96 lines
3.3 KiB
C++
96 lines
3.3 KiB
C++
/*
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* Copyright (C) 2022 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_SERVERS_CAMERA_CAMERA3_PREVIEWFRAMESPACER_H
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#define ANDROID_SERVERS_CAMERA_CAMERA3_PREVIEWFRAMESPACER_H
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#include <queue>
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#include <gui/Surface.h>
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#include <utils/Condition.h>
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#include <utils/Mutex.h>
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#include <utils/Thread.h>
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#include <utils/Timers.h>
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namespace android {
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namespace camera3 {
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class Camera3OutputStream;
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/***
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* Preview stream spacer for better frame spacing
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*
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* The ideal viewfinder user experience is that frames are presented to the
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* user in the same cadence as outputed by the camera sensor. However, the
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* processing latency between frames could vary, due to factors such
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* as CPU load, differences in request settings, etc. This frame processing
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* latency results in variation in presentation of frames to the user.
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*
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* The PreviewFrameSpacer improves the viewfinder user experience by:
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* - Cache the frame buffers if the intervals between queueBuffer is shorter
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* than the camera readout intervals.
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* - Queue frame buffers in the same cadence as the camera readout time.
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* - Maintain at most 1 queue-able buffer. If the 2nd preview buffer becomes
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* available, queue the oldest cached buffer to the buffer queue.
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*/
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class PreviewFrameSpacer : public Thread {
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public:
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explicit PreviewFrameSpacer(wp<Camera3OutputStream> parent, sp<Surface> consumer);
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virtual ~PreviewFrameSpacer();
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// Queue preview buffer locally
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status_t queuePreviewBuffer(nsecs_t timestamp, nsecs_t readoutTimestamp,
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int32_t transform, ANativeWindowBuffer* anwBuffer, int releaseFence);
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bool threadLoop() override;
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void requestExit() override;
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private:
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// structure holding cached preview buffer info
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struct BufferHolder {
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nsecs_t timestamp;
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nsecs_t readoutTimestamp;
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int32_t transform;
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sp<ANativeWindowBuffer> anwBuffer;
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int releaseFence;
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BufferHolder(nsecs_t t, nsecs_t readoutT, int32_t tr, ANativeWindowBuffer* anwb, int rf) :
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timestamp(t), readoutTimestamp(readoutT), transform(tr), anwBuffer(anwb),
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releaseFence(rf) {}
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};
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void queueBufferToClientLocked(const BufferHolder& bufferHolder, nsecs_t currentTime);
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wp<Camera3OutputStream> mParent;
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sp<ANativeWindow> mConsumer;
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mutable Mutex mLock;
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Condition mBufferCond;
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std::queue<BufferHolder> mPendingBuffers;
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nsecs_t mLastCameraReadoutTime = 0;
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nsecs_t mLastCameraPresentTime = 0;
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static constexpr nsecs_t kWaitDuration = 5000000LL; // 50ms
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static constexpr nsecs_t kFrameIntervalThreshold = 80000000LL; // 80ms
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static constexpr nsecs_t kMaxFrameWaitTime = 10000000LL; // 10ms
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static constexpr nsecs_t kFrameAdjustThreshold = 2000000LL; // 2ms
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};
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}; //namespace camera3
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}; //namespace android
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#endif
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