ffmpeg+sdl教程——编写一个简单的播放器2(输出视频到屏幕)

下面完整代码，在vc2005下编译通过。可以看到，程序运行后视频播放出来了，但是由于没有加入播放延迟，视频简直跑疯了，为视频加入延迟将在教程五中实现，目前可以简单地让程序在播放完一帧后，sleep若干秒，改善一下运行状况。

// ffmpegExe.cpp: 主项目文件。

#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
                /*sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize,
                      0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);*/
                // Save the frame to disk
                /*if(++i<=5)
                    SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i);*/
                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
                /*img_convert(&pict, PIX_FMT_YUV420P,
                    (AVPicture *)pFrame, pCodecCtx->pix_fmt,
                    pCodecCtx->width, pCodecCtx->height);*/
                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;
}

// ffmpegExe.cpp: 主项目文件。 #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 /*sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);*/ // Save the frame to disk /*if(++i<=5) SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i);*/ 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 /*img_convert(&pict, PIX_FMT_YUV420P, (AVPicture *)pFrame, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);*/ 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; }

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