this post was submitted on 19 Nov 2023
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This may be a stupid question, but I just got back into pirating some shows and movies and realize that many of the QxR files are much smaller than what I downloaded in the past. Is it likely that I am sacrificing a noticeable amount of quality if I replace my files with the smaller QxR ones?

For example, I have Spirited Away from 2017 at 9.83 GB, but I see the QxR is only 6.1 GB. I also have the office from 2019 and the entire show (no bonus content) is about 442 GB, while the QxR version is only 165.7 GB. Dates are what they are dated on my hard drive, can't speak to their actual origin, but they would've been from RARBG. (Edit to add: I also can't really speak to the quality of the downloads, back then I was just grabbing whatever was available at a reasonable size, so I wasn't deliberately seeking out high quality movies and shows - a simple 1080p in the listing was enough for me).

I did some side by side on episodes of the Office (on my PC with headphones, nothing substantial), and I don't notice any differences between the two.

Thoughts on this? Are people better at ripping/compressing/whatever now that they can do so at a smaller size without sacrificing noticeable quality?

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[–] antlion@lemmy.dbzer0.com 4 points 1 year ago (1 children)

It’s quite remarkable really. A single layer DVD stores 4.7 GB, for a movie with 576p (H.262). A while later those videos could be compressed using DivX or Xvid (H.263) down to 700 MB to fit on a standard CD, though full quality was more like 2 GB.

The Blu-ray standard came along with 25 GB per layer, and 1080p video, stored in H.262 or H.264.

Discs encoded in MPEG-2 video typically limit content producers to around two hours of high-definition content on a single-layer (25 GB) BD-ROM. The more-advanced video formats (VC-1 and MPEG-4 AVC) typically achieve a video run time twice that of MPEG-2, with comparable quality. MPEG-2, however, does have the advantage that it is available without licensing costs, as all MPEG-2 patents have expired.

Now H.265 is now even smaller than H.264, so now you could record a full 1080p movie onto a 4.7 GB DVD. Now the Ultra HD Blu-ray Discs are only slightly larger (33 GB per layer), but they store 4K video by supporting H.265 codec. I guess by now a 720p video encoded to H.265 could make a decent copy on a 700 MB CD.

[–] roofuskit@lemmy.world 1 points 1 year ago* (last edited 1 year ago) (1 children)

You're right except for that last part. The newer smaller file size video codecs are really only effective on higher resolution video. So a 720p movie encoded with H.265 to fit on a 700MB CD isn't going to look much better if at all than older codecs (maybe better than DivX). H.265 really shines at 4K and up but does offer some benefit at 1080p.

[–] antlion@lemmy.dbzer0.com 1 points 1 year ago (1 children)

That is interesting. Of course there aren’t any HDMI CD Video players so it doesn’t much matter. But it’s interesting how a 4 GB DVD in H.262 would compare to a 1080p copy of the same movie in H.265.

I wonder if there’s a lot of room for encoders to improve the quality per byte without changing the format. For instance jpeg and mozjpeg.

There's so much room that format specifications don't tell you how to encode, only how to decode. Designing the best encoder is a huge research project.