File compression (?)

[hug0mac]

hi everyone.

 

 

i am just wondering what type of file compression fits to compress large files (1-2gb's) each to a somehow smaller size. in 7zip or winrar etc, as far as i know about it, its loss-less eh its just math kinda with numbers... *cough*

 

 

what settings in 7zip should i be using? any tips? i tried to compress files but its like 1-2mb's smaller and im like "what.."

 

so help a little new user out (with compression) other than converting to smaller size/loosing quality... or better said, help me to optimize archiving! 

 

 

[EposVox]

It depends on what type of files you're compressing. Every different type of file compresses differently.

 

In some cases, you can compress a file to 1/4th of its size. Rare, but I've seen it. In other cases, you can only lower it by a MB or two. In other cases, you can actually make the file size larger.

[burnttoastnice]

hi everyone.

 

 

i am just wondering what type of file compression fits to compress large files (1-2gb's) each to a somehow smaller size. in 7zip or winrar etc, as far as i know about it, its loss-less eh its just math kinda with numbers... *cough*

 

 

what settings in 7zip should i be using? any tips? i tried to compress files but its like 1-2mb's smaller and im like "what.."

 

so help a little new user out (with compression) other than converting to smaller size/loosing quality... or better said, help me to optimize archiving! 

 

 

 

If it's something like a video file (particularly h264) or a .zip file you are compressing, you won't see much difference at all - because it's already compressed. 7zip has performed optimally for me when compressing word documents, pictures (such as jpegs and bitmaps) and audio files.

 

Linus did a techquickie on compression at some point...

[hug0mac]

It depends on what type of files you're compressing. Every different type of file compresses differently.

 

In some cases, you can compress a file to 1/4th of its size. Rare, but I've seen it. In other cases, you can only lower it by a MB or two. In other cases, you can actually make the file size larger.

 

its video files, mp4. h.264. and i got lets say 100 files... 100gb total. it become like 98gb or sometimes even 101-102gb and i dont understand how some can get it like (when transfer on internet) 200mb out of a 2-3gb file. and there are so many types of ways to compress...and that i dont even know! 

[hug0mac]

If it's something like a video file (particularly h264) or a .zip file you are compressing, you won't see much difference at all - because it's already compressed. 7zip has performed optimally for me when compressing word documents, pictures (such as jpegs and bitmaps) and audio files.

 

Linus did a techquickie on compression at some point...

 

 

ah. how about png picture files? like 2-3000 of them... any smart way to get that working? 

[alpenwasser]

ah. how about png picture files? like 2-3000 of them... any smart way to get that working? 

png has integrated lossless compression. If that's already set to maximum, you're unlikely to see any additional compression. Pretty much the only way to decrease filesize in that case is lossy compression such as jpeg. But as said, that means you lose quality. Might be acceptable, might not be, depends on your priorities.

As a general guidelines, pure text files tend to compress very well, files which are already compressed (as mentioned, h264, zip, png, jpeg etc.) will usually not yield significant improvements as long as you stick to lossless compression.

[prolemur]

png has integrated lossless compression. If that's already set to maximum, you're unlikely to see any additional compression. Pretty much the only way to decrease filesize in that case is lossy compression such as jpeg. But as said, that means you lose quality. Might be acceptable, might not be, depends on your priorities.

As a general guidelines, pure text files tend to compress very well, files which are already compressed (as mentioned, h264, zip, png, jpeg etc.) will usually not yield significant improvements as long as you stick to lossless compression.

Blasphemy! There's a program called PNG Gauntlet that combines 3 lossless compression tools into one and shrinks pngs.

 

And in the case of doing a batch of 3000 images pnggauntlet will work or just optipng which i believe has a linux cli tool.

[alpenwasser]

Blasphemy! There's a program called PNG Gauntlet that combines 3 lossless compression tools into one and shrinks pngs.

 

And in the case of doing a batch of 3000 images pnggauntlet will work or just optipng which i believe has a linux cli tool.

Oh, sweet, hadn't tried optipng yet. On a few non-optimized ffmpeg screengrabs it seems to yield somewhere around 30% smaller file size, not bad. And yeah, it is easily scriptable via commandline.

As a reference, I also compressed the same pngs with jpeg, quality 90 (using imagemagick). File size went down to between 10% and 20% of the original. Detail preservation was very good, but colors got washed out. I am however definitely no jpeg expert, nor have I had time to fiddle around with this extensively, so maybe the color issue could be fixed, not entirely sure. Just thought I'd add this.

As for toolz like 7zip etc.: Since those are truly lossless (as in: you get the same bits back when you reverse the process, which isn't usually the case with png optimization as far as I'm aware), space gains are mostly negligible with already compressed files in my experience, as mentioned (hell, I even managed to increase filesize slightly by putting some png files into xz ).

[prolemur]

Oh, sweet, hadn't tried optipng yet. On a few non-optimized ffmpeg screengrabs it seems to yield somewhere around 30% smaller file size, not bad. And yeah, it is easily scriptable via commandline.

As a reference, I also compressed the same pngs with jpeg, quality 90 (using imagemagick). File size went down to between 10% and 20% of the original. Detail preservation was very good, but colors got washed out. I am however definitely no jpeg expert, nor have I had time to fiddle around with this extensively, so maybe the color issue could be fixed, not entirely sure. Just thought I'd add this.

As for toolz like 7zip etc.: Since those are truly lossless (as in: you get the same bits back when you reverse the process, which isn't usually the case with png optimization as far as I'm aware), space gains are mostly negligible with already compressed files in my experience, as mentioned (hell, I even managed to increase filesize slightly by putting some png files into xz ).

Ya I'm pretty sure these png optimizations are more complex. Like shrinking amount of colours, and rectangles of same coloured pixels etc. otherwise like you mentioned 7zip would get the same results as optipng