audio

audio/audio.c

@@ -93,9 +93,13 @@ bool mp_audio_config_valid(const struct mp_audio *mpa)
 
 char *mp_audio_config_to_str_buf(char *buf, size_t buf_sz, struct mp_audio *mpa)
 {
+    char ch[128];
+    mp_chmap_to_str_buf(ch, sizeof(ch), &mpa->channels);
+    char *hr_ch = mp_chmap_to_str_hr(&mpa->channels);
+    if (strcmp(hr_ch, ch) != 0)
+        mp_snprintf_cat(ch, sizeof(ch), " (%s)", hr_ch);
     snprintf(buf, buf_sz, "%dHz %s %dch %s", mpa->rate,
-             mp_chmap_to_str(&mpa->channels), mpa->channels.num,
-             af_fmt_to_str(mpa->format));
+             ch, mpa->channels.num, af_fmt_to_str(mpa->format));
     return buf;
 }
 

audio/chmap.c

@@ -508,6 +508,25 @@ bool mp_chmap_from_str(struct mp_chmap *dst, bstr src)
     return true;
 }
 
+// Output a human readable "canonical" channel map string. Converting this from
+// a string back to a channel map can yield a different map, but the string
+// looks nicer. E.g. "fc-fl-fr-na" becomes "3.0".
+char *mp_chmap_to_str_hr_buf(char *buf, size_t buf_size, const struct mp_chmap *src)
+{
+    struct mp_chmap map = *src;
+    mp_chmap_remove_na(&map);
+    for (int n = 0; std_layout_names[n][0]; n++) {
+        struct mp_chmap s;
+        if (mp_chmap_from_str(&s, bstr0(std_layout_names[n][0])) &&
+            mp_chmap_equals_reordered(&s, &map))
+        {
+            map = s;
+            break;
+        }
+    }
+    return mp_chmap_to_str_buf(buf, buf_size, &map);
+}
+
 void mp_chmap_print_help(struct mp_log *log)
 {
     mp_info(log, "Speakers:\n");

audio/chmap.h

@@ -128,6 +128,9 @@ int mp_chmap_diffn(const struct mp_chmap *a, const struct mp_chmap *b);
 char *mp_chmap_to_str_buf(char *buf, size_t buf_size, const struct mp_chmap *src);
 #define mp_chmap_to_str(m) mp_chmap_to_str_buf((char[64]){0}, 64, (m))
 
+char *mp_chmap_to_str_hr_buf(char *buf, size_t buf_size, const struct mp_chmap *src);
+#define mp_chmap_to_str_hr(m) mp_chmap_to_str_hr_buf((char[128]){0}, 128, (m))
+
 bool mp_chmap_from_str(struct mp_chmap *dst, bstr src);
 
 struct mp_log;

audio/out/ao.c

@@ -414,20 +414,14 @@ bool ao_chmap_sel_adjust(struct ao *ao, const struct mp_chmap_sel *s,
     if (mp_msg_test(ao->log, MSGL_DEBUG)) {
         for (int i = 0; i < s->num_chmaps; i++) {
             struct mp_chmap c = s->chmaps[i];
-            struct mp_chmap cr = c;
-            mp_chmap_reorder_norm(&cr);
-            mp_chmap_remove_na(&cr);
             MP_DBG(ao, "chmap_sel #%d: %s (%s)\n", i, mp_chmap_to_str(&c),
-                   mp_chmap_to_str(&cr));
+                   mp_chmap_to_str_hr(&c));
         }
     }
     bool r = mp_chmap_sel_adjust(s, map);
     if (r) {
-        struct mp_chmap mapr = *map;
-        mp_chmap_reorder_norm(&mapr);
-        mp_chmap_remove_na(&mapr);
         MP_DBG(ao, "result: %s (%s)\n", mp_chmap_to_str(map),
-               mp_chmap_to_str(&mapr));
+               mp_chmap_to_str_hr(map));
     }
     return r;
 }

player/command.c

@@ -1664,6 +1664,7 @@ static int property_audiofmt(struct mp_audio a, int action, void *arg)
         {"samplerate",      SUB_PROP_INT(a.rate)},
         {"channel-count",   SUB_PROP_INT(a.channels.num)},
         {"channels",        SUB_PROP_STR(mp_chmap_to_str(&a.channels))},
+        {"hr-channels",     SUB_PROP_STR(mp_chmap_to_str_hr(&a.channels))},
         {"format",          SUB_PROP_STR(af_fmt_to_str(a.format))},
         {0}
     };