http://www.tuicool.com/articles/jiUzua
主题 FFmpeg
任务：需要把一个视频文件的每一帧提取出来，每帧存储成单独的文件。
以前用Matlab处理过这个问题，可是感觉比较慢，而且最近正在逐步转向使用开源的东西。因此搜到ffmpeg这个好东西。
ffmpeg可用来处理视频文件的提取和各种转换，跨平台，官网上有Linux，WINDOWS和MAC版本。
以下是windows 命令行下使用ffmpeg提取视频帧的方法：
SET PATH=%PATH%;[path_to_ffmpeg]
SET VIDEOFILE=demo.mp4
SET DESTDIR=video_frame\
ffmpeg -i %VIDEOFILE% -q:v 2 -f image2 %DESTDIR%%07d.jpeg- 1
- 2
- 3
- 4
- 1
- 2
- 3
- 4
其中-i 后面是输入文件，-q:v 2 q代表质量quality, v代表视频流，2是控制质量的参数。-f指定输出的格式是image2. %07d是图片命名的pattern
//--------------------------------------------------------------------------------------------
第一次接触ffmpeg，可以算是hello world程序。
下面的代码全部都是直接可以使用的，借鉴了官方学习样例，也算是翻译吧。
但是解决了，保存bmp图像时，图像颠倒和色彩异常问题。
// x_ffmpeg.cpp : Defines the entry point for the console application.
// #include "stdafx.h"
#include <windows.h>
#include <iostream>
#include <iosfwd>
#include <fstream>
using namespace std; #define FILE_OUT
#ifdef FILE_OUT
std::ofstream file_debugout("frameandpacketinfo.txt");
#endif static int av_create_bmp(char* filename,uint8_t *pRGBBuffer,int width,int height,int bpp)
{
BITMAPFILEHEADER bmpheader;
BITMAPINFO bmpinfo;
FILE *fp; fp = fopen(filename,"wb");
if(!fp)return -1; bmpheader.bfType = ('M'<<8)|'B';
bmpheader.bfReserved1 = 0;
bmpheader.bfReserved2 = 0;
bmpheader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
bmpheader.bfSize = bmpheader.bfOffBits + width*height*bpp/8;
bmpinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmpinfo.bmiHeader.biWidth = width;
/*----注意，这里的bmpinfo.bmiHeader.biHeight变量的正负决定bmp文件的存储方式，如果
为负值，表示像素是倒过来的*/
bmpinfo.bmiHeader.biHeight = -height;
bmpinfo.bmiHeader.biPlanes = 1;
bmpinfo.bmiHeader.biBitCount = bpp;
bmpinfo.bmiHeader.biCompression = BI_RGB;
bmpinfo.bmiHeader.biSizeImage = 0;
bmpinfo.bmiHeader.biXPelsPerMeter = 100;
bmpinfo.bmiHeader.biYPelsPerMeter = 100;
bmpinfo.bmiHeader.biClrUsed = 0;
bmpinfo.bmiHeader.biClrImportant = 0; fwrite(&bmpheader,sizeof(BITMAPFILEHEADER),1,fp);
fwrite(&bmpinfo.bmiHeader,sizeof(BITMAPINFOHEADER),1,fp);
fwrite(pRGBBuffer,width*height*bpp/8,1,fp);
fclose(fp); return 0;
} static int av_create_bmp(char* filename, AVFrame *pRGBBuffer,int width,int height,int bpp)
{
BITMAPFILEHEADER bmpheader;
BITMAPINFO bmpinfo;
FILE *fp; fp = fopen(filename, "wb");
if(!fp)return -1; bmpheader.bfType = ('M'<<8)|'B';
bmpheader.bfReserved1 = 0;
bmpheader.bfReserved2 = 0;
bmpheader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
bmpheader.bfSize = bmpheader.bfOffBits + width*height*bpp/8;
bmpinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmpinfo.bmiHeader.biWidth = width;
bmpinfo.bmiHeader.biHeight = -height;
bmpinfo.bmiHeader.biPlanes = 1;
bmpinfo.bmiHeader.biBitCount = 24;
bmpinfo.bmiHeader.biCompression = BI_RGB;
bmpinfo.bmiHeader.biSizeImage = 0;
bmpinfo.bmiHeader.biXPelsPerMeter = 100;
bmpinfo.bmiHeader.biYPelsPerMeter = 100;
bmpinfo.bmiHeader.biClrUsed = 0;
bmpinfo.bmiHeader.biClrImportant = 0;
fwrite(&bmpheader,sizeof(BITMAPFILEHEADER),1,fp);
fwrite(&bmpinfo.bmiHeader,sizeof(BITMAPINFOHEADER),1,fp);
//fwrite(pRGBBuffer,width*height*bpp/8,1,fp);
for(int y=0; y<height; y++)
fwrite(pRGBBuffer->data[0] + y*pRGBBuffer->linesize[0], 1, width*3, fp);
fclose(fp);
return 0;
} static void print_packet_info(AVPacket info)
{
#ifdef FILE_OUT
file_debugout << "print_packet_info" << " convergence_duration:" << info.convergence_duration
<< " dts:" << info.dts
<< " duration:" << info.duration
<< " flags:" << info.flags
<< " pos:" << info.pos
<< " pts:" << info.pts
<< " size:" << info.size
<< " stream_index:" << info.stream_index << endl;
#else
cout << "print_packet_info" << " convergence_duration:" << info.convergence_duration
<< " dts:" << info.dts
<< " duration:" << info.duration
<< " flags:" << info.flags
<< " pos:" << info.pos
<< " pts:" << info.pts
<< " size:" << info.size
<< " stream_index:" << info.stream_index << endl;
#endif
} static void print_frame_info(AVFrame* pinfo)
{
#ifdef FILE_OUT
file_debugout << "print_frame_info" << " coded_picture_number:" << pinfo->coded_picture_number
<< " display_picture_number:" << pinfo->display_picture_number
<< " type:" << pinfo->type << endl;
#else
cout << "print_frame_info" << " coded_picture_number:" << pinfo->coded_picture_number
<< " display_picture_number:" << pinfo->display_picture_number
<< " type:" << pinfo->type << endl;
#endif } int decode_video_packet(AVFormatContext * fmt_ctx_for_decode, \
AVCodecContext* dec_ctx, int video_stream_index)
{
int ret = 0; AVFrame* pFrame=avcodec_alloc_frame();
AVFrame* pFrameRGB = avcodec_alloc_frame(); int numBytes=avpicture_get_size(PIX_FMT_BGR24, dec_ctx->width,dec_ctx->height);
uint8_t* buffer = new(std::nothrow) uint8_t[numBytes]; avpicture_fill((AVPicture *)pFrameRGB, buffer, PIX_FMT_BGR24,\
dec_ctx->width, dec_ctx->height); SwsContext *pSWSCtx = sws_getContext(dec_ctx->width, dec_ctx->height, \
dec_ctx->pix_fmt, dec_ctx->width, dec_ctx->height, PIX_FMT_BGR24,\
SWS_BICUBIC, NULL, NULL, NULL); if (NULL == pFrame || NULL == pFrameRGB || NULL == buffer || NULL == pSWSCtx)
{
ret = -1;
goto exit;
} AVPacket packet;
int key_frame_picture_count = 0; while (av_read_frame(fmt_ctx_for_decode, &packet) >= 0)
{
if (packet.stream_index == video_stream_index)
{
int got_frame = 0;
avcodec_decode_video2(dec_ctx, pFrame,&got_frame, &packet); if (got_frame) //一个完整的帧
{
if (pFrame->key_frame)
{
sws_scale(pSWSCtx, pFrame->data, pFrame->linesize,0, \
dec_ctx->height, pFrameRGB->data, pFrameRGB->linesize); // 保存到磁盘
char pic[200];
sprintf(pic,"keyframe%d.bmp", ++key_frame_picture_count);
av_create_bmp(pic,pFrameRGB->data[0],dec_ctx->width,dec_ctx->height,24);
//av_create_bmp(pic, pFrameRGB, dec_ctx->width,dec_ctx->height,24);
}
print_frame_info(pFrame); } print_packet_info(packet);
} } exit:
avcodec_free_frame(&pFrame);
avcodec_free_frame(&pFrameRGB);
delete [] buffer;
sws_freeContext(pSWSCtx);
return ret;
} static int open_input_file(const char *filename)
{
int ret;
bool video_codec_init = false;
int video_stream_index = -1;
AVCodecContext* suitable_dec_ctx = NULL;
AVFormatContext *video_fmt_ctx = NULL; if ((ret = avformat_open_input(&video_fmt_ctx, filename, NULL, NULL)) < 0) {
av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
return ret;
} if ((ret = avformat_find_stream_info(video_fmt_ctx, NULL)) < 0) {
av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
avformat_close_input(&video_fmt_ctx);
return ret;
} for (int i = 0; i < video_fmt_ctx->nb_streams; i++)
{
// 找到视频码流
if (video_fmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
{
video_stream_index = i;
// 初始化解码器信息
if (!video_codec_init)
{
suitable_dec_ctx = video_fmt_ctx->streams[i]->codec; AVCodec* pcodec = avcodec_find_decoder(suitable_dec_ctx->codec_id); if (NULL == pcodec)
{
printf("cannot find decoder");
avformat_close_input(&video_fmt_ctx);
return 1;
} if(0 != avcodec_open2(suitable_dec_ctx, pcodec, NULL))
{
printf("open codecer failed");
avformat_close_input(&video_fmt_ctx);
return 1;
} video_codec_init = true;
} }
} // 解码视频
if (video_codec_init && suitable_dec_ctx)
{
decode_video_packet(video_fmt_ctx, suitable_dec_ctx, video_stream_index);
} // 关闭文件
avformat_close_input(&video_fmt_ctx); return 0;
} int _tmain(int argc, _TCHAR* argv[])
{
// 注册库中所有可能有用的文件格式和编码器
av_register_all();
open_input_file("C:\\Users\\xukaijun.HIK\\Desktop\\hikvison.mp4"); #ifdef FILE_OUT
file_debugout.close();
#endif return 0;
}