Ogg(ogg Vorbis) is a new audio compression format, similar to existing music formats such as MP3. But one difference is that it is completely free, open and without patent restrictions. Vorbis is the name of this audio compression mechanism, while Ogg is the name of a project to design a completely open multimedia system. At present, the plan has only realized OggVorbis.

The extension of Ogg Vorbis file is. OGG。 The design format of this file is very advanced. The OGG file created now can be played on any player in the future, so this file format can be continuously improved in size and sound quality without affecting the old encoder or player.

■ Why use Ogg Vorbis format?

As we all know, MP3 is a lossy compression format, so the compressed data is lossy compared with standard CD music. VORBIS is also lossy compression, but the loss is reduced by using a more advanced acoustic model. Therefore, OGG coding at the same bit rate sounds better than MP3. In addition, there is another reason, MP3 format is protected by patent. If you want to publish your own works in MP3 format, you need to pay royalties to Flawn Hof (the company that invented MP3). VORBIS has no such problem at all.

For music fans, the obvious advantage of using OGG files is that they can get better sound quality with smaller files. Moreover, because OGG is completely open and free, making OGG files will not be restricted by any patents, and it is expected to obtain a large number of encoders and players. This is why there are so few MP3 encoders, and most of them are commercial software, because Flawn Hof collects royalties.

Having said that, in fact, sound quality is the most concerned issue for everyone.

■ Is the sound quality of Og Vorbis really comparable to that of MP3?

Because Vorbis uses a completely different mathematical principle from MP3, it faces different challenges when compressing music. In the current listening test, Vorbis and MP3 files encoded at the same bit rate have the same sound quality.

■ Will the sound quality of Og Vorbis continue to improve?

Because Vorbis uses a flexible format, after the file format is fixed, it is obviously possible to adjust the sound quality and train new algorithms. So its sound quality will get better and better.

Because Ogg is still in the BETA testing stage, there are still some problems in the encoder at this stage. Ogg developers have promised to improve existing problems in the next BETA version. The key point is that these problems are only caused by the writing of software, and have nothing to do with the algorithm used in Ogg format itself.

■ How does the file size of ■Ogg compare with MP3?

If two files are encoded with the same bit rate and CBR (constant bit rate, which means that files have a bit rate from beginning to end), they must be the same size. At present, Vorbis adopts VBR (Variable Bit Rate) mode to encode, which makes the file of Ogg smaller, because VBR mode can handle audio data that can be greatly compressed (such as silent period), saving space. How much bit rate can Vorbis encode?

Theoretically, there is no fixed bit rate. The designed coding bit rate of Vorbis is 16kbps~ 128kbps/ channel. However, there is nothing in the specification that restricts you from encoding files at 5 12kbps or 8kbps.

■ Does ■Ogg Vorbis support ID3 information similar to MP3?

Support. Vorbis format includes a flexible and complete comment column, which can be used to fill in all kinds of relevant information.

■ How fast can the encoder/decoder be?

Current codecs/decoders are close to some commercial codecs in speed. As the program has not been optimized, I believe that when everything is finished, it will be at least equal to MP3.

■ Does ■Ogg Vorbis format support streaming playback?

Audio stream is an important part of vorbis. Vorbis format is based on simple streaming transmission from the beginning of design. In addition, the designers of Vorbis are cooperating with the creators of Icecast streaming media software to make Icecast compatible with Vorbis. When the official version is released, there will be a variety of software or software plug-ins to support streaming OGG playback.

■ What software and hardware currently support Ogg Vorbis?

So far, Sonique, FreeAmp, Winamp, XMMS and kmpg all support playing Ogg Vorbis files through plug-ins. In view of the influence of these softwares, more softwares will support OGG format. In addition, LAME and BladeEnc, the two most popular MP3 encoders, also announced that they will support encoding Ogg Vorbis files.

■ What is the uniqueness of ■Ogg Vorbis?

Vorbis has a well-designed and flexible annotation, which avoids such complicated operations as ID3 tagging of MP3 files. Vorbis also has a bit rate scaling function: the bit rate of a file can be adjusted without recoding. Vorbis file can be divided into small pieces and edited with sample granularity; Vorbis supports multiple channels; Vorbis files can be logically connected and so on.

■ Where can I find relevant software and development materials to download?

This is the official website of Ogg Vorbis.