Many people want to get the best results with the least cost, which is often difficult to achieve, but there are still people who expect to see such a miracle. Obviously this practice is extreme, can not hold too much expectations or it is best not to believe, this is a crazy scam. I believe that many people probably remember that about 1 year ago someone used to compress 100MB of empty files into 1MB, and then loaded into 1.44MB floppy disk, which attracted countless spit. Recently, I saw such a famous forum in China. Then post: A Russian who compresses a 755MB ARPG game file is only 13.4MB in size! From 755MB to 13.4MB, this is an amazing compression rate! It can be said that a stone has stirred up thousands of waves and immediately attracted the forum. The incredible evaluation of many netizens. Is it really so magical? Is it a scam? According to the download address of the file prompted by the post, the author also curiously started the following test. I witnessed the download of this "magic" file to the local hard disk, opened its properties, and found that it uses the 7.zip self-extracting file format that we usually do not, and the size is only 13.4MB, the compression rate is 1%! Figure 1: The 755MB file compression is actually 13.4MB!? Figure 2: This high and amazing compression ratio! We should know that the latest version of WinRAR already supports the 7.zip file format, and directly extract it with the latest version of WinRAR. Get 3 files, one of which is really 755MB in size. If you have played Sacred, you should know that this is a CD1 image that can be loaded with Deamon. Figure 3: File size The author is not interested in the game itself, but knowing the compression ratio of MDF files is unlikely to be so high. Why is there such a high compression ratio? And uncompressing a file as large as 755MB is not enough. 1 minute! Figure 4: The amazing speed. For this reason, I tried to recompress the extracted 755MB file with the highest compression ratio that WinRAR can achieve. Tip: How to get the highest compression ratio with WinRAR? 1. Use "Best" compression method, run "Options → Settings → Compression Options → Create Default Compression Configuration" in WinRAR to open the "Set Default Compression Options" window, in " Select "Best" in the "Compression" column of the General tab. 2. For compressing a large number of small files or files of the same type, you can check "Create fixed archive file" in the "Archive Options" field, and do not use the recovery record. Uncheck "Setup Recovery" in "Default Settings Compression Options" recording". 3. Use the best dictionary file: In the "Default Settings Compression Options" window, switch to the "Advanced" tab, click the "Compress" button, select the "Dictionary File" size in the "General Compression Bar" of the pop-up window as The largest "4096KB". The author has compressed several times, and the results obtained are between 16MB and 20MB, which is quite close to the compression ratio of 13.4MB, and it takes less than 4 minutes to compress! "God" Figure 5: After we personally compress it, we can get such a high compression ratio. Figure 6: Recompression However, this is not confusing for the author who often uses file compression. It is certain that the original author is against the file source. Made hands and feet. Since there is no original CD of the game, it is impossible to compare the two CDs with the CD comparison software such as CDCheck. So, I thought of using the 16-bit text editor UltraEdit to directly analyze the source code. It took a lot of time to open this 755MB file, and found that the source code of the file is mostly 00! Look, this is another scam of empty file compression! Figure 7: The source code of the file is actually 00! Empty file?!