FFmpegTut1

extern "C"
{
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libavutil/imgutils.h>
}
#include <stdio.h>
#include <iostream>

// compatibility with newer API
#if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(55,28,1)
#define av_frame_alloc avcodec_alloc_frame
#define av_frame_free avcodec_free_frame
#endif

void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame) {
    FILE *pFile;
    char szFilename[32];
    int  y;

    // Open file
    sprintf(szFilename, "frame%d.ppm", iFrame);
    pFile = fopen(szFilename, "wb");
    if (pFile == NULL)
        return;

    // Write header
    fprintf(pFile, "P6\n%d %d\n255\n", width, height);

    // Write pixel data
    for (y = 0; y < height; y++)
        fwrite(pFrame->data[0] + y*pFrame->linesize[0], 1, width * 3, pFile);

    // Close file
    fclose(pFile);
}

int main(int argc, char *argv[]) {
    // Initalizing these to NULL prevents segfaults!
    AVFormatContext   *pFormatCtx = NULL;
    int               i, videoStream;
    AVCodecContext    *pCodecCtxOrig = NULL;
    AVCodecContext    *pCodecCtx = NULL;
    AVCodecParameters *pCodecParams = NULL;
    AVCodec           *pCodec = NULL;
    AVFrame           *pFrame = NULL;
    AVFrame           *pFrameRGB = NULL;
    AVPacket          packet;
    int               frameFinished;
    int               numBytes;
    uint8_t           *buffer = NULL;
    struct SwsContext *sws_ctx = NULL;
    AVPixelFormat     pxFormat = AV_PIX_FMT_YUV420P;

    if (argc < 2) {
        printf("Please provide a movie file\n");
        return -1;
    }
    // Register all formats and codecs
    av_register_all();

    // 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]->codecpar->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
    // Find the decoder for the video stream
    pCodec = avcodec_find_decoder(pFormatCtx->streams[videoStream]->codecpar->codec_id);
    std::cout << pCodec->pix_fmts;
    if (pCodec == NULL) {
        fprintf(stderr, "Unsupported codec!\n");
        return -1; // Codec not found
    }


    pCodecCtx = avcodec_alloc_context3(pCodec);


    //Copy context

    if (avcodec_parameters_to_context(pCodecCtx, pFormatCtx->streams[videoStream]->codecpar) != 0) {
        fprintf(stderr, "Couldn't copy codec context");
        return -1; // Error copying codec context
    }

    // Open codec

    if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
        return -1; // Could not open codec

                   // Allocate video frame
    pFrame = av_frame_alloc();

    // Allocate an AVFrame structure
    pFrameRGB = av_frame_alloc();
    if (pFrameRGB == NULL)
        return -1;

    // Determine required buffer size and allocate buffer
    numBytes = av_image_get_buffer_size(pxFormat, pCodecCtx->width, pCodecCtx->height, 32);
    buffer = (uint8_t *)av_malloc(numBytes * sizeof(uint8_t));

    // Assign appropriate parts of buffer to image planes in pFrameRGB
    // Note that pFrameRGB is an AVFrame, but AVFrame is a superset
    // of AVPicture
    av_image_fill_arrays(pFrameRGB->data, pFrameRGB->linesize, buffer, pxFormat, pCodecCtx->width, pCodecCtx->height, 32);

    // initialize SWS context for software scaling
    sws_ctx = sws_getContext(pCodecCtx->width,
        pCodecCtx->height,
        pCodecCtx->pix_fmt,
        pCodecCtx->width,
        pCodecCtx->height,
        pxFormat,
        SWS_BILINEAR,
        NULL,
        NULL,
        NULL
    );

    // Read frames and save first five frames to disk
    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
            frameFinished = avcodec_receive_frame(pCodecCtx, pFrame);

            // Did we get a video frame?
            if (frameFinished) {
                // Convert the image from its native format to RGB
                std::cout << "Frame finished";
                sws_scale(sws_ctx, (uint8_t const * const *)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);
            }
        }

        // Free the packet that was allocated by av_read_frame
        av_packet_unref(&packet);
    }

    // Free the RGB image
    av_free(buffer);
    av_frame_free(&pFrameRGB);

    // Free the YUV frame
    av_frame_free(&pFrame);

    // Close the codecs
    avcodec_parameters_free(&pCodecParams);
    avcodec_close(pCodecCtx);
    avcodec_close(pCodecCtxOrig);

    // Close the video file
    avformat_close_input(&pFormatCtx);

    return 0;
}