ffmpeg视频编解码实例

视频解码

// ffmpegdemo.cpp : 定义控制台应用程序的入口点。
//#include "stdafx.h"
#include #define __STDC_CONSTANT_MACROS#ifdef _WIN32//Windows
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavutil/imgutils.h"
};
#else//Linux...
#ifdef __cplusplus
extern "C"
{
#endif#include
#include
#include
#include
#ifdef __cplusplus
};
#endif
#endifint main()
{//文件格式上下文AVFormatContext *pFormatCtx;int i &＃61; 0, videoindex;AVCodecContext *pCodecCtx;AVCodec *pCodec;AVFrame *pFrame, *pFrameYUV;unsigned char *out_buffer;AVPacket *packet;int y_size;int ret, got_picture;struct SwsContext *img_convert_ctx;char filepath[] &＃61; "input.mkv";FILE *fp_yuv &＃61; fopen("output.yuv", "wb&＃43;");av_register_all();avformat_network_init();pFormatCtx &＃61; avformat_alloc_context();if (avformat_open_input(&pFormatCtx, filepath, NULL, NULL) !&＃61; 0) {printf("Couldn&＃39;t open input stream.\n");return -1;}//读取一部分视音频数据并且获得一些相关的信息if (avformat_find_stream_info(pFormatCtx, NULL) <0) {printf("Couldn&＃39;t find stream information.\n");return -1;}//查找视频编码索引videoindex &＃61; -1;for (i &＃61; 0; i nb_streams; i&＃43;&＃43;){if (pFormatCtx->streams[i]->codec->codec_type &＃61;&＃61; AVMEDIA_TYPE_VIDEO){videoindex &＃61; i;break;}}if (videoindex &＃61;&＃61; -1){printf("Didn&＃39;t find a video stream.\n");return -1;}//编解码上下文pCodecCtx &＃61; pFormatCtx->streams[videoindex]->codec;//查找解码器pCodec &＃61; avcodec_find_decoder(pCodecCtx->codec_id);if (pCodec &＃61;&＃61; NULL) {printf("Codec not found.\n");return -1;}//打开解码器if (avcodec_open2(pCodecCtx, pCodec, NULL) <0) {printf("Could not open codec.\n");return -1;}//申请AVFrame&＃xff0c;用于原始视频pFrame &＃61; av_frame_alloc();//申请AVFrame&＃xff0c;用于yuv视频pFrameYUV &＃61; av_frame_alloc();//分配内存&＃xff0c;用于图像格式转换out_buffer &＃61; (unsigned char *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height, 1));av_image_fill_arrays(pFrameYUV->data, pFrameYUV->linesize, out_buffer,AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height, 1);packet &＃61; (AVPacket *)av_malloc(sizeof(AVPacket));//Output Info-----------------------------printf("--------------- File Information ----------------\n");//手工调试函数&＃xff0c;输出tbn、tbc、tbr、PAR、DAR的含义av_dump_format(pFormatCtx, 0, filepath, 0);printf("-------------------------------------------------\n");//申请转换上下文img_convert_ctx &＃61; sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);//读取数据while (av_read_frame(pFormatCtx, packet) >&＃61; 0) {if (packet->stream_index &＃61;&＃61; videoindex) {ret &＃61; avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);if (ret <0) {printf("Decode Error.\n");return -1;}if (got_picture >&＃61; 1) {//成功解码一帧sws_scale(img_convert_ctx, (const unsigned char* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,pFrameYUV->data, pFrameYUV->linesize);//转换图像格式y_size &＃61; pCodecCtx->width*pCodecCtx->height;fwrite(pFrameYUV->data[0], 1, y_size, fp_yuv); //Y fwrite(pFrameYUV->data[1], 1, y_size / 4, fp_yuv); //Ufwrite(pFrameYUV->data[2], 1, y_size / 4, fp_yuv); //Vprintf("Succeed to decode 1 frame!\n");}else{//未解码到一帧&＃xff0c;可能时结尾B帧或延迟帧&＃xff0c;在后面做flush decoder处理}}av_free_packet(packet);}//flush decoder//FIX: Flush Frames remained in Codecwhile (true) {if (!(pCodec->capabilities & CODEC_CAP_DELAY))return 0;ret &＃61; avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);if (ret <0){break;}if (!got_picture){break;}sws_scale(img_convert_ctx, (const unsigned char* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,pFrameYUV->data, pFrameYUV->linesize);int y_size &＃61; pCodecCtx->width*pCodecCtx->height;fwrite(pFrameYUV->data[0], 1, y_size, fp_yuv); //Y fwrite(pFrameYUV->data[1], 1, y_size / 4, fp_yuv); //Ufwrite(pFrameYUV->data[2], 1, y_size / 4, fp_yuv); //Vprintf("Flush Decoder: Succeed to decode 1 frame!\n");}sws_freeContext(img_convert_ctx);av_frame_free(&pFrameYUV);av_frame_free(&pFrame);avcodec_close(pCodecCtx);avformat_close_input(&pFormatCtx);fclose(fp_yuv);return 0;
}

视频编码

// ffmpegdemo.cpp : 定义控制台应用程序的入口点。
//#include "stdafx.h"
#include #define __STDC_CONSTANT_MACROS#ifdef _WIN32//Windows
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavutil/imgutils.h"
};
#else//Linux...
#ifdef __cplusplus
extern "C"
{
#endif#include
#include
#include
#include
#ifdef __cplusplus
};
#endif
#endifint flush_encoder(AVFormatContext *fmt_ctx, unsigned int stream_index)
{int ret;int got_frame;AVPacket enc_pkt;if (!(fmt_ctx->streams[stream_index]->codec->codec->capabilities &CODEC_CAP_DELAY)){return 0;}while (true) {enc_pkt.data &＃61; NULL;enc_pkt.size &＃61; 0;av_init_packet(&enc_pkt);ret &＃61; avcodec_encode_video2(fmt_ctx->streams[stream_index]->codec, &enc_pkt,NULL, &got_frame);av_frame_free(NULL);if (ret <0){break;}if (!got_frame){ret &＃61; 0;break;}printf("Flush Encoder: Succeed to encode 1 frame!\tsize:%5d\n", enc_pkt.size);/* mux encoded frame */ret &＃61; av_write_frame(fmt_ctx, &enc_pkt);if (ret <0){break;}}return ret;
}int main()
{AVFormatContext* pFormatCtx;AVOutputFormat* pOutputFmt;AVStream* video_st;AVCodecContext* pCodecCtx;AVCodec* pCodec;AVPacket pkt;uint8_t* picture_buf;AVFrame* pFrame;int picture_size;int y_size;int framecnt &＃61; 0;int in_w &＃61; 640, in_h &＃61; 272; //视频图像宽高const char* out_file &＃61; "output.h264";int i, j;int num;int index_y, index_u, index_v;uint8_t *y_, *u_, *v_, *in;int got_picture &＃61; 0;int ret;av_register_all();//alloc avformat contextpFormatCtx &＃61; avformat_alloc_context();//猜测类型,返回输出类型。pOutputFmt &＃61; av_guess_format(NULL, out_file, NULL);pFormatCtx->oformat &＃61; pOutputFmt;//打开FFmpeg的输入输出文件,成功之后创建的AVIOContext结构体。if (avio_open2(&pFormatCtx->pb, out_file, AVIO_FLAG_READ_WRITE,NULL,NULL) <0) {//Failed to open output filereturn -1;}//除了以下方法&＃xff0c;另外还可以使用avcodec_find_encoder_by_name()来获取AVCodec pCodec &＃61; avcodec_find_encoder(pOutputFmt->video_codec);//获取编码器 if (!pCodec) {//cannot find encoder return -1;}pCodecCtx &＃61; avcodec_alloc_context3(pCodec);//申请AVCodecContext&＃xff0c;并初始化。 if (!pCodecCtx) {//failed get AVCodecContext return -1;}FILE * in_file &＃61; fopen("640-272.yuv", "rb"); //打开原始yuv数据文件/* 创建输出码流的AVStream */video_st &＃61; avformat_new_stream(pFormatCtx, 0);video_st->time_base.num &＃61; 1;video_st->time_base.den &＃61; 25;if (video_st &＃61;&＃61; NULL) {return -1;}//Param that must set pCodecCtx &＃61; video_st->codec;//pCodecCtx->codec_id &＃61;AV_CODEC_ID_HEVC; //H265pCodecCtx->codec_id &＃61; AV_CODEC_ID_H264;pCodecCtx->codec_type &＃61; AVMEDIA_TYPE_VIDEO;pCodecCtx->pix_fmt &＃61; AV_PIX_FMT_YUV420P;pCodecCtx->width &＃61; in_w;pCodecCtx->height &＃61; in_h;pCodecCtx->b_frame_strategy &＃61; true;/*码率bit_rate/-bt tolerance 设置视频码率容忍度kbit/s &＃xff08;固定误差&＃xff09;rc_max_rate/-maxrate bitrate设置最大视频码率容忍度 &＃xff08;可变误差&＃xff09;rc_min_rate/-minrate bitreate 设置最小视频码率容忍度&＃xff08;可变误差&＃xff09;rc_buffer_size/-bufsize size 设置码率控制缓冲区大小如何设置固定码率编码 ?bit_rate是平均码率&＃xff0c;不一定能控制住c->bit_rate &＃61; 400000;c->rc_max_rate &＃61; 400000;c->rc_min_rate &＃61; 400000;提示 [libx264 &＃64; 00c70be0] VBV maxrate specified, but no bufsize, ignored再设置 c->rc_buffer_size &＃61; 200000; 即可。如此控制后编码质量明显差了。*/pCodecCtx->bit_rate &＃61; 400000; //采样码率越大&＃xff0c;目标文件越大//pCodecCtx->bit_rate_tolerance &＃61; 8000000; // 码率误差&＃xff0c;允许的误差越大&＃xff0c;视频越小//两个I帧之间的间隔pCodecCtx->gop_size &＃61; 15;//编码帧率&＃xff0c;每秒多少帧。下面表示1秒25帧pCodecCtx->time_base.num &＃61; 1;pCodecCtx->time_base.den &＃61; 25;//最小的量化因子pCodecCtx->qmin &＃61; 10;//最大的量化因子pCodecCtx->qmax &＃61; 30;//最大B帧数pCodecCtx->max_b_frames &＃61; 3;// Set Option AVDictionary *param &＃61; 0;//H.264 if (pCodecCtx->codec_id &＃61;&＃61; AV_CODEC_ID_H264) {/*preset的参数主要调节编码速度和质量的平衡&＃xff0c;有ultrafast、superfast、veryfast、faster、fast、medium、slow、slower、veryslow、placebo这10个选项&＃xff0c;从快到慢。*/av_dict_set(¶m, "preset", "fast", 0);/* tune的参数主要配合视频类型和视觉优化的参数。tune的值有&＃xff1a; film&＃xff1a; 电影、真人类型&＃xff1b;animation&＃xff1a; 动画&＃xff1b;grain&＃xff1a; 需要保留大量的grain时用&＃xff1b;stillimage&＃xff1a; 静态图像编码时使用&＃xff1b;psnr&＃xff1a; 为提高psnr做了优化的参数&＃xff1b;ssim&＃xff1a; 为提高ssim做了优化的参数&＃xff1b;fastdecode&＃xff1a; 可以快速解码的参数&＃xff1b;zerolatency&＃xff1a;零延迟&＃xff0c;用在需要非常低的延迟的情况下&＃xff0c;比如电视电话会议的编码。*/av_dict_set(¶m, "tune", "zerolatency", 0);/*画质,分别是baseline, extended, main, high1、Baseline Profile&＃xff1a;基本画质。支持I/P 帧&＃xff0c;只支持无交错&＃xff08;Progressive&＃xff09;和CAVLC&＃xff1b;2、Extended profile&＃xff1a;进阶画质。支持I/P/B/SP/SI 帧&＃xff0c;只支持无交错&＃xff08;Progressive&＃xff09;和CAVLC&＃xff1b;(用的少)3、Main profile&＃xff1a;主流画质。提供I/P/B 帧&＃xff0c;支持无交错&＃xff08;Progressive&＃xff09;和交错&＃xff08;Interlaced&＃xff09;&＃xff0c; 也支持CAVLC 和CABAC 的支持&＃xff1b;4、High profile&＃xff1a;高级画质。在main Profile 的基础上增加了8x8内部预测、自定义量化、 无损视频编码和更多的YUV 格式&＃xff1b;H.264 Baseline profile、Extended profile和Main profile都是针对8位样本数据、4:2:0格式(YUV)的视频序列。在相同配置情况下&＃xff0c;High profile&＃xff08;HP&＃xff09;可以比Main profile&＃xff08;MP&＃xff09;降低10%的码率。 根据应用领域的不同&＃xff0c;Baseline profile多应用于实时通信领域&＃xff0c;Main profile多应用于流媒体领域&＃xff0c;High profile则多应用于广电和存储领域。*///av_dict_set(¶m, "profile", "main", 0); }else if (pCodecCtx->codec_id &＃61;&＃61; AV_CODEC_ID_H265 || pCodecCtx->codec_id &＃61;&＃61; AV_CODEC_ID_HEVC){av_dict_set(¶m, "preset", "fast", 0);av_dict_set(¶m, "tune", "zerolatency", 0);}//Output Info-----------------------------printf("--------------- out_file Information ----------------\n");//手工调试函数&＃xff0c;输出tbn、tbc、tbr、PAR、DAR的含义av_dump_format(pFormatCtx, 0, out_file, 1); //最后一个参数&＃xff0c;如果是输出文件时&＃xff0c;该值为1&＃xff1b;如果是输入文件时&＃xff0c;该值为0printf("-----------------------------------------------------\n");/* 查找编码器 */pCodec &＃61; avcodec_find_encoder(pCodecCtx->codec_id);if (!pCodec) {printf("Can not find encoder! \n");return -1;}/* 打开编码器 */if (avcodec_open2(pCodecCtx, pCodec,¶m) <0) {printf("Failed to open encoder! \n");return -1;}pFrame &＃61; av_frame_alloc();picture_size &＃61; avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);picture_buf &＃61; (uint8_t *)av_malloc(picture_size);avpicture_fill((AVPicture *)pFrame, picture_buf, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);//Write File Header /* 写文件头&＃xff08;对于某些没有文件头的封装格式&＃xff0c;不需要此函数。比如说MPEG2TS&＃xff09; */avformat_write_header(pFormatCtx, NULL);/* Allocate the payload of a packet and initialize its fields with default values. */av_new_packet(&pkt, picture_size);j &＃61; 1;y_size &＃61; pCodecCtx->width * pCodecCtx->height;unsigned int uiReadSize &＃61; 0;while (true){//Read raw YUV dataif (feof(in_file)) //文件结束{break;}else{uiReadSize &＃61; fread(picture_buf, 1, y_size * 3 / 2, in_file);if (uiReadSize <&＃61; 0){printf("Failed to read raw data! \n");break;}else if (uiReadSize data[0] &＃61; picture_buf; // Y pFrame->data[1] &＃61; picture_buf &＃43; y_size; // U pFrame->data[2] &＃61; picture_buf &＃43; y_size * 5 / 4; // V //PTS pFrame->pts &＃61; j*(video_st->time_base.den) / ((video_st->time_base.num) * 25);//Encode /* 编码一帧视频。即将AVFrame&＃xff08;存储YUV像素数据&＃xff09;编码为AVPacket&＃xff08;存储H.264等格式的码流数据&＃xff09; */int ret &＃61; avcodec_encode_video2(pCodecCtx, &pkt, pFrame, &got_picture);if (ret <0){printf("Failed to encode! \n");return -1;}if (got_picture &＃61;&＃61; 1){printf("Succeed to encode frame: %5d\tsize:%5d\n",framecnt,pkt.size); framecnt&＃43;&＃43;;pkt.stream_index &＃61; video_st->index;/* 将编码后的视频码流写入文件 */ret &＃61; av_write_frame(pFormatCtx, &pkt);av_free_packet(&pkt);}j&＃43;&＃43;;}//Flush Encoder /* 输入的像素数据读取完成后调用此函数。用于输出编码器中剩余的AVPacket */ret &＃61; flush_encoder(pFormatCtx, 0);if (ret <0) {printf("Flushing encoder failed\n");return -1;}//Write file trailer /* 写文件尾&＃xff08;对于某些没有文件头的封装格式&＃xff0c;不需要此函数。比如说MPEG2TS&＃xff09; */av_write_trailer(pFormatCtx);//Clean if (video_st) {avcodec_close(video_st->codec);av_free(pFrame);av_free(picture_buf);}avio_close(pFormatCtx->pb);avformat_free_context(pFormatCtx);av_free_packet(&pkt);fclose(in_file);return 0;
}