AVCHD is a file-based format for the digital recording and playback of high-definition video. Developed jointly by Sony and Panasonic, the format was introduced in 2006 for use in high definition consumer camcorders. Favorable comparisons of AVCHD against HDV and XDCAM EX solidified perception of AVCHD as a format acceptable for professional use. Both Panasonic and Sony released the first consumer AVCHD camcorders in spring of 2007. Panasonic released the first AVCHD camcorder aimed at the professional market in 2008, though it was nothing more than the FLASH card consumer model rebadged with a different model number. In 2011 the AVCHD specification was amended to include 1080-line 50-frame/s and 60-frame/s modes and stereoscopic video; the new video modes require double the data rate of previous modes. AVCHD and its logo are trademarks of Panasonic. For video compression, AVCHD uses the MPEG-4 AVC/H.264 standard, supporting a variety of standard, high definition, stereoscopic video resolutions.
For audio compression, it uncompressed linear PCM audio. Stereo and multichannel surround are both supported. Aside from recorded audio and video, AVCHD includes many user-friendly features to improve media presentation: menu navigation, simple slide shows and subtitles; the menu navigation system is similar to DVD-video, allowing access to individual videos from a common intro screen. Slide shows are prepared from a sequence of AVC still frames, can be accompanied by a background audio track. Subtitles are used in some camcorders to timestamp the recordings. Audio, video and ancillary streams are multiplexed into an MPEG transport stream and stored on media as binary files. Memory cards and HDDs use the FAT file system, while optical discs employ UDF or ISO9660. At the file system level, the structure of AVCHD is derived from the Blu-ray Disc specification, but is not identical to it. In particular, it uses legacy "8.3" file naming convention, while Blu-ray Discs utilize long filenames. Another difference is location of the BDMV directory.
On a DVD-based camcorder the BDMV directory is placed at the root level, as on the Blu-ray Disc. On the HDD-based Canon HG10 camcorder the BDMV directory is located in the AVCHD directory, placed at the root level. Solid-state Panasonic and Canon camcorders nest the AVCHD directory inside the PRIVATE directory. Following a standard agreed upon by many still camera manufacturers, solid-state camcorders have a root-level DCIM directory for still images. AVCHD is compatible with the Blu-ray disc format and can be authored without re-encoding on Blu-ray discs or DVDs, though not all Blu-ray Disc players are compatible with AVCHD video authored on DVD media, a format known as AVCHD disc. AVCHD recordings can be transferred to a computer by connecting the camcorder via the USB connection. Removable media like SDHC and Memory Stick cards or DVDs can be read on a computer directly. Copying files from an AVCHD camcorder or from removable media can be performed faster than from a tape-based camcorder, because the transfer speed is not limited by realtime playback.
Just as editing DVCPRO HD and HDV video once demanded an expensive high-end computer, AVCHD editing software requires powerful machines. Compared to HDV, AVCHD requires 2-4x the processing power for realtime playback, placing a greater burden on the computer's CPU and graphics card. Improvements in multi-core computing and graphics processor acceleration bring AVCHD playback to mainstream desktops and laptops. AVCHD supports a variety of video resolutions and scanning methods, further extended with the 2011 amendment of the specification; the licensing body of the specification defines a variety of labels for products compliant with specific features. Most AVCHD camcorders support only a handful of the video and audio formats allowed in the AVCHD standard. AVCHD supports high definition interlaced video. AVCHD 1080i is available on most AVCHD camcorders. For some models this is the only recording mode offered. AVCHD-SD is used in the shoulder-mount Panasonic HDC-MDH1, as well as on its North American AG-AC7 cousin.
A successor model - the AG-AC8, is capable of recording in AVCHD-SD mode. Several models from JVC like the consumer camcorders GZ-HM650, GZ-HM670 and GZ-HM690 as well as the professional camcorder JVC GY-HM70 can record AVCHD-SD video. AVCHD-SD is not compatible with consumer DVD players, because it employs AVC video encoding instead of MPEG-2 Part 2. AVCHD-SD can be played on a Blu-ray Disc player without re-encoding. Interlaced video had been designed for watching on a cathode-ray tube television set. Material recorded for interlaced presentation may exhibit combing or ghosting when it is rescaled, filmed out or watched on a computer or another progressive-scan device without proper deinterlacing; some AVCHD 1080i camcorders can capture progressive video and record it within interlaced stream borrowing techniques from television industry. In particular, Progressive segmented frame is utilized in some Panasonic and Sony camcorders; the 2:3 pulldown technique is used in some 60 Hz versions of Canon and Panasonic camcorders for recording 24-frame/s progressive video.
Most editing tools treat progressive video recorded within an interlaced stream as interlaced, though some editing systems and most standalone Blu-ray Disc players are capable of recognizing the pulldown p
Soundtrack Pro is a discontinued music composing and audio editing application made by Apple Inc. featured in Logic Studio and Final Cut Studio that included a collection of just over 5,000 royalty free professional instrument loops and sound effects. It was discontinued with the release of Final Cut Pro X, Motion 5, Compressor 4. An earlier incarnation of the package, was first sold as part of Apple's Final Cut Pro 4 video editor, released in April 2003, it was released as a stand-alone product, but due to low demand it was discontinued. The main concept of Soundtrack was to allow people who are not professional composers to produce original music for their videos or DVDs, royalty-free; the music could be scored to QuickTime movies and Final Cut Pro projects. Soundtrack was reinstated in January 2005 as part of Final Cut Express HD. Soundtrack Pro was introduced on April 17, 2005 as a stand-alone product and as part of the Final Cut Studio suite, where it integrates with Final Cut Pro. Soundtrack was removed from Final Cut Pro.
There was an upgrade package for users of Soundtrack. As of January 10, 2006, the stand-alone product has been dropped again. Soundtrack Pro adds features for professional audio engineers and sound designers, focuses more on sound editing than the original Soundtrack. Since September 2007 Soundtrack Pro comes as part of the Logic Studio bundle, Apple's own audio and midi sequencing software, but it was removed from Logic Studio when Logic Pro was moved to the App Store on December 8, 2011. Soundtrack Pro 2 is included in Final Cut Studio 2. See a release history in context with the rest of Final Cut Studio. Soundtrack Pro has two main modes: multitrack editing mode. Multitrack mode is where the royalty-free instrument loops and sound effects can be arranged in synchronisation with the video track, where narration or other external audio sources can be recorded. There are both multi-take recording features; as with all of Apple's loop arranging software, the project's master key and tempo can be set, all of the loops will automatically be played at those settings, regardless of the key and tempo at which they were recorded.
At the same time, the key and tempo for the whole project can be varied over time with the master envelopes. Envelopes are a sequence of keyframes; each individual track pan by default. Adding keyframes to these envelopes allows the parameters to be varied over time; each track can have filters and effects applied to it. Every parameter of these effects can be automated. In addition, there is a mixer interface. Using the'touch' or'latch' modes, changes to volume and effects parameters can be recorded in real time as the project plays. Soundtrack Pro supports external hardware mixers, or control surfaces; the audio-editing mode is. The waveform, as well as a frequency spectrum, can be viewed for the clip; the audio can be analyzed for common audio problems such as clicks and pops, power line hum and clipped signals, any discovered problems can be fixed. Audio can be faded in and out, the amplitude can be altered for a selection, noise can be removed and silence and ambient noise can be inserted. There is a selection history tool that cycles between previous selections.
After zooming in on the individual samples in the audio waveform, the pen tool can be used to edit the wave directly. There is a time-stretch tool for changing the speed of a part thereof. Sound editing in the application is based on actions; the actions performed on a clip, such as reversing it, inverting it or normalizing it, are listed on the left-hand side, where they can be reviewed, reverted or re-ordered. Unchecking the check box for one action removes its effect. Moving the purple tag upwards cycles back through the actions history; the program features AppleScript automation and batch processing, for which it provides actions for Mac OS X v10.4's Automator application. Soundtrack Pro is designed to be used in combination with Final Cut Pro, both of which are included in the Final Cut Studio box set, it supports a'roundtrip' workflow, in which Final Cut Pro sequences can be exported as small reference files that include scoring markers. These reference files are dragged from Soundtrack Pro's Browser tab to the video pane.
The video track includes thumbnails of the video at each scoring marker. Once the soundtrack is finished, it is exported as a mix and can be imported into Final Cut. If the soundtrack needs to be changed, the Soundtrack Pro project file can be re-opened at any time, but the changes will only show up in Final Cut when the mix has been re-exported; the program allows multitrack projects to be exported directly with Compressor settings. Walter Murch, an editor who advocated for Soundtrack Pro. GarageBand, a similar program aimed at home users. Logic Express, a similar program aimed at amateur musicians. Logic Pro, a professional music-production application. Apple.com—Soundtrack Pro
MacOS is a series of graphical operating systems developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac family of computers. Within the market of desktop and home computers, by web usage, it is the second most used desktop OS, after Microsoft Windows.macOS is the second major series of Macintosh operating systems. The first is colloquially called the "classic" Mac OS, introduced in 1984, the final release of, Mac OS 9 in 1999; the first desktop version, Mac OS X 10.0, was released in March 2001, with its first update, 10.1, arriving that year. After this, Apple began naming its releases after big cats, which lasted until OS X 10.8 Mountain Lion. Since OS X 10.9 Mavericks, releases have been named after locations in California. Apple shortened the name to "OS X" in 2012 and changed it to "macOS" in 2016, adopting the nomenclature that they were using for their other operating systems, iOS, watchOS, tvOS; the latest version is macOS Mojave, publicly released in September 2018.
Between 1999 and 2009, Apple sold. The initial version, Mac OS X Server 1.0, was released in 1999 with a user interface similar to Mac OS 8.5. After this, new versions were introduced concurrently with the desktop version of Mac OS X. Beginning with Mac OS X 10.7 Lion, the server functions were made available as a separate package on the Mac App Store.macOS is based on technologies developed between 1985 and 1997 at NeXT, a company that Apple co-founder Steve Jobs created after leaving the company. The "X" in Mac OS X and OS X is pronounced as such; the X was a prominent part of the operating system's brand identity and marketing in its early years, but receded in prominence since the release of Snow Leopard in 2009. UNIX 03 certification was achieved for the Intel version of Mac OS X 10.5 Leopard and all releases from Mac OS X 10.6 Snow Leopard up to the current version have UNIX 03 certification. MacOS shares its Unix-based core, named Darwin, many of its frameworks with iOS, tvOS and watchOS.
A modified version of Mac OS X 10.4 Tiger was used for the first-generation Apple TV. Releases of Mac OS X from 1999 to 2005 ran on the PowerPC-based Macs of that period. After Apple announced that they were switching to Intel CPUs from 2006 onwards, versions were released for 32-bit and 64-bit Intel-based Macs. Versions from Mac OS X 10.7 Lion run on 64-bit Intel CPUs, in contrast to the ARM architecture used on iOS and watchOS devices, do not support PowerPC applications. The heritage of what would become macOS had originated at NeXT, a company founded by Steve Jobs following his departure from Apple in 1985. There, the Unix-like NeXTSTEP operating system was developed, launched in 1989; the kernel of NeXTSTEP is based upon the Mach kernel, developed at Carnegie Mellon University, with additional kernel layers and low-level user space code derived from parts of BSD. Its graphical user interface was built on top of an object-oriented GUI toolkit using the Objective-C programming language. Throughout the early 1990s, Apple had tried to create a "next-generation" OS to succeed its classic Mac OS through the Taligent and Gershwin projects, but all of them were abandoned.
This led Apple to purchase NeXT in 1996, allowing NeXTSTEP called OPENSTEP, to serve as the basis for Apple's next generation operating system. This purchase led to Steve Jobs returning to Apple as an interim, the permanent CEO, shepherding the transformation of the programmer-friendly OPENSTEP into a system that would be adopted by Apple's primary market of home users and creative professionals; the project was first code named "Rhapsody" and officially named Mac OS X. Mac OS X was presented as the tenth major version of Apple's operating system for Macintosh computers. Previous Macintosh operating systems were named using Arabic numerals, as with Mac OS 8 and Mac OS 9; the letter "X" in Mac OS X's name refers to a Roman numeral. It is therefore pronounced "ten" in this context. However, it is commonly pronounced like the letter "X"; the first version of Mac OS X, Mac OS X Server 1.0, was a transitional product, featuring an interface resembling the classic Mac OS, though it was not compatible with software designed for the older system.
Consumer releases of Mac OS X included more backward compatibility. Mac OS applications could be rewritten to run natively via the Carbon API; the consumer version of Mac OS X was launched in 2001 with Mac OS X 10.0. Reviews were variable, with extensive praise for its sophisticated, glossy Aqua interface but criticizing it for sluggish performance. With Apple's popularity at a low, the makers of several classic Mac applications such as FrameMaker and PageMaker declined to develop new versions of their software for Mac OS X. Ars Technica columnist John Siracusa, who reviewed every major OS X release up to 10.10, described the early releases in retrospect as'dog-slow, feature poor' and Aqua as'unbearably slow and a huge resource hog'. Apple developed several new releases of Mac OS X. Siracusa's review of version 10.3, noted "It's strange to have gone from years of uncertainty and vaporware to a steady annual supply of major new operating system releases." Version 10.4, Tiger shocked executives at Microsoft by offering a number of features, such as fast file s
Compositing is the combining of visual elements from separate sources into single images to create the illusion that all those elements are parts of the same scene. Live-action shooting for compositing is variously called "chroma key", "blue screen", "green screen" and other names. Today, though not all, compositing is achieved through digital image manipulation. Pre-digital compositing techniques, however, go back as far as the trick films of Georges Méliès in the late 19th century, some are still in use. All compositing involves the replacement of selected parts of an image with other material but not always, from another image. In the digital method of compositing, software commands designate a narrowly defined color as the part of an image to be replaced; the software replaces every pixel within the designated color range with a pixel from another image, aligned to appear as part of the original. For example, one could record a television weather presenter positioned in front of a plain blue or green background, while compositing software replaces only the designated blue or green color with weather maps.
In television studios, blue or green screens may back news-readers to allow the compositing of stories behind them, before being switched to full-screen display. In other cases, presenters may be within compositing backgrounds that are replaced with entire "virtual sets" executed in computer graphics programs. In sophisticated installations, cameras, or both can move about while the computer-generated imagery environment changes in real time to maintain correct relationships between the camera angles and virtual "backgrounds". Virtual sets are used in motion picture filmmaking photographed in blue or green screen environments, as for example in Sky Captain and the World of Tomorrow. More composited backgrounds are combined with sets – both full-size and models – and vehicles and other physical objects that enhance the realism of the composited visuals. "Sets" of unlimited size can be created digitally because compositing software can take the blue or green color at the edges of a backing screen and extend it to fill the rest of the frame outside it.
That way, subjects recorded in modest areas can be placed in large virtual vistas. Most common are set extensions: digital additions to actual performing environments. In the film Gladiator, for example, the arena and first tier seats of the Roman Colosseum were built, while the upper galleries were computer graphics, composited onto the image above the physical set. For motion pictures recorded on film, high-quality video conversions called "digital intermediates" enable compositing and other operations of computerized post production. Digital compositing is a type of matting, one of four basic compositing methods; the others are physical compositing, multiple exposure, background projection, a method which utilizes both front projection and rear projection. In physical compositing the separate parts of the image are placed together in the photographic frame and recorded in a single exposure; the components are aligned. The most common physical compositing elements are partial models and glass paintings.
Partial models are used as set extensions such as ceilings or the upper stories of buildings. The model, built to match the actual set but on a much smaller scale, is hung in front of the camera, aligned so that it appears to be part of the set. Models are quite large because they must be placed far enough from the camera so that both they and the set far beyond them are in sharp focus. Glass shots are made by positioning a large pane of glass so that it fills the camera frame, is far enough away to be held in focus along with the background visible through it; the entire scene is painted on the glass, except for the area revealing the background where action is to take place. This area is left clear. Photographed through the glass, the live action is composited with the painted area. A classic example of a glass shot is the approach to Ashley Wilkes' plantation in Gone with the Wind; the plantation and fields are all painted, while the road and the moving figures on it are photographed through the glass area left clear.
A variant uses the opposite technique: most of the area is clear, except for individual elements affixed to the glass. For example, a ranch house could be added to an empty valley by placing an appropriately scaled and positioned picture of it between the valley and the camera. An in-camera multiple exposure is made by recording on only one part of each film frame, rewinding the film to the same start point, exposing a second part, repeating the process as needed; the resulting negative is a composite of all the individual exposures. Exposing one section at a time is made possible by enclosing the camera lens in a light-tight box fitted with maskable openings, each one corresponding to one of the action areas. Only one opening is revealed per exposure. Multiple exposure is difficult. However, as early as 1900 Georges Méliès used seven-fold exposure in L'homme-orchestre/The One-man Band.
Chief executive officer
The chief executive officer or just chief executive, is the most senior corporate, executive, or administrative officer in charge of managing an organization – an independent legal entity such as a company or nonprofit institution. CEOs lead a range of organizations, including public and private corporations, non-profit organizations and some government organizations; the CEO of a corporation or company reports to the board of directors and is charged with maximizing the value of the entity, which may include maximizing the share price, market share, revenues or another element. In the non-profit and government sector, CEOs aim at achieving outcomes related to the organization's mission, such as reducing poverty, increasing literacy, etc. In the early 21st century, top executives had technical degrees in science, engineering or law; the responsibility of an organization's CEO are set by the organization's board of directors or other authority, depending on the organization's legal structure.
They can be far-reaching or quite limited and are enshrined in a formal delegation of authority. Responsibilities include being a decision maker on strategy and other key policy issues, leader and executor; the communicator role can involve speaking to the press and the rest of the outside world, as well as to the organization's management and employees. As a leader of the company, the CEO or MD advises the board of directors, motivates employees, drives change within the organization; as a manager, the CEO/MD presides over the organization's day-to-day operations. The term refers to the person who makes all the key decisions regarding the company, which includes all sectors and fields of the business, including operations, business development, human resources, etc; the CEO of a company is not the owner of the company. In some countries, there is a dual board system with two separate boards, one executive board for the day-to-day business and one supervisory board for control purposes. In these countries, the CEO presides over the executive board and the chairman presides over the supervisory board, these two roles will always be held by different people.
This ensures a distinction between management by the executive board and governance by the supervisory board. This allows for clear lines of authority; the aim is to prevent a conflict of interest and too much power being concentrated in the hands of one person. In the United States, the board of directors is equivalent to the supervisory board, while the executive board may be known as the executive committee. In the United States, in business, the executive officers are the top officers of a corporation, the chief executive officer being the best-known type; the definition varies. In the case of a sole proprietorship, an executive officer is the sole proprietor. In the case of a partnership, an executive officer is a managing partner, senior partner, or administrative partner. In the case of a limited liability company, executive officer is any manager, or officer. A CEO has several subordinate executives, each of whom has specific functional responsibilities referred to as senior executives, executive officers or corporate officers.
Subordinate executives are given different titles in different organizations, but one common category of subordinate executive, if the CEO is the president, is the vice-president. An organization may have more than one vice-president, each tasked with a different area of responsibility; some organizations have subordinate executive officers who have the word chief in their job title, such as chief operating officer, chief financial officer and chief technology officer. The public relations-focused position of chief reputation officer is sometimes included as one such subordinate executive officer, but, as suggested by Anthony Johndrow, CEO of Reputation Economy Advisors, it can be seen as "simply another way to add emphasis to the role of a modern-day CEO – where they are both the external face of, the driving force behind, an organisation culture". In the US, the term chief executive officer is used in business, whereas the term executive director is used in the not-for-profit sector; these terms are mutually exclusive and refer to distinct legal duties and responsibilities.
Implicit in the use of these titles, is that the public not be misled and the general standard regarding their use be applied. In the UK, chief executive and chief executive officer are used in both business and the charitable sector; as of 2013, the use of the term director for senior charity staff is deprecated to avoid confusion with the legal duties and responsibilities associated with being a charity director or trustee, which are non-executive roles. In the United Kingdom, the term director is used instead of chief officer". Business publicists since the days of Edward Bernays and his client John D. Rockefeller and more the corporate publicists for Henry Ford, promoted the concept of the "celebrity CEO". Business journalists have adopted this approach, which assumes that the corporate achievements in the arena of manufacturing, wer
IMovie is a video editing software application sold by Apple Inc. for the Mac and iOS. It was released in 1999 as a Mac OS 8 application bundled with the first FireWire-enabled consumer Mac model – the iMac DV. Since version 3, iMovie has been a macOS-only application included with the iLife suite of Mac applications. Since 2003, iMovie is included free with all new Mac computers. IMovie imports video footage to the Mac using either the FireWire interface on most MiniDV format digital video cameras or the computer's USB port, it can import video and photo files from a hard drive. From there, the user can edit the photos and video clips and add titles, themes and effects, including basic color correction and video enhancement tools and transitions such as fades and slides. IMovie is available as an app for the iPhone. Starting with version 5, iMovie processes high-definition video from HDV camcorders, in versions from AVCHD camcorders and H.264-compressed video from MPEG-4 or QuickTime Movie files.
E.g. as generated by a number of digital photo cameras with HD video recording feature. To facilitate this, iMovie/iLife installs the Apple Intermediate Codec on the system as a QuickTime component. IMovie transcodes HD video upon ingestion using this codec and stores it in the QuickTime file format; the latest version of iMovie includes options to modify and enhance video color settings and rotate of a video clip, stabilizing shaky videos, adding video "effects", changing the speed of clips.iMovie can manipulate and enhance the audio of a project by reducing background noise and boosting audio levels of quiet clips. IMovie HD included support for HDV and integration with the rest of the iLife suite, with toolbox buttons allowing the importing of images from iPhoto, music from iTunes and the setting of chapter markers ready for exporting to iDVD. iMovie HD 5 imported mjpeg files as dv by default, which introduces noise. Another new feature was included called "Magic iMovie", which attempted to automate the whole process of video editing, by allowing a common transition to be added between scenes, a music track to be synchronised with the video and a DVD to be created with the accompanying iDVD software.
IMovie 6 was released in January 2006 as part of the iLife'06 suite, was originally optionally included with iLife'08 as a substitution for iMovie'08. However, this option was removed, it was integrated with iPhoto, iTunes, iDVD, GarageBand and iWeb. iMovie HD 6 was designed for ease of use, included new themes. Themes allow the user to drop movie photos into professionally designed backdrops; each theme transitions. IMovie HD 6 added real-time effects, which took advantage of the computer's graphic processing unit to perform some effects without rendering, it introduced real-time titling, enhanced audio tools and effects, the ability to have multiple projects open at once, video podcasts and blogs, a refined look based on iTunes 5 and 6. IMovie'08 was released in August 2007 as a part of the iLife'08 suite. IMovie'08 was a complete rewrite of iMovie, it had much better HD output, more formats to convert to. This was limited, however, by an undocumented restriction on supported codecs. IPhoto uses the QuickTime library and can create thumbnails for all QuickTime supported formats, but most of these cannot be used by iMovie'08.
Some of the formats that iMovie'08 is able to import will not be recognized when they are added to an iPhoto library. Though Motion JPEG-encoded AVI files do appear to be recognized, this was the most common format used by digital cameras; the tile-based editing interface was promoted as something unique and groundbreaking though it is functionally identical to the interface of the Toaster Flyer non-linear digital video editing systems released for Amiga computers by NewTek, Inc. in 1993. A new feature called "skimming" for previewing video in the library at a user controlled speed was added, so was a feature that allows the user to highlight parts of video clips just like highlighting text. IMovie 08 had the ability to add more than two layers of background sound, including multiple music and sounds, it included more exportation formats, including iPhone-sized video. It supported non-tape-based HD video, such as AVCHD and footage from DVD and HDD camcorders. IMovie'08 has the ability to export movies to the YouTube video sharing website.
According to Apple's system requirements, iMovie'08 requires a Mac with either a 1.9 GHz or faster PowerPC G5 or Intel processor. G4s are not supported though Apple sold its last G4-based Computers 14 months before the release of iLife'08. However, a system hack enables iMovie 7.1 or higher to run on a PowerPC G4. IMovie 08 was criticized due to its drastic abandonment of some iMovie HD 6 features. Former New York Times reviewer David Pogue said "iMovie ‘08 is an utter bafflement... incapable of the more sophisticated editing that the old iMovie made so enjoyable... All visual effects are gone — basic options like slow motion, reverse motion, fast motion, black-and-white, and you can’t have more than one project open at a time."Features removed included the classic timeline, the ability to create DVD chapter markers, support for plugins, in-
Sound recording and reproduction
Sound recording and reproduction is an electrical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, instrumental music, or sound effects. The two main classes of sound recording technology are analog digital recording. Acoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record. In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current, converted to a varying magnetic field by an electromagnet, which makes a representation of the sound as magnetized areas on a plastic tape with a magnetic coating on it. Analog sound reproduction is the reverse process, with a bigger loudspeaker diaphragm causing changes to atmospheric pressure to form acoustic sound waves. Digital recording and reproduction converts the analog sound signal picked up by the microphone to a digital form by the process of sampling.
This lets the audio data be transmitted by a wider variety of media. Digital recording stores audio as a series of binary numbers representing samples of the amplitude of the audio signal at equal time intervals, at a sample rate high enough to convey all sounds capable of being heard. A digital audio signal must be reconverted to analog form during playback before it is amplified and connected to a loudspeaker to produce sound. Prior to the development of sound recording, there were mechanical systems, such as wind-up music boxes and player pianos, for encoding and reproducing instrumental music. Long before sound was first recorded, music was recorded—first by written music notation also by mechanical devices. Automatic music reproduction traces back as far as the 9th century, when the Banū Mūsā brothers invented the earliest known mechanical musical instrument, in this case, a hydropowered organ that played interchangeable cylinders. According to Charles B. Fowler, this "...cylinder with raised pins on the surface remained the basic device to produce and reproduce music mechanically until the second half of the nineteenth century."
The Banū Mūsā brothers invented an automatic flute player, which appears to have been the first programmable machine. Carvings in the Rosslyn Chapel from the 1560s may represent an early attempt to record the Chladni patterns produced by sound in stone representations, although this theory has not been conclusively proved. In the 14th century, a mechanical bell-ringer controlled by a rotating cylinder was introduced in Flanders. Similar designs appeared in barrel organs, musical clocks, barrel pianos, music boxes. A music box is an automatic musical instrument that produces sounds by the use of a set of pins placed on a revolving cylinder or disc so as to pluck the tuned teeth of a steel comb; the fairground organ, developed in 1892, used a system of accordion-folded punched cardboard books. The player piano, first demonstrated in 1876, used a punched paper scroll that could store a long piece of music; the most sophisticated of the piano rolls were hand-played, meaning that the roll represented the actual performance of an individual, not just a transcription of the sheet music.
This technology to record a live performance onto a piano roll was not developed until 1904. Piano rolls were in continuous mass production from 1896 to 2008. A 1908 U. S. Supreme Court copyright case noted that, in 1902 alone, there were between 70,000 and 75,000 player pianos manufactured, between 1,000,000 and 1,500,000 piano rolls produced; the first device that could record actual sounds as they passed through the air was the phonautograph, patented in 1857 by Parisian inventor Édouard-Léon Scott de Martinville. The earliest known recordings of the human voice are phonautograph recordings, called phonautograms, made in 1857, they consist of sheets of paper with sound-wave-modulated white lines created by a vibrating stylus that cut through a coating of soot as the paper was passed under it. An 1860 phonautogram of Au Clair de la Lune, a French folk song, was played back as sound for the first time in 2008 by scanning it and using software to convert the undulating line, which graphically encoded the sound, into a corresponding digital audio file.
On April 30, 1877, French poet, humorous writer and inventor Charles Cros submitted a sealed envelope containing a letter to the Academy of Sciences in Paris explaining his proposed method, called the paleophone. Though no trace of a working paleophone was found, Cros is remembered as the earliest inventor of a sound recording and reproduction machine; the first practical sound recording and reproduction device was the mechanical phonograph cylinder, invented by Thomas Edison in 1877 and patented in 1878. The invention soon spread across the globe and over the next two decades the commercial recording and sale of sound recordings became a growing new international industry, with the most popular titles selling millions of units by the early 1900s; the development of mass-production techniques enabled cylinder recordings to become a major new consumer item in industrial countries and the cylinder was the main consumer format from the late 1880s until around 1910. The next major technical development was the invention of the gramophone record credited to Emile Berliner and patented in 1887, though others had demonstrated simi