标签:
=====================================================
最简单的基于FFmpeg的AVfilter例子系列文章:
=====================================================
有关FFmpeg的avfilter已经写过一个水印叠加的例子《最简单的基于FFmpeg的AVfilter例子(水印叠加)》,本文作为补充再记录一个纯净版的avfilter的例子。此前libavfilter一直是结合着libavcodec等类库的接口函数使用的,因此我一直以为libavfilter库与libavcodec等类库是高度耦合的(也就是如果想使用libavfilter的视音频特效功能的话必须使用libavcodec等类库的函数)。这两天空闲的时候研究了一下libavfilter的代码后发现实际情况不是这样的:libavfilter可以独立于libavcodec等类库的接口函数作为一个“纯粹”的视音频特效类库进行使用。本文记录的“纯净版”的avfilter的例子即实现了一个纯粹的视频特效添加的功能。该例子输入为一个YUV文件,输出也是一个YUV文件,通过avfilter的功能可以处理该YUV文件实现去色调、模糊、水平翻转、裁剪、加方框、叠加文字等功能。
该程序的流程图如下所示。AVFilter的初始化比较复杂,而使用起来比较简单。初始化的时候需要调用avfilter_register_all()到avfilter_graph_config()一系列函数。而使用的时候只有两个函数:av_buffersrc_add_frame()用于向FilterGraph中加入一个AVFrame,而av_buffersink_get_frame()用于从FilterGraph中取出一个AVFrame。
avfilter_register_all():注册所有AVFilter。
avfilter_graph_alloc():为FilterGraph分配内存。
avfilter_graph_create_filter():创建并向FilterGraph中添加一个Filter。
avfilter_graph_parse_ptr():将一串通过字符串描述的Graph添加到FilterGraph中。
avfilter_graph_config():检查FilterGraph的配置。
av_buffersrc_add_frame():向FilterGraph中加入一个AVFrame。av_buffersink_get_frame():从FilterGraph中取出一个AVFrame。
/** * 最简单的基于FFmpeg的AVFilter例子 - 纯净版 * Simplest FFmpeg AVfilter Example - Pure * * 雷霄骅 Lei Xiaohua * leixiaohua1020@126.com * 中国传媒大学/数字电视技术 * Communication University of China / Digital TV Technology * http://blog.csdn.net/leixiaohua1020 * * 本程序使用FFmpeg的AVfilter实现了YUV像素数据的滤镜处理功能。 * 可以给YUV数据添加各种特效功能。 * 是最简单的FFmpeg的AVFilter方面的教程。 * 适合FFmpeg的初学者。 * * This software uses FFmpeg‘s AVFilter to process YUV raw data. * It can add many excellent effect to YUV data. * It‘s the simplest example based on FFmpeg‘s AVFilter. * Suitable for beginner of FFmpeg * */ #include <stdio.h> #define __STDC_CONSTANT_MACROS #ifdef _WIN32 #define snprintf _snprintf //Windows extern "C" { #include "libavfilter/avfiltergraph.h" #include "libavfilter/buffersink.h" #include "libavfilter/buffersrc.h" #include "libavutil/avutil.h" #include "libavutil/imgutils.h" }; #else //Linux... #ifdef __cplusplus extern "C" { #endif #include <libavfilter/avfiltergraph.h> #include <libavfilter/buffersink.h> #include <libavfilter/buffersrc.h> #include <libavutil/avutil.h> #include <libavutil/imgutils.h> #ifdef __cplusplus }; #endif #endif int main(int argc, char* argv[]) { int ret; AVFrame *frame_in; AVFrame *frame_out; unsigned char *frame_buffer_in; unsigned char *frame_buffer_out; AVFilterContext *buffersink_ctx; AVFilterContext *buffersrc_ctx; AVFilterGraph *filter_graph; static int video_stream_index = -1; //Input YUV FILE *fp_in=fopen("sintel_480x272_yuv420p.yuv","rb+"); if(fp_in==NULL){ printf("Error open input file.\n"); return -1; } int in_width=480; int in_height=272; //Output YUV FILE *fp_out=fopen("output.yuv","wb+"); if(fp_out==NULL){ printf("Error open output file.\n"); return -1; } //const char *filter_descr = "lutyuv=‘u=128:v=128‘"; const char *filter_descr = "boxblur"; //const char *filter_descr = "hflip"; //const char *filter_descr = "hue=‘h=60:s=-3‘"; //const char *filter_descr = "crop=2/3*in_w:2/3*in_h"; //const char *filter_descr = "drawbox=x=100:y=100:w=100:h=100:color=pink@0.5"; //const char *filter_descr = "drawtext=fontfile=arial.ttf:fontcolor=green:fontsize=30:text=‘Lei Xiaohua‘"; avfilter_register_all(); char args[512]; AVFilter *buffersrc = avfilter_get_by_name("buffer"); AVFilter *buffersink = avfilter_get_by_name("ffbuffersink"); AVFilterInOut *outputs = avfilter_inout_alloc(); AVFilterInOut *inputs = avfilter_inout_alloc(); enum PixelFormat pix_fmts[] = { PIX_FMT_YUV420P, PIX_FMT_NONE }; AVBufferSinkParams *buffersink_params; filter_graph = avfilter_graph_alloc(); /* buffer video source: the decoded frames from the decoder will be inserted here. */ snprintf(args, sizeof(args), "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d", in_width,in_height,PIX_FMT_YUV420P, 1, 25,1,1); ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in", args, NULL, filter_graph); if (ret < 0) { printf("Cannot create buffer source\n"); return ret; } /* buffer video sink: to terminate the filter chain. */ 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); av_free(buffersink_params); if (ret < 0) { printf("Cannot create buffer sink\n"); return ret; } /* Endpoints for the filter graph. */ outputs->name = av_strdup("in"); outputs->filter_ctx = buffersrc_ctx; outputs->pad_idx = 0; outputs->next = NULL; inputs->name = av_strdup("out"); inputs->filter_ctx = buffersink_ctx; inputs->pad_idx = 0; inputs->next = NULL; if ((ret = avfilter_graph_parse_ptr(filter_graph, filter_descr, &inputs, &outputs, NULL)) < 0) return ret; if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0) return ret; frame_in=av_frame_alloc(); frame_buffer_in=(unsigned char *)av_malloc(av_image_get_buffer_size(PIX_FMT_YUV420P, in_width,in_height,1)); av_image_fill_arrays(frame_in->data, frame_in->linesize,frame_buffer_in, PIX_FMT_YUV420P,in_width, in_height,1); frame_out=av_frame_alloc(); frame_buffer_out=(unsigned char *)av_malloc(av_image_get_buffer_size(PIX_FMT_YUV420P, in_width,in_height,1)); av_image_fill_arrays(frame_out->data, frame_out->linesize,frame_buffer_out, PIX_FMT_YUV420P,in_width, in_height,1); frame_in->width=in_width; frame_in->height=in_height; frame_in->format=PIX_FMT_YUV420P; while (1) { if(fread(frame_buffer_in, 1, in_width*in_height*3/2, fp_in)!= 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; } /* 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==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,fp_out); } 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,fp_out); } 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,fp_out); } } printf("Process 1 frame!\n"); } fclose(fp_in); fclose(fp_out); av_frame_free(&frame_in); av_frame_free(&frame_out); avfilter_graph_free(&filter_graph); return 0; }
本程序输入为一个名称为“sintel_480x272_yuv420p.yuv”的YUV420P视频数据,输出为一个名称为“output.yuv” 的YUV420P视频数据。输入的视频数据的内容如下所示。
可以通过修改程序中的filter_descr字符串实现上述几种特效。下面展示几种特效的效果图。
lutyuv=‘u=128:v=128‘SourceForge:https://sourceforge.net/projects/simplestffmpegvideofilter/
Github:https://github.com/leixiaohua1020/simplest_ffmpeg_video_filter
开源中国:http://git.oschina.net/leixiaohua1020/simplest_ffmpeg_video_filter
标签:
原文地址:http://blog.csdn.net/leixiaohua1020/article/details/50618190