To get file size 24, the following length should be cut from file size 20:
1- 1mm.
2- 2mm. ***
3- 3mm.
4- 4mm.
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To make a file occupy less, there are various compression formats, as well as programs. Compression has been with us for almost 30 years, and allows a file to take up to several times less than its original size. Thanks to this compression it has been possible to store and transmit more information in less time, especially in Internet connections whose speeds are even slow today.
Compression is used in all types of files, and there are two types: lossless compression and lossy compression, depending on the format and type of compression we are talking about. We will see in depth what each of them consists of.
Lossless compression:
This type of compression basically works by eliminating redundancy. That is, if we have BBBEEEEETTT, the compressor program will interpret B3E5T3, reducing the repetition and the space that occupies the same amount of information. In this way, the information that is repeated is replaced by instructions that tell the computer how many times the identical data is repeated. This in programming language cannot be done as such, but it is a way of representing the process that these programs follow, and there are other more complex processes of size reduction.
Due to the operation of this system, it is logical that computers with more powerful processors compress files faster, since they process more instructions per second, while it is necessary to have high-speed drives. A file will compress faster in an SSD than in an HDD.
This type of compression is used by formats such as RAR or ZIP. That is why the program has the key to unzip and reset the code as it was at the beginning. This ‘reinterpretation’ is the reason why we cannot open a compressed file directly without decompressing it before.
Lossless compression is also widely used in video games. When we download a Steam game, it can take up to 30 GB, but only 7 to 10 GB are downloaded. Or a 60 GB game usually has a download of 25 or 30 GB. With the DVDs, installations could take hours due to the slow reading speed of these units along with the long decompression processes.
Another format that benefits greatly from this type of compression is the PNG. This image format has no losses, so if we use it for a photograph the final space it will occupy will be larger. However, if we use images with many uniform parts, we can have a file that would occupy less than in JPG format, because PNG uses redundancy to reduce the size of the files, in addition to the fact that PNG photos can be saved without background.
In the two images below we have on the left a PNG image that occupies 6 KB. The second is JPEG at 100% compression and 35 KB in size. The third is 30% JPEG and 15 KB in size, and finally JPEG at 1% compression with 11 KB, giving a compression ratio of 100: 1.
Loss compression (lossy compression):
Unlike lossless compression, lossy compression does leave information along the way, and does not allow you to rebuild the original file from the compressed file. This compression format is used in all types of audiovisual format, such as movies, series, music, images, and so on.
In the case of MP3 files, what happens is that the compression process eliminates frequencies that are above or below what the human ear can hear, as well as the amount of information the song contains. Therefore, when a song is compressed too much, it starts to sound flat and of poor quality.
In the case of the video, we have very clear examples with YouTube videos, which occupy much less than the original videos, sacrificing quality along the way to work according to most slower connections. To compress the videos, as in the case of photographs with JPEG formats, pixels close to each other are associated to take advantage of redundancy as much as possible.
--------------------------
To make a file occupy less, there are various compression formats, as well as programs. Compression has been with us for almost 30 years, and allows a file to take up to several times less than its original size. Thanks to this compression it has been possible to store and transmit more information in less time, especially in Internet connections whose speeds are even slow today.
Compression is used in all types of files, and there are two types: lossless compression and lossy compression, depending on the format and type of compression we are talking about. We will see in depth what each of them consists of.
Lossless compression:
This type of compression basically works by eliminating redundancy. That is, if we have BBBEEEEETTT, the compressor program will interpret B3E5T3, reducing the repetition and the space that occupies the same amount of information. In this way, the information that is repeated is replaced by instructions that tell the computer how many times the identical data is repeated. This in programming language cannot be done as such, but it is a way of representing the process that these programs follow, and there are other more complex processes of size reduction.
Due to the operation of this system, it is logical that computers with more powerful processors compress files faster, since they process more instructions per second, while it is necessary to have high-speed drives. A file will compress faster in an SSD than in an HDD.
This type of compression is used by formats such as RAR or ZIP. That is why the program has the key to unzip and reset the code as it was at the beginning. This ‘reinterpretation’ is the reason why we cannot open a compressed file directly without decompressing it before.
Lossless compression is also widely used in video games. When we download a Steam game, it can take up to 30 GB, but only 7 to 10 GB are downloaded. Or a 60 GB game usually has a download of 25 or 30 GB. With the DVDs, installations could take hours due to the slow reading speed of these units along with the long decompression processes.
Another format that benefits greatly from this type of compression is the PNG. This image format has no losses, so if we use it for a photograph the final space it will occupy will be larger. However, if we use images with many uniform parts, we can have a file that would occupy less than in JPG format, because PNG uses redundancy to reduce the size of the files, in addition to the fact that PNG photos can be saved without background.
In the two images below we have on the left a PNG image that occupies 6 KB. The second is JPEG at 100% compression and 35 KB in size. The third is 30% JPEG and 15 KB in size, and finally JPEG at 1% compression with 11 KB, giving a compression ratio of 100: 1.
Loss compression (lossy compression):
Unlike lossless compression, lossy compression does leave information along the way, and does not allow you to rebuild the original file from the compressed file. This compression format is used in all types of audiovisual format, such as movies, series, music, images, and so on.
In the case of MP3 files, what happens is that the compression process eliminates frequencies that are above or below what the human ear can hear, as well as the amount of information the song contains. Therefore, when a song is compressed too much, it starts to sound flat and of poor quality.
In the case of the video, we have very clear examples with YouTube videos, which occupy much less than the original videos, sacrificing quality along the way to work according to most slower connections. To compress the videos, as in the case of photographs with JPEG formats, pixels close to each other are associated to take advantage of redundancy as much as possible.
The compression of multimedia files is very practical, since there are compression factors that may not generate differences that are noticeable by humans. For example, a 50 MB FLAC file can be compressed into a 10 MB MP3, and the difference is virtually imperceptible, or a video file can be compressed up to 50 times without noticing loss. The same usually happens with JPEG if it is not abused too much.
The case of JPEGs compressed in excess is in the photos that circulate ad infinitum on WhatsApp, which are compressed every time they are forwarded. In other platforms such as Telegram you can send the file, which is associated with your link in the cloud, so it is not recompressed.
Because there is loss of information, this type of compression would not work for example with a text file, since it would not be possible to recover the original information.
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