“The Origin of Ogg Vorbis”
■ What is Ogg Vorbis?
“Ogg Vorbis” is another audio format similar to the term used so far. Strictly speaking, Ogg and Vorbis are separate, Ogg refers to a container, a container for storing audio data, and Vorbis is the audio codec method.
You can think of it as the same as storing videos from video codecs like CinePak, Indeo, WMV, and DivX in a video format called AVI. However, Ogg itself is not as popular as AVI.
So far, Ogg supports “FLAC – Lossless Audio Codec”, “Speex – Specialized Audio Codec for Conversation Recording”, “Theora – Free Video Codec”, “Icecast – Streaming Audio”. Of these, is FLAC the only one that is relatively widely known during the period? For this reason, there is a section where Ogg and Vorbis are generally recognized as the same thing, and the facts support it.
■ Establishment of Ogg Vorbis
Ogg Vorbis, the container named Ogg and the Vorbis codec, was created by Xiph.Org. This is a non-profit organization whose purpose is to provide multimedia technology that anyone can use freely. Ogg Vorbis is a typical example of this, and it can be used for free even for commercial use, with no royalties or license fees, only with the following conditions.
-Specifications: Public Domain (that is, it can be modified in addition to free, there are no restrictions)
Software: The utility provided by Xiph.Org is GNU GPL (There are no restrictions on use, but there is an obligation to publish the source). Also, most libraries / SDKs have a modified BSD license (the copyright notation of Xiph.org author is not removed when distributing or modifying). From
So, PC games made in Japan often use Ogg Vorbis. However, one of the reasons is said to be that there are no royalties. Behind this movement is the fact that the popular MP3 format license is actually loaded. MP3 encoded music data is exempt from the license fee depending on certain conditions, but basically it is charged. Thomson of France obtained a patent and obtained it under license. The specific license fee is the one shown here, which has hindered the spread of free encoders / decoders.
Even in Japan, “It’s afternoon” temporarily stopped distribution (click here for details on this process) .Xiph.Org has started work to create a free format that is not subject to patents, etc., so to counteract these movements. The development work started in 1993 and the distribution of Ogg Vorbis already started in 2000 (although the version is recent).
Since then, FLAC has joined Xiph.Org (which was previously developed into its own project), and Speex and Theora have joined. Checking the current version, Icecast is 0.8.6 and Theoa is 1.0 Alpha 7 (both as of Dec 2006), which is a bit recent, but all other libraries are over 1.0 so it can be used stably by the moment. I can see that it is.
■ Ogg Features
First, let’s look at Ogg’s features. Ogg was adopted by RFC in May 2003 as “RFC3533 (The Ogg Version 0 Encapsulation Format)” and “RFC3534 (The Application Media Type / ogg)”. By the way, the name Ogg has been popular as a “strategy (tactic?) Of attacking a special attack (Kamikaze Attack) with the Orion G ship (commonly known as Og)”, and this is converted to counter the enemy’s strategy. which is called Ogg. It seems to have been converted. In this case, it seems to have the meaning of counteracting the strategy of the major licensees to earn revenue through patent licensing.
Ogg’s structure is surprisingly easy. First, the original bitstream is divided into 255-byte “packets”. This 255 bytes is the maximum value, so it can be 254 bytes or less. Then put this package on a “page”. Each page has a 27-byte header, for a maximum total page length of 282 bytes. The Ogg file is built by grouping several pages together.
The page header at the top of each page has the structure shown in Table 1. This header is interesting. For example, even if you rearrange the order after dividing it by page, you can still see the header and revert to the original order. It’s more like looking at the Ethernet or IP headers rather than the file format.
