Compressor programs look for areas where they can minimise the amount of 'wasted' space, for example if you have 7 files of the same type they will all have the same header so you can store one copy of the header and cut it from the others.
Other algorithms look at the actual file contents and look for patterns, things that can be reduced. There is no guarantee that the program will be able tor educe the size f every single file - it doesn't work like that. If your files aren't getting smaller then you have one of the few files that can't be made any smaller.
For example putting audio tracks in ZIP files will not always reduce its size, many audio formats can't be compressed any further than they already are, same goes for video. If you have a compressed archive with a video in it at 8.5 GB that expands out to 280 GB then the format of the video at 280 GB is redundant.
Take .wav files and .mp3 files. A .wav is a pure wave form audio file and is massive. A .mp3 is a compressed version that removes a lot of detail that is unnoticeable to you. The audible difference is negligible because the information removed is data that can be dropped. Same goes with Video, the visual difference of video can be unrecognizable between two videos, one double the size of the other. People like you need to get over this hang up that a larger file size means better quality - this is not true.
· 9 years ago