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
25 namespace android {
26
27 static const int64_t kMaxJitterUs = 2000;
28
FrameDropper()29 FrameDropper::FrameDropper()
30 : mDesiredMinTimeUs(-1),
31 mMinIntervalUs(0) {
32 }
33
~FrameDropper()34 FrameDropper::~FrameDropper() {
35 }
36
setMaxFrameRate(float maxFrameRate)37 status_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
shouldDrop(int64_t timeUs)46 bool 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