decode_vol_header(s, gb);
if(decode_vol_header(s, gb) < 0) return -1;
int ff_mpeg4_decode_picture_header(MpegEncContext * s, GetBitContext *gb){    int startcode, v;    /* search next start code */    align_get_bits(gb);    startcode = 0xff;    for(;;) {        v = get_bits(gb, 8);        startcode = ((startcode << 8) | v) & 0xffffffff;                if(get_bits_count(gb) >= gb->size_in_bits){            if(gb->size_in_bits==8 && s->divx_version){                printf("frame skip %d\n", gb->size_in_bits);                return FRAME_SKIPED; //divx bug            }else                return -1; //end of stream        }        if((startcode&0xFFFFFF00) != 0x100)            continue; //no startcode                if(s->avctx->debug&FF_DEBUG_STARTCODE){            printf("startcode: %3X ", startcode);            if     (startcode<=0x11F) printf("Video Object Start");            else if(startcode<=0x12F) printf("Video Object Layer Start");            else if(startcode<=0x13F) printf("Reserved");            else if(startcode<=0x15F) printf("FGS bp start");            else if(startcode<=0x1AF) printf("Reserved");            else if(startcode==0x1B0) printf("Visual Object Seq Start");            else if(startcode==0x1B1) printf("Visual Object Seq End");            else if(startcode==0x1B2) printf("User Data");            else if(startcode==0x1B3) printf("Group of VOP start");            else if(startcode==0x1B4) printf("Video Session Error");            else if(startcode==0x1B5) printf("Visual Object Start");            else if(startcode==0x1B6) printf("Video Object Plane start");            else if(startcode==0x1B7) printf("slice start");            else if(startcode==0x1B8) printf("extension start");            else if(startcode==0x1B9) printf("fgs start");            else if(startcode==0x1BA) printf("FBA Object start");            else if(startcode==0x1BB) printf("FBA Object Plane start");            else if(startcode==0x1BC) printf("Mesh Object start");            else if(startcode==0x1BD) printf("Mesh Object Plane start");            else if(startcode==0x1BE) printf("Still Textutre Object start");            else if(startcode==0x1BF) printf("Textutre Spatial Layer start");            else if(startcode==0x1C0) printf("Textutre SNR Layer start");            else if(startcode==0x1C1) printf("Textutre Tile start");            else if(startcode==0x1C2) printf("Textutre Shape Layer start");            else if(startcode==0x1C3) printf("stuffing start");            else if(startcode<=0x1C5) printf("reserved");            else if(startcode<=0x1FF) printf("System start");            printf(" at %d\n", get_bits_count(gb));        }        switch(startcode){        case 0x120:            decode_vol_header(s, gb);            break;        case USER_DATA_STARTCODE:            decode_user_data(s, gb);            break;        case GOP_STARTCODE:            mpeg4_decode_gop_header(s, gb);            break;        case VOP_STARTCODE:            return decode_vop_header(s, gb);        default:            break;        }        align_get_bits(gb);        startcode = 0xff;    }}