The two, back together for “Amar Singh Chamkila”, say theirs is a connection that goes beyond a simple director-composer equation. It’s one that started on a poetic note with Ali reciting Punjabi preacher-poet Baba Farid's famous lines "Kaga Sab Tan Khaiyo" to the Tamil speaking Rahman during the narration of "Rockstar".

"He didn't know anything about my work," Ali told PTI, recalling his first meeting with the Oscar winning music maestro.

"I liked his hair," added Rahman about his director’s famous unruly mop of curls that have become a signature of sorts for him.

Ali, of course, knew everything there was to know about Rahman's music, not just in Hindi cinema but in Tamil as well. But they really connected over Baba Farid.

The conversation inspired the 2012 film's famous song “Naadan Parindey”, sung by Mohit Chauhan.

"I felt I had your attention," Ali told Rahman about the meeting at the musician’s Chennai studio years ago.

Ali said his producers had told him to "catch hold" of the musician at any cost for the movie, starring Ranbir Kapoor and Nargis Fakhri.

"Working with him, all borders disappear. We don’t think, 'He is the director and I’m the composer'. We just jam with it and we think how we can make this interesting, and how we go deeper into something. He has a great sense of picking up tunes, lyrics, so I trust his instinct. He's a fan of music, lyrics, great poetry, psychology and philosophy," Rahman told PTI.

Their latest collaboration "Amar Singh Chamkila", about the popular 80s grassroots Punjabi singer who was shot dead along with his wife and singing partner Amarjot, will start streaming on Netflix from April 12.

The challenge with the film, Rahman said, was that Chamkila wrote and sang his own songs.

"My question was, ‘Chamkila already has songs, so what am I going to do in it?’ We sat and figured it out," he said.

The film will see lead stars Diljit Dosanjh and Parineeti Chopra sing several songs. The other numbers, sung by Alka Yagnik, Mohit Chauhan, Rahman, Arijit Singh and others, play in the backdrop.

Ali and Rahman, both in their 50s, want to take Chamkila’s music across the world as they are catering to a global audience by telling the story of a person who came from rural Punjab.

Alka Yagnik sang “Agar Tum Saath Ho”, a popular romantic number from “Tamasha” and is back for “Naram Kaalja” in “Amar Singh Chamkila”.

Asked why veteran singers don’t get too many chances in playback singing today, Ali, 52, said, it was Rahman’s idea to rope in Yagnik, a popular voice of the leading ladies in the 90s and 2000s.

“She (sang), ‘Agar Tum Saath Ho’ and now, in retrospect, the whole world knows why. Alka ji’s voice could be very nice because it has a vintage quality but I couldn't see it at that time. Even this time, she has sung, ‘Naram Kaalja’ and it was his (Rahman’s) idea. Again we didn’t expect it.”

Rahman, 57, who is particular about the singers he collaborates with, added, “The unfortunate truth is if somebody becomes popular, everybody goes to the person. They overuse that person and kill them.”

According to the music maestro, it is important to cast singers correctly and he said he managed to do that with both Yagnik and Richa Sharma in “Maidaan”, another Hindi film he has composed for.

“It's great to hear all these voices together, like a symphony.”

Are there creative clashes when they are working together?

“No, never. I never argue with Rahman sir. The only point of conflict has been that I like something that he's made, and he thinks it's not good. This has happened two-three times,” Ali said.

Rahman, on his part, said things can always be improved further and he has no hesitation in revisiting his compositions even if he has given it to the director to be used in the movie. This is true of Ali as well as of Mani Ratnam, the man who introduced Rahman to the world with “Roja” in 1992.

“If I’ve time, I tell them, ‘I’ll give you something better’. Then they say, ‘This is better, thanks’. For me, time is the biggest resource and gift, because you can get anything back, you can’t get time. In this, we had a bit of time to rethink one of the songs, which was a repeat song, ‘Vida Karo’,” Rahman said.

Ali said when Rahman decides to change a song and he has already grown fond of it, there is a bit of sadness to let it go.

“The song ‘Agar Tum Saath Ho’ was the third or the fourth composition that he had made and I had approved. Then I already shot the song situation on some other song and then he said, “No, we'll do this’.”

After “Amar Singh Chamkila'', Ali is already ready with a new script and has told Rahman about it.

Other than Ali’s film and “Maidaan”, Rahman has Aanand L Rai’s new film “Tere Ishk Mein” and a silent film, “Gandhi Talks”.

Rahman has worked on consecutive Hindi movies after a long time and said he never went away.

“I never feel like I’m taking a break or anything because all the songs are my ambassadors, whether it's ‘Roja’, ‘Bombay’, ‘Taal’, ‘Rockstar’, ‘Highway’, ‘Tamasha’ or ‘Raanjhanaa’. Sometimes, it’s nice to take a break and do other things in life. I don’t want to get stuck with just film soundtracks. You have to learn about life,” Rahman said.