What is bit rate? Knowledge of the MP3 audio format. Part 3
ABR (average bit rate, average bit rate)
ABR is an interpolation parameter of VBR. It is an encoding method developed on the basis of VBR. This encoding mode is created for the large file size of CBR and the variable size of files generated by VBR. ABR is within the specified file size, with every 50 frames (about 1 second for 30 frames) as a segment, low-frequency and insensitive frequencies use relatively low traffic, high-frequency and large dynamic performance use high traffic , which can be used as VBR and CBR A compromise.
3, WMA (Windows Media Audio, Windows Media Audio)
WMA is Microsoft’s media compression method. It is a technology that only compresses audio data in Microsoft Windows media technology, and the sound quality is similar to MP3. From the perspective of compression rate, under the condition of encoding rate less than 192kbps, WMA can get lower volume than MP3 file in the same sound quality condition, even half (but when the encoding rate encoding is higher than 192 kbps, the general thinking is that MP3 has better sound quality than WMA). According to Microsoft’s official announcement, the WMA format is extremely protectable and can even limit the playback machine, playback time and number of playback, and has considerable copyright protection capabilities.
4. WAV (sound resource file)
WAV is a kind of waveform file, which directly records sound waveform without compression. The audio track captured from CD is wav file, which is large in size.
5. AMICD
ADPCM is short for Adaptive Differential Pulse Code Modulation, the full name is Adaptive Differential Pulse Code, and it is also a lossy compressed digital audio format. This format is commonly used in MP3 Walkman recordings. It can provide a very high compression ratio. Generally, a 128MB MP3 Walkman can record up to 16 hours of recording, but the pursuit of long recording time comes at the expense of sound quality.
6. AAC (Advanced Audio Coding, Advanced Audio Coding)
AAC is a lossy compressed audio format jointly developed by the Fraunhofer Institute (creator of the MP3 format), Dolby Laboratory (DOLBY), and AT&T (American Telephone and Telegraph Company), and is part of the MPEG-2 specification. Compared with MP3, AAC adds features that MP3 audio formats do not have, such as perfect stereo sound playback, streaming effect sound scanning, multimedia control, and noise reduction optimization, and also supports more sampling rates and bit rates, and multiple languages. compatibility and higher decoding efficiency. In conclusion, AAC can provide better sound quality with 30% smaller file size than MP3 files.
However, in the current MP3 Walkman, only a few have applied this format.
