int img_get_alpha_info(AVPicture *src, int pix_fmt, int width, int height)
int img_get_alpha_info(const AVPicture *src, int pix_fmt, int width, int height)
int img_get_alpha_info(AVPicture *src, int pix_fmt, int width, int height){    PixFmtInfo *pf = &pix_fmt_info[pix_fmt];    int ret;    pf = &pix_fmt_info[pix_fmt];    /* no alpha can be represented in format */    if (!pf->is_alpha)        return 0;    switch(pix_fmt) {    case PIX_FMT_RGBA32:        ret = get_alpha_info_rgba32(src, width, height);        break;    case PIX_FMT_RGB555:        ret = get_alpha_info_rgb555(src, width, height);        break;    case PIX_FMT_PAL8:        ret = get_alpha_info_pal8(src, width, height);        break;    default:        /* we do not know, so everything is indicated */        ret = FF_ALPHA_TRANSP | FF_ALPHA_SEMI_TRANSP;        break;    }    return ret;}