What is lossless sound quality?
What is the sound quality of the music we usually listen to?
▲ Both AAC and MP3 are destructive compression, while FLAC and ALAC are lossless compression
Before we go into the details, let’s talk about what is called lossless sound quality; From the author’s concept and cognition, the so-called lossless sound quality is a relative word rather than an absolute word. The main source is the relative word born due to the emergence of the MP3 music compression format. ; After the music industry entered the digital format, digital music files were generally recorded through PCM encoding, and WAVE files were generally used on CDs. The time and space situation of MP3 was Due to the fact that the capacity of the hard disk was generally not large at that time, in order to be limited in the limited space, a large amount of music data is stored in the storage space and you may need to compress the files. .
The reason why MP3 cannot be called a lossless format is because its essence is to compress the original WAVE file with a limited bit rate by combining concepts such as the psychology of sound. In bitrate compression mode, compared to the original WAVE file, the bitrate is at least 1:4 to 12:1. The higher the bitrate, the greater the amount of information retained . For example, AAC format also uses similar audio psychology for compression, but the efficiency is better than MP3. Therefore, the lossless sound quality of most streaming platforms today is mostly AAC as the mainstream.
▲ Although the waveform of digital music in PCM format will appear jagged, but as the sampling rate increases, it will be closer to the analog arc curve
The principle of these audio compression methods is to preserve places that are easily heard by the human ear as much as possible. In conventional fixed bit rate (CBR) mode, the audible data in the audio is removed and is easier for the human ear to hear. The more information that is withheld, the less information that is withheld when the part is inaudible. As the complexity of the sound increases, the degree of deterioration in sound quality becomes more apparent. For example, when listening to pure voice Performances and performances combined with background music, pure compressed music for vocals, sounds less degraded than the original file.
As for the lossless sound quality offered by the current streaming platform, there are many formats, but in fact, strictly speaking, these formats, including flac and ALAC, belong to lossless compression (non-destructive data compression) in place of lossless sound quality in a strict sense. The performance is almost the same as WAVE, but the file size is small, the decoding speed is fast, and at the same time, it can be used in streaming services. Therefore, it is also the representative format of lossless sound quality enters the era of non-optical disc media, and it is also the current music streaming service.
Also, Tidal’s MQA is a more controversial format, because although MQA is a generalized lossless audio reduction, it focuses on making high quality music files higher than CD quality to be similar to files. CD-quality flac. original high-quality sound format, but the point of controversy is whether the higher compression ratio can maintain the same real listening experience as the original high-quality sound quality has been controversial, and MQA requires a specific device to perform the hardware decoding. many devices are still only able to do MQA decoding through software.
