Data Rate And Audio Data File Format

- Jun 13, 2018-

The data rate is bits per second, which is directly related to the real-time transmission of information in the computer, and its total data volume is directly related to the storage space of the computer. Therefore, the data rate is the basic technical parameter to be mastered by the computer. The uncompressed digital audio data rate can be calculated as follows:

Data rate = sampling frequency (Hz) × quantization bit (bit) × number of channels (bit/s)

The data generated with digital audio is generally stored in the WAVE file format, with ".WAV" as the file extension. The WAV file consists of three parts: the file header, which indicates the total bytes of the WAVE file, the file structure, and the data; the digitizing parameters such as the sampling rate, the number of channels, the encoding algorithm, and so on; and finally, the actual waveform data. The WAVE format is a universal digital audio standard under Windows. You can play WAV files using Windows' own media player. Although the application of MP3 is very promising, but at present there is a need for special playback software, of which the more mature is RealPlayer.

In order to store digital music, only high-capacity storage systems can be developed. In the late 1970s, finally developed an optical disk storage system that uses laser read and write. Because this type of disc is much smaller and lighter than a compact disc, it is called a compact disc (CD), which means a compact disc. A CD has a capacity of about 650MB, and it can only store 61.4 minutes of music.

Pure music CDs are also commonly referred to as CD-DA. DA is an abbreviation of Digital Audio. Its technical indicators are defined by a so-called "red book." This red book was published by Philips and Sony in 1980. Later, in 1987, the International Electrotechnical Commission (IEC) established the IEC 908 standard. Based on these criteria, the music time that a CD can store can be calculated more accurately. In fact, in the CD disc is in units of sectors, each sector contains 2352 bytes. There are a total of 345k sectors. Therefore, the total number of bytes is 345kx2352=811440kB. 76.92 minutes of stereo music can be stored. There is also a method to calculate the playing time. When the CD is playing, the playing speed is 75 sectors per second. A CD has 345k sectors, so the playback time is 345k/75=4600 seconds = 76 minutes and 40 seconds. The results of the two methods are the same.

 

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