audio/out: make draining a separate operation

Until now, this was always conflated with uninit. This was ugly, and
also many AOs emulated this manually (or just ignored it). Make draining
an explicit operation, so AOs which support it can provide it, and for
all others generic code will emulate it.

For ao_wasapi, we keep it simple and basically disable the internal
draining implementation (maybe it should be restored later).

Tested on Linux only.

1 files changed, 7 insertions, 1 deletions

diff --git a/audio/out/ao_lavc.c b/audio/out/ao_lavc.c
index afb021f7a0..073ff8ebdb 100644
--- a/audio/out/ao_lavc.c
+++ b/audio/out/ao_lavc.c
@@ -181,7 +181,7 @@ fail:
 
 // close audio device
 static int encode(struct ao *ao, double apts, void **data);
-static void uninit(struct ao *ao, bool cut_audio)
+static void uninit(struct ao *ao)
 {
     struct priv *ac = ao->priv;
     struct encode_lavc_context *ectx = ao->encode_lavc_ctx;
@@ -462,6 +462,11 @@ static int play(struct ao *ao, void **data, int samples, int flags)
     return bufpos;
 }
 
+static void drain(struct ao *ao)
+{
+    // pretend we support it, so generic code doesn't force a wait
+}
+
 const struct ao_driver audio_out_lavc = {
     .encode = true,
     .description = "audio encoding using libavcodec",
@@ -470,4 +475,5 @@ const struct ao_driver audio_out_lavc = {
     .uninit    = uninit,
     .get_space = get_space,
     .play      = play,
+    .drain     = drain,
 };