MP3 audio technical features
Sampling Frequency: 44.1 KHz
Bit rate: from 192 Kbit/s to 320 Kbit/s
Number of channels: 2 (stereo)
Resolution: 16 bit
WHAT IS AN MP3 AUDIO FORMAT?
An Mp3 file is a compressed audio file. The compression is given by an algorithm called MPEG 1 Layer III which can reach a compression ratio up to 1/12 over the original. Such compression involves a slight quality loss, imperceptible to the human ear. The Mp3 audio format is the outcome of the need to broadcast audio data saving on the bandwidth occupied, throughout the whole electronic network.
WHAT IS THE SAMPLING FREQUENCY?
The sampling frequency is the expression in Hertz of the number of times per second taken from a continuous analogue signal to make it a discrete digital signal. In other words, it is the parameter used in order to translate a natural phenomenon – understandable for humans – into a numerical representation – understandable and usable for a PC and all those devices the operation of which depends on the bit.
WHAT IS THE BITRATE?
“Bit rate” means the number of bit that each second of sound uses and it is identified with Kbit/s (thousands of bit per second or 1000 bit/s). The input audio signal of a CD has a bit rate of 1411,2 Kbit/s; and Mp3 with CD quality has a bit rate of only 128 Kbit/s. For example, if in 1 second there is 128 Kbit/s of essential data, these will be allocate in the second of a encoded sound, but if there were more data, many basic information would be lost by choosing an encoded at 128 Kbit: in this case would the convenient increase the encoded bit rate from the standard 64 Kbit/s per channel (indeed 128 Kbit/s) to higher resolution up to 160Kbit/s per channel (320 Kbit/s).
WHAT IS THE NUMBER OF CHANNELS?
Shows the working methods: mono, dual-mono, stereo, joint-stereo.
WHAT IS THE RESOLUTION?
The resolution of a analog to digital converter shows the number of discrete data that can produce. It is usually exoressed in Bit. For Example, a converter that encodes an analogue input on 256 descreet levels has a 8 bit resolution, being 28 = 256.