பாடல் உருவான கதைகள்

The topic is quite old and got discussed in tfmpage and many times here as well in different threads.

This thread is to collect all such stories in a single place

rAsA starts his concerts with the janani janani song and this thread can have the story behind it to begin with
(Actually a post on webdunia I saw today is the reason behind starting this thread : 
http://tamil.webdunia.com/memorable-cinemas-and-events/janani-janani-song-ilayaraja-music-fond-memories-115102400003_1.html )

டைரக்டர் கே.ஷங்கர் என்னிடம் 'தாய் மூகாம்பிகை' படத்திற்கென ஒரு சிச்சுவேஷன் சொல்லியிருந்தார். அந்த சமயங்களில் இரவு இரண்டு மணிவரை எனக்கு கம்போஸிங் இருக்கும்.

மீண்டும் காலையில் ரெக்கார்டிங் இருக்கும். இவர்களுக்கு கம்போஸிங்கிற்காக எனக்கு நேரம் ஒதுக்க இயலாமல் இருந்தது. அந்த சமயத்தில் நான் ‘நார்த் உஸ்மான் ரோட்டில்’ ஒரு வாடகை வீட்டில் இருந்தேன்.
 
அடுத்த நாள் பூஜை. பாட்டு இன்னும் தயாராகவில்லையே என்று டைரக்டர் பதறத் துவங்கிவிட்டிருந்தார். நான் அவரிடம் ‘பதறத் தேவையில்லை. இரவு வீட்டிற்கு வாருங்கள்.. அங்கேயே கம்போஸிங் வைத்துக்கொள்ளலாம்’ என்று கூறினேன்.
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There's a download link for Kannadasan's pAdal piRandha kadhai:
http://www.mediafire.com/download/16gx48122db9i1v/Paadal+Pirantha+Kathai.pdf

Only one IR song gets covered (kaNNE kalaimAnE) and the story is well-known for most IRFs

It is in the 67th page of this pdf, for those interested.

As told by Kavignar Vaali in Doordarshan

All songs of Sagalakalavallavan were written by Kavignar vaali and he said post many ir songs were written for the tune but in this movie there was an exception
TAMIZH LETTER AH SENTINMENT OF AVM
Amman koil kizhakkale - The pallavi lyrics were written first and then the tune was set to this. This is sentiment which AVM Chettiar had since the first thing in any movie should be only the tamizh first alphabet - AH. Thats why when Vjayanthimala picks up the phone in kalayana parisu she says AHALO

Ilamai Idho Idho - When vaali wrote the lyrics like this as Ilamai...idho ..idho..AVM Kumaran told him that the lyrics were very weak but vaali insisted to have them and said hear the song post raaja's full orchestration was added to this, No wonder the song became a super duper hit and raaja was launched into a higher pedestal. Vaali also said he had written about kamal too in that song. Hindilyum paduven....Naan dan sagalakalavallavan. He said Ilayaraaja is unbeatable in orchestration and some songs when written would look dull but actually when the orchestration was done they looked grand.

Nethu Yathiri Yemma and Nila kayuthu - He said both were excellent tunes and he spoke about working with the combination of SP Muthuraman, Panju Arunchalam and Ilayaraaja and how did the lyrics for Guru Sishyan and Veera.

Janani Janani - Thai Mookambikai - story behind the song

Ilayaraaja sir narrated this incident on sankara tv and that was the first time he shared this story with all of us.

When composing for the movie Thai mookambikai, ilayaraaja sir went to the pooja room and there was a photo of sri adi sankara. Ilayaraaja saw the photo and said "My guru, you have to compose this song for me" and then he left for the studio.

He composed the tune and kavignar vaali wrote the lyrics and some how ilayaraaja was not happy with the tune and he said he will compose one more tune. At first they had decided that Sri K J Yesudas will sing the song but later due to the tight schedule and change in the programme of K J Yesudas ilayaraaja himself had to sing the song.
Then he sat and composed this tune " tanana tananna" and everyone had tears in their eyes and kavignar vaali wrote the lyrics and the song was recorded.
The next day Ilayaraaja went to his pooja room and from somewhere a paper fell on him and he took it and saw it was sri adi sankarar's bhaja govindam. It is a genius of ilayaraaja that the metre of bhaja govindam and janani janani are the same.  (Ilayaraaja sings bhaja govindam in tune of Janani Janani)

A really superb story behind the song. thank god  THE MUSIC god sang the song...