audio: allow more than 20 channel map entries

This could trigger an assertion when using ao_alsa or ao_coreaudio. The
code was simply assuming the number of channel maps was bounded
statically (which was true at first in both AOs).

Fix by using dynamic memory allocation. It needs to be explicitly
enabled by the AOs by setting a temp context, because otherwise the
memory couldn't be freed. (Or at least this seems to be the most elegant
solution.)

Fixes #1306.

1 files changed, 5 insertions, 1 deletions

diff --git a/audio/chmap_sel.h b/audio/chmap_sel.h
index c9d75196a5..7758ca5d74 100644
--- a/audio/chmap_sel.h
+++ b/audio/chmap_sel.h
@@ -26,8 +26,12 @@ struct mp_chmap_sel {
     // should be considered opaque
     bool allow_any, allow_waveext;
     bool speakers[MP_SPEAKER_ID_COUNT];
-    struct mp_chmap chmaps[20];
+    struct mp_chmap *chmaps;
     int num_chmaps;
+
+    struct mp_chmap chmaps_storage[20];
+
+    void *tmp; // set to any talloc context to allow more chmaps entries
 };
 
 void mp_chmap_sel_add_any(struct mp_chmap_sel *s);