can anybody tell me what is a standard english accent?

>>the original form of English

Oh, eek. The original form of English?

Sreekar,

Like you, I'm multi-lingual. And like you, or rather until I came to China, I "had" access to CNN and BBC, but had thought about over your question long before as I'm a typical American immigrant. So I completely understand where you're coming from. But if there were a world standard it'd have to be CLARITY & knowing (that is being sensitive to) one's listening audience when speaking English. The best answer I can offer you in addition to what the others have said is a technique whose efficacy it's almost impossible to ascertain (largely because people move on and you lose contact) but I believe it's worked for those I've coached in the past.

SHIFT FOCUS from your pursuit of a world standard English and think instead:
1) Good; clear enough English; but begin first, by "really"
2) coming to terms with your most comfortable "tongue."

Accents are great, and I think it's appalling that there's so much pressure on people (immigrants especially) to lose their accent and replace with some impossible "American" or "English" accent that may be akin to asking one to fold their arms in a way unnatural to them. These days, it's common to hear what some of my friends call the "forced American" accent wherever one goes. Suggestion #2 is key because take for instance, the Japanese. Most Japanese do not have the "L" pronunciation coming to them as naturally as it does for others. If you think I'm kidding, try getting a good Japanese friend to say the word "Really" after you. It may sound funny at first because you'd hear "R" all over the place. and yet that kind of problem exists the world over. Because it's in the "tongue," you see. Just like some from both Africa and the Caribbean can't say "H" in words like "happy."

Point:
What I've suggested to my Japanese friends therefore is that having identified what "accent" your native or most frequent "tongue" works with the most, go with that! You'd find that what you glean such as good pronunciations from as you mentioned, watching "various English channels like movie channels, Discovery and so on..." (and believe me, to this day, I do the same) would enable you speak "fine English" which I'm sure you probably already do!! I suggest, the "international" accent as Claire mentioned, is cool and works perhaps for a greater number than few would disagree the (North) American accent is the more understandable of the bunch. In its peak form however Sreekar, your IDEAL world standard English accent because of your "tongue," could mean you produce practically speaking, a tonal rich blend of spoken English (with for example, Scot-style soounds) and some North American here and there! Anyway, best of luck and should you need additional feedback you may find me at the google-searchable Open-Minded Community.

Sorry. The point I meant to make in mentioning the "Japanese" is that having interacted with so many Japanese for decades, I personally believe their "tongue" as far as impeccable or at least "clear" English accent goes, "is" better suited for adoption of the English/British accent.