AAC, MP3, MP3 Pro, Ogg Vorbis, WMA. In the digital age, choosing one or the other of these standards is not easy. Especially since their properties lend them to one use instead of another. Detailed review

Which format for digital music should you choose?

MP3 is far from alone in the world. Feeling that compressed digital music is likely to change the record market, many developers have begun designing formats designed to offer the best compromise between the amount of data used and the sound quality. Thus, AAC for Apple, WMA from Microsoft and other OGG Vorbis communities were born. So many standards that have their advantages and disadvantages and that it is advisable to know them well before choosing the most appropriate coding software for your needs.

First, remember that an audio CD uses uncompressed data. Music is digitized on its surface at a rate of 44,100 samples per minute. Second, each of these samples is encoded in 16 bits (2 bytes) and in stereo. This gives a total of 176 KB per Second music, or about 10 MB per second. Minute. Even if an increasing number of Internet users use broadband, websites that sell music for download cannot afford to offer 40-minute four-minute songs. Compression formats allow this amount of data to be shared by a factor ranging from 8 to 15, with little or no loss of quality.

All of these compression algorithms work on the same principle: eliminate frequencies that the human ear does not perceive at all, or very little, and level the frequencies close to each other for identical values ​​to increase compression. These are the so-called “destructive” algorithms. In other words, when converting a compressed audio file from an audio CD to an audio CD format, the resulting data will not be the same as the original file. Depending on the formats and needs, compression may be more or less important. It is defined by what is called bitrate, that is, the flow of information per. Second of music. It can range from 32 kbps (kilobits per second) to 320 kbps. Detailed review of the different formats.

MP3

Commonly designed by the Fraunhofer Institute and Thomson and standardized in 1992, it is a derivative of audio compression used for MPEG-1 format videos (MP3 also stands for MPEG-1 Audio Layer 3).
This is the format offered by the main configuration panel. In fact, we can define a bit rate (“bit rate” in jargon) that ranges from 32 to 320 kbps. From 128 Kbps the sound quality becomes enough to encode songs. At 192 Kbps, the quality is similar to an audio CD. At this compression rate, one minute of music equals 1.4 MB of data. But it is also possible to choose a variable bit rate called VBR (variable bit rate). In this case, the encoder increases the compression ratio in less complex music regions, reducing the size of the final file slightly. The benefit depends largely on the type of song: 5 to 10% with an extract from classical or jazz music, not much with rock or rap.
The great advantage of MP3 remains its compatibility with all portable audio players, but also certain hi-fi systems, car radios and DVD players in the living room. Almost universal, it appears on all free download sites such as Kazaa or eDonkey. On the other hand, this format sinks slightly at the level of high frequency recovery and is therefore less suitable for e.g. Classical music.
Free MP3 encoding software includes WinAmp and MusicMatch JukeBox. Lastly, note that there are several MP3 coding algorithms, with “Fraunhofer” being the most widely used, and “Lame” being the most effective, with the latter being especially compatible with Pinnacle’s CDex.

WMA

Launched in 1999 by Microsoft, WMA (Windows Media Audio) was only intended to counter the rise of MP3. With compelling arguments. By utilizing the features of the human ear more effectively in the audible spectrum, WMA is able to eliminate frequencies that are truly useless while maintaining certain high frequencies that affect sound quality. The relatively efficient compression algorithm maintains a quality that corresponds to an audio CD with a 128 kbps bit rate, or 1 MB per second. Minute of a song.
Completely free of charge, WMA also has the advantage of having an encoder built into Windows Media Player. An effective way to ensure the spread of this support. Especially since this format is linked to precise copyright management (DRM or Digital Right Management) that allows, for example, to define a limited useful life of files or prohibit recording options. That’s why some music download sites use it. Many digital audio players also support WMA and reputable shareware such as WinAmp allows encoding in this format.

AAC

Contrary to belief, AAC (Advanced Audio Coding) is not a format developed by Apple, but by a consortium that includes the Fraunhofer Institute (father of MP3), Sony and even Dolby. Prestigious names that grow well. In fact, AAC is arguably the most efficient compression algorithm. Unlike MP3 and WMA, it is not based on MPEG-1 but on MPEG-4 (the format behind DivX). This choice seems to have paid off as it allows you to get a better compromise between compression ratio and sound quality. That’s why at AAC we get the equivalent of audio CD quality with a bit rate of only 96 kbps. In addition, as with WMA, the DRM (copyright management) features and the ability to control sounds on 48 different channels,
We found AAC on the Apple iTunes online music site and on your iPod player. But it is also integrated into software like WinAmp.

OGG Vorbis

OGG Vorbis is in audio compression format, as Linux is in operating systems. In fact, it is an “open” format whose source codes are public and can be customized and changed by anyone. It’s still a pretty effective format. At 128 kbps, we reach the quality level of an audio CD (1 MB in 1 minute). The compression structure of OGG format is also significantly different from MP3, WMA and other AACs. Segmenting audio sources into successive packets, the compression algorithm works first on each packet independently of the others. This allows you to not really have weakness at certain frequencies and to maintain the same quality regardless of the type of music.
In addition, polyphony features allow playback of up to 255 audio channels (sic). The package structure also makes it very suitable for streaming on the Internet, especially for online radios. Open, OGG Vorbis needed to evolve quickly and maybe move closer to AAC in terms of performance.

Digitizing music involves compressing the original sound that may distort the work. AAC, MP3, WMA or Wav: which of these formats offers the best representation?

If we are not aware of or no longer aware of the quality of today’s music in its digital form, it is often because our audio rendering tools are so poor. This is due to the speakers that come with desktops or built-in laptops, but also to the headphones / earphones that come with MP3 players, which are mostly entry-level products. On the other hand, for those with high performance equipment, listening to poorly recorded or poorly coded songs quickly becomes unpleasant.

Therefore, choosing the best audio format for the same recording is best for fun. Today, there are 5 main audio file formats: AAC (promoted by Apple, iPod and iPhone in mind), WMA (promoted by Microsoft), MP3, Wav and Ogg (the last three are neutral).

In addition to the file format, there is another criterion called the compression ratio. The more a file is compressed, the more it removes the frequency bands in the music and therefore potentially small nuances that enrich the listening. The compression ratio is expressed in the number of bits, the basic computing unit. Values ​​range from 56 Kbits / s (56,000 bits per second, minimum quality for radio or podcasts) to 320 Kbits / s. The lower the number, the more compressed and small the file will be, but the less comfortable it is to listen to.

The sampling frequency is also important. This value is expressed in Hz and must be as large as possible to preserve the shape of the original audio signal and therefore the accuracy of the recording. In general, we prefer a file with a sampling rate for CD quality (44,100 Hz), but we also found lower quality files (22,000 Hz).

The study from the Musiclassics studio.

This online digital music sales site dedicated exclusively to classical music launched a modernization of its interface during 2009. On this occasion, the question arose about the best audio formats that its customers could offer. To make it right, the site invited 15 people (bloggers, musicians, fans, audiophiles) to a listening session in a professional studio. They had to judge from 1 to 5 the quality of 4 different musical excerpts representative of the diversity of classical music (voice, violin, piano, orchestra and heart), coded in 6 different ways: MP3 320 Kbps, Wav, WMA 192 Kbps and 320 Kbps, AAC 192 Kbps and 320 Kbps. Here are the results of this study:

Examine listening results
File formats average rating received (out of 5)
MP3 320 Kbps ……………… 3.1
Wav ………………………………. 3.5
WMA 192 Kbps …………… 3.7
AAC 192 Kbps ……………. 3.8
AAC 320 Kbps ……………. 3.8
WMA 320 Kbps …………. 4.0

Since formats compressed at 128 Kbps or less have not been studied, the difference in ratings is relatively small. However, the MP3 format, even compressed at 320 Kbps, is the worst with a significant difference. More surprisingly, the CD (Wav file) is located behind the WMA and AAC formats. These files seem to change the rendering slightly. It is observed that the difference in notation between the 192 and 320 Kbps compression is not significant.

But too bad MusiClassics did not want to integrate the free and open OGG file format into these results. However, we noticed that as a consumer it would be better to choose 192 Kbps AAC or WMA files instead of 320 Kbps MP3 and 192 192 Kbps MP3. 128 Kbps files would score less than 3/5, which is not satisfactory.