FFMPEG中的filter使用一

准备

ffmpeg 4.4

一段YUV420p的原始视频

滤镜流程

1.创建一个AVFilterGraph，用来管理整个过滤器流程

2.创建buffer和buffersink过滤器，buffer是过滤器的源头用来，buffersink作为过滤器的终结点

3.创建我们需要使用的各类过滤器

4.avfilter_link根据处理流程连接过滤器，图中有两条处理线路,参考下图

 5.使用avfilter_graph_config检查过滤流程配置

6.循环读取文件

7.av_buffersrc_add_frame发送一帧到buffer过滤器中

8.av_buffersink_get_frame从buffersink获取处理过的帧数据

9.文件读取完成后清理工作

 源码

#include <stdio.h>

extern "C" {

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
    //#include <libavfilter/avfiltergraph.h>
#include <libavfilter/avfilter.h>
#include <libavfilter/buffersink.h>
#include <libavfilter/buffersrc.h>
#include <libavutil/opt.h>
#include <libavutil/imgutils.h>
}

int mainfgdgd(int argc, char** argv)
{
    int ret = 0;

    // input yuv
    FILE* inFile = NULL;
    const char* inFileName = "D:/测试工程/sound/yuv420p_1280x720.yuv";
    fopen_s(&inFile, inFileName, "rb+");
    if (!inFile) {
        printf("Fail to open file\n");
        return -1;
    }

    int in_width = 1280;
    int in_height = 720;

    // output yuv
    FILE* outFile = NULL;
    const char* outFileName = "D:/测试工程/sound/filter.yuv";
    fopen_s(&outFile, outFileName, "wb");
    if (!outFile) {
        printf("Fail to create file for output\n");
        return -1;
    }


    AVFilterGraph* filter_graph = avfilter_graph_alloc();
    if (!filter_graph) {
        printf("Fail to create filter graph!\n");
        return -1;
    }

    // source filter
    char args[512];
    sprintf(args,
        "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
        in_width, in_height, AV_PIX_FMT_YUV420P, 1, 30, 1, 1);

    printf("%s", args);

    AVFilter* bufferSrc = (AVFilter *)avfilter_get_by_name("buffer");   // AVFilterGraph的输入源
    AVFilterContext* bufferSrc_ctx;
    ret = avfilter_graph_create_filter(&bufferSrc_ctx, bufferSrc, "in", args, NULL, filter_graph);
    if (ret < 0) {
        printf("Fail to create filter bufferSrc\n");
        return -1;
    }

    // sink filter
    //AVBufferSinkParams bufferSink_params;
    AVFilterContext* bufferSink_ctx;
    AVFilter* bufferSink = (AVFilter*)avfilter_get_by_name("buffersink");
    enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_YUV420P, AV_PIX_FMT_NONE };
   // bufferSink_params = av_buffersink_params_alloc();
   // bufferSink_params.pixel_fmts = pix_fmts;
    ret = avfilter_graph_create_filter(&bufferSink_ctx, bufferSink, "out", NULL, nullptr, filter_graph);
    if (ret < 0) {
        printf("Fail to create filter sink filter\n");
        return -1;
    }

    // split filter
    AVFilter* splitFilter = (AVFilter*)avfilter_get_by_name("split");
    AVFilterContext* splitFilter_ctx;
    ret = avfilter_graph_create_filter(&splitFilter_ctx, splitFilter, "split", "outputs=2",
        NULL, filter_graph);
    if (ret < 0) {
        printf("Fail to create split filter\n");
        return -1;
    }

    // crop filter
    AVFilter* cropFilter = (AVFilter*)avfilter_get_by_name("crop");
    AVFilterContext* cropFilter_ctx;
    ret = avfilter_graph_create_filter(&cropFilter_ctx, cropFilter, "crop",
        "out_w=iw:out_h=ih/2:x=0:y=0", NULL, filter_graph);
    if (ret < 0) {
        printf("Fail to create crop filter\n");
        return -1;
    }

    // vflip filter
    AVFilter* vflipFilter = (AVFilter*)avfilter_get_by_name("vflip");
    AVFilterContext* vflipFilter_ctx;
    ret = avfilter_graph_create_filter(&vflipFilter_ctx, vflipFilter, "vflip", NULL, NULL, filter_graph);
    if (ret < 0) {
        printf("Fail to create vflip filter\n");
        return -1;
    }

    // overlay filter
    AVFilter* overlayFilter = (AVFilter*)avfilter_get_by_name("overlay");
    AVFilterContext* overlayFilter_ctx;
    ret = avfilter_graph_create_filter(&overlayFilter_ctx, overlayFilter, "overlay",
        "y=0:H/2", NULL, filter_graph);
    if (ret < 0) {
        printf("Fail to create overlay filter\n");
        return -1;
    }

    // src filter to split filter
    ret = avfilter_link(bufferSrc_ctx, 0, splitFilter_ctx, 0);
    if (ret != 0) {
        printf("Fail to link src filter and split filter\n");
        return -1;
    }
    // split filter's first pad to overlay filter's main pad
    ret = avfilter_link(splitFilter_ctx, 0, overlayFilter_ctx, 0);
    if (ret != 0) {
        printf("Fail to link split filter and overlay filter main pad\n");
        return -1;
    }
    // split filter's second pad to crop filter
    ret = avfilter_link(splitFilter_ctx, 1, cropFilter_ctx, 0);
    if (ret != 0) {
        printf("Fail to link split filter's second pad and crop filter\n");
        return -1;
    }
    // crop filter to vflip filter
    ret = avfilter_link(cropFilter_ctx, 0, vflipFilter_ctx, 0);
    if (ret != 0) {
        printf("Fail to link crop filter and vflip filter\n");
        return -1;
    }
    // vflip filter to overlay filter's second pad
    ret = avfilter_link(vflipFilter_ctx, 0, overlayFilter_ctx, 1);
    if (ret != 0) {
        printf("Fail to link vflip filter and overlay filter's second pad\n");
        return -1;
    }
    // overlay filter to sink filter
    ret = avfilter_link(overlayFilter_ctx, 0, bufferSink_ctx, 0);
    if (ret != 0) {
        printf("Fail to link overlay filter and sink filter\n");
        return -1;
    }

    // check filter graph
    ret = avfilter_graph_config(filter_graph, NULL);
    if (ret < 0) {
        printf("Fail in filter graph\n");
        return -1;
    }

    char* graph_str = avfilter_graph_dump(filter_graph, NULL);
    FILE* graphFile = NULL;
    fopen_s(&graphFile, "graphFile.txt", "w");  // 打印filtergraph的具体情况
    fprintf(graphFile, "%s", graph_str);
    av_free(graph_str);

    AVFrame* frame_in = av_frame_alloc();
    unsigned char* frame_buffer_in = (unsigned char*)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P, in_width, in_height, 1));
    av_image_fill_arrays(frame_in->data, frame_in->linesize, frame_buffer_in,
        AV_PIX_FMT_YUV420P, in_width, in_height, 1);

    AVFrame* frame_out = av_frame_alloc();
    unsigned char* frame_buffer_out = (unsigned char*)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P, in_width, in_height, 1));
    av_image_fill_arrays(frame_out->data, frame_out->linesize, frame_buffer_out,
        AV_PIX_FMT_YUV420P, in_width, in_height, 1);

    frame_in->width = in_width;
    frame_in->height = in_height;
    frame_in->format = AV_PIX_FMT_YUV420P;
    uint32_t frame_count = 0;
    while (1) {
        // 读取yuv数据
        if (fread(frame_buffer_in, 1, in_width * in_height * 3 / 2, inFile) != in_width * in_height * 3 / 2) 
        {
            break;
        }
        //input Y,U,V
        frame_in->data[0] = frame_buffer_in;
        frame_in->data[1] = frame_buffer_in + in_width * in_height;
        frame_in->data[2] = frame_buffer_in + in_width * in_height * 5 / 4;

        if (av_buffersrc_add_frame(bufferSrc_ctx, frame_in) < 0) {
            printf("Error while add frame.\n");
            break;
        }
        // filter内部自己处理
        /* pull filtered pictures from the filtergraph */
        ret = av_buffersink_get_frame(bufferSink_ctx, frame_out);
        if (ret < 0)
            break;

        //output Y,U,V
        if (frame_out->format == AV_PIX_FMT_YUV420P) 
        {
            for (int i = 0; i < frame_out->height; i++) 
            {
                fwrite(frame_out->data[0] + frame_out->linesize[0] * i, 1, frame_out->width, outFile);
            }
            for (int i = 0; i < frame_out->height / 2; i++) 
            {
                fwrite(frame_out->data[1] + frame_out->linesize[1] * i, 1, frame_out->width / 2, outFile);
            }
            for (int i = 0; i < frame_out->height / 2; i++) 
            {
                fwrite(frame_out->data[2] + frame_out->linesize[2] * i, 1, frame_out->width / 2, outFile);
            }
        }
        ++frame_count;
        if (frame_count % 25 == 0)
            printf("Process %d frame!\n", frame_count);
        av_frame_unref(frame_out);
    }   

    fclose(inFile);
    fclose(outFile);

    av_frame_free(&frame_in);
    av_frame_free(&frame_out);
    avfilter_graph_free(&filter_graph); // 内部去释放AVFilterContext产生的内存
    return 0;
}