by May 5, 2003 0 comments



Ogg Vorbis. No, it’s not another tongue twister from French cuisine. It is a format for encoding your music, one that can give MP3 a run for its money. Money is the one major difference between Ogg Vorbis and MP3. Fraunhofer Institute in Germany holds the patent for MP3, while Ogg Vorbis is free.

If you develop an application involving MP3, you have to pay royalty/licensing fee. If, as an artist, you want to distribute your music online as MP3 files for free, you need to pay royalty. Ogg Vorbis can be music for such ears. It comes as an open source, patent-free format for music compression that works as well as, if not better than, MP3. It is being promoted by Xiphophorus (www.xiph .org), dedicated to making open source audio/video protocols.

Ogg on your Mobile
Sony Ericsson P800, a Mobile PDA, now gets an Ogg Vorbis player of its own. This mobile has a Symbian-based OS and a built in MP3 functionality.
Also, an Austria-based independent developer Philipp Schmid is making the AudioMagic player. It supports Ogg Vorbis playback, but may support MP3 in the future. The interesting part about the player is that it can run in full screen as well as small-screen mode. In the small-screen mode, the software can be operated using the jog dial. Check it out at http://gro.o000o.org/projects/symbian/audiomagic/

Ogg Vorbis has two parts: Ogg and Vorbis. Ogg is the wrapper format that can group various audio/ video streams that belong together. Vorbis, on the other hand, is the codec written inside the Ogg framework, and is used to compress various audio sources with good results.

Any compression is of two types: lossy and lossless. In lossy compression, the data that cannot be perceived by the human eye or ear is eliminated from the source data (for example, jpeg). On the other hand, in the case of a loss-less algorithm, the data is compressed and then decoded for it to be used (for example, zip). Ogg Vorbis and MP3 are both lossy formats. 
Like MP3s, Vorbis supports both variable bitrate and constant bitrate conversions. However, unlike MP3, which uses bitrate as a measure of quality, Ogg Vorbis uses a quality measure from —1 to 10 (like the jpeg algorithm). Quality level 4 is equivalent to 128 Kbps ripping. 

Since it’s free, most commercially available rippers and encoders–Winamp, Quicktime and Real–support ripping to Ogg Vorbis directly. You will find it in the Options menu of these software. 

Sounds interesting? But don’t go changing your MP3s to Oggs right away. You may be disappointed. Changing from one lossy format to another generally gives, in the best-case, equivalent results, if not bad. This is because MP3 algorithms are different from the Ogg algorithms. When you change from MP3 to Ogg, you have to make an intermediate wav file. This wav file does not have the parts that were stripped by the MP3 encoder. Subsequently, when the wav file is converted into Ogg, the Ogg encoder may strip other parts of the audio. This may make the audio sound worse.

Ogg on your Palm
The first commercial audio player for the Palm Tungsten T was not from any of the biggies, but from
Normsoft. It is called Pocket Tunes. Though from version 1.4 it supports MP3, natively it was just an Ogg Vorbis player. This player also supports skin features like Winamp that are quite intuitive. Other features include a graphic equalizer, background playback and
playlists. Check it out at www.pocket-tunes.com

We ran a series of tests, which looked at file sizes, time required for encoding, effects of bit-rates and sampling frequencies and the sound quality. These tests were done on 16 wav files that were a total of 755 MB. These files were converted into Ogg Vorbis and MP3 formats. For MP3, we used a freely available encoder that used the Lame 3 engine for encoding and for Ogg Vorbis we used OggdropXPd, freely available at www.vorbis.com. You’ll find our test results in the table . 

Ogg on your Palm
Format Quality Sampling
Frequency
File
Size
Time
Taken
MP3 128 kbps
(constant bitrate)
44khz 68.5 MB 16’59”
Ogg Vorbis Quality 4 (128 Kbps
Nominal Bitrate)
44khz 65.5 MB 8’29”

As you can see from the results, the Ogg output is 3 MB lesser. The time taken to encode is half as much as of the MP3.

What about the performance? We did some subjective blind listening tests and found that there was no major difference in the quality of music produced. It is more a matter of choice for a format.

Ogg Vorbis has reached version 1.0 with a lot of bugs in the earlier betas removed. The next logical step after making the codec was to make it capable of streaming. This has been done using Icecast (www.icecast .org), but this is still in development stage. Most players, including Winamp, support Ogg Vorbis and Icecast streaming. 

Geetaj Channana

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