視頻過濾器案例

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目錄

AVFilter主體框架流程

視頻過濾器案例代碼實現

graph顯示

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1. AVFilter主體框架流程

在利?AVFilter進??視頻數據處理前先將在進?的處理流程繪制出來，現在以FFmpeg filter官??檔中的?個例?為例進?說明。

這個例?的處理流程如上所示，?先使?split濾波器將input流分成兩路流（main和tmp），然后分別對兩路流進?處理。對于tmp流，先經過crop濾波器進?裁剪處理，再經過flip濾波器進?垂直?向上的翻轉操作，輸出的結果命名為flip流。再將main流和flip流輸?到overlay濾波器進?合成操作。上圖的input就是上?提過的buffer源濾波器，output就是上?的提過的buffersink濾波器。上圖中每個節點都是?個AVFilterContext，每個連線就是AVFliterLink。所有這些信息都統?由AVFilterGraph來管理。

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2. 視頻過濾器案例代碼實現

#include <stdio.h>#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 main(int argc, char *argv) {int ret = 0;// input yuvFILE *inFile = NULL;const char *inFileName = "768x320.yuv";fopen_s(&inFile, inFileName, "rb+");if (!inFile) {printf("Fail to open file\n");return -1;}int in_width = 768;int in_height = 320;// output yuvFILE *outFile = NULL;const char *outFileName = "out_crop_vfilter.yuv";fopen_s(&outFile, outFileName, "wb");if (!outFile) {printf("Fail to create file for output\n");return -1;}avfilter_register_all();AVFilterGraph *filter_graph = avfilter_graph_alloc();if (!filter_graph) {printf("Fail to create filter graph!\n");return -1;}// source filterchar 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, 25, 1, 1);AVFilter *bufferSrc = avfilter_get_by_name("buffer"); // AVFilterGraph的輸入源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 filterAVBufferSinkParams *bufferSink_params;AVFilterContext *bufferSink_ctx;AVFilter *bufferSink = 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,bufferSink_params, filter_graph);if (ret < 0) {printf("Fail to create filter sink filter\n");return -1;}// split filterAVFilter *splitFilter = 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 filterAVFilter *cropFilter = 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 filterAVFilter *vflipFilter = 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 filterAVFilter *overlayFilter = 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 filterret = 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 padret = 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 filterret = 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 filterret = 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 padret = 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 filterret = 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 graphret = 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的具體情況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) {// 讀取yuv數據if (fread(frame_buffer_in, 1, in_width * in_height * 3 / 2, inFile) != in_width * in_height * 3 / 2) {break;}//input Y,U,Vframe_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內部自己處理/* pull filtered pictures from the filtergraph */ret = av_buffersink_get_frame(bufferSink_ctx, frame_out);if (ret < 0)break;//output Y,U,Vif (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); // 內部去釋放AVFilterContext產生的內存return 0; }

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3. graph顯示

+----------+ | in |default--[768x320 1:1 yuv420p]--split:default | (buffer) | +----------++--------------+ overlay:default--[768x320 1:1 yuv420p]--default| out || (buffersink) |+--------------++---------+ in:default--[768x320 1:1 yuv420p]--default| split |output0--[768x320 1:1 yuv420p]--overlay:main| (split) |output1--[768x320 1:1 yuv420p]--crop:default+---------++--------+ split:output1--[768x320 1:1 yuv420p]--default| crop |default--[768x160 1:1 yuv420p]--vflip:default| (crop) |+--------++---------+ crop:default--[768x160 1:1 yuv420p]--default| vflip |default--[768x160 1:1 yuv420p]--auto_scaler_0:default| (vflip) |+---------++-----------+ split:output0----------[768x320 1:1 yuv420p]------main| overlay |default--[768x320 1:1 yuv420p]--out:default auto_scaler_0:default--[768x160 1:1 yuva420p]--overlay| (overlay) |+-----------++---------------+ vflip:default--[768x160 1:1 yuv420p]--default| auto_scaler_0 |default--[768x160 1:1 yuva420p]--overlay:overlay| (scale) |+---------------+

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