Because of its huge size, WAV files are difficult to save, back up, and share on the Internet, and it is impossible to enjoy them with you. At this time, you need to compress it. This is also the last "process" of our audio processing.
Audio compression methods are divided into lossless compression and lossy compression. Using lossy compression, you can select the required sampling frequency and bit rate to compress and encode digital audio files. The compressed audio file will be much smaller than the original file, but the quality will be reduced accordingly, and this loss is no Retrievable, even if it is converted to the file format before compression and encoding, the lost part cannot be recovered; while the audio file using lossless compression encoding can maintain the sound quality, and it can be restored to the same quality before compression and encoding after decompression, but The compression ratio is relatively small.
Basically, you don't need to compare lossless compression with lossy compression, they have their own applications. For example, when you need to choose a compression format for your portable digital audio equipment, the large compression ratio of lossy compression is undoubtedly the most attractive; when you want to copy the CD disc to the hard disk, then lossless compression is the best choice . What you need to be clear is just which coding technologies are available for lossless compression and lossy compression, and at the same time understand the advantages and disadvantages of these compression coding technologies, so that you can make wise choices when you need them.
1. Lossy compression coding
The lossy compression of digital audio files has been developed for many years. The once popular formats such as VQF have gradually been out of sight, replaced by OGG, MPC, ACC, and WMA formats, which are as popular as the MP3 format that has remained vigorous. . So which of these lossy compression coding techniques is the best? This requires comprehensive comparisons in terms of compression rate, compression speed, and compressed sound quality. Taking into account the technical characteristics of various compression methods, we also need to compare the compression quality at low bit rate and high bit rate respectively in order to get results with reference value.
The most difficult thing is that the difference between high-quality audio files is quite small. How do we compare them and find the best one? In fact, every compression technology has its own supporters, and it is difficult to have a test result that is unanimously agreed upon. However, here I can provide you with a table based on the test results of Hydrogen Audio, the most famous audio technology forum abroad. The test results are widely recognized on the technical forums, and I believe it will also have a certain reference value for you.
Through Hydrogen Audio’s test, it’s not difficult to find that all the currently popular lossy compression technologies have better compression ratios. The difference between them lies in the difference in quality at low bit rates and high bit rates, and the result of a comprehensive comparison, MPC, QGG, MP3 will be the most attractive digital audio lossy compression technologies. Let's take a look at how to use these three compression technologies to encode our own audio files.
(1) MP3
In the comparison between MPC and OGG, the aura of MP3 is no longer as dazzling as it used to be, but MP3 can achieve better results regardless of low bit rate or high bit rate compression, and it can be played on a variety of portable devices. For most digital audio enthusiasts, MP3 is still the most commonly used lossy compression encoding method for audio files.
Lame is currently the best MP3 encoder, its original auditory mental model combined with VBR , ABR and other encoding modes, allowing you to freely choose the MP3 encoding effect and file size you need.
Lame encoders are mostly used to be called by other software (such as the aforementioned EAC). If you are not going to call it through other audio software, you can directly encode MP3 files in the command line state. But the most convenient way is to download a RazorLame software, this software allows you to set Lame encoding parameters on the graphical interface, which can help you stay away from the nightmare of memorizing Lame parameters , Easily choose the coding scheme. Please check the Lame encoder version that comes with the software before use. If there is a new version, you can copy the new version of Lame encoder to replace Lame.exe in the software directory.
(2) MPC
MPC has the best quality under high-bit-rate encoding, and is the best lossy compression encoding method under high-bit-rate compression that has been unanimously recognized abroad. However, the encoding method is of poor quality at low bit rates, and the number of supported devices and software is quite small. Although it can be expected that it will improve with the increase of users, for now, it is still only suitable for use on your own computer. Used when storing and playing.
Similar to Lame, MusePack Encoder is an encoding program under the command line. Unzip the downloaded compressed package to get an exe program, select "Compression Options" in the "EAC" menu on the main interface of EAC, and use the drop-down menu in the "External Compressor" dialog box to change the "Parameter Transfer Scheme" to "User Custom program", type ".mpc" in the "Use file extension" input box, and then click the "Browse" button next to "Compressor and path" to select the exe file you just downloaded. Clear the check mark on the check box of "Add ID3 Tag" below, and then define the encoding parameters of the MPC encoder in the "Additional Command Line Parameters" input box. For example: --quality 5 --xlevel --artist "%a" --title "%t" --album "%g" --year "%y" --track "%n" --genre "%m "%s, you can use EAC to encode MPC files just like calling Lame.
Like Lame, the MPC encoder also has an external program that you can call in the graphical interface. You can find a program called MuseDrop on the page where you download the encoder, which is currently the most popular MPC encoder. After running the program, you can set various parameters of the encoder by right-clicking with the mouse, and then drag the file to be encoded to the floating window of the program to perform encoding.
(3) OGG
OGG has the best low-bit-rate compression quality, so it may be a good choice to encode voice or other low-demand audio files into OGG format. However, you should be cautious when using this format. Although some manufacturers have begun to try to produce portable audio players that support OGG, this is not the mainstream after all. Set up on the EAC the same as setting up the Lame encoder, the only difference is that the "parameter transfer scheme" selects "Ogg Vorbis encoder", and the encoding program is changed to the downloaded OGG encoder "oggenc.exe". You can also find the plug-ins required by various players on the above website.
2. Lossless compression format
At present, the most popular lossless compression coding technologies include APE, FLAC, PAC, and WV. Lossless compression and lossy compression of digital audio files obviously have different purposes, so the method of distinguishing between good and bad compression technology is also different. Compression rate is the key to selection, and encoding speed and supported platforms are also very important. A table based on the test results of Hydrogen Audio, the most famous audio technology forum abroad, is still provided below for your reference.
Through Hydrogen Audio's test, it is not difficult to find that APE is the best lossless compression coding technology. It is undeniable that FLAC's platform support, high fault tolerance and other advantages are also quite attractive, but it is clear that it cannot replace the position of APE.
(1) APE
APE is a popular digital audio file format. Since the compressed APE file is only about half the size of the original file, and the quality of the decompressed audio file is exactly the same as before compression, there is no loss. Therefore, the APE format suffers Loved by many music lovers, especially for friends who want to transmit audio CDs over the network, APE can help them save a lot of resources.
Set the APE code in EAC.
To encode audio CDs into APE format, you need to install Monkey's Audio, an audio processing software. After installation, in the "Wave" tab that was originally used to set the WAV file in the EAC "Compression Options" dialog box, set the "Wave Format" to "Monkey's Audio Lossless Encoder V3.xx dll", and then select the sample you need format. In this way, you can let EAC automatically call Monkey's Audio and directly encode the data read from the audio CD into a lossless APE format.
In addition, for the WAV files you have saved or the APE files downloaded from the Internet, you can also use Monkey's Audio to compress and decompress. During operation, you only need to select whether to compress or decompress in the "Scheme" menu on Monkey's Audio. Compress, and then add the files that need to be encoded to Monkey's Audio through the "Add File" and "Add Directory" options in the "File" menu, or directly use the mouse to drag the file to the main window of Monkey's Audio, and then click Main "Compress" or "Unzip" on the interface can compress WAV files into APE format or decompress APE files into WAV files. If you copy the "Lame.exe" file of the Lame encoder to the "External" subdirectory of the Monkey's Audio installation directory, and then select Lame from the encoding method, you can also use Monkey's Audio to directly encode the APE file into MP3 format.
Set up an external encoding program in Monkey's Audio.
(2) FLAC
If you often use lossless compression coding technology to process your own CDs or other audio files, some features of FLAC may appeal to you. The compression rate of FLAC is not as high as that of APE, but it also has many advantages. For example, the encoder of this technology supports the most operating systems, and it occupies less system resources during playback, and it can still play normally even when the file point is damaged.
Download the FLAC encoder from http://flac.sourceforge.net/download.html, select "Compression Options" in the "EAC" menu on the EAC main interface, and use the drop-down menu in the "External Compressor" dialog box Change "parameter transfer scheme" to "user-defined scheme", type ".flac" in the "use file extension" input box, and then click the "browse" button next to "compressor and path", select the download just now Exe file. Clear the check mark in the "Add ID3 tag" checkbox below, and then define the encoding parameters of the MPC encoder in the "Additional command line parameters" input box, for example: -V -8 -T "artist=%a" -T "title=%t" -T "album=%g" -T "date=%y" -T "tracknumber=%n" -T "genre=%m" %s, you can call Lame just like , Use EAC to encode FLAC files. Parameters are the main points for controlling encoding. Most of the above suggested parameters are used to define file information. Only "-V -8" is important. FLAC encoding uses "-V" to define the level of encoding, and "-8" is the highest Compression level. In addition, you can find the plug-ins needed for playback on the webpage where you download the encoder.
Due to space limitations, we will not describe the other encoding methods and the conversion between encodings one by one here. You can try to find some more in-depth information, study and explore by yourself. I believe that through this article, you will definitely find that audio editing has so much fun, maybe it will help you become a master of computer music production soon.
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