1 files changed, 63 insertions, 0 deletions
diff --git a/src/com/android/tv/util/TimeShiftUtils.java b/src/com/android/tv/util/TimeShiftUtils.java
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+++ b/src/com/android/tv/util/TimeShiftUtils.java
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+/*
+ * Copyright (C) 2016 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.
+ */
+
+package com.android.tv.util;
+
+import java.util.concurrent.TimeUnit;
+
+// TODO: move related functions in TimeShiftManger here.
+/**
+ * A class that includes convenience methods for time shift plays.
+ */
+public class TimeShiftUtils {
+    private static final String TAG = "TimeShiftUtils";
+    private static final boolean DEBUG = false;
+
+    private static final long SHORT_PROGRAM_THRESHOLD_MILLIS = TimeUnit.MINUTES.toMillis(46);
+    private static final int[] SHORT_PROGRAM_SPEED_FACTORS = new int[] {2, 4, 12, 48};
+    private static final int[] LONG_PROGRAM_SPEED_FACTORS = new int[] {2, 8, 32, 128};
+
+    /**
+     * The maximum play speed level support by time shift play. In other words, the valid
+     * speed levels are ranged from 0 to MAX_SPEED_LEVEL (included).
+     */
+    public static final int MAX_SPEED_LEVEL = SHORT_PROGRAM_SPEED_FACTORS.length - 1;
+
+    /**
+     * Returns real speeds used in time shift play. This method is only for fast-forwarding and
+     * rewinding. The normal play speed is not addressed here.
+     *
+     * @param speedLevel the valid value is ranged from 0 to {@link MAX_SPPED_LEVEL}.
+     * @param programDurationMillis the length of program under playing.
+     * @throws IndexOutOfBoundsException if speed level is out of its range.
+     */
+    public static int getPlaybackSpeed(int speedLevel, long programDurationMillis)
+            throws IndexOutOfBoundsException {
+        return (programDurationMillis > SHORT_PROGRAM_THRESHOLD_MILLIS) ?
+                LONG_PROGRAM_SPEED_FACTORS[speedLevel] : SHORT_PROGRAM_SPEED_FACTORS[speedLevel];
+    }
+
+    /**
+     * Returns the maxium possible play speed according to the program's length.
+     * @param programDurationMillis the length of program under playing.
+     */
+    public static int getMaxPlaybackSpeed(long programDurationMillis) {
+        return (programDurationMillis > SHORT_PROGRAM_THRESHOLD_MILLIS) ?
+                LONG_PROGRAM_SPEED_FACTORS[MAX_SPEED_LEVEL]
+                : SHORT_PROGRAM_SPEED_FACTORS[MAX_SPEED_LEVEL];
+    }
+}
+