aaudio: lower latency using MMAP capture

MMAP can be enabled by setting system properties.

Bug: 38267780
Test: input_monitor.cpp
Change-Id: I5e86fd1d9baef4fe59837ccbca7971acbb54d8b5
Signed-off-by: Phil Burk <philburk@google.com>
diff --git a/services/oboeservice/AAudioServiceEndpointPlay.h b/services/oboeservice/AAudioServiceEndpointPlay.h
new file mode 100644
index 0000000..b977960
--- /dev/null
+++ b/services/oboeservice/AAudioServiceEndpointPlay.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef AAUDIO_SERVICE_ENDPOINT_PLAY_H
+#define AAUDIO_SERVICE_ENDPOINT_PLAY_H
+
+#include <atomic>
+#include <functional>
+#include <mutex>
+#include <vector>
+
+#include "client/AudioStreamInternal.h"
+#include "client/AudioStreamInternalPlay.h"
+#include "binding/AAudioServiceMessage.h"
+#include "AAudioServiceStreamShared.h"
+#include "AAudioServiceStreamMMAP.h"
+#include "AAudioMixer.h"
+#include "AAudioService.h"
+
+namespace aaudio {
+
+class AAudioServiceEndpointPlay : public AAudioServiceEndpoint {
+public:
+    explicit AAudioServiceEndpointPlay(android::AAudioService &audioService);
+    virtual ~AAudioServiceEndpointPlay();
+
+    aaudio_result_t open(int32_t deviceId) override;
+
+    AudioStreamInternal *getStreamInternal() override {
+        return &mStreamInternalPlay;
+    }
+
+    void *callbackLoop() override;
+
+private:
+    AudioStreamInternalPlay  mStreamInternalPlay; // for playing output of mixer
+    bool                     mLatencyTuningEnabled = false; // TODO implement tuning
+    AAudioMixer              mMixer;    //
+};
+
+} /* namespace aaudio */
+
+#endif //AAUDIO_SERVICE_ENDPOINT_PLAY_H