The HTML5 specification introduces the video element for the purpose of playing the video, partially replacing the object element. The HTML5 video is intended by its creator to be a new standard way of displaying video on the web, not the previous de facto standard using proprietary Adobe Flash plugins, although early adoption is hampered by a lack of agreement on video encoding formats and audio encoding formats to be supported in web browsers.
Video HTML5 video
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& Lt; video & gt; Elements was proposed by Opera Software in February 2007. Opera also released a build preview on display that same day, and a manifesto that calls for video to become a world class web citizen.
Maps HTML5 video
& lt; video & gt; example element
The following HTML5 code fragment will embed WebM video into web pages.
The "control" attribute allows the user interface of the browser itself to control playback. Alternatively, playback can be controlled with JavaScript, which web designers can use to create custom user interfaces. The optional "poster" attribute specifies the image to be displayed in place of the video before playback begins. The goal is to become a video representative.
Many sources
Video format support varies between browsers (see below), so web pages can provide videos in various formats. For other features, browser sniffing is used occasionally, which may be error-prone: the web developer's knowledge of the browser is bound to be incomplete or not up-to-date. The browser in question "knows best" what format can be used. The "video" element supports fallback through various source specifications. Using a number of & lt; source & gt; element, as shown below, the browser will automatically select which files will be downloaded. Alternatively, the JavaScript function canPlayType () can be used to accomplish the same thing. The "type" attribute specifies the MIME type and possibly a list of codecs, which helps the browser to determine whether it can decode the file. Even with only one option, such instructions may be required for browsers to query the multimedia framework for third-party codecs.
Supported video and audio formats
The HTML5 specification does not specify what video and audio formats the browser should support. Free user agents support any video formats that they feel are appropriate, but content writers can not assume that any video is accessible to all qualified user agents, since the user agent does not have a minimum set of video and audio formats to support it.
The HTML5 Working Group considers it necessary to specify at least one video format that must be supported by all user agents (browsers). The ideal format in this case is:
- It has good compression, good image quality, and low decode processor usage.
- Royalty free.
- In addition to the software decoder, a hardware video decoder must exist for that format, as many embedded processors do not have the performance to decipher the video.
Originally, Ogg Theora is the standard video format recommended in HTML5, as it is unaffected by known patents. However on December 10, 2007, the HTML5 specification was updated, replacing the reference to a concrete format:
The user agent must support Theora video and Vorbis audio, as well as Ogg container format.
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It will be helpful for interoperability if all browsers can support the same codec. However, there is no known codec that meets all current players: we need a codec that is known to not require per-unit or per-distributor licenses, compatible with open source development models, which are of sufficient quality to use, and that is not a risk additional submarine patents for large companies. This is an ongoing issue and this section will be updated once more information is available.
The result is an HTML5 video polarization between industry standards, an ISO-certified but patented format, and a free open format.
Free format
Although Theora is unaffected by any known non-free patents, Apple has expressed concerns about unknown patents that may affect it, whose owners may wait for companies with vast financial resources to use the format before suing. Formats such as H.264 may also be subject to unknown patents in principle, but they have been used much more widely and thus it is suspected that each patent holder will make himself known. Apple is also opposed to requiring Ogg format support in HTML standards (even as a "must" requirement) on the grounds that some devices may support other formats much easier, and that HTML is historically unnecessary to any special format.
Some web developers have criticized the removal of the Ogg format from the specification. Follow-up discussion also occurs on W3C questions and blog answers.
Mozilla and Opera only support open formats Theora and WebM. Google declared its intention to remove support for H.264 in 2011, specifically for HTML5 video tags. Although it was removed from Chromium, in November 2016, it has not been removed from Google Chrome five years later.
MPEG-DASH_Support_via_the_HTML5_Media_Source_Extensions_.28MSE.29 "> MPEG-DASH support via HTML5 Media Source Extensions (MSE)
MPEG-DASH standard adaptive bitrate streams can be used in Web browsers via HTML5 Media Source Extensions (MSE) and JavaScript-based DASH players. Such players, for example, open-source dash.js projects from the DASH Industry Forum, but there are also products such as bitdash bitmovin (using HTML5 with JavaScript, but also Flash-based DASH players for older Web browsers that do not support MSE HTML5).
Google Purchase from On2
Google's acquisition of On2 in 2010 resulted in the acquisition of the VP8 video format. Google has granted a royalty-free license to use VP8. Google also started WebM, which incorporates the standard open source VP8 video codec with Vorbis audio in Matroska based containers. The opening of VP8 was greeted by the Free Software Foundation.
When Google announced in January 2011 that it would end H.264 genuine support in Chrome, criticism came from many places including Peter Bright from Ars Technica and Microsoft web evangelist Tim Sneath, who compared Google's move to declare Esperanto's official language from United States. However, Haavard Moen of the Opera Software strongly criticized Ars Technica's article and Google responded to the reaction by clarifying its intention to promote WebM in its products based on openness.
After the launch of WebM, Mozilla and Opera have called for VP8 inclusion in HTML.
On March 7, 2013, Google Inc. and MPEG LA, LLC announced an agreement that included "potentially significant" techniques for VP8, with Google receiving licenses from MPEG LA and 11 patent holders, and MPEG LA terminated its efforts to establish a VP8 pool patent.
In 2012, VP9 was released by Google as VP8's successor, also open and royalty free.
By the end of 2017 the new AV1 format developed by Alliance for Open Media (AOMedia) as the VP9 evolution has reached a feature freeze, and bitstream freezing is expected for January 2018. Firefox every night includes support for AV1.
Non-free format
H.264/MPEG-4 AVC is widely used, and has speed, compression, hardware decoder, and good video quality, but is burdened with patents. H.264 users require either a license from an individual patent holder, or from MPEG LA, a group of patent holders including Microsoft and Apple, except for some use of Internet broadcast videos. H.264 is commonly used in MP4 container format, along with advanced Audio Coding (AAC) audio. AAC is also patented by itself, so MP4 users must have H.264 and AAC licenses.
In June 2009, WHATWG concluded that there is no format that complies with the specified requirements.
Apple still only supports H.264, but Microsoft now supports VP9 and WebM, and has promised support for AV1.
Cisco creates a licensed H.264 binary module available for free
On October 30, 2013, Cisco announced that they created a H.264 binary module available for download. Cisco will pay patent licensing fees for the binary module when downloaded by the currently used software , making H.264 free to use in certain cases.
In the announcement, Cisco mentioned its intention to continue using the WebRTC project as the reason, because the WebRTC video chat feature would benefit from having a supported video format across all browsers. The H.264 module will be available on "all popular or eligible platforms that can be loaded into any app".
Cisco also plans to publish the source code for those modules under the BSD license, but without paying royalties, so this code will practically be free software only in countries without H.264 software patents, which is correct about other implementations which exists.
Also on October 30, 2013, Mozilla's Brendan Eich announced that Firefox will automatically download H.264 Cisco modules when required by default. He also noted that the binary module is not a perfect solution, because users do not have full free software rights to "modify, recompile, and redistribute without license agreement or fees". So Xiph and Mozilla continue the development of Daala.
OpenH264 only supports the baseline profile of H.264, and does not necessarily handle the need for an AAC decoder. Therefore, it is not considered adequate for regular MP4 web video, which is usually in high profiles with AAC audio. However, for use in WebRTC, AAC removal is justified in the release announcement: "standard bodies are aligned to Opus and G.711 as common audio codecs for WebRTC". There are doubts about whether a closed global AAC license, such as Cisco for H.264, can be done after the AAC license bureau removes the price limit shortly after the release of OpenH264.
Browser support
This table shows which video formats may are supported by certain user agents. Most browsers listed here use multimedia templates to decode and display videos, rather than incorporating such software components. It is generally not possible to tell a set of formats supported by a multimedia framework without querying it, as it depends on the operating system and third-party codecs. In this case, the video format support is an attribute of the framework, not the browser (or layout engine), assuming the browser correctly questions the multimedia framework before rejecting unknown video formats. In some cases, the support listed here is not a function of codecs available within the basic media framework of the operating system, or the capabilities of codecs built into the browser, but it could also be possible browser add-ons, for example, cutting out HTML parsing normal browser from & lt; video & gt; tags to embed a plug-in-based video player.
Note that video files typically contain video and audio content, each encoded in its own format. The browser must support video and audio formats. View HTML5 audio for the table where the audio format is supported by each browser.
The video format can be determined by the MIME type in HTML (see example). The MIME type is used to question the multimedia templates for supported formats.
From this browser, Firefox and Opera only use library for integrated coding. In practice, Internet Explorer and Safari can also guarantee the support of certain formats, because their manufacturers also create their multimedia framework. At the other end of the scale, Konqueror has an identical format support for Internet Explorer when it runs in Windows, and Safari when running on a Mac, but the support chosen here for Konqueror is typical for GNU/Linux, where Konqueror has most of its users.. In general, browser format support is largely determined by the conflicting interests of vendors, specifically that Media Foundation and QuickTime support commercial standards, while GStreamer and Phonon can not legally support other than the default format by default on the free operating systems they are intended for.
- Notes
Digital rights management (Media Extensions Encryption)
HTML has support for digital rights management (DRM, limiting how content can be used) via HTML5 Encrypted Media Extensions (EME). The addition of DRM is controversial as it allows to restrict the freedom of users to use media that is restricted by DRM, even if fair use gives the user the legal right to do so. The main argument in W3C approval of EME is that video content will be submitted in plugins and applications, and not in web browsers.
In 2013 Netflix adds support for HTML5 videos using EME, in addition to their old delivery methods using the Silverlight plugin (also with DRM).
Usage
In 2010, after the launch of the Apple iPad and after Steve Jobs announced that Apple's mobile device would not support Flash, a number of high-profile sites began presenting H.264 HTML5 video instead of Adobe Flash for the user-agent that identified it as iPad. HTML5 videos are not as widespread as Flash videos, although there is the introduction of HTML5 experimental based video player from DailyMotion (using Ogg Theora and Vorbis format), YouTube (using H.264 and WebM format), and Vimeo (using.264 format).
Support for HTML5 videos continues to increase. As of June 2013, Netflix added support for HTML5 video. In January 2015, YouTube switched to using HTML5 video instead of using Flash by default. In December 2015, Facebook switched from Flash to HTML5 for all video content.
In 2016, Flash is still widely installed on the desktop, while it's generally not supported on mobile devices like smartphones. Flash plugins are widely assumed, including by Adobe, destined to be deleted, which will leave HTML5 videos as the only widely supported method for playing videos on the World Wide Web. Chrome, Firefox, Safari, and Edge, have plans to make almost all click flash content to play in 2017. The only major browser that does not announce a plan to stop Flash is Internet Explorer. Adobe announced on July 25, 2017 that they will permanently end flash development by 2020.
See also
- HTML5 audio
- Comparison of layout engine (HTML5 Media)
- Comparison of HTML5 and Flash
References
External links
- "HTML5 - Video Elements", What WG , W3C , retrieved September 23 2016 .
- Daoust, Francois; Hoschka, Philipp; Patrikakis, Charalampos Z (2010), Go to Video on the Web with HTML5 (PDF) , Barcelona: NEM Summit Ã, .
- Lawson, Bruce; Lauke, Patrick H. (February 11, 2010), Introduction to HTML5 video , Opera .
- HTML5 Video video platform software and news.
- Pieters, Simon (March 3, 2010), Everything you need to know about HTML5 video and audio , Opera < span title = "ctx_ver = Z39.88-2004 & amp; rft_val_fmt = info% 3Aofi% 2Ffmt% 3Akev% 3Amtx% 3Abook & amp; rft.genre = books & amp; rft.btitle = Everything you need to know about HTML5 video and audio & amp; rft.pub = Opera & amp; rft.date = 2010-03-03 & amp; rft.aulast = Pieters & amp; rft.aufirst = Simon & amp; rft_id = http% 3A% 2F% 2Fmy.opera.com% 2Fcore% 2Fblog% 2F2010% 2F03% 2F03% 2All you need to know about html5-video-and-audio-2 & amp; rfr_id = info% 3Asid% 2Fen.wikipedia.org% 3AHTML5 video ">
- HTML5 Video: A Practical Guide: Conversion, Cropping, Javascript, and Flash Backup for HTML5 Videos
- Mozilla about media formats supported by browsers
Source of the article : Wikipedia
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