Coding and decoding study notes (10): Ogg Series

Ogg is a free and open standard container format maintained by the xiph. Org Foundation. The Ogg format is not restricted by software patents and is designed for efficient streaming media and high-quality digital multimedia processing.

Ogg refers to a file format that can be incorporated into a wide range of free and open source code codecs, including sound effects, video, text (like subtitles) and metadata processing.

Ogg theora

Theora is a premium-free and open-format lossy image compression technology developed by the xiph. Org Foundation. The Foundation also developed the famous Audio Encoding Technology Vorbis and the multimedia container file Ogg. Theora is derived from the on2 technologies proprietary VP3 encoder after the open source code. Theora is named after a TV program Max headroom.

Theora is an image compression format that can be modified at a rate based on DCT. Like multi-Number Image Encoding formats, theora uses color sampling, Block Based Motion Compensation, and 8x8 DCT blocks. It also supports video compression image types and video compression image types, however, it cannot be used in H. bi-predictive frames (B-frame) for 264 and VC-1, theora does not support line scans, Variable Frame rates, or bit-Depths larger than 8 bits per component.

The image stream of theora can be stored in whatever container file format, and is most often stored in the Ogg file format together with the Audio Code Vorbis, this method can provide multimedia files that are fully open and free of rights. Theora images can also be stored in the matroska file.

According to Google's official blog, there is no standard for web videos. Some websites use flash, but this requires users to have flash players. Some use Java players, however, in order to decode videos and audios In the JVM virtual machine, users need a machine with a very high configuration, and so on.

The good news is that the new-generation HTML 5 standard introduces video elements, and Web developers can specify the video appearance in a standard way. Now the question is which video format to use.

Google thinks that the open standard format can be the bottom line of the unordered video format competition. The final interest solution does not require the most complex format or the most vigorous publicity. It almost has become the industry standard format, so they decided to support the widely used open-source Ogg theora format.

Theora is an open-source derivative version of The on2 technologies VP3 encoder. Google acquired on2 last year.

Source: http://tech.it168.com/a2010/0412/872/000000872493.shtml

On April 9, March 2002, on2 changed the license to lgpl for the VP3 open source code next week. In June 2002, on2 used VP3 as an open source license for xiph. Org and the following similar BSD. On2 has also issued an unchangeable copyright-free statement, no matter who can use whatever software, No matter what derivative products and no matter what purpose. In March 2002, on2 signed an agreement with xiph. Org to use VP3 as a new free video codec and become theora. On2 declared theora as a successor of VP3. On July 6, October 3, 2002, on2 and xiph announced the release of theora's earliest alpha code.

The bit stream format was frozen in 2004 (version 1.0 alpha3). After several years of beta version, theora's first stable version (V1.0) was released in November 2008. Theora is compatible with future players regardless of the video encoding version number after the format is frozen. The current focus is on bug fixes in the "thusnelda" branch. The current version is Beta and will be released as theora1.1.

Theora video compression format is basically compatible with the VP3 video compression format, including a later compatible superset. Theora is a superset of VP3 and VP3 streams (with a small number of syntax revisions). The VP3 stream can be changed to theora stream without further compression, but in turn it is true. VP3 video compression can be decoded by theora. However, theora video demonstration cannot be decoded using the old VP3.

Theora builds the video format on the basis of open source and uses it as the encoding format selected for the video content of Wikipedia. However, theora lacks commercial support and is trying to obtain the acceptance of distributors, especially network distributors.

Mozilla uses this technology to provide HTML5 videos on Firefox. HTML5 videos from Apple and Microsoft are both prepared to use the H.264 File managed by mpeg la. Members of the Group include Microsoft, apple, and many technology companies.

The key to the dispute lies in the issue of license. H.264 requires license.

Mozilla issued the following statement: "We believe that HTML5 videos are in the public interest only when they are supported by multiple parties, open and non-Premium encoding/decoding standards in the same way as W3C authorization standards. If mpga la is willing to provide H.264 based on the open network conditions defined by W3C standards, we will definitely consider using this technology. The organization adheres to our position on theora ."

Opera chief technology officer Hakon Wium lie also provides the following statement: "To enable the growth of the network, all media (including videos) must be used without the need to pay the encoding/decoder license fee. To truly support an open network browser manufacturer, efforts must be made to build a basic audio/video encoding/decoder with no license fee ."

"The difference between source code and intellectual property rights lies in the fact that the usable source code is extremely necessary," Microsoft's blog wrote. At present, H.264's intellectual property rights can be obtained through a clearly defined solution managed by mpeg la. The rights of other codecs are usually unclear ."

Ogg Vorbis

　　Ogg supports audio encoding with excellent quality, especially at low bit rates. The maximum bit rate can reach 500 kbps, which is a strong competitor of AAC.

The term "Ogg" usually refers to the Ogg Vorbis audio file format, that is, the format of the Vorbis-encoded audio file included in the Ogg container. In the past, the extended name of .oggwas used in the form of "no-argument" oggsupport. However, in 2007, the xiph.orgfund will submit a request to allow later compatible users to leave .ogg only in the Vorbis format for use. Xiph. the Org Foundation decided to create new extensions and media formats to describe different types of content, such as those used only for sound effects. OGA, used by a video that includes or does not contain sound (including theora. OGV and program used. OGX.

Vorbis is an open source free software project owner and is the xiph. Org Foundation. The digital audio format specification and software implementation (decoder) generated by this project are lossy audio compression. Vorbi is the most commonly used combination with the Ogg container format. Therefore, it is usually called the Ogg Vorbis format.

Vorbis is a continuation of audio compression development that began in 1993 after Chris Montgomery intensive development began in September 1998, the company announced that it would charge license fees in MP3 audio format. The Vorbis project started as part of the company, the Ogg project of the xiph. Org Foundation (also known as the oggsquish multimedia project ). Chris Montgomery started working on projects and assisted more and more developers. They kept their source code intact until the file format of Vorbis was frozen. In May 2000, 1.0 was released, and a stable version number (1.0) was released on July 19, 2002.

Ogg speex

Ogg Speech Encoding specifically for low bit rate speech encoding.

Ogg FLAC

　　Ogg lossless audio encoding.

On2 vpx Series

　　On2 has developed a series of excellent video codes. I am afraid Nullsoft video is the most widely used video nowadays. They use VP3, Vp5, and VP6 video encoding.

VP3

It has been released as an open source code and is now the Ogg theora project. Of course, theora has a much better quality than VP3.

VP4

The on2 company boasted the world's best video encoding, and later proved that the quality was very general.

VP5

So far it is amazing that on2 has not been released, and he is only seen in Nullsoft video.

VP6

From the very beginning, on2 provided this encoder for everyone to download, and the quality was good. It seems that it has been disabled again recently. There is only one decoder on the home page. On2 truemotion VP6 is a proprietary lossy video codec format and video codec. It is a detailed embodiment of truemotion video codec. It is a series of video codec developed by on2. it is widely used in Adobe Flash, Flash video, and javafx media files.

VP7

The newest encoder of on2 has made many progress in vp6. In January 2005, on2 announced the release of a new version of VP7 with a better compression ratio than vp6. In June April, on2 licensed the on2 Video Encoder 9 to contain VP6 and VP7) for Macromedia Flash. On July 15, August 2005, Macromedia announced that they chose VP6 as the flagship codec for playback of the new flash player8 video.

Vp8

Google acquired on2 technologies in 2009 and announced open-source Vp8 in the form of a BSD license at the Google I/O conference in May 19, 2010 .. Vp8 is the second codec released by on2 technologies after VP3. (The xiph. Org Foundation took over VP3 in 2002 and named theora as the title, and then opened theora in the form of a BSD license ). The biggest requirement for Google to open source Vp8 is from the Free Software Foundation. In 264, the Free Software Foundation sent an open letter to Google requesting Google to gradually replace Adobe Flash and H.264 on YouTube with open-source Vp8 and HTML 5.

In July May 19, 2010, webm was launched. Webm has contributed from Mozilla, opera, Google and more than 40 other publishers and computer software and hardware vendors (including AMD and NVIDIA), and aims to vigorously advocate the use of Vp8 in HTML5. Internet Explorer 9 supports vp8.

Note: The above materials are from Wikipedia.

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