最簡單的基於FFmpeg的AVfilter例子（浮水印疊加）

FFMPEG中有一個類庫：libavfilter。該類庫提供了各種視音頻過濾器。之前一直沒有怎麼使用過這個類庫，最近看了一下它的使用說明，發現還是很強大的，有很多現成的filter供使用，完成視頻的處理很方便。在此將它的一個例子基礎上完成了一個浮水印疊加器，並且移植到了VC2010下，方便開發人員學習研究它的使用方法。

該例子完成了一個浮水印疊加的功能。可以將一張透明背景的PNG圖片作為浮水印疊加到一個視頻檔案上。

下面直接貼上代碼：

 

/*  * 最簡單的基於FFmpeg的AVFilter例子（疊加浮水印） * Simplest FFmpeg AVfilter Example (Watermark) * * 雷霄驊 Lei Xiaohua * leixiaohua1020@126.com * 中國傳媒大學/數字電視技術 * Communication University of China / Digital TV Technology * http://blog.csdn.net/leixiaohua1020 *  * 本程式使用FFmpeg的AVfilter實現了視頻的浮水印疊加功能。 * 可以將一張PNG圖片作為浮水印疊加到視頻上。 * 是最簡單的FFmpeg的AVFilter方面的教程。 * 適合FFmpeg的初學者。 * * This software uses FFmpeg's AVFilter to add watermark in a video file. * It can add a PNG format picture as watermark to a video file. * It's the simplest example based on FFmpeg's AVFilter.  * Suitable for beginner of FFmpeg  * */#include "stdafx.h"#define ENABLE_SDL 1#define ENABLE_YUVFILE 1extern "C"{#include "libavcodec/avcodec.h"#include "libavformat/avformat.h"#include "libavfilter/avfiltergraph.h"#include "libavfilter/avcodec.h"#include "libavfilter/buffersink.h"#include "libavfilter/buffersrc.h"#include "libavutil/avutil.h"#include "libswscale/swscale.h"//SDL#include "sdl/SDL.h"#include "sdl/SDL_thread.h"};const char *filter_descr = "movie=my_logo.png[wm];[in][wm]overlay=5:5[out]";static AVFormatContext *pFormatCtx;static AVCodecContext *pCodecCtx;AVFilterContext *buffersink_ctx;AVFilterContext *buffersrc_ctx;AVFilterGraph *filter_graph;static int video_stream_index = -1;static int64_t last_pts = AV_NOPTS_VALUE;static int open_input_file(const char *filename){    int ret;    AVCodec *dec;    if ((ret = avformat_open_input(&pFormatCtx, filename, NULL, NULL)) < 0) {        av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");        return ret;    }    if ((ret = avformat_find_stream_info(pFormatCtx, NULL)) < 0) {        av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");        return ret;    }    /* select the video stream */    ret = av_find_best_stream(pFormatCtx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);    if (ret < 0) {        av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");        return ret;    }    video_stream_index = ret;    pCodecCtx = pFormatCtx->streams[video_stream_index]->codec;    /* init the video decoder */    if ((ret = avcodec_open2(pCodecCtx, dec, NULL)) < 0) {        av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");        return ret;    }    return 0;}static int init_filters(const char *filters_descr){    char args[512];    int ret;    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_GRAY8, 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",            pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,            pCodecCtx->time_base.num, pCodecCtx->time_base.den,            pCodecCtx->sample_aspect_ratio.num, pCodecCtx->sample_aspect_ratio.den);    ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",                                       args, NULL, filter_graph);    if (ret < 0) {        av_log(NULL, AV_LOG_ERROR, "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) {        av_log(NULL, AV_LOG_ERROR, "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(filter_graph, filters_descr,                                    &inputs, &outputs, NULL)) < 0)        return ret;    if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)        return ret;    return 0;}int _tmain(int argc, _TCHAR* argv[]){    int ret;    AVPacket packet;    AVFrame frame;    int got_frame;    if (argc != 2) {        fprintf(stderr, "Usage: %s file\n", argv[0]);        return -1;    }    avcodec_register_all();    av_register_all();    avfilter_register_all();    if ((ret = open_input_file(argv[1])) < 0)        goto end;    if ((ret = init_filters(filter_descr)) < 0)        goto end;#if ENABLE_YUVFILEFILE *fp_yuv=fopen("test.yuv","wb+");#endif#if ENABLE_SDLSDL_Surface *screen; SDL_Overlay *bmp; SDL_Rect rect;if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {  printf( "Could not initialize SDL - %s\n", SDL_GetError()); return -1;} screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);if(!screen) {  printf("SDL: could not set video mode - exiting\n");  return -1;}bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,SDL_YV12_OVERLAY, screen); #endif    /* read all packets */    while (1) {        AVFilterBufferRef *picref;        if ((ret = av_read_frame(pFormatCtx, &packet)) < 0)            break;        if (packet.stream_index == video_stream_index) {            avcodec_get_frame_defaults(&frame);            got_frame = 0;            ret = avcodec_decode_video2(pCodecCtx, &frame, &got_frame, &packet);            if (ret < 0) {                av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");                break;            }            if (got_frame) {                frame.pts = av_frame_get_best_effort_timestamp(&frame);                /* push the decoded frame into the filtergraph */                if (av_buffersrc_add_frame(buffersrc_ctx, &frame) < 0) {                    av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");                    break;                }                /* pull filtered pictures from the filtergraph */                while (1) {                    ret = av_buffersink_get_buffer_ref(buffersink_ctx, &picref, 0);                    if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)                        break;                    if (ret < 0)                        goto end;                    if (picref) {#if ENABLE_YUVFILEint y_size=picref->video->w*picref->video->h;fwrite(picref->data[0],1,y_size,fp_yuv);fwrite(picref->data[1],1,y_size/4,fp_yuv);fwrite(picref->data[2],1,y_size/4,fp_yuv);#endif#if ENABLE_SDLSDL_LockYUVOverlay(bmp);bmp->pixels[0]=picref->data[0];bmp->pixels[2]=picref->data[1];bmp->pixels[1]=picref->data[2];     bmp->pitches[0]=picref->linesize[0];bmp->pitches[2]=picref->linesize[1];   bmp->pitches[1]=picref->linesize[2];SDL_UnlockYUVOverlay(bmp); rect.x = 0;    rect.y = 0;    rect.w = picref->video->w;    rect.h = picref->video->h;    SDL_DisplayYUVOverlay(bmp, &rect); //Delay 40msSDL_Delay(40);#endif                        avfilter_unref_bufferp(&picref);                    }                }            }        }        av_free_packet(&packet);    }#if ENABLE_YUVFILEfclose(fp_yuv);#endifend:    avfilter_graph_free(&filter_graph);    if (pCodecCtx)        avcodec_close(pCodecCtx);    avformat_close_input(&pFormatCtx);    if (ret < 0 && ret != AVERROR_EOF) {        char buf[1024];        av_strerror(ret, buf, sizeof(buf));        fprintf(stderr, "Error occurred: %s\n", buf);        return -1;    }    return 0;}

 

 

程式的運行效果。

需要疊加的浮水印為一張PNG（透明）圖片（在這裡是my_logo.png）。

需要疊加的視頻為一個普通的FLV格式的視頻（在這裡是cuc_ieschool.flv）。

 

程式啟動並執行時候，會通過SDL顯示浮水印疊加的結果，。此外，也可以將浮水印疊加後的解碼資料輸出成檔案。

註：SDL顯示和輸出YUV可以通過程式最前面的宏控制：

#define ENABLE_SDL 1#define ENABLE_YUVFILE 1

輸出的YUV檔案。

SourceForge項目首頁：

https://sourceforge.net/projects/simplestffmpegvideofilter/

CSDN項目：

http://download.csdn.net/detail/leixiaohua1020/7465861