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MySQL (beta) at CHEARSdotinfo.co.uk Digital Audio Recording versus MIDI Recording When a MIDI sequencer records a human performance on a keyboard, only a relatively small amount of control information is actually transmitted from the keyboard to the sequencer. MIDI does not transmit the sampled waveform of the sound. For example, a 48-track MIDI sequence recorder program running on a small computer might cost less than $100 and handle 4000 bytes/second. In contrast, a 48-track digital tape recorder costs tens of thousands of dollars and handles more than 4.6 Mbytes of audio information per second over a thousand times the data rate of MIDI. The advantage of a digital audio recording is that it can capture any sound that can be recorded by a microphone, including the human voice. MIDI sequence recording is limited to recording control signals that indicate the start, end, pitch, and amplitude of a series of note events. If you plug the MIDI cable from the sequencer into a synthesizer that is not the same as the synthesizer on which the original sequence was played, the resulting sound may change radically.
MySQL (beta) at CHEARSdotinfo.co.uk Analog Representations of Sound Analog: continuous-time representation of the sound stored in the record. Fundamental limitations associated with analog recording：the copy is never as good as the original. Reproducing digital sound involves converting a string of numbers into one of the time-varying changes that we have been discussing. Digital Representations of Sound Analog-to-digital Conversion Rather than the continuous-time signals of the analog world, a digital recorder handles discrete-time signals. A microphone transduces air pressure variations into electrical voltages, and the voltages are passed through a wire to the analog-to-digital converter, commonly abbreviated ADC (pronounced "A D C"). This device converts the voltages into a string of binary numbers at each period of the sample clock. The binary numbers are stored in a digital recording mediuma type of memory. Binary numbers: In contrast to decimal (or base ten) numbers, which use the ten digits 0 9, binary (or base two) numbers use only two digits, 0 and 1. The term bit is an abbreviation of binary digit. On a digital audio tape recorder, a 1 might be represented by a positive magnetic charge, while a 0 is indicated by the absence of such a charge. This is different from an analog tape recording, in which the signal is represented as a continuously varying charge. Digital-to-analog Conversion, abbreviated DAC (pronounced "dack"). In summary, we can change a sound in the air into a string of binary numbers that can be stored digitally. The central component in this conversion process is the ADC. When we want to hear the sound again, a DAC can change those numbers back into sound.
