Submitted 4 weeks ago by Patnou@lemmy.world to [deleted]
Oh any help how to get the maximum compression out winrar or a step by step guide would be appreciated. Thank you in advance.
No, movies and music files are already compressed, so compressing them further won’t gain anything. In fact it will actually increase the file size because compressed files require some overhead. So even winrar won’t help, though it might be convenient to have one big file with everything in it (you can even break it up into multiple part files.)
just throw away every second frame. repeat for more compression. at some point you ll be left with a couple of pictures to remember the story and replay it faithfully in your head.
you welcome !
As most have said, doubling up compression won’t usually get you much.
However, video compression is usually designed to facilitate performance of sequential reads because videos are typically played beginning to end, so theoretically there may be ways to compress them more if you’re willing to make sacrifices there.
I doubt RAR is the way to do it, though. It just hasn’t been designed for this kind of data.
Maybe there’s a video compression format out there designed specifically for archival storage, but I’m not aware of it.
ISO won’t get you any further compression, that’s for sure.
You could certainly test this out yourself and let us know if you get any space savings.
If I use winrar to compress 80gb of tv and movies.
You haven’t gained anything by doing so since video is already compressed. Compressing data that is already compressed will usually make it slightly bigger or if you’re lucky maybe you’ll save like a megabit space, not really anything worth the trouble.
Then can I compress it further by making it an iso?
ISO is not compression.
Iso is a container format; it’s a 1:1 mapping to how the bits are stored on disk with a header at the start describing the structure. Bin/cue separates the header into a separate file and can include data structured in ways that don’t comply with the ISO-9660 standard.
WinRAR is a compression/decompression program. It supports multiple archive types and compression formats.
Depending on the type of data you are compressing and whether you want lossless or lossy compression, you’ll want to select a different compression algorithm.
Depending on how you plan to use the files, you’ll want to use a different archive format.
Assuming you use the rar archive format, you still have a lit of options to consider. Should the data be encrypted or not? Should the directory structure be encrypted or not? Do you want parity files and segmented archives, so that if one of the parts gets corrupted (or goes missing), you can still extract the original data in a lossless way?
Beyond all that and selecting the compression algorithm that best compresses the type of structured data you’re storing, the general rule is that if you’ve got lots of data, using the largest dictionary and the largest compression window you can will result in the best compression.
So the dictionary is essentially a code book that says “when I see data x, represent it with data y in the file”. The compression window is how much of your original data is loaded into memory at any given time for the dictionary to look at and compress.
If you can sacrifice quality, you can encode the videos at a lower bitrate, but that is lossy compression, not lossless. Also, if your videos are in h.264 codec, then transcoding them to h.265 and preserving the quality may be a way to get the files smaller. You would use a tool meant for video, like Handbrake for this, and not winrar or other generic compression tool.
No. And that’s a bad plan. Uncompressed them, and then reencode them to h256/x265 with handbrake (use the SuperHQ 1080p setting)
If you want to compress video files, you’ll need to reencode them. Maybe using something like HEVC (High Efficiency Video Codec). But for 80GB of videos, you’ll be there for a while and probably won’t shrink them enough to be worth it. It would likely take less time to simply re-download the files later, even with a mediocre internet connection. In practical terms, you won’t get that 80GB to be any smaller.
ISOs don’t compress anything, as far as I know, or at least not by default. I think they’re basically just a container.
To reencode your videos, you can use the free HandBrake.
well you can’t compress anything by making it into an iso. Because iso does exactly zero compression whatsoever.
80 gb is not a lot for movies. My average 4K movie is between 60 and 80 gb per movie. If you start encoding and compressing them you start seing compression artifacts and reduction in quality very quickly.
What. If you compress them to zip, 7zip, rar, etc. You will never get any artifacts
I guess they are talking about re-encoding because video files are already compressed.
To get the maximum compression out of video you should use a video codec like av1 or hevc. WinRAR wont compress video well at all and making it an ISO is also pointless.
I would suggest checking out handbrake for a good user friendly video compression tool.
For lossless compression, things other then video/audio, you should movr to 7zip over winRAR.
I gave up encoding movies with Handbrake. I can always see the difference in the resulting picture quality and if I don’t, the file is probably only reduced from 80gb to 70gb and it’s not worth it.
I usually just rip the blu-rays, strip out the unnecessary languages and leave the rest as it is.
To answer the specific question (and im rusty on winrar but familiar with 7zip), you should be able to change flags for compression ratio and dictionary size.
When a file is compressed using a general purpose compression algorithm it looks for long repeating patterns and substitutes it for a smaller ‘code’ , it builds a dictionary of these codes which is stored in the file so the decompression algorithm knows how to expand it.
Take Morse code for example, E is represented by a single dot while Z is dash dash dot dot and as E is used a lot more frequently in the language. And if we only used the 26 letters, we could compress sentences down to a compact binary code of 1’s and 0’s with dashes as 1’s and 0’s as dots.
Others have said that handbrake is a good tool and i recommend it too. and as i dont know you use case, im assuming you might want to transfer all these from one computer to another. I believe you could use winrar to make volumes up at 4.7gig (or 25gig) and burn a series of DVDs (or blu-rays) with each disc being full, however if one of the discs gets scratched, corrupted (say disc 12 of 20) then all following data might also get corrupted.
Im going to assume that you’ve got these from a recording of a set-top box from a playback transfer of a VHS on its last legs and you’re digitising an old family home movies.
Lets also assume the video was also recorded at full HD, 1080p (ie. 1920x1080 pixels. The video stream is going to show 2,073,600 pixels every frame), and it also recorded the audio as stereo and the box had an encode rate of 25,000kbps (kilobits per second. This figure is used as an example and may be way off reality bitrates).
So every minute of video might equate to 5megabytes of file size (again picking numbers as guesses).
Handbrake can help make this smaller.
You can do this by shrinking the pixels to be displayed. you could downscale the video to 720p (1280x720 pixels. So 921,600 pixels for every frame) and if everything else was kept the same, the files could be nearly halved but you lose out on some of the fine detail.
You could take this even further by compressing down to something like 360 pixels high and that would be ok to watch on a mobile device, but you’d notice the lack of detail on a 4k monitor.
You could keep the resolution the same at 1080p, and get handbrake to compress it further by lowering the bitrate from 25,000kbps to say 8,000kbps, this would affect the image quality, but handbrake does a good job unless you go for a really small bitrate.
Say my video was of a sunset and the camera doesnt move, the pixels displaying the building in the foreground arent going to change colour often so its compression algorithm adapts. Lets say a bird flies across the screen, so the pixels do change, but there might be a bit of blur around the bird as it flies and with more compression this could be more noticable.
One thing handbrake can do that the Set top box couldnt is look ahead with multipass encoding, so it ‘watches’ the movie and takes notes of when there are large changes in the image and can use more bits in the file on the segments of change, for example you watch a tv show and it cuts from a indoor scene to outdoors, this change would use a lot of data, but once it shows the first frame, it can switch to just changing a few pixels each frame.
You can also adjust the audio recorded by lowering its bitrate, and also merging the audio tracks from stereo to mono, but compared to video compression, this isnt significant.
Without knowing your usecase, id suggest something like a compression down to a 480pixel or 360 pixel resolution and lowered bitrate as a way to burn a low resolution copy of the movies that could be stored offsite as cheap way to have a backup of last resort.
I hope it helps,
Just buy another hard drive, damn.
Well, it’s sort of possible to compress large things into small sizes. But I don’t think it would work for this situation.
There are things called “.zip bombs”. Where an otherwise small file, when unpacked, can take up a large amount of space.
A famous example of a zip bomb is titled 42.zip, which is a zip file of unknown authorship consisting of 42 kilobytes of compressed data, containing five layers of nested zip files in sets of 16, each bottom-layer archive containing a 4.3-gigabyte file for a total of 4.5 petabytes of uncompressed data.
Zip bombs wouldn’t apply here, from what I understand to create those you’d have to start with uncompressed data. The typical example is using a bunch of zeroes as the starting point, not only is that compressible but the compression algorithm will look for redundancies in the data to increase the compression efficiency (a bunch of zeroes would have tons of redundancy).
Stackoverflow has a good discussion on it stackoverflow.com/…/how-does-one-make-a-zip-bomb
Bottom line, winrar isn’t the tool to compress video files. In short it’s more complex, but zipping, raring etc… those methods are all the ideal way to compress executables, word documents etc… In short, most likely your video files are already compressed as much as they can be without loss of quality. However if you were to attempt to make them smaller, most likely you’d use something like handbrake or some other video codec converter to actually try to shrink them.
The short answer is no.
You can do an easy experiment to see this using image files. Grab a random JPG file and open it in a graphics program and save it as a BMP format image.
JPG is already compressed, and BMP is absolutely not compressed. Then try compressing each image. You’ll find that the JPG doesn’t get much smaller, or might even be a bit bigger when compressed. Now do the same with the BMP - that one makes for a smaller RAR!
The main issue here is that compression is about removing empty space in a file (it’s a weak analogy but bear with me). If the file itself already had some kind of compression (basically every AVI or MP4 or MKV you download probably is already compressed), then there’s already a lot less empty space inside the file. RAR doesn’t have much empty space left to work with, so it can’t really reduce the file size any more.
It’s worth doing some testing on a single movie to see how this all works. You’ll probably find that it’s best to just leave the files exactly the way they are. No RAR. No ISO. No tricks. The gains simply aren’t there.
If you’re looking to save on some disk space with your movies, you’d get a lot farther by just deleting one movie you don’t really want that badly. The amount of space you get back from that will exceed your compression gains. It also means you don’t have to go and uncompressed the movies every time you want to watch one.
Put the data inside a mini-black hole and activate Future Gadget #8 PhoneWave (name subject to change)
Wow, this is a very technical question. Judging by the “does my doggy understand his birthday?” post, I thought you were a r*tared 10-year-old.
freamon@preferred.social 4 weeks ago
TV shows and movies are already compressed. If you try to compress something that's already compressed, it typically ends up bigger if anything.
EveryMuffinIsNowEncrypted@lemmy.blahaj.zone 4 weeks ago
Why does it get bigger? I’ve wondered that for a while now.
I would think that compressing something that’s already compressed would still compress it further but at diminishing returns.
MrNesser@lemmy.world 4 weeks ago
Once the files are added to the zip folder your also adding information about the files so they can be removed.
Tungsten5@lemm.ee 4 weeks ago
Have you tried compressing it again?