while (av_read_frame(formatContext, &packet)>=0)
    {

        result = decodeVideo(videoCodecContext, frame, &frameFinished, &packet);

        if (result < 0 && result != AVERROR_EOF)
        {
            showLog("Error on decoding video");

            showErrorMessage(result);

            freeMemory();

            return -1;
        }

        showLog("Decoding video successful");

        if (frameFinished && packet.stream_index==videoStream)
        {
            result = sws_scale(swsContext, (uint8_t const * const *)frame->data, frame->linesize, 0, frame->height, rgbFrame->data, rgbFrame->linesize);

            if (result < 0)
            {
                showLog("Error on converting image");

                showErrorMessage(result);

                freeMemory();

                return -1;
            }

            showLog("Image scaling successful");
        }

        av_packet_unref(&packet);

    }

int decodeVideo(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *pkt)
{
    int ret = 0;

    *got_frame = 0;

    if (pkt)
    {
        ret = avcodec_send_packet(avctx, pkt);

        // In particular, we don't expect AVERROR(EAGAIN), because we read all
        // decoded frames with avcodec_receive_frame() until done.
        if (ret < 0)
        {
            return ret == AVERROR_EOF ? 0 : ret;
        }
    }

    ret = avcodec_receive_frame(avctx, frame);

    if (ret < 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)
    {
        return ret;
    }

    if (ret >= 0)
    {
        *got_frame = 1;
    }

    return ret;
}