Pasi..You will get the police clearance from the ppt office where your ppt was issued in India. But you can even obtain it from your country where you are currently residing through the Indian embassy.
Regarding the query on "seal". The ppt office has a preformatted document which mentions your name, ppt number and no criminal record and eligibility for immigration to (name of country). It has the seal of ppt office and ministry of external affairs. I was given two copies of the certificate with the original seal, along with the seal that was endorsed in my ppt.
However, I think you need to get the certificate from your Indian embassy, though I dont know abt where you are exactly and how long u have been in that country.
Regarding the time period I was given in a week as my police verification had already been done, otherwise it easily takes more than a month.
PND: Even in your case you have to get it from the Indian consulate.. check the link http://www.cic.gc.ca/english/information/security/police-cert/asia-pacific/india.asp