Audio Basics
Common audio formats
Common WAV files use uncompressed PCM encoding, which makes the quality of WAV files extremely high and the volume surprisingly high. For PCM WAV, I’m afraid only lossless compressed audio can have the same quality. What we usually see mp3, the quality of wma (excluding wmalossless) and wav is much worse! You can see this on the spectrum, even if you compare 320kbps mp3 to wav, it will be inferior!
MP3 audio format
Introduction to the MP3 audio format
The full name of MP3 is Moving Picture Experts Group Audio Layer III. One of the most popular lossy compression and digital audio coding formats today, it is designed to greatly reduce the amount of audio data, while for most users the playback quality is not significantly different from the original. original uncompressed audio. It was invented and standardized in 1991 by a group of engineers from the Fraunhofer-Gesellschaft research organization in Erlangen, Germany.
The so-called MP3 also refers to the audio part in the MPEG standard, ie the MPEG audio layer. It is divided into 3 layers according to the difference of compression quality and encoding processing, corresponding to *.mp1/ *.mp2/ *.mp3 these 3 types of sound files respectively. It should be remembered that compression of MPEG audio files is lossy compression. MPEG3 audio encoding has a high compression ratio of 10:1~12:1, while basically keeping the lower part of the audio undistorted, but at the expense of sound files. the quality of high-frequency audio from 12 KHz to 16 KHz is changed by file size. Music files of the same length are stored in the *.mp3 format, usually only *.wav1/10 of the file, and the sound quality is lower than the . files in CD format or WAV format. Due to its small file size and good sound quality, no other audio format can match it at the beginning of its existence, which provides good conditions for the development of the *.mp3 format.
Characteristics of the MP3 audio format
MP3 is a data compression format.
It discards pulse code modulation (PCM) audio data that is not important to the human ear (similar to how JPEG is lossy image compression), resulting in a much smaller file size.
MP3 audio can be compressed at different bit rates, providing a variety of trade-offs between data size and sound quality. The MP3 format uses a hybrid conversion mechanism to convert time domain signals to frequency domain signals.
32-band polyphase integrator filter (PQF).
Modified discrete cosine filter of 36 or 12 taps (MDCT); each subband size can be independently selected between 0…1 and 2…31.
MP3 not only has extensive client software support, but also has a lot of hardware support, such as portable media players (referring to MP3 players), DVD and CD players.
