Converter file midi mp3

EM's ABCs of DTM in POE (Plain Old English).

This month we're going to wade through the morass of acronyms and abbreviations you need to know to make sense of articles and ads aimed at desktop musicians. A truly comprehensive glossary would fill a book, so we've focused on common, yet commonly misunderstood, alphanumeric combinations from the audio, computer, and Internet vernaculars. To dig deeper, check out the excellent audio reference at Rane's Web site (www.rane.com/digi-dic.htm), E-mu's Glossary of Electronic Music Terms (www.emu.com/support/free_expert/glossary.html), or the PC Technology Guide (www.pctechguide.com).

Our goal is to help you attain a practical understanding of basic concepts and terminology, so if you're looking for obscure details to impress the Ph.D.s at your next MENSA soiree, you're out of luck. Pragmatic readers, read on.

AC-3 (also Dolby Digital). A perceptual-encoding format that compresses six channels of digital audio in the now common "5.1" surround setup. The "5" refers to five full-range channels- left, center, right, left rear, and right rear-and the ".1" refers to the LFE (low-frequency effects) channel. The 5.1 surround standard for DVD-Audio does not use AC-3. Instead, it uses Meridian Lossless Packing (MLP) to compress six full-range channels of 24bit, 96 kHz audio without data loss.

ADC (also A/D converter). Analog-to-digital converter. A circuit that translates analog audio into digital format. In simple terms, an ADC measures (samples) the amplitude of a waveform 44,100 times per second and describes it as a 16-bit binary number for "CD quality" audio. First, however, it must filter out the frequencies above 22.1 kHz to avoid the distortion predicted by the Nyquist Theorem, which is beyond the scope of this month's column.

ADSL. Asymmetric digital subscriber line. A very high-speed Internet connection that's called "asymmetric" because it's capable of much faster download speeds than upload speeds. ADSL is faster than ISDN but cheaper than T-1.

AES/EBU. Audio Engineering Society/European Broadcasting Union. A 2-channel digital audio transfer protocol. AES/ EBU is transmitted on balanced XLR connections. Similar in format to S/PDIF, it was intended from the start to be the "pro" format and was never saddled with copy protection (see S/PDIF and SCMS).

AGP. Accelerated graphics port. A special type of interface for PC graphics cards. In a musical context, one advantage of AGP cards is that they don't interfere with audio transfer on the PCI bus, as some PCI graphics cards have been known to do.

AIFF. Audio interchange file format. An uncompressed digital audio file format common on Macs (see WAV).

ASIO. Audio Stream Input/Output. Steinberg's driver protocol for communication between audio hardware and software. It bypasses the operating system's standard multimedia audio drivers to provide multichannel support, improve audio timing, and reduce monitoring latency. The recently released version 2.0 adds sample-accurate positioning, decreased latency, and the ability for multiple applications to share hardware. Although ASIO is not a universal standard, it has been implemented by quite a few major hardware and software vendors (see EASI).

BNC. Bayonet Neill-Concelman. A locking bayonet-style connector used with coaxial cable (see Fig. 1).

DAC (also D/A converter). Digital-to-analog converter. A circuit that translates digital audio information into smoother analog waveforms. A DAC has special filters that interpolate the shape of the waveform between samples to restore its continuously variable analog shape from the disjunct "stepped" shape of its digital representation.

DIN. Deutsches Institut fur Normung. A German standards organization. The most common DIN standard found in the United States is the ubiquitous five pin DIN plug used for MIDI connections (see Fig. 1).

DLS. Downloadable sound (or sample). A standard for transferring sample data. To overcome the widely varying quality of General MIDI (GM) playback devices the DLS specification was developed, allowing for some or all of a sound set t be transmitted along with a MIDI file.

DSP. Digital signal processing (or processor). A type of computation optimized for manipulating audio signals From relatively simple processes such as level changes to complex operations such as vocoding, digital signal processing is the fundamental technology of the desktop music revolution. While DSP is by nature a software process, audio hardware is increasingly incorporating DSP chips. Like a math or graphics coprocessor, these chips are specially designed to perform a limited type of computation efficiently.

DVD. Digital Versatile Disc (originally) Digital Video Disc). Similar to the CD format but capable of significantly higher data density. The additional storage allows for high-resolution digital video and multichannel audio. Recordable (DVD-RAM/DVD-R), rewritable (DVD-RW), and audio-only (DVD-A) variants have been defined.

EASI. Enhanced Audio Streaming Interface. Emagic's multichannel alternative to stock multimedia audio drivers. EASI provides a direct and consistent way for audio software and hardware to communicate, resulting in improved audio timing and reduced latency. Introduced in May 1999, it hasn't yet achieved widespread support (see ASIO).

EIDE. Enhanced integrated device (or intelligent drive) electronics. Until recently, the most common disk drive interface on the PC platform. While capable of decent throughput, it was limited to four devices, two of which were commonly the floppy drive and CD drive. Also called ATA-2, its now common successor is UltraATA or UltraDMA, sometimes with a -33 or -66 to specify its bus speed.

FTP. File transfer protocol. A standard for sending and receiving files on the Internet.

HTML. Hyper Text Markup Language. The basic formatting language for Web pages. It uses simple tags to designate format attributes and allows for "hypertext" links, which allow users to associate a segment of text with another page or other object (see SGML and XML).

HTTP. HyperText transfer protocol. A standard for transferring hypertext files on the Internet. In simpler terms, the behind-the-scenes stuff that goes on every time you expect a Web page to appear in your browser (see HTML).

IEEE-1394. Institute of Electrical and Electronics Engineers standard 1394 (also known as FireWire or Serial SCSI). A very high-speed standard for attaching external devices. It supports the daisy-chaining of multiple devices, making it ideal for external audio disk drives. It's common on Macs but hasn't yet achieved the same popularity for PCs.

ISDN. Integrated services digital network. A high-speed Internet connection using fiber-optic lines (see T-1 and ADSL).

LTC. Longitudinal time code. A common implementation of time code in audio, in which the time code signal is "striped" (recorded) on an analog audio track. Most current digital audio gear is capable of sending and receiving time code through a dedicated connection, rendering LTC striping unnecessary (see SMPTE).

MDM. Modular digital multitrack. A digital tape recorder designed to link easily with others of its type to build a multitrack recording setup eight tracks at a time. MDMs, such as the Alesis ADAT and Tascam DA-88, brought digital multitrack recording within the reach of personal studios, enabling musicians to add tracks as their finances allowed or their needs dictated (see Fig. 2).

MMC. MIDI Machine Control. A set of MIDI commands enabling a device to control other devices. MMC includes such commands as Start, Stop, and Locate but does not provide synchronization information (see MTC).

MMX. Multimedia extensions. A set of 57 instructions incorporated into the third generation of Intel's Pentium chips, designed to facilitate processing of audio and video. Pentium/MMX chips also featured more Level-1 cache and other enhancements, resulting in better performance even for applications that didn't specifically use the new instructions.

MO. Magneto-optical. A format for long-term data storage. Magneto-optical disks represent a compromise between the stability and longevity of optical storage, such as CD and DVD, and the speed and rewritability of magnetic storage, such as hard disk and tape. Newer MO technology approaches the speed of modern hard disks, making it viable for digital recording.

MOD. Module. A type of file containing sampled sounds and a set of musical instructions for playing a song using those sounds exclusively.