More Mb/s not always better quality ?

[Kees Draaihuis]

I always thought that when you have a MKV-file with a higher number in the Mb/s the quality would be better. The movie would look better, sharper, more colourfull etc. etc.

But now I have a mkv-file which is 64Gig and 94Mb/s and I have the same movie which is 25Gig and 30Mb/s and I think the last one looks better (sharper, I'm not talking about the colour). Can anybody explain me why that could be as I always was thinking: The larger the better.



The left one is the large file. I know I see more grain in the left one so maybe that is the reason but I still think the right one looks sharper (maybe because the grain has been removed). But that would mean, more Mb/s is not always better.

[Woodstock]

Using MakeMKV, you will get the same resolution that was on the original disk; it's a copy of that file.

Once you do things like compress it to different sizes, you are limited by what the software you use does. It is not likely to be better resolution, even if you increase the size, than the original.

Choice of compressing software is important; you can chose QUICK (Intel Quiksync or other hardware encoders), or slow (x264 or x265 software encoders), but the output rarely will be "better" than the input, just "less distorted".

[Kees Draaihuis]

@Woodstock, but that's just the question I have. When compressing, the filesize decreases,.and normally the quality decreases as well....so how is it possible that the quality of the file which is 64Gig is worse than the quality of the file which is 25Gig?

[Woodstock]

It depends on what the source is, and how it is compressed.

Take a typical anime movie. There isn't a lot of detail in it so when it's put onto a UHD disk, it's almost not compressed.

Take a simple movie with little action, and most of the change is when scenes change, so they can compress fairly well. The differences between a Bluray and a UHD aren't that great, so going from BD to UHD makes a big difference in space, but not a lot visually.

Now take a very active movie with complex backgrounds and a fast pace, and the difference in detail makes the UHD much more appealing to watch, especially on something that was shot at a higher speed than 24 frame per second. Even the UHD version is a compromise, and compression removes detail that our eyes usually toss out.

Sometimes, that detail is distracting to our brains. A video can appear "dirty" at highest resolution, but "better" when those details are compressed out. The popular compressors like x265 and x264 all have settings that tell them how much of that detail is important. The further away from the screen you are, the less of that detail reaches your brain anyway. And if your vision isn't perfect, that's a hit on quality, too.

Now throw marketing into the equation. It's easy to sell super-duty resolution to people. When UHD hit the market, who didn't want to see the highest resolution possible? When it still fit on a disk, it was great... then it grew to the point that it has to be sent to you via a very fast internet connection.

[flojo]

...how is it possible that the quality of the file which is 64Gig is worse than the quality of the file which is 25Gig?

Filtering such as sharpening, denoise and Ai upscaling are the big ones but of course "quality" is in the eye of the beholder. It's also how it is digitally acquired, for instance the retail UHD 4k Blu-ray of the movie "Far and away" (1992) doesn't just look but objectively is a lot worse than the retail 1080p Blu-ray.