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30-497: ISO images can be created from optical discs by disk imaging software , or from a collection of files by optical disc authoring software , or from a different disk image file by means of conversion . Software distributed on bootable discs is often available for download in ISO image format. And like any other ISO image, it may be written to an optical disc such as CD, DVD and Blu-Ray. Optical-disc images are uncompressed and do not use

60-607: A CD image. Emulators such as Dolphin and PCSX2 use .iso files to emulate Wii and GameCube games, and PlayStation 2 games, respectively. They can also be used as virtual CD-ROMs for hypervisors such as VMware Workstation or VirtualBox . Other uses are burning disk images of operating systems to physical install media. Comparison of disc image software Notable software applications that can access or manipulate disk image files are as follows, comparing their disk image handling features. Super Video CD Super Video CD ( Super Video Compact Disc or SVCD )

90-410: A DVD or Blu-ray disc anyway. Interlaced video is supported for SVCD video. 23.976 frames per second video is supported by use of interlacing and 3:2 pulldown . The combined audio and video bit rates should not exceed 2.7 Mbps . This data rate was chosen, in part, to ensure compatibility with slower and less expensive "2 × speed" CD drives. As with most compact disc-based video formats, SVCD audio

120-728: A continuous stream of encoded audio data. This audio is stored on sectors of 2352 bytes different from those that store a file system and it is not stored inside files; it is addressed with track numbers , index points and a CD time code that are encoded into the lead-in of each session of the CD-Audio disc. Video CDs and Super Video CDs require at least two tracks on a CD, so it is also not possible to store an image of one of these discs inside an ISO image file, however an .IMG file can achieve this. Formats such as CUE/BIN , CCD/IMG and MDS/MDF formats can be used to store multi-track disc images, including audio CDs. These formats store

150-428: A particular container format; they are a sector -by-sector copy of the data on an optical disc, stored inside a binary file. Other than ISO 9660 media, an ISO image might also contain a UDF (ISO/IEC 13346) file system (commonly used by DVDs and Blu-ray Discs ), including the data in its files in binary format, copied exactly as they were stored on the disc. The data inside the ISO image will be structured according to

180-437: A raw disc image of the complete disc, including information from all tracks, along with a companion file describing the multiple tracks and the characteristics of each of those tracks. This would allow an optical media burning tool to have all the information required to correctly burn the image on a new disc. For audio CDs, one can also transfer the audio data into uncompressed audio files like WAV or AIFF , optionally reserving

210-489: A resolution of 704x480 (480i, analog NTSC compatible) or 704x576 (576i, analog PAL/SECAM compatible). Play back of SVCD titles is impaired when played on most DVD players, causing dropped frames, choppy video playback or skipping of sound. This is due to the chosen two-thirds video ratio in the SVCD format specifications, which doesn't align well with the other more common video formats VCD and DVD . Most DVD players support

240-431: A single ISO image; at most, an ISO image will contain the data inside one of those multiple tracks, and only if it is stored inside a standard file system. This also means that audio CDs , which are usually composed of multiple tracks, can not be stored inside an ISO image. Furthermore, not even a single track of an audio CD can be stored as an ISO image, since audio tracks do not contain a file system inside them, but only

270-446: A suitable driver software, an ISO can be " mounted " – allowing the operating system to interface with it, just as if the ISO were a physical optical disc. Most Unix -based operating systems, including Linux and macOS , have this built-in capability to mount an ISO. Versions of Windows, beginning with Windows 8 , also have such a capability. For other operating systems, separately available software drivers can be installed to achieve

300-473: Is 2,048 bytes, the size of an ISO image will be a multiple of 2,048. Any single- track CD-ROM , DVD or Blu-ray disc can be archived in ISO format as a true digital copy of the original. Unlike a physical optical disc, an image can be transferred over any data link or removable storage medium. An ISO image can be opened with almost every multi-format file archiver . Native support for handling ISO images varies from operating system to operating system. With

330-620: Is a digital format for storing video on standard compact discs . SVCD was intended as a successor to Video CD and an alternative to DVD-Video , and falls somewhere between both in terms of technical capability and picture quality. Similar to VCDs , SVCDs comply with the CD-i Bridge format, and are authored (or "burned") using the CD-ROM XA format. The first track is in CD-ROM XA Mode 2, Form 1, and contains metadata about

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360-537: Is a recognized DVD resolution, CVD video (but not audio) is fully compatible with the DVD-Video standard, and avoids the "foldover" (or aliasing ) problems encountered when playing SVCDs on DVD players. The lower resolution also allows the bitrate to be reduced while keeping compression artifacts to a minimum. CVD also supports all of the additional features (selectable subtitles, multiple audio tracks, and so on) which are supported by SVCD. XSVCD (eXtended Super VCD)

390-539: Is effectively synonymous with Super VCD. A Super VCD player must be able to play a variety of formats, including SVCD, CVD, VCD 2.0, VCD 1.1 and CD audio discs. On July 15, 2000, the IEC certified SVCD an international standard CD format, as IEC 62107. Philips added an SVCD logo to its canon of official Compact Disc logos. SVCD titles were available commercially in China, Hong Kong , and several other Asian countries (except

420-635: Is incompatible with the DVD-Video standard due to the difference in frequency; DVDs require 48 kHz, whereas SVCDs use 44.1 kHz. SVCDs may have two separate stereo, or four mono audio tracks (for commentary or additional languages). Audio may have up to 6 channels (in a 5.1 arrangement) using the MPEG Multichannel surround sound format, although space constraints and inconsistent hardware support make it impractical, and very uncommon. Variable bit rate encoding, while not supported by

450-403: Is sometimes used to indicate that the file system inside the ISO image is actually UDF and not ISO 9660. ISO files store only the user data from each sector on an optical disc, ignoring the control headers and error correction data, and are therefore slightly smaller than a raw disc image of optical media. Since the size of the user-data portion of a sector (logical sector) in data optical discs

480-549: Is the name generally given to any format that stores MPEG-2 video on a compact disc in mode 2/XA, at SVCD resolution, but does not strictly meet the SVCD standard. To reduce the data rate without significantly reducing quality, the size of the GOP can be increased, the maximum data rate can be exceeded, and a different MPEG-2 quantization matrix can be used. These changes can be advantageous for those who want to either maximize video quality, or use fewer discs. RSVCD (RoBa SVCD) uses

510-411: The file system that was used on the optical disc from which it was created. The .iso file extension is the one most commonly used for this type of disc images. The .img extension can also be found on some ISO image files, such as in some images from Microsoft DreamSpark ; however, IMG files , which also use the .img extension, tend to have slightly different contents. The .udf file extension

540-495: The 480p format doesn't fit well over a 720p output. The aliasing artifacts that result from this bad fit are usually buried in noise from other sources, such as camera, quantization, and MPEG artifacts . China Video Disc (CVD) is a CD-based video format which was created during the development of the SVCD standard and is almost identical to SVCD. The primary technical difference is a lower (horizontal) video resolution of 352×480 (NTSC) or 352×576 (PAL/SECAM). Because 352×480/576

570-565: The Chinese government to force a compromise between the competing standards in order to maintain compatibility. The SVCD and CVD standards were combined into one composite standard known as Chaoji Video CD ("Chaoji" in Pinyin or 超级 in written Chinese, meaning "super") in November 1998, which was adopted by the Chinese government as the "official" next-generation video disc standard. Chaoji VCD

600-531: The MPEG-1 Audio Layer II standard, is part of the SVCD specification. However, variable bit rate audio is not consistently supported by standalone players, and thus the format is rarely used. The SVCD standard supports several other features, including interactive menus, hyperlinks , karaoke lyric highlighting, four selectable overlay graphic subtitle streams, chapters, playlists, and DVD-quality still images/slide shows, along with audio, with

630-563: The Robshot-Bach (RoBa) method for encoding MPEG-2 video using CCE in creating SVCD-compliant discs. RSVCD was popularized on the Doom9 forum. MVCD (Mole VCD) is a XSVCD variant that can be created using the MVCD templates included with TMPGEnc . MVCD can encode either MPEG-1 or MPEG-2 video to VCD, SVCD, or DVD standard resolution. Many players accept MVCD encoded discs. Super Video CD

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660-488: The development of a domestic format that could deliver comparable quality without the restrictions of DVD. It was also hoped that SVCD's development would help to drive down the cost of consumer DVD players and DVD licensing fees in China . Three independent efforts attempted to solve these problems: CVD, SVCD, and HQ-VCD. China Video Disc (CVD), developed by C-Cube Microsystems (a major producer of chips for Video CD players),

690-481: The disc. The other tracks are in Mode 2, Form 2, and contain audio and video multiplexed in a MPEG program stream (MPEG-PS) container. This allows roughly 800 megabytes of data to be stored on one 80 minute CD (versus 700 megabytes when using Mode 1). One CD can hold up to 35 minutes of full quality SVCD-format video and audio. Because of its 480x480 resolution, SVCD picture quality is more than double that of VCD. On

720-455: The downside, this increase in picture resolution sacrifices video length capacity by over 50%. Because of this, titles released on SVCD had to come on twice the number of discs. Unlike other CD-based formats, such as China Video Disc and Video CD , Super Video CD video is incompatible with both the DVD-Video and Blu-ray standards due to a conflict in resolution. However, many DVD and Blu-ray players will play back SVCD resolution video from

750-503: The metadata (see CD ripping ). Most software that is capable of writing from ISO images to hard disks or recordable media (CD / DVD / BD) is generally not able to write from ISO disk images to flash drives . This limitation is more related to the availability of software tools able to perform this task, than to problems in the format itself. However, since 2011, various software has existed to write raw image files to USB flash drives. .ISO files are commonly used in emulators to replicate

780-558: The original Video CD specification) was a relatively late entry. The Chinese Ministry of Information and the Video CD Consortium agreed to join forces, incorporating the features of HQ-VCD under a unified SVCD format. But by the time the SVCD specification was ready in July 1998, CVD had already been adopted by major manufacturers and had quickly established a significant installed base of about 600,000 players. This prompted

810-452: The same objective. A CD can have multiple tracks , which can contain computer data, audio, or video. File systems such as ISO 9660 are stored inside one of these tracks. Since ISO images are expected to contain a binary copy of the file system and its contents, there is no concept of a "track" inside an ISO image, since a track is a container for the contents of an ISO image. This means that CDs with multiple tracks can not be stored inside

840-427: The video formats VCD, SVCD and DVD (with horizontal resolutions of 352, 480 and 720 pixels respectively) but the best resolution usually dictates the design of all the electronics components, most notably the low pass filter. With only one analog low pass filter optimised for one video format (usually DVD 720), the other two video format will suffer from aliasing. The SVCD format is especially prone to " foldover " because

870-466: Was developed as part of a late 1990s Chinese government -sponsored effort to create a next-generation CD-based video standard. The primary motivating factor was the need for an alternative to the DVD format that would not be restricted by technology royalties . The Chinese government was concerned that the DVD format was too tightly controlled by foreign companies, and that a significant opportunity existed for

900-558: Was the earliest entry, having completed its specification in 1997, before the other two had even reached a draft stage. Super Video CD (SVCD) was second, being developed by the government-backed China Recording Standards Committee, under direction from the Chinese Ministry of Information Industry, with technical support from ESS Technology . High-Quality Video CD (HQ-VCD), developed by the Video CD Consortium (consisting of Philips , Sony , Matsushita and JVC — creators of

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