1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17//#define LOG_NDEBUG 0
18#define LOG_TAG "FrameDropper"
19#include <utils/Log.h>
20
21#include "FrameDropper.h"
22
23#include <media/stagefright/foundation/ADebug.h>
24
25namespace android {
26
27static const int64_t kMaxJitterUs = 2000;
28
29FrameDropper::FrameDropper()
30    : mDesiredMinTimeUs(-1),
31      mMinIntervalUs(0) {
32}
33
34FrameDropper::~FrameDropper() {
35}
36
37status_t FrameDropper::setMaxFrameRate(float maxFrameRate) {
38    if (maxFrameRate <= 0) {
39        ALOGE("framerate should be positive but got %f.", maxFrameRate);
40        return BAD_VALUE;
41    }
42    mMinIntervalUs = (int64_t) (1000000.0f / maxFrameRate);
43    return OK;
44}
45
46bool FrameDropper::shouldDrop(int64_t timeUs) {
47    if (mMinIntervalUs <= 0) {
48        return false;
49    }
50
51    if (mDesiredMinTimeUs < 0) {
52        mDesiredMinTimeUs = timeUs + mMinIntervalUs;
53        ALOGV("first frame %lld, next desired frame %lld",
54                (long long)timeUs, (long long)mDesiredMinTimeUs);
55        return false;
56    }
57
58    if (timeUs < (mDesiredMinTimeUs - kMaxJitterUs)) {
59        ALOGV("drop frame %lld, desired frame %lld, diff %lld",
60                (long long)timeUs, (long long)mDesiredMinTimeUs,
61                (long long)(mDesiredMinTimeUs - timeUs));
62        return true;
63    }
64
65    int64_t n = (timeUs - mDesiredMinTimeUs + kMaxJitterUs) / mMinIntervalUs;
66    mDesiredMinTimeUs += (n + 1) * mMinIntervalUs;
67    ALOGV("keep frame %lld, next desired frame %lld, diff %lld",
68            (long long)timeUs, (long long)mDesiredMinTimeUs,
69            (long long)(mDesiredMinTimeUs - timeUs));
70    return false;
71}
72
73}  // namespace android
74