FFmpeg简单使用：过滤器 ---- 视频过滤
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FFmpeg简单使用：过滤器 ---- h264_mp4toannexb
FFmpeg简单使用：解封装h264 ---- 提取SPS PPS
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基本流程：
1 [main] 2 input --> split ---------------------> overlay --> output 3 | ^ 4 |[tmp] [flip]| 5 +-----> crop --> vflip -------+
这个例⼦的处理流程如上所示，⾸先使⽤split滤波器将input流分成两路流（main和tmp），然后分别对两路流进⾏处理。对于tmp流，先经过crop滤波器进⾏裁剪处理，再经过flip滤波器进⾏垂直⽅向上的翻转操作，输出的结果命名为flip流。再将main流和flip流输⼊到overlay滤波器进⾏合成操作。上图的input就是上⾯提过的buffer源滤波器，output就是上⾯的提过的buffersink滤波器。上图中每个节点都是⼀个AVFilterContext，每个连线就是AVFliterLink。所有这些信息都统⼀由AVFilterGraph来管理。
编码：
#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 yuv FILE* 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 yuv FILE* 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 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, 25, 1, 1); AVFilter* bufferSrc = 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_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 filter AVFilter *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 filter AVFilter *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 filter AVFilter *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 filter AVFilter *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 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; }
