s->img_size = avpicture_get_size(s->pix_fmt, s->width, s->height);
s->img_size = avpicture_get_size(s->pix_fmt, (s->width+15)&(~15), (s->height+15)&(~15));
static int img_read_header(AVFormatContext *s1, AVFormatParameters *ap){    VideoData *s = s1->priv_data;    int ret, first_index, last_index;    char buf[1024];    ByteIOContext pb1, *f = &pb1;    AVStream *st;    st = av_new_stream(s1, 0);    if (!st) {        av_free(s);        return -ENOMEM;    }    if (ap && ap->image_format)        s->img_fmt = ap->image_format;    strcpy(s->path, s1->filename);    s->img_number = 0;    s->img_count = 0;        /* find format */    if (s1->iformat->flags & AVFMT_NOFILE)        s->is_pipe = 0;    else        s->is_pipe = 1;            if (!ap || !ap->frame_rate) {        st->codec.frame_rate      = 25;        st->codec.frame_rate_base = 1;    } else {        st->codec.frame_rate      = ap->frame_rate;        st->codec.frame_rate_base = ap->frame_rate_base;    }        if (!s->is_pipe) {        if (find_image_range(&first_index, &last_index, s->path) < 0)            goto fail;        s->img_first = first_index;        s->img_last = last_index;        s->img_number = first_index;        /* compute duration */        st->start_time = 0;        st->duration = ((int64_t)AV_TIME_BASE *                         (last_index - first_index + 1) *                         st->codec.frame_rate_base) / st->codec.frame_rate;        if (get_frame_filename(buf, sizeof(buf), s->path, s->img_number) < 0)            goto fail;        if (url_fopen(f, buf, URL_RDONLY) < 0)            goto fail;    } else {        f = &s1->pb;    }        ret = av_read_image(f, s1->filename, s->img_fmt, read_header_alloc_cb, s);    if (ret < 0)        goto fail1;    if (!s->is_pipe) {        url_fclose(f);    } else {        url_fseek(f, 0, SEEK_SET);    }        st->codec.codec_type = CODEC_TYPE_VIDEO;    st->codec.codec_id = CODEC_ID_RAWVIDEO;    st->codec.width = s->width;    st->codec.height = s->height;    st->codec.pix_fmt = s->pix_fmt;    s->img_size = avpicture_get_size(s->pix_fmt, s->width, s->height);    return 0; fail1:    if (!s->is_pipe)        url_fclose(f); fail:    av_free(s);    return -EIO;}