tutorial02.c

// 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 `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/SDL.h>
#include <SDL/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;
    static struct SwsContext *img_convert_ctx;
    
    /// SDL variables
    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();
    
    
    /// Init SDL
    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(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0)
        return -1; // Couldn't open file
    
    // Retrieve stream information
    if(avformat_find_stream_info(pFormatCtx, NULL)<0)
        return -1; // Couldn't find stream information
    
    // Dump information about file onto standard error
    av_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==AVMEDIA_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;
    
    // 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_open2(pCodecCtx, pCodec, NULL)<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,
                               screen);
    

    int w = pCodecCtx->width;
    int h = pCodecCtx->height;
    img_convert_ctx = sws_getContext(w, h, pCodecCtx->pix_fmt,
                                     w, h, PIX_FMT_YUV420P,
                                     SWS_BICUBIC, NULL, NULL, NULL);
    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);
            avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
            
            // Did we get a video frame?
            if(frameFinished) {
                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, (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;
        }
        
    }
    
    // Free the YUV frame
    av_free(pFrame);
    
    // Close the codec
    avcodec_close(pCodecCtx);
    
    // Close the video file
    avformat_close_input(&pFormatCtx);
    
    printf("Finished tutorial 02");
    return 0;
}