FFmepg中文例子—指导1：制作屏幕录像

#include "stdafx.h"  
#include "libavformat/avformat.h"  
#include "libswscale/swscale.h"  
//#include <windows.h>  
  
#include <stdlib.h>  
#include <stdio.h>  
#include <string.h>  
#include <math.h>  
#include <SDL/SDL.h>  
  
#ifdef main  
#undef main  
#endif  
  
#define SDL_AUDIO_BUFFER_SIZE 1024  
static int sws_flags = SWS_BICUBIC;  
  
int main(int argc, char *argv[])  
{  
    AVFormatContext *pFormatCtx;  
    int i, videoStream(-1);  
    AVCodecContext *pCodecCtx;  
    AVCodec *pCodec;  
    AVFrame *pFrame;  
    AVPacket packet;  
    int frameFinished;  
    float aspect_ratio;  
    AVCodecContext *aCodecCtx;  
    SDL_Overlay *bmp;  
    SDL_Surface *screen;  
    SDL_Rect rect;  
    SDL_Event event;  
    if(argc < 2)  
    {  
        fprintf(stderr, "Usage: test \n");  
        exit(1);  
    }  
  
    av_register_all();  
    pFormatCtx = av_alloc_format_context();  
    if (!pFormatCtx) {  
        fprintf(stderr, "Memory error\n");  
        exit(1);  
    }  
    if(av_open_input_file(&pFormatCtx, argv[1], NULL, 0, NULL)!=0)  
        return -1; // Couldn't open file  
    if(av_find_stream_info(pFormatCtx)<0)  
        return -1; // Couldn't find stream information  
    // Dump information about file onto standard error  
    dump_format(pFormatCtx, 0, argv[1], 0);  
  
    // Find the first video stream  
    for(i=0; i<pFormatCtx->nb_streams; i++)  
    {  
        if(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_VIDEO && videoStream<0)  
        {  
            videoStream=i;  
        }  
    }  
    if(videoStream==-1)  
      return -1; // Didn't find a video stream  
  
    // Get a pointer to the codec context for the video stream  
  
    pCodecCtx=pFormatCtx->streams[videoStream]->codec;  
    pCodec=avcodec_find_decoder(pCodecCtx->codec_id);  
    if(pCodec==NULL)  
    {  
        fprintf(stderr, "Unsupported codec!\n");  
        return -1; // Codec not found  
    }  
    // Open codec  
    if(avcodec_open(pCodecCtx, pCodec)<0)  
        return -1; // Could not open codec  
  
    // Allocate video frame  
    pFrame=avcodec_alloc_frame();  
  
    uint8_t *buffer;  
    int numBytes;  
    // Determine required buffer size and allocate buffer  
    numBytes=avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,  
        pCodecCtx->height);  
    buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));  
  
    if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER))  
    {  
        fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());  
        exit(1);  
    }  
  
#ifndef __DARWIN__  
    screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);  
#else  
    screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0);  
#endif  
    if(!screen)  
    {  
        fprintf(stderr, "SDL: could not set video mode - exiting\n");  
        exit(1);  
    }  
  
    bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,  
        SDL_YV12_OVERLAY, screen);  
  
    static struct SwsContext *img_convert_ctx;  
    if (img_convert_ctx == NULL)  
    {  
        img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,  
                                         pCodecCtx->pix_fmt,  
                                         pCodecCtx->width, pCodecCtx->height,  
                                         PIX_FMT_YUV420P,  
                                         sws_flags, NULL, NULL, NULL);  
        if (img_convert_ctx == NULL)  
        {  
            fprintf(stderr, "Cannot initialize the conversion context\n");  
            exit(1);  
        }  
    }  
    i=0;  
    while(av_read_frame(pFormatCtx, &packet)>=0)  
    {  
        // Is this a packet from the video stream?  
        if(packet.stream_index==videoStream)  
        {  
            // Decode video frame  
            avcodec_decode_video(pCodecCtx, pFrame, &frameFinished,  
                packet.data, packet.size);  
            // Did we get a video frame?  
            if(frameFinished)  
            {  
                // Convert the image from its native format to RGB  
                  
                // Save the frame to disk  
                  
                SDL_LockYUVOverlay(bmp);  
                AVPicture pict;  
                pict.data[0] = bmp->pixels[0];  
                pict.data[1] = bmp->pixels[2];  
                pict.data[2] = bmp->pixels[1];  
  
                pict.linesize[0] = bmp->pitches[0];  
                pict.linesize[1] = bmp->pitches[2];  
                pict.linesize[2] = bmp->pitches[1];  
  
                // Convert the image into YUV format that SDL uses  
                  
                sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize,  
                    0, pCodecCtx->height, pict.data, pict.linesize);  
                SDL_UnlockYUVOverlay(bmp);  
                rect.x = 0;  
                rect.y = 0;  
                rect.w = pCodecCtx->width;  
                rect.h = pCodecCtx->height;  
                SDL_DisplayYUVOverlay(bmp, &rect);  
                //Sleep(60);  
            }  
        }  
  
        // Free the packet that was allocated by av_read_frame  
        av_free_packet(&packet);  
  
        SDL_PollEvent(&event);  
        switch(event.type)  
        {  
        case SDL_QUIT:  
            SDL_Quit();  
            exit(0);  
            break;  
        default: break;  
        }  
    };  
    // Free the RGB image  
    av_free(buffer);  
    //av_free(pFrameRGB);  
    // Free the YUV frame  
    av_free(pFrame);  
    // Close the codec  
    avcodec_close(pCodecCtx);  
    // Close the video file  
    av_close_input_file(pFormatCtx);  
    return 0;  
}