1 files changed, 70 insertions, 0 deletions
diff --git a/media/libstagefright/omx/FrameDropper.cpp b/media/libstagefright/omx/FrameDropper.cpp
new file mode 100644
index 0000000..9fba0b7
--- /dev/null
+++ b/media/libstagefright/omx/FrameDropper.cpp
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+//#define LOG_NDEBUG 0
+#define LOG_TAG "FrameDropper"
+#include <utils/Log.h>
+
+#include "FrameDropper.h"
+
+#include <media/stagefright/foundation/ADebug.h>
+
+namespace android {
+
+static const int64_t kMaxJitterUs = 2000;
+
+FrameDropper::FrameDropper()
+    : mDesiredMinTimeUs(-1),
+      mMinIntervalUs(0) {
+}
+
+FrameDropper::~FrameDropper() {
+}
+
+status_t FrameDropper::setMaxFrameRate(float maxFrameRate) {
+    if (maxFrameRate <= 0) {
+        ALOGE("framerate should be positive but got %f.", maxFrameRate);
+        return BAD_VALUE;
+    }
+    mMinIntervalUs = (int64_t) (1000000.0f / maxFrameRate);
+    return OK;
+}
+
+bool FrameDropper::shouldDrop(int64_t timeUs) {
+    if (mMinIntervalUs <= 0) {
+        return false;
+    }
+
+    if (mDesiredMinTimeUs < 0) {
+        mDesiredMinTimeUs = timeUs + mMinIntervalUs;
+        ALOGV("first frame %lld, next desired frame %lld", timeUs, mDesiredMinTimeUs);
+        return false;
+    }
+
+    if (timeUs < (mDesiredMinTimeUs - kMaxJitterUs)) {
+        ALOGV("drop frame %lld, desired frame %lld, diff %lld",
+                timeUs, mDesiredMinTimeUs, mDesiredMinTimeUs - timeUs);
+        return true;
+    }
+
+    int64_t n = (timeUs - mDesiredMinTimeUs + kMaxJitterUs) / mMinIntervalUs;
+    mDesiredMinTimeUs += (n + 1) * mMinIntervalUs;
+    ALOGV("keep frame %lld, next desired frame %lld, diff %lld",
+            timeUs, mDesiredMinTimeUs, mDesiredMinTimeUs - timeUs);
+    return false;
+}
+
+}  // namespace android