- Lossy audio codecs achieve the highest compression, highlighting MP3, AAC and OGG/Vorbis.
- Formats like FLAC and ALAC offer lossless compression, ideal for maximum quality.
- Compatibility and bit rate are key factors in choosing the most efficient codec.
The world of digital audio has undergone a radical transformation in recent years, especially when it comes to the way we store, stream, and enjoy our favorite soundtracks. As surprising as it may seem, the key to this revolution lies in the existence of the audio codecs, small programs and algorithms that allow audio files to be reduced in size and facilitate their digital transport, without compromising quality more than necessary. If you've ever wondered what the secret is to listening to thousands of songs on your mobile or for the streaming straight to the point, here's the answer.
However, not all codecs are the same or perform the same function. Some are designed to compress as much as possible, sacrificing some fidelity, others preserve every nuance of the original sound; some are designed to be compatible with different devices, and others were born out of the need to share music legally online. Choosing the right codec can make the difference between a sublime music experience and a mediocre one, between saving storage space and storage or waste it, between having universal compatibility or finding files that your player doesn't recognize. In this guide we will delve into the most compressed audio codecs, comparing their features, applications and advantages., and giving you all the keys to choosing the most appropriate format according to your needs and tastes.
What is an audio codec and how does it work?
Before diving into the jungle of formats, it's worth clarifying what exactly an audio codec is. Basically, a codec (a word derived from encoder-decoder) is an algorithm or software whose mission is to transform an analog audio signal into a digital one, compress it to reduce its size and then decompress it when we want to play it. Thanks to codecs, we can enjoy our favorite songs over the internet, carry them on our phones, or play them on smart speakers, among many other uses.
The fundamental process of a codec is simple in appearance but sophisticated in practice: First, it takes the raw audio (PCM, for example), fragments it into small blocks and removes (or not) duplicate, redundant or information that the human ear does not perceive well. Depending on the codec philosophy, this lost information can be recovered (lossless compression) or not (lossy compression). Finally, when you hit 'play', the player decodes the file to output the sound.
Types of audio compression: lossy, lossless, and uncompressed
Audio compression is the heart of the matter. There are three main families of formats depending on how they manage sound information:
- At a loss: They eliminate information that is considered irrelevant to the human ear, thus achieving significantly smaller files. The most famous are MP3, AAC, OGG/Vorbis and WMAThis type is the king of streaming and portable playback thanks to its enormous degree of compression.
- No loss: They compress the file but without sacrificing any detail. When you play them back, you can exactly reconstruct the original audio. Here they stand out FLAC, ALAC and WMA (lossless).
- Uncompressed: They store the signal in its purest state; they take up a lot of space but retain all the information. Prime examples are WAV, AIFF and DSD.
Lossy audio codecs: which ones compress the most?
Lossy compression codecs are optimized for reduce the file size very significantly, in exchange for eliminating some of the sound information that, in theory, does not affect the listening experience too much. This is achieved by using psychoacoustic models to decide which sounds our hearing can ignore.
Among the most notable lossy compression formats are:
- MP3 (MPEG-1 Layer III)
- AAC (Advanced Audio Coding)
- OGG/Vorbis
- opus
- WMA (Windows Media Audio)
- aptX and Bluetooth variants (aptX HD, aptX Low Latency, LDAC)
Each of these codecs has specific characteristics, advantages, and limitations in terms of quality, compatibility, and compression rates. Let's analyze them one by one.
MP3: The Universal King of Lossy Compression
Few formats have marked such a before and after in the history of digital audio as the MP3. Its name comes from MPEG-1 Layer III, and its success is due to its ability to Reduce audio files by up to 90% of the original without most listeners noticing a noticeable loss of quality.This feat, unthinkable at the time, was achieved by sacrificing data that our auditory system is unable to clearly perceive.
MP3 is used in countless contexts: from music downloaded from the internet to audiobooks, podcasts, and car audio systems. It's almost ubiquitous, and its main advantage is its near-universal compatibility. An MP3 compressed at 128 kbps already sounds decent, but from 192 kbps and especially at 320 kbps, it becomes very difficult to distinguish it from the original quality in casual listening..
However, its compression algorithm is less efficient than more modern ones. The files are still not as small as they could be, and compared to current options, MP3 achieves less quality at the same bit rate. Even so, due to compatibility and simplicity, it remains the preferred format for many users.
AAC: The Evolved Successor
Developed as the natural evolution of MP3, AAC (Advanced Audio Coding) It stands out for its efficiency and flexibility. It was created by the MPEG group with the intention of offering better quality for the same file size and, therefore, allowing for greater compression without compromising the listening experience.
AAC has become the standard streaming format for Apple Music, YouTube and mobile platforms. iOS. It offers a more accurate frequency response and representation of vocals and instruments than MP3 when using similar bit rates.
Thanks to its efficiency, AAC allows for greater compression, while maintaining a much more faithful sound; that's why it's common to find it on streaming services and mobile devices. Its files have extensions such as .aac, .m4a and .mp4 (the latter when it accompanies video).
OGG/Vorbis: The Open Source Champion
vorbis, best known for its association with the container OGG, is a free and open source format, developed by the Xiph.Org foundation as an alternative to proprietary codecs.
OGG/Vorbis achieves a compression ratio and quality very similar (and even superior) to MP3 and AAC, especially at low bit rates.. This format became the favorite of many streaming platforms, and it is no coincidence that Spotify Use OGG/Vorbis compressed at 320 kbps for your highest quality streaming.
As a distinguishing feature, its open and royalty-free nature favors its use in independent projects and freely distributed software.
Opus: The New Wave in Versatile Compression
opus It is another open source codec mainly oriented to Voice over IP streaming and real-time audio transmission, although it's perfectly suited for music. It's based on technologies developed for both voice (Skype's SILK) and music (CELT), allowing it to flexibly adapt to the content.
Opus stands out for offering an outstanding quality/file size ratio, in addition to supporting variable bit rates from 6 kbps to 510 kbps, thus adapting to unstable network connections and allowing quality to be maintained even if bandwidth varies. Its adoption is growing in applications such as Discord, WhatsApp and other communication platforms.
WMA: Microsoft's bet
Windows Media Audio (WMA) It was Microsoft's response to compete in the field of lossy compression. Although it became popular during the golden age of Windows XP, its use has decreased significantly outside the Microsoft environment..
WMA boasts of better quality than MP3 at low bit rates, but its limited compatibility with systems other than Windows led to its relegation. Even so, it's still used on some devices and as a secondary format in certain applications.
aptX, LDAC and other Bluetooth codecs
In the era of wireless devices, specific codecs have emerged to solve the problem of Bluetooth audio transmission. Among them are: aptX (in its aptX HD and aptX Low Latency variants) and LDAC. aptX was developed by Qualcomm and seeks to reduce latency and improve quality. compared to standard Bluetooth codecs (SBC).
aptX HD allows streaming high resolution audio, while aptX Low Latency is focused on minimizing delay, which is essential for gamers and video users. Meanwhile, LDAC It is Sony's bid to transmit high-fidelity audio over wireless connections, allowing for much higher bit rates than the competition.
However, compression with these codecs is still lossy, and the final quality depends on both the codec itself and the compatibility of the transmitting and receiving devices.
Lossless Audio Formats: Compression without Compromise
For those seeking maximum fidelity without sacrificing compression, the lossless audio codecs are the option. These formats allow the file to be compressed without losing any data, recovering exactly the original sound when decompressed.
- FLAC (Free Lossless Audio Codec)
- ALAC (Apple Lossless Audio Codec)
- WMA (lossless)
They use advanced algorithms to detect patterns and redundancies, allowing for a File size reduction of between 30% and 60% compared to the original. Quality remains intact, ensuring that playback is identical to the original recording.
FLAC: The Open Standard for Lossless Audio
FLAC It has become the most widely used lossless format outside the Apple universe. It allows files almost half the size of a WAV or AIFF, but with quality indistinguishable from the original.It's a favorite among audiophiles and those who want to enjoy their digital music library at its highest quality without filling up their hard drive in the blink of an eye.
FLAC is supported by most modern players and has helped make high-resolution music accessible to a wide audience.
ALAC: Apple's answer to FLAC
For those immersed in the Apple ecosystem, ALAC (Apple Lossless Audio Codec) is the standard option. Like FLAC, this format offers lossless compression and smaller files., but with the advantage of being specially optimized for iOS devices and Apple brand software.
Since a time ago, Apple Music offers its entire catalog in ALAC at CD quality or better.. It should be noted, however, that the size of ALAC files is usually slightly larger than that of FLAC.
WMA Lossless: Microsoft's Alternative
Less common than its rivals, WMA Lossless It was designed as the lossless option for Windows users. Allows you to store audio with maximum quality and respectable compression, although neither compatibility nor efficiency reaches FLAC or ALAC. It is still useful in Windows environments and some specific players.
Uncompressed audio formats: maximum fidelity, maximum weight
For sound purists and those with no storage limitations, the uncompressed files They maintain every detail and nuance of the original recording. Although they take up a lot of space, they offer the highest possible quality. The main ones are:
- WAV (Waveform Audio File Format)
- AIFF (Audio Interchange File Format)
- DSD (Direct Stream Digital)
They are ideal for musical production, editing and storing files in their highest quality.
WAV: The Industry Standard
WAV, developed by Microsoft and IBM, is the preferred format in professional environments and on Windows systems. It uses PCM (Pulse Code Modulation) to store uncompressed audio and is used in CD mastering. A 3-minute WAV song can take up over 30MB, but preserves all the fidelity.
AIFF: Apple's choice for uncompressed audio
AIFF, developed by Apple, is very similar to WAV, using PCM for encoding. It is widely used in Mac and in professional audio projects. It offers maximum compatibility and quality, although at the cost of large size..
DSD: High Definition Audio for the Most Demanding
DSD (Direct Stream Digital) It is used in SACD and by audiophiles seeking maximum resolution. It uses a single bit sampled at extremely high frequencies (2,8 to 11,2 MHz), achieving an experience that emulates analog. Its use is minor due to the size of the files and hardware and.
What factors determine the compression efficiency of a codec?
When we talk about 'greater compression', we are referring to the the codec's ability to reduce audio file size maintaining acceptable quality. Several technical variables influence this:
- Bit rate (bitrate): Lower reduces size, but may affect quality.
- Compression algorithm: Different strategies to eliminate redundant information.
- Coding mode: Stereo, mono, dual channel, etc.
- Psychoacoustic efficiency: Ability to remove inaudible data.
Audio codecs and everyday use: When to choose maximum compression and when to prioritize quality?
There is no single answer, the choice depends on needs:
- Streaming and mobile playback: MP3 or AAC at 256-320 kbps for convenience and compatibility.
- Personal libraries and high quality: FLAC or ALAC, which offer the lossless compressed original.
- Wireless transmission: aptX HD or LDAC if both devices support these codecs.
- Musical production: WAV and AIFF, which maintain all the details for editing.
- Podcasts and audiobooks: MP3 or AAC at low bitrates, ideal for voice and space.
Under normal conditions, the difference between a 3 kbps MP320 and a FLAC may be negligible on standard speakers, but on high-end systems and to trained ears, the differences in detail can be evident.
Bit rate and its impact on compression and quality
One of the key concepts is the bit rateThis value indicates how many kilobits per second (kbps) the file has. The higher the bitrate, the higher the quality and size; the lower the bitrate, the greater the compression and possible sound artifacts.
For example, a MP3 at 128 kbps It is acceptable for everyday use, but many prefer 256 or 320 kbps. OGG/Vorbis and AAC maintain quality at lower bitrates, and Opus can go even lower without losing intelligibility.Most streaming platforms use 320 kbps for an optimal experience on formats like Spotify or Apple Music.
Codecs and compatibility: the importance of choosing well
Compatibility is key to ensuring you can play your files without issues. The choice of format should take into account the devices and programs you use:
- MP3: almost universal.
- AAC: Compatible with Apple devices and mobile platforms.
- OGG/Vorbis: ideal for free software and royalty-free projects.
- FLAC y ALAC: increasingly accepted in devices and services.
- WMA y AIFF: : mostly on Windows and Mac, respectively.
You can take advantage of Bluetooth codecs such as aptX HD and LDAC if both devices support these standards to optimize quality in wireless transmission.
High-Resolution Codecs: Beyond CD
With the advent of high-resolution audio, formats like WAV and AIFF can be encoded at 24-bit/96-192 kHz, capturing more detail and dynamics. FLAC and ALAC also support these higher resolutions, allowing platforms such as Tidal or Qobuz to offer streaming in superior quality.
The use of DSD, although rare, provides extreme resolutions, but requires specific hardware. The difference is usually only noticeable on high-end systems and for highly trained listeners.
The future of compression: flexible codecs and adaptive streaming
In an environment where streaming predominates, modern codecs like Opus and adaptive formats They automatically adjust their bit rate according to the quality of the connection, ensuring fluidity and quality. The advancement in compression technologies and the incorporation of Artificial Intelligence They aim to further reduce size, preserving fidelity and expanding compatibility across diverse devices.
How to choose the most suitable audio codec for you?
The choice will depend on your priorities. For streaming and casual use: MP3 or AAC at 256-320 kbps, or OGG/Vorbis. For collection files in maximum quality: FLAC or ALAC. For music production: WAV and AIFF. For wireless transmission: aptX HD or LDAC if both devices support it.
Less common formats and new trends
There are pioneering or specialized formats on the market such as MQAs for high-resolution audio streaming, used by Tidal, or DSD for audiophiles seeking the utmost in fidelity. Innovations in compression techniques and the application of IA will continue to expand the possibilities of digital audio in the coming years.
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