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 could also adjust the framerate of the video if it was recorded in 60 frames per second to 30.

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.

Edit: in summary, try handbrake, use two pass encoding and just adjust the bitrate first and see if the quality is still ‘good enough’, and if you need smaller files, then try and change the resolution, the frame rate, and audio encoding.

I hope it helps,