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I bought a PC that has Intel HD graphics card built it, which supports Full HD Video at its best (1080p).

But many videos online are not in HD Format (less than 720p). Hence if I need to convert to HD (720 or 1080) how can I do that without losing much on quality?

I am using Windows Media Player, Real Player or VLC Media Player.

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Any lossy re-encoding will result in some loss of quality. Is it not suitable to just make the media player's window bigger? –  boehj May 29 '11 at 10:02
    
I agree.. some loss in quality would be there... It doesn't help by making media player window bigger because then you see the pixels...In fact i was lookn for solution so that problem doesn't arise.. –  Romil N May 29 '11 at 10:19
    
I agree with @boehj - what you are looking for is "upscaling". Which video player do you use? –  slhck May 29 '11 at 10:29
    
@slhck: I use either of WMP, Real or VLC Media Player –  Romil N May 29 '11 at 10:47

1 Answer 1

up vote 13 down vote accepted

Short answer: Don't do it (unless you really have to).

The process you are looking for is called "upscaling". In its simplest form, every pixel in the video will be (almost) doubled or stretched and the resulting video will look like 1080p. The problem with this approach is that it doesn't look any different from a full screen option in any normal video player.

What you can do:

So if you take a video and upscale it with a very basic algorithm, and then re-encode it, the quality will be worse than before. As @boehj mentioned in the comments, you will always lose a certain amount of quality when you take an already encoded video and encode it again. Even if you upscale it and encode it with a lossless encoder, this will result in huge files – but in no noticeable difference from the full screen version.

Naturally, how a player displays a full screen version also influences your experienced quality. If the player is bad, then upscaling the video before you play it is a viable option. Of course, there are more approaches to upscaling. You can use bilinear or bicubic filters to smooth out edges and then apply some grain or edge sharpening. Our favorite codec library, FFmpeg, when compiled with the swscale lib, can do this. It uses bilinear filtering as far as I remember.

What movie companies do

Well, most old movies are available on film. Either the stock film they used before cutting or the final film that is delivered to cinemas. As film naturally has a higher spatial resolution than any of today's HD specifications, you can just scan the negatives again and thus get a movie in HD resolution. This is what is mostly done when old movies are re-released as BluRay discs or in "digitally remastered" versions.

More recent movies are actually shot in HD. Or even more, up to 4K resolution. This means that after the movie is cut, color-corrected, etc., the final movie will be downscaled to fit distribution needs. So, iTunes might downscale it to 720p before making it available, or BluRay distributors downscale it do 1080p. This is only possible because they have the original material.


Practical solution

Phew. That all being said you can always download Handbrake, which relies on FFmpeg, and upscale the video using the "Size" options under "Picture Settings". There aren't that many options though.

Just try it on a video and see if you can spot any difference. If not, don't upscale, it won't pay off.

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thanks for the inputs!.. but then how the videos in general are converted to HD compliant? –  Romil N May 29 '11 at 11:29
    
What do you mean with "in general"? Any old movie will be scanned from negatives with a higher than HD resolution. Any recent (digital) movie is filmed in HD (or higher than HD) resolution anyway. They are then downscaled by the distributors, e.g. for BluRay, online rental, etc. –  slhck May 29 '11 at 11:42
    
so there is by no means any non-HD video can be converted to HD video..?! –  Romil N May 29 '11 at 12:12
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No, don't get me wrong :) You can do it (see the part about using Handbrake), but there is no point in doing it if the quality gets worse. –  slhck May 29 '11 at 12:16
    
So how could do that without losing quality? Basically, these days some old non-HD videos are converted to HD Videos without giving up quality... so how does this happen? do they use any software for that? –  Romil N May 29 '11 at 12:58

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