int ff_mpeg4_encode_picture_header(MpegEncContext *s, int picture_number)
{
    int time_incr;
    int time_div, time_mod;

    if (s->pict_type == AV_PICTURE_TYPE_I) {
        if (!(s->avctx->flags & AV_CODEC_FLAG_GLOBAL_HEADER)) {
            if (s->strict_std_compliance < FF_COMPLIANCE_VERY_STRICT)  // HACK, the reference sw is buggy
                mpeg4_encode_visual_object_header(s);
            if (s->strict_std_compliance < FF_COMPLIANCE_VERY_STRICT || picture_number == 0)  // HACK, the reference sw is buggy
                mpeg4_encode_vol_header(s, 0, 0);
        }
        if (!(s->workaround_bugs & FF_BUG_MS))
            mpeg4_encode_gop_header(s);
    }

    s->partitioned_frame = s->data_partitioning && s->pict_type != AV_PICTURE_TYPE_B;

    put_bits(&s->pb, 16, 0);                /* vop header */
    put_bits(&s->pb, 16, VOP_STARTCODE);    /* vop header */
    put_bits(&s->pb, 2, s->pict_type - 1);  /* pict type: I = 0 , P = 1 */

    time_div  = FFUDIV(s->time, s->avctx->time_base.den);
    time_mod  = FFUMOD(s->time, s->avctx->time_base.den);
    time_incr = time_div - s->last_time_base;
    av_assert0(time_incr >= 0);

    // This limits the frame duration to max 1 hour
    if (time_incr > 3600) {
        av_log(s->avctx, AV_LOG_ERROR, "time_incr %d too large\n", time_incr);
        return AVERROR(EINVAL);
    }
    while (time_incr--)
        put_bits(&s->pb, 1, 1);

    put_bits(&s->pb, 1, 0);

    put_bits(&s->pb, 1, 1);                             /* marker */
    put_bits(&s->pb, s->time_increment_bits, time_mod); /* time increment */
    put_bits(&s->pb, 1, 1);                             /* marker */
    put_bits(&s->pb, 1, 1);                             /* vop coded */
    if (s->pict_type == AV_PICTURE_TYPE_P) {
        put_bits(&s->pb, 1, s->no_rounding);    /* rounding type */
    }
    put_bits(&s->pb, 3, 0);     /* intra dc VLC threshold */
    if (!s->progressive_sequence) {
        put_bits(&s->pb, 1, s->current_picture_ptr->f->top_field_first);
        put_bits(&s->pb, 1, s->alternate_scan);
    }
    // FIXME sprite stuff

    put_bits(&s->pb, 5, s->qscale);

    if (s->pict_type != AV_PICTURE_TYPE_I)
        put_bits(&s->pb, 3, s->f_code);  /* fcode_for */
    if (s->pict_type == AV_PICTURE_TYPE_B)
        put_bits(&s->pb, 3, s->b_code);  /* fcode_back */

    return 0;
}
Unknown