static int get_alpha_info_pal8(AVPicture *src, int width, int height)
static int get_alpha_info_pal8(const AVPicture *src, int width, int height)
static int get_alpha_info_pal8(AVPicture *src, int width, int height){    const unsigned char *p;    int src_wrap, ret, x, y;    unsigned int a;    uint32_t *palette = (uint32_t *)src->data[1];        p = src->data[0];    src_wrap = src->linesize[0] - width;    ret = 0;    for(y=0;y<height;y++) {        for(x=0;x<width;x++) {            a = palette[p[0]] >> 24;            if (a == 0x00) {                ret |= FF_ALPHA_TRANSP;            } else if (a != 0xff) {                ret |= FF_ALPHA_SEMI_TRANSP;            }            p++;        }        p += src_wrap;    }    return ret;}