Dolby Pro Logic

Dolby Pro Logic is a surround sound processing technology developed by Dolby Laboratories, designed to decode soundtracks encoded with Dolby Surround. Dolby Stereo was originally developed by Dolby in 1976 for analog cinema sound systems. The format was adapted for home use in 1982 as Dolby Surround when HiFi capable consumer VCRs were introduced; it was then replaced by the newer and improved Pro-Logic system in 1987. However, the term "Dolby Surround" is still used to describe the encoding technology or matrix-encoded soundtrack, whereas Pro Logic refers to the decoding technology and processor. It is the domestic equivalent of the theatrical Dolby Stereo technology used in movie cinemas in the 1970s and '80s. The two technologies are mostly identical but a change in marketing was needed so as not to confuse cinema stereo which is at least four channels of audio with home stereo which is only two. Thus Dolby Pro Logic is the consumer version of theatrical Dolby Stereo.

Dolby Surround/Pro Logic is based on basic matrix technology. When a Dolby Surround soundtrack is created, four channels of sound are matrix-encoded into an ordinary stereo (two channel) sound track. The centre channel is encoded by placing it equally in the left and right channels; the rear channel is encoded using phase shift techniques, typically an out of phase stereo mixdown. A Pro Logic decoder/processor "unfolds" the sound into the original 4.0 surround—left and right, center, and a single limited frequency-range (7 kHz low-pass filtered) mono rear channel—while systems lacking the decoder play back the audio as standard stereo.

Logic Pro

Logic Pro is a digital audio workstation and Musical Instrument Digital Interface MIDI sequencer software application for the Mac OS X platform. Originally created by German software developer C-Lab, later Emagic. Logic Pro became an Apple product when Apple bought Emagic in 2002.

A consumer-level version based on the same interface and audio engine but with reduced features, called Logic Express, was also available at a reduced cost. Apple's GarageBand, another application using Logic’s audio engine, is bundled in iLife, a suite of software which comes included on any new Macintosh computer. On December 8, 2011, the boxed version of Logic Pro was discontinued, along with Logic Express, and Logic Pro is now only available through the Apple App Store at the price of $199 in the United States, which used to be the price of Logic Express.

Features

Logic Pro provides software instruments, audio effects and recording facilities for music synthesis. It also supports Apple Loops – royalty-free professionally recorded instrument loops. Logic Pro and Express share many functions and the same interface. Logic Express is limited to two-channel stereo mixdown, while Logic Pro can handle multichannel surround sound. Both can handle up to 255 audio tracks, depending on system performance (CPU and hard disk throughput and seek time). Logic Pro can work with MIDI keyboards and control surfaces for input and processing, and for MIDI output. It features real-time scoring in musical notation, supporting guitar tablature, chord abbreviations and drum notation.

Logic

Logic (from the Ancient Greek: λογική, logike) is the branch of philosophy concerned with the use and study of valid reasoning. The study of logic also features prominently in mathematics and computer science.

Logic was studied in several ancient civilizations, including Greece, India, and China. In the West, logic was established as a formal discipline by Aristotle, who gave it a fundamental place in philosophy. The study of logic was part of the classical trivium, which also included grammar and rhetoric. Logic was further extended by Al-Farabi who categorized it into two separate groups (idea and proof). Later, Avicenna revived the study of logic and developed relationship between temporalis and the implication. In the East, logic was developed by Hindus, Buddhists and Jains.

Logic is often divided into three parts: inductive reasoning, abductive reasoning, and deductive reasoning.

The study of logic

The concept of logical form is central to logic. The validity of an argument is determined by its logical form, not by its content. Traditional Aristotelian syllogistic logic and modern symbolic logic are examples of formal logic.