这一节我们将继续来学习 ACodec 的剩余部分。

    enum {kFlagIsSecure                                 = 1,kFlagPushBlankBuffersToNativeWindowOnShutdown = 2,kFlagIsGrallocUsageProtected                  = 4,kFlagPreregisterMetadataBuffers               = 8,};enum {kVideoGrallocUsage = (GRALLOC_USAGE_HW_TEXTURE| GRALLOC_USAGE_HW_COMPOSER| GRALLOC_USAGE_EXTERNAL_DISP)| static_cast<uint64_t>(BufferUsage::VIDEO_DECODER),};struct BufferInfo {enum Status {OWNED_BY_US,OWNED_BY_COMPONENT,OWNED_BY_UPSTREAM,OWNED_BY_DOWNSTREAM,OWNED_BY_NATIVE_WINDOW,UNRECOGNIZED,            // not a tracked buffer};static inline Status getSafeStatus(BufferInfo *info) {return info == NULL ? UNRECOGNIZED : info->mStatus;}IOMX::buffer_id mBufferID;Status mStatus;unsigned mDequeuedAt;sp<MediaCodecBuffer> mData;  // the client's buffer; if not using data conversion, this is// the codec buffer; otherwise, it is allocated separatelysp<RefBase> mMemRef;         // and a reference to the IMemory, so it does not go awaysp<MediaCodecBuffer> mCodecData;  // the codec's buffersp<RefBase> mCodecRef;            // and a reference to the IMemorysp<GraphicBuffer> mGraphicBuffer;bool mNewGraphicBuffer;int mFenceFd;FrameRenderTracker::Info *mRenderInfo;// The following field and 4 methods are used for debugging onlybool mIsReadFence;// Store |fenceFd| and set read/write flag. Log error, if there is already a fence stored.void setReadFence(int fenceFd, const char *dbg);void setWriteFence(int fenceFd, const char *dbg);// Log error, if the current fence is not a read/write fence.void checkReadFence(const char *dbg);void checkWriteFence(const char *dbg);};