Ubuntu 编译 ffmpeg tutorial02.c

1. 需要安装SDL库，SDL相关的文档见http://sdl.beuc.net/sdl.wiki/FrontPage

sudo apt-get install libsdl1.2-dev

2. 使用swscale函数替换img_convert函数，以下是修改后的代码

// tutorial02.c
// A pedagogical video player that will stream through every video frame as fast as it can.
//
// Code based on FFplay, Copyright (c) 2003 Fabrice Bellard,
// and a tutorial by Martin Bohme (boehme@inb.uni-luebeckREMOVETHIS.de)
// Tested on Gentoo, CVS version 5/01/07 compiled with GCC 4.1.1
// Use
//
// gcc -o tutorial02 tutorial02.c -lavformat -lavcodec -lz -lm -lswscale `sdl-config --cflags --libs`
// to build (assuming libavformat and libavcodec are correctly installed,
// and assuming you have sdl-config. Please refer to SDL docs for your installation.)
//
// Run using
// tutorial02 myvideofile.mpg
//
// to play the video stream on your screen.


#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

#include <SDL.h>
#include <SDL_thread.h>

#ifdef __MINGW32__
#undef main /* Prevents SDL from overriding main() */
#endif

#include <stdio.h>

int main(int argc, char *argv[]) {
    AVFormatContext *pFormatCtx;
    int             i, videoStream;
    AVCodecContext  *pCodecCtx;
    AVCodec         *pCodec;
    AVFrame         *pFrame;
    AVPacket        packet;
    int             frameFinished;
    float           aspect_ratio;

    struct SwsContext *img_convert_ctx;

    SDL_Overlay     *bmp;
    SDL_Surface     *screen;
    SDL_Rect        rect;
    SDL_Event       event;

    if(argc < 2) {
        fprintf(stderr, "Usage: test <file>\n");
        exit(1);
    }
    // Register all formats and codecs
    av_register_all();

    if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
        fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
        exit(1);
    }

    // Open video file
    if(av_open_input_file(&pFormatCtx, argv[1], NULL, 0, NULL)!=0)
        return -1; // Couldn't open file

    // Retrieve stream information
    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
    videoStream=-1;
    for(i=0; i<pFormatCtx->nb_streams; i++)
        if(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_VIDEO) {
            videoStream=i;
            break;
        }
    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;

    // construct the scale context, conversing to PIX_FMT_YUV420P
    img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);// other codes
    if (img_convert_ctx == NULL) {
        fprintf(stderr, "Cannot initialize the conversion context!\n");
        return -1;
    }

    // Find the decoder for the video stream
    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();

    // Make a screen to put our video
#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);
    }

    // Allocate a place to put our YUV image on that screen
    bmp = SDL_CreateYUVOverlay(pCodecCtx->width,
                               pCodecCtx->height,
                               SDL_YV12_OVERLAY,    /* Planar mode: Y + V + U */ 
                               screen);


    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) {
                SDL_LockYUVOverlay(bmp);

                AVPicture pict;
                pict.data[0] = bmp->pixels[0];  /*Y*/
                pict.data[1] = bmp->pixels[2];  /*U*/
                pict.data[2] = bmp->pixels[1];  /*V*/

                pict.linesize[0] = bmp->pitches[0]; /*Y*/
                pict.linesize[1] = bmp->pitches[2]; /*U*/
                pict.linesize[2] = bmp->pitches[1]; /*V*/

                // 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, (const uint8_t * const*)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);

            }
        }

        // 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;
        }

    }
    sws_freeContext(img_convert_ctx);

    // Free the YUV frame
    av_free(pFrame);

    // Close the codec
    avcodec_close(pCodecCtx);

    // Close the video file
    av_close_input_file(pFormatCtx);

    return 0;
}