在项目中需要将解码出来的l两个YUV420P格式的图像合并在一起，然后重新编码为H264，最后封装为mp4文件。主要说明一下两个YUV420P使用FFmpeg合并的过程，需要提前理解YUV420P格式图像的存储结构，然后依次将Y、U、V数据分别写进去就可以了。 举例：将两张相同大小的图片合并为一张大图片 640*320 640*320 合并为1280*320 假设YUV420P的宽度为FRAMEWITH 高度为FRAMEHEIGTH, Y存储在 FRAMEWITH*2/3 U存储在 FRAMEWITH*2/3—FRAMEWITH*5/6 V存储在 FRAMEWITH*5/6—FRAMEWITH 本实例主要将FFmpeg解码出来的YUV420P数据进行合并，然后写为一个YUV文件。
代码语言：javascript复制#include <stdio.h>
#define __STDC_CONSTANT_MACROS
#define FRAMEWITH 640
#define FRAMEHEIGTH 360
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
};
#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "avdevice.lib")
#pragma comment(lib, "avfilter.lib")
#pragma comment(lib, "postproc.lib")
#pragma comment(lib, "swresample.lib")
#pragma comment(lib, "swscale.lib")
int main(int argc, char* argv[])
{
AVFormatContext *pFormatCtx;
int i, videoindex;
AVCodecContext *pCodecCtx;
AVCodec *pCodec;
AVFrame *pFrame, *pFrameYUV, *pDstFrame;
uint8_t *out_buffer;
AVPacket *packet;
int y_size;
int ret, got_picture;
struct SwsContext *img_convert_ctx;
//输入文件路径
char filepath[]="test1280_720.mp4";
int frame_cnt;
av_register_all();
avformat_network_init();
pFormatCtx = avformat_alloc_context();
if(avformat_open_input(&pFormatCtx,filepath,NULL,NULL)!=0){
printf("Couldn't open input stream.n");
return -1;
}
if(avformat_find_stream_info(pFormatCtx,NULL)<0){
printf("Couldn't find stream information.n");
return -1;
}
videoindex=-1;
for(i=0; i<pFormatCtx->nb_streams; i )
if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO){
videoindex=i;
break;
}
if(videoindex==-1){
printf("Didn't find a video stream.n");
return -1;
}
pCodecCtx=pFormatCtx->streams[videoindex]->codec;
pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
if(pCodec==NULL){
printf("Codec not found.n");
return -1;
}
if(avcodec_open2(pCodecCtx, pCodec,NULL)<0){
printf("Could not open codec.n");
return -1;
}
/*
* 在此处添加输出视频信息的代码
* 取自于pFormatCtx，使用fprintf()
*/
pFrame=av_frame_alloc();
pFrameYUV=av_frame_alloc();
out_buffer = (uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_YUV420P, FRAMEWITH, FRAMEHEIGTH));
avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, FRAMEWITH, FRAMEHEIGTH);
pDstFrame = av_frame_alloc();
int nDstSize = avpicture_get_size(PIX_FMT_YUV420P, FRAMEWITH * 2, FRAMEHEIGTH);
uint8_t *dstbuf = new uint8_t[nDstSize];
avpicture_fill((AVPicture*)pDstFrame, dstbuf, PIX_FMT_YUV420P, FRAMEWITH * 2, FRAMEHEIGTH);
pDstFrame->width = FRAMEWITH * 2;
pDstFrame->height = FRAMEHEIGTH;
pDstFrame->format = PIX_FMT_YUV420P;
//将预先分配的AVFrame图像背景数据设置为黑色背景
memset(pDstFrame->data[0], 0, FRAMEWITH * FRAMEHEIGTH * 2);
memset(pDstFrame->data[1], 0x80, FRAMEWITH * FRAMEHEIGTH / 2);
memset(pDstFrame->data[2], 0x80, FRAMEWITH * FRAMEHEIGTH / 2);
packet=(AVPacket *)av_malloc(sizeof(AVPacket));
//Output Info-----------------------------
printf("--------------- File Information ----------------n");
av_dump_format(pFormatCtx,0,filepath,0);
printf("-------------------------------------------------n");
img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
FRAMEWITH, FRAMEHEIGTH, PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
int count = 0;
frame_cnt=0;
//FILE *fp_h264 = fopen("test264.h264", "wb ");
FILE *fp_yuv420 = fopen("test.yuv", "wb ");
while(av_read_frame(pFormatCtx, packet)>=0){
if(packet->stream_index==videoindex){
/*
* 在此处添加输出H264码流的代码
* 取自于packet，使用fwrite()
*/
//fwrite(packet->data,1,packet->size,fp_h264);
ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
if(ret < 0){
printf("Decode Error.n");
return -1;
}
if(got_picture){
sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
pFrameYUV->data, pFrameYUV->linesize);
printf("Decoded frame index: %dn",frame_cnt);
/*
* 在此处添加输出YUV的代码
* 取自于pFrameYUV，使用fwrite()
*/
/* 如果需要直接写为YUV文件
for (int i = 0; i <FRAMEHEIGTH; i )
{
fwrite(pFrameYUV->data[0] i*FRAMEWITH, 1, FRAMEWITH, fp_yuv420); //Y
fwrite(pFrameYUV->data[0] i*FRAMEWITH, 1, FRAMEWITH, fp_yuv420); //Y
}
for (int i = 0; i < FRAMEHEIGTH / 4; i )
{
fwrite(pFrameYUV->data[1] i*FRAMEWITH, 1, FRAMEWITH, fp_yuv420); //U
fwrite(pFrameYUV->data[1] i*FRAMEWITH, 1, FRAMEWITH, fp_yuv420); //U
}
for (int i = 0; i < FRAMEHEIGTH / 4; i )
{
fwrite(pFrameYUV->data[2] i*FRAMEWITH, 1, FRAMEWITH, fp_yuv420); //V
fwrite(pFrameYUV->data[2] i*FRAMEWITH, 1, FRAMEWITH, fp_yuv420); //V
}
*/
if (pFrameYUV)
{
int nYIndex = 0;
int nUVIndex = 0;
for (int i = 0; i < FRAMEHEIGTH; i )
{
//Y
memcpy(pDstFrame->data[0] i*FRAMEWITH * 2, pFrameYUV->data[0] nYIndex*FRAMEWITH, FRAMEWITH);
memcpy(pDstFrame->data[0] FRAMEWITH i*FRAMEWITH * 2, pFrameYUV->data[0] nYIndex*FRAMEWITH, FRAMEWITH);
nYIndex ;
}
for (int i = 0; i < FRAMEHEIGTH / 4; i )
{
//U
memcpy(pDstFrame->data[1] i*FRAMEWITH * 2, pFrameYUV->data[1] nUVIndex*FRAMEWITH, FRAMEWITH);
memcpy(pDstFrame->data[1] FRAMEWITH i*FRAMEWITH * 2, pFrameYUV->data[1] nUVIndex*FRAMEWITH, FRAMEWITH);
//V
memcpy(pDstFrame->data[2] i*FRAMEWITH * 2, pFrameYUV->data[2] nUVIndex*FRAMEWITH, FRAMEWITH);
memcpy(pDstFrame->data[2] FRAMEWITH i*FRAMEWITH * 2, pFrameYUV->data[2] nUVIndex*FRAMEWITH, FRAMEWITH);
nUVIndex ;
}
}
fwrite(pDstFrame->data[0], 1, FRAMEWITH*FRAMEHEIGTH * 2, fp_yuv420);
fwrite(pDstFrame->data[1], 1, FRAMEWITH*FRAMEHEIGTH / 2, fp_yuv420);
fwrite(pDstFrame->data[2], 1, FRAMEWITH*FRAMEHEIGTH / 2, fp_yuv420);
frame_cnt ;
}
}
count ;
av_free_packet(packet);
}
//fclose(fp_h264);
fclose(fp_yuv420);
sws_freeContext(img_convert_ctx);
av_frame_free(&pFrameYUV);
av_frame_free(&pFrame);
avcodec_close(pCodecCtx);
avformat_close_input(&pFormatCtx);
return 0;
}合并后的图像用YUV播放器打开的效果为：
欢迎大家一起加入视音频图像算法交流群：490722388 Reference: https://blog.csdn.net/occupy8/article/details/49153731 https://blog.csdn.net/wh8_2011/article/details/52026254 http://blog.csdn.net/u010380485/article/details/78720215 http://blog.csdn.net/leixiaohua1020/article/details/47068015 http://blog.csdn.net/zwz1984/article/details/50403150 http://blog.csdn.net/doublefi123/article/details/44200939
