Most users know that sometimes to reduce the size of the source files in order to increase the convenience of storing or sending them, for example, compression is used by e-mail. However, for some reason, in this case, the association occurs only with archiver applications, and other data compression techniques are not taken into account. Next, we will consider what the degree of file compression depends on, as an example of several of the most common situations.
What is meant by file compression ratio?
Let's start with theoretical questions. What is the file compression ratio? Based on the simplest interpretations of this term, it means the ratio of the size of the final (compressed) object to the initial volume. However, this explanation to a greater extent may relate exclusively to archival data, since it does not at all affect some issues related to changing the multimedia format, where compression is also very common. In general, it is impossible to say that the degree of file compression depends on only one feature. In this case, the role is played by the type of object, the programs used to compress the data, and the speed of the compression process. Next, we briefly dwell on some important aspects that may affect the final result of reducing the size of the source data.
The degree of file compression depends only on the type of file: is this really so?
Yes, indeed, the type of data being compressed has a rather large effect on reducing the final file size, and not all formats can be subjected to such procedures. This can be explained by the example of MP3 audio files , which are initially compressed in their own right.
When you try to pack such data into an archive, it is almost impossible to achieve a significant reduction in size. The same goes for the WAV format. However, if you do not compress, but transcode from WAV to MP3, the size can be reduced by a factor of ten or more. Many users immediately start from the fact that the degree of file compression depends on the initial and final format. This is not entirely true, since the applied transcoding algorithm also plays an important role, which will be discussed separately. In the meantime, focus on the use of archivers.
What determines the degree of file compression when packing into an archive?
To initially understand the essence of compression of this type, for simplicity of explanation, we give an example of the most common WinRAR archiver. We don’t touch the types of packed data, but we will focus on the tools of the application itself.
First, you should pay attention to the final format of the archive, as well as to the packaging method used. It is clear that in this case the degree of file compression by the archiving program depends on the preferred technique. With the high-speed method, compression will be minimal, but when setting the maximum compression ratio, the size will be reduced more significantly, and it will take longer.
If, as applied to archivers, file formats are considered, text documents of any formats can be selected from the most compressed ones.
Some executable files of the EXE format are relatively well compressed (with the standard compression method, you can achieve a reduction in size by more than half). The most, as already mentioned, incompressible are multimedia objects. And if the pictures can be reduced in size at least somehow, such actions do not work with audio and video without changing the initial format, and archivers have nothing to do with it.
Types of compression graphics, video and audio
In relation to multimedia, two main types of compression are distinguished: with lossy quality and lossless. And in this case, the degree of file compression depends on the compression technology used.
In the first case, the compression is maximum, in the second it can vary, which is affected by the used set of codecs and the final container format. So, for example, the same AVI file can be just a container containing completely different data types and with varying degrees of compression. Because of this, by the way, sometimes there may be problems with playing videos on household players.
In general, when it comes to multimedia, you need to clearly understand that it is almost impossible to achieve the maximum reduction in the size of the source file of any format without a significant loss of quality, despite the technology for removing excessive content (for example, for graphics or video, this only works in the case of immutable scenes). In the case of audio, the bitrate is reduced and certain frequencies are cut out. An ordinary user may not feel the difference, but a professional with a subtle ear will immediately say what is missing.
The most common programs for all occasions
On what the degree of file compression depends, a little figured out. Now a few words should be said about the software products used. Among archivers, the most common can be called WinRAR, WinZIP and 7-Zip.
As for multimedia compression, in the simplest case, you can use special converter applications that work on the principle of transcoding the source material into another format in order to reduce the file size.
Brief Summary
Summing up a peculiar result, it can be noted that the degree of compression of the file by the archiver depends on several factors, and most often on the type of data being compressed, the software used and compression methods (usually, Huffman and Lempel-Ziv algorithms that work in pairs are used). In the case of multimedia content, the situation is almost the same, however, the prevailing position is the conversion of the format from one to another.