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AVFrame 结构体分析
AVFrame 相关函数
AVFrame 引用计数
测试代码
Test_AVFrame.cpp
#include <iostream> using namespace std; extern "C" // 指定函数是 C
语言函数,函数目标名不包含重载标识,C++ 中调用 C 函数需要使用 extern "C" { // 引用 ffmpeg 头文件 #include
"libavcodec/avcodec.h" } // 预处理指令导入库 #pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avutil.lib") int main() { cout << "fitst ffmpeg" << endl;
cout << avcodec_configuration() << endl; // 生成一个 AVFrame 对象 AVFrame* frame1 =
av_frame_alloc(); int ret = 0; frame1->width = 400; frame1->height = 300;
frame1->format = AV_PIX_FMT_ABGR; // 分配 buf 内存空间,16字节对齐方式,默认为32字节对齐 ret =
av_frame_get_buffer(frame1, 16); if (ret != 0) { char buf[1024] = { 0 };
av_strerror(ret, buf, sizeof(buf)); cout << buf << endl; } if (frame1->data[0]
!= nullptr) { cout << "frame->linesize[0] = " << frame1->linesize[0] << endl; }
cout << "frame1->buf[0] ref count = " <<
av_buffer_get_ref_count(frame1->buf[0]) << endl; AVFrame* frame2 =
av_frame_alloc(); // 让 frame2 引用 frame1 的 buf,引用计数加一 av_frame_ref(frame2,
frame1); cout << "frame1->buf[0] ref count = " <<
av_buffer_get_ref_count(frame1->buf[0]) << endl; cout << "frame2->buf[0] ref
count = " << av_buffer_get_ref_count(frame2->buf[0]) << endl; cout <<
"av_frame_unref(frame2)" << endl; // 将 frame2 中 buf 的引用计数减一,buf 引用计数减为0时,则销毁
buf 所占用的内存空间,并将它的 buf 置为空 av_frame_unref(frame2); cout << "frame1->buf[0] ref
count = " << av_buffer_get_ref_count(frame1->buf[0]) << endl; // 销毁一个 AVFrame
对象,并将它内部的 buf 引用计数减一,buf 引用计数减为0时,则销毁 buf 所占用的内存空间 av_frame_free(&frame1);
av_frame_free(&frame2); return 0; }
测试结果