1、創建一個濾鏡圖

AVFilterGraph *filter_graph = avfilter_graph_alloc();

2、創建濾鏡的輸入和輸出

AVFilterInOut *inputs = avfilter_inout_alloc();

AVFilterInOut *outputs = avfilter_inout_alloc();

3、每個濾鏡創建上下文

AVFilterContext *filter1_ctx = avfilter_graph_alloc_filter(filter_graph, filter1, "filter1");

AVFilterContext *filter2_ctx = avfilter_graph_alloc_filter(filter_graph, filter2, "filter2");

4、設置濾鏡參數

snprintf(args, sizeof(args), "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d", codecContext->width, codecContext->height, codecContext->pix_fmt, codecContext->time_base.num, codecContext->time_base.den, codecContext->sample_aspect_ratio.num, codecContext->sample_aspect_ratio.den);

5、添加輸入濾鏡

avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "input", args, nullptr, filter_graph);

6、添加輸出濾鏡

avfilter_graph_create_filter(&buffersink_ctx, buffersink, "output", nullptr, nullptr, filter_graph);

7、將濾鏡的輸入和輸出與對應的濾鏡上下文關聯起來

inputs->name = av_strdup("input");

inputs->filter_ctx = filter1_ctx;

inputs->pad_idx = 0;

inputs->next = NULL;

outputs->name = av_strdup("output");

outputs->filter_ctx = filter2_ctx;

outputs->pad_idx = 0;

outputs->next = NULL;

8、解析濾鏡描述

avfilter_graph_parse_ptr(filter_graph, filter_descr, &inputs, &outputs, nullptr);

9、連接濾鏡鏈接

avfilter_graph_config(filter_graph, nullptr);

10、清理資源

avfilter_inout_free(&inputs);

avfilter_inout_free(&outputs);

avfilter_graph_free(&filter_graph);