*buf_size=
int ff_combine_frame( MpegEncContext *s, int next, uint8_t **buf, int *buf_size){    ParseContext *pc= &s->parse_context;#if 0    if(pc->overread){        printf("overread %d, state:%X next:%d index:%d o_index:%d\n", pc->overread, pc->state, next, pc->index, pc->overread_index);        printf("%X %X %X %X\n", (*buf)[0], (*buf)[1],(*buf)[2],(*buf)[3]);    }#endif    /* copy overreaded byes from last frame into buffer */    for(; pc->overread>0; pc->overread--){        pc->buffer[pc->index++]= pc->buffer[pc->overread_index++];    }        pc->last_index= pc->index;    /* copy into buffer end return */    if(next == END_NOT_FOUND){        pc->buffer= av_fast_realloc(pc->buffer, &pc->buffer_size, (*buf_size) + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);        memcpy(&pc->buffer[pc->index], *buf, *buf_size);        pc->index += *buf_size;        return -1;    }        pc->overread_index= pc->index + next;        /* append to buffer */    if(pc->index){        pc->buffer= av_fast_realloc(pc->buffer, &pc->buffer_size, next + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);        memcpy(&pc->buffer[pc->index], *buf, next + FF_INPUT_BUFFER_PADDING_SIZE );        pc->index = 0;        *buf= pc->buffer;        *buf_size= pc->last_index + next;    }    /* store overread bytes */    for(;next < 0; next++){        pc->state = (pc->state<<8) | pc->buffer[pc->last_index + next];        pc->overread++;    }#if 0    if(pc->overread){        printf("overread %d, state:%X next:%d index:%d o_index:%d\n", pc->overread, pc->state, next, pc->index, pc->overread_index);        printf("%X %X %X %X\n", (*buf)[0], (*buf)[1],(*buf)[2],(*buf)[3]);    }#endif    return 0;}