WMA is a compression technology for digital audio formats. The patent was filed by Microsoft in 1999. Faced with the success of MP3 and the enthusiasm of Internet users for this format, Microsoft was forced to respond. As a result, the "Windows Media Audio Codec" was born.
WMA first uses the properties of the ear to reduce the size of the song, then handles the stereo aspect, and finally encodes it with Huffman coding.
All of the aforementioned reduction possibilities can be used, depending on how much space you want to give to a compressed minute of sound, and thus the compression ratio that must be applied.
When encoding audio files in WMA, we will focus on the bit rate rather than the compression ratio.
The bit rate is the number of bits that can be encoded per second.
The relationship is such that the more you compress a song (so that it takes up as little space as possible), the lower bit rate you should choose. Files encoded with a WMA encoder have the extension .wma.
WMA today encodes digital audio from an analog audio signal with a frequency of 8kHz to 48kHz, 8-bit or 16-bit, mono or stereo. Encoding is done at a fixed bit rate. The bit rate can be set to any value between 5 kbps and 192 kbps.
Uncompressed audio files are saved in WAV format by default. This is a file format developed by Microsoft. One minute of audio can range from 644KB (kilobytes) to 27MB (megabytes). The size of this file will vary depending on the sample rate, the type of sound (mono or stereo), and the number of bits used for sampling (8-bit or 16-bit).
Using the codecs described in this manual, the size of the audio file can be greatly reduced.
Waveform file structure :
Various programs, various formats (MP3, OGG ......) Files that are compressed with Compressed files are usually given a value of kbps, which relates to the compression ratio (and thus the loss ratio).
If you do the math, a 44Khz/16bit/stereo WAV is 1375Kbps, so an MP3 compressed to 128Kbps would have a compression ratio of 11 to 1.