AAC, M4A, MP3, WAV, WMA… These are some file extensions that you've probably heard of or even know more about.
Digital audio is the reality for almost every computer user. Due to the immeasurable popularization of MP3 in the last decade, it is common to consider the extension as the representation of an audio file. But the fact is, MP3 is just a way to create music files.
All the aforementioned extensions attest to the advancement and popularity of sound digitization. In this article, you will learn the basic differences between them and other formats that may not be common for you.
Before formats, PCM
That's the acronym for Pulse Code Modulation, and this is the oldest sound digitization technology. The history of PCM begins in the 1930s, as a way to represent analog signals digitally, that is, with their waves represented at regular intervals.
In the same way that a video is in fact a sequence of still images, the amplitude, that is, the extension of a digitized sound wave is not constant. Sound digitization basically involves two parameters: sample rate and bit depth. The first indicates the number of times the amplitude of a wave is measured, while the second indicates the number of bits in each sampling. The variation of these parameters indicates the fidelity of the audio to the recording.
PCM originated the different ways of digitizing audio. Sony and Philips, in the 70's, developed the technology and created the CD, which has 44100 samples per second (44.1 KHz) and 16-bit amplitude. PCM with 8 KHz of sampling and 8 bits of resolution is used in the telephone system.
Uncompressed and compressed formats
Digital audio formats are basically divided into two groups: uncompressed and compressed. The former guarantee maximum quality, as they do not modify any bit of the original. On the other hand, they require space. An audio CD uses the CDDA (Compact Disc Digital Audio) format and holds 80 minutes of music, for example. WAV and AIFF are examples of uncompressed.
Compressed formats, as the name suggests, compress data in order to reduce their size. Formats like APE, FLAC and M4A are known as lossless and capable of compressing audio without losing quality.
Other formats further compress the files, taking up a lot of space. However, they already use the principle of giving up absolute quality to gain more space and convenience. One way to achieve this is to remove audio tracks theoretically imperceptible to the human ear. There is a loss of quality, but it is often really imperceptible. Therefore, compressed formats are more popular for the average user. An example is the MP3.
WAV e AIFF, big and with quality
WAV and AIFF are two good examples of uncompressed formats that use the PCM method.
WAV stands for Waveform Audio File Format, and was developed by Microsoft and IBM for storing audio on PCs. It is based on PCM and does not “sacrifice” data, so it requires a lot of space. On average, it occupies up to 10 MB per minute. It is compatible with virtually any player today. Due to its maximum quality, it is suitable for editing, mixing and professional work.
As a limitation, files in this format cannot be larger than 4 GB. Common extensions are WAV and WAVE.
AIFF is the acronym for Audio Interchangeable File Format, and it can be said that it is for Apple (which developed it based on technology from Electronic Arts) what WAV is for Microsoft. Also based on PCM, it is an uncompressed format, therefore of quality, but it takes up space. The common extension is AIFF or AIF, but the list of supported players is a little shorter than the WAV format.
Compression without losing quality
There are formats that manage to compress data without sacrificing quality, such as M4A, APE and FLAC. They are known as lossless or without loss, in free translation. These formats are like a bridge between quality and convenience, as they are able to maintain the original, unaltered quality in less space than WAV or AIFF.
FLAC
It's the acronym for Free Lossless Audio Codec, created in 2003. As the developers say, it's like a ZIP, but made specifically for audio and with the advantage of being able to run on several players. It is also based on PCM, and the data has a kind of signature that allows checking the integrity of the file.
It's the acronym for Free Lossless Audio Codec, created in 2003. As the developers say, it's like a ZIP, but made specifically for audio and with the advantage of being able to run on several players. It is also based on PCM, and the data has a kind of signature that allows checking the integrity of the file.
Monkey Lossless Audio File (extension APE)
This is the Monkey Lossless Audio File extension, another way to compress audio without losing quality, which is also described as a ZIP for music. It has open source code available, and has an error detection system and its own tag system.
Compared to FLAC, it has better compression ratios, but requires more processing resources, according to benchmark results.
ALAC (Apple Lossless)
Acronym for Apple Lossless Encoder format. MP4 is a type of extension that uses this format, joining audio and video in a container. M4A is an extension with the audio tracks of movies with MPEG-4 codec.
FLAC, APE and ALAC on average digitize audio at half the original file size, ranging from 40% to 60%. These formats are good for editing and for users who value maximum quality. An option for a backup of your CD collection, for example. Imagine that you made your entire collection in MP3, and then you realize that a better technology has emerged? By backing up with lossless technology, copies remain faithful to the originals regardless of advances.
But it's worth remembering that these formats are not as compressed as the ones you see now.
The convenience of compression
There are audio formats that give up quality — to a certain extent — to take up less space. They are useful for those who suffer with space or want to load more files in a player, for example.
They are more common because, for the user in general, the loss of quality is not something noticeable.
MP3
Undoubtedly, MP3 is the most popular format, compatible with all software and media players. Created in Germany, the format uses perceptual encoding, that is, it encodes only the sound frequencies captured by the human ear.
The reason for the success of MP3 is the fact that it manages to balance good rates of compression and quality. There is, yes, a loss of quality compared to the original, but at levels that are practically imperceptible to most users. MP3 even creates files that are 10% the size of PCM files.
MP3 maxes out at 320 kbps. Between 192 kbps and 320 kbps, the quality is comparable to a CD. Between 128 kbps and 192 kbps, some people already notice a loss of quality, but that depends a lot on who listens.
OGG Vorbis (extension OGG)
It is a non-proprietary format and even with better compression rates than MP3. However, the explosion of MP3 makes the support and dissemination of OGG encounter many difficulties. In addition, the fact that it is open source makes it difficult to standardize the format.
The developers claim that the format is designed to "completely replace all proprietary and patented formats". MP3 is a proprietary extension, and that's the appeal OGG tries to appeal to artists and labels. For some time now, OGG has been considerably used in games.
AAC
Acronym for Advanced Audio Coding (Advanced Audio Coding, in free translation) is considered the strongest competitor of MP3. The format is based on the MPEG-4 standard and was popularized by Apple, which adhered to the format on the iPod and iTunes, even selling the store's audio files in that format, to the detriment of MP3.
Tests show that the AAC format has more flexibility than MP3, resulting in higher compression quality. In general, the AAC format has better quality at lower bitrates (128 kbps, for example).
AAC is not a proprietary format, despite what it looks like. The confusion is due to the adoption of Apple, but it is not confirmed. AAC is supported by devices from Sony, PSP, Nintendo DSi, Xbox 360, Zune, iPod, iPhone, Windows Mobile. In terms of software, Media Player Classic, BSPlayer, Foobar, AIMP and Winamp are compatible.
WMA
Microsoft's format, it has copying abilities with content protection, in response to the distribution problems that plague the MP3. It is a proprietary technology with four distinct codecs: WMA as a competitor to MP3; WMA Pro, more modern and with support for high definition audio; WMA Lossless, which compresses without loss of quality; and WMA Voice, intended for voice content encoded at low bit rates.
WMA came up with the promise of creating MP3-equivalent files at half the size, but it didn't work. However, at low rates of 128 kbps, the quality of the two is comparable.
Why do they arise?
There are a multitude of audio formats. The File Info site, a database of file extensions, lists hundreds of them, as you can see at this link. We have listed just a few of them that are among the most popular or growing in popularity.
As you can see, they arise from company interests, user needs, opportunities, etc. MP3 is the best known because it combined small size with good quality and spread uncontrollably with Napster. Since then, it has gained a loyal following. However, that doesn't mean he's the best.
The choice of audio format depends on your need. As you've seen, formats that don't sacrifice quality take up disk space, but are ideal for backup purposes and anyone looking for advanced or professional sound.
Compressed formats, on the other hand, value convenience, multi-player compatibility, and storage for a much larger amount of music. And you, what's your preference?
DJMusic Mag Editor
Source Tecmundo
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