MPEG 1 Layer 3 (MP3) - Normal Quality

Xing has been a major force in the MP3 industry. Their encoder has been both praised (for it's speed) and put down (because it's perceptual model lacked finesse) for a long long time. Well, they have revamped their encoding engine. Addressing the most common complaint, the new Xing encoder now encodes frequencies up to 20 kHz. It also uses the fact that the MP3 standard allows for a lot of encoding parameters to change frame by frame. The latest incarnation of the encoder even changes the stereo model on a frame by frame basis..

Audio Catalyst 2

This allows for files which can compete in size with other encoders but still maintain greater quality. Think of most other current encoders as maintaining constant bitrate and thereby having variable quality throughout the stream. Variable bit rate does the opposite and maintains constant quality throughout the stream. I have included a link to a very good explanation of the subject on the Phillips web site (see the conclusion page). Note, however, that MP3s have a bit rate limit of 160 kbps per channel.

For the purpose of this comparison, I used the Xing encoder in two different modes (other than using it as the CD ripper). For the Normal Quality level, I used a setting of 160 kbps Constant Bit Rate (CBR), joint stereo (M/S stereo) and with the high frequency option disabled. This brings down the maximum frequency to 16 kHz. Now before shouting at me for this, consider the fact that the normal setting is not for very high-end hardware and that most such speakers cannot produce much more than 16 kHz. For the High Quality setting I use the "High" Variable Bit Rate setting with the high frequency option enabled. Joint stereo was enabled (following the instructions of the manual).

Keep in mind that while I have used Winamp to playback for this test, the Sonique player sounds a lot better.

Observations - Normal Quality

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The music encoded at this level didn't really exhibit compression artefacts but you could tell that it is not as good as the original. At times the dynamic range would seem to be not as much and other times different sounds were emphasized. Overall we agree that this is a very good technology plus setting for everyday use unless you have high quality audio equipment.

(Rating: B+)
 

Observations - High Quality

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We came across a big surprise when encoding the Alanis Morissette CD. Even though we were expecting file sizes to stay around those of 192 kbps, we got some files which were more in line with 160 if not 128 kbps. This, folks, is VBR in action. And this is enough for a lot of people to consider using this over the MP2 technology which has a slight edge in quality probably due to a very polished acoustic perceptual model. Overall we had no complaints over the quality here and had to repeatedly listen to sections of music to really compare it with MP2. Another thing we noticed was that the MP2 was suffering at a few rare points. We did not see that happen here because the bitrate just goes up in such places. This may actually make this a more enjoyable listening experience. Well done to Xing for moving the MP3 technology scene along in at a time when most people have stopped working on it.

(Rating: A)
 
 

Table of contents
Introduction	TwinVQ (VQF)
Basics of audio compression	Real Audio G2
Methods of comparison	Microsoft Audio 4
Software and hardware	MPEG 1 layer 2 (MP2)
Selection of music for the comparison	MPEG 1 layer 3 (MP3)
Index of results	Conclusion