And why there are some 4-5 GB size blu ray movies available for download? If both the 50GB and 5GB versions are 1080p, what has been lost due to compression? Will there be a huge difference to visual & audio?
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EDIT: Thanks everyone, now I have a new found perspective on quality.
In: Technology
Some time ago I compared Star Trek: Into Darkness (1080p) at 3 different bitrates (sizes).
Here are the screenshots:
[3GB (Low bitrate)](https://i.imgur.com/R58qeRq.png)
[12GB (Medium bitrate)](https://i.imgur.com/9P7Ir8g.png)
[35GB (High bitrate)](https://i.imgur.com/Xw5dSsr.png)
All of these are technically 1080p but the the smallest one looks awful because there’s just not enough data to encode a clean image.
The middle one is pretty close to how streaming services look (nowadays they’re smaller filesizes but use newer more efficient compression algorithms – I took the screenshots at least 5 years ago).
Still the middle one is not as detailed as the biggest one which should be nearly identical to true blu-ray quality. The difference might not be as noticeable on smaller screes, especially with movement, but the bigger the screen the more apparent it will be.
So to answer the question – blu-ray movies are big to give the viewer the highest possible quality, it wouldn’t make sense to make the movie smaller and more compressed if the disk can fit more anyway.
But some (actually most, judging by the supply and demand) people prefer convenience over quality so they go for the awful looking versions just so they can see the movie – so that’s why the lower quality versions exist.
Edit: just a heads up, if you’re trying to compare these on a phone you might not see much of a difference – that was actually a big problem people had last time I posted this comparison.
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