# China Video Disc **Wikidata**: [Q2755194](https://www.wikidata.org/wiki/Q2755194) **Source**: https://4ort.xyz/entity/china-video-disc ## Summary China Video Disc (CVD) is a type of optical disc, identified as a machine-readable medium used for physical data distribution. It functions as a flat, usually circular, removable medium that encodes binary data in laser-readable pits and lands. As a specific instance of optical storage, it shares the core technologies and physical characteristics standard to the optical disc family, such as being readable by optical drives and used for data archival or distribution. ## Key Facts - **Aliases**: Also known as CVD. - **Classification**: Instance of **Optical Disc**; subclass of optical storage, machine-readable medium, and removable media. - **Data Encoding**: Stores binary data as microscopic pits and lands read by a laser. - **Physical Form**: Flat, circular disk shape (typically 120 mm or 80 mm in diameter). - **Material Composition**: Polycarbonate substrate with a reflective layer (aluminum or gold) and protective lacquer. - **Google Knowledge Graph ID**: /g/122l3cst. - **Wikipedia Presence**: Available in 5 languages (Catalan, Spanish, Italian, Polish, Swedish). - **Contextual Family**: Belongs to the technology family that includes LaserDisc, CD, DVD, Blu-ray, and Archival Disc. ## FAQs ### Q: What exactly is a China Video Disc (CVD)? A: CVD is a specific format of optical disc, a storage medium used to encode binary data via laser-readable pits on a flat, circular surface. It is classified as a type of optical media used for data distribution. ### Q: How does CVD store and read data? A: Like other optical discs, CVD stores data as physical depressions (pits) and flat areas (lands) on its surface. A low-power laser in a drive reflects off these features, interpreting the variations as binary 0s and 1s. ### Q: What materials are used in the construction of CVD? A: As an optical disc, it typically consists of a polycarbonate substrate, a reflective layer of aluminum or gold, and a protective lacquer coating to ensure durability. ### Q: How does CVD differ from magnetic storage? A: CVD uses light (lasers) to read and write data and is typically removable, whereas magnetic storage (like hard drives) uses magnetic fields on non-removable platters accessed by electrical heads. ## Why It Matters As an optical disc format, China Video Disc represents a component of the digital storage ecosystem that revolutionized how media and software are distributed. Optical media offers a low-cost, durable, and portable solution that does not require power to retain data. While specific applications for CVD depend on its regional or technical implementation, its classification as an optical disc places it within a lineage of technology that enabled the widespread adoption of digital audio, video, and software. It serves a role in environments where offline distribution, backup, and data integrity are critical, functioning independently of network connectivity. ## Notable For - **Optical Classification**: Being a distinct instance of the broader "optical disc" class, which is the primary standard for physical data distribution. - **Data Preservation**: Belonging to a format family known for durability and suitability for long-term archival (ranging from decades to centuries in specialized formats like M-Disc). - **Removability**: Functioning as a removable medium, allowing for the physical transport of data between devices without network transfer. - **Multilingual Documentation**: Possessing a digital footprint across multiple European language wikis (Catalan, Spanish, Italian, Polish, Swedish). ## Body ### Definition and Classification China Video Disc (CVD) is defined in the knowledge base as an instance of an **optical disc**. It falls under the broader categories of optical storage, machine-readable media, and computer storage media. As an optical disc, it is a flat, usually circular, removable medium that encodes binary data. It is distinguished from magnetic storage by its use of laser technology for reading data stored as pits and lands, rather than magnetic fields. ### Technical Architecture and Operation The fundamental operation of CVD relies on the standard principles of optical storage: - **Encoding**: Data is encoded physically on the disc surface as microscopic pits (depressions) and lands (flat areas). - **Reading Mechanism**: An optical disc drive directs a low-power laser beam at the spinning disc surface. The laser light reflects off the pits and lands differently; a photodetector interprets these variations in reflected light intensity as binary data (0s and 1s). - **Physical Structure**: The standard construction involves a polycarbonate plastic substrate that forms the main body of the disc. This is coated with a reflective layer (typically aluminum, though sometimes gold for archival purposes) and sealed with a protective lacquer to prevent oxidation and physical damage. ### Physical Characteristics As an optical disc, CVD adheres to the standard physical form factors associated with the medium: - **Shape**: Circular disk. - **Dimensions**: While specific dimensions depend on the exact variant, standard optical discs are typically **120 mm** (approx. 4.7 inches) in diameter. A smaller "mini" version of **80 mm** (approx. 3.1 inches) also exists within the optical disc family. ### Context and Related Formats CVD exists within the extensive ecosystem of optical disc formats developed since the late 1970s. While CVD is a specific instance, the technology class it belongs to includes a wide range of major formats: - **LaserDisc (1978)**: The first commercial optical disc format, used primarily for analog video. - **Compact Disc (CD)**: Introduced in 1979, standardized digital audio and data storage (typically 700 MB). - **DVD**: Introduced in 1995, offering higher capacity (4.7 GB) for video and data. - **Blu-ray Disc**: Introduced in 2006, utilizing blue-violet lasers for high-definition video storage (25 GB per layer). - **Archival Formats**: Technologies like M-Disc and Archival Disc are engineered for multi-decade data preservation. ### Identifiers and Web Presence - **Google Knowledge Graph**: CVD is tracked under the ID `/g/122l3cst`. - **Wikipedia Coverage**: The entity has a presence on Wikipedia across five specific language editions: **Catalan (ca), Spanish (es), Italian (it), Polish (pl), and Swedish (sv)**. - **Sitelinks**: The entity has an aggregated sitelink count of 5 across these languages.