(1) As far as I understand, if the original memory card is produced on which the voice is recorded originally, it should be sufficient since this is the primary evidence. No need to produce the DVR in such case. Also, no need to give certificate under Section 65-B of Evidence Act in such case, since it is the primary evidence itself.
(2) I think, generally, it is the memory card, etc., where the voice is recorded which is the subject of scientific analysis. If you are referring to requirements of Section 65-B of the Evidence Act for the purposes of secondary evidence, then the DVR would be equivalent to “computer” referred to in that section; the certificate has to mention that the DVR was working properly, etc., as required under Section 65-B(2) of the Evidence Act.
(3) Section 65-B(4)(b) requires “giving such particulars of any device involved in the production of that electronic record as may be appropriate for the purpose of showing that the electronic record was produced by a computer”. Therefore, you may have to sufficiently identify the DVR used in the process.
(4) It is advisable to do so, but if my information is correct it is not mandatory in law. Just last week, I saw a case from a southern state where it had not been done. It appears that different investigating agencies in India are using different processes in this regard.
Dr. Ashok Dhamija is a New Delhi based Supreme Court Advocate and author of law books. Read more about him by clicking here. List of his Forum Replies. List of his other articles. List of his Quora Answers. List of his YouTube Videos.