Dissecting Audio Lossy Formats

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Dissecting Audio Lossy Formats: Technical Mechanisms and Trade-offs

Understanding Audio Compression

As an audio enthusiast, I have always been fascinated by the technology behind audio compression. Audio compression is the process of reducing the size of an audio file by removing or reducing redundant or irrelevant information. This is done to make the file smaller and more manageable, especially for streaming and other bandwidth-limited applications.
There are two types of audio compression: lossless and lossy. Lossless compression preserves all of the original audio data, while lossy compression removes some of the data to achieve a smaller file size. Lossy compression is the most common type of audio compression used today, and it is used in a wide range of applications, from music streaming services to podcasting.

Audio Compression Techniques

There are many different techniques used in audio compression, each designed to optimize audio quality and reduce file size. One of the most important techniques is perceptual coding, which involves analyzing the human perception of sound and using that information to remove or reduce irrelevant information.
Another important technique is psychoacoustic modeling, which is used to identify and remove sounds that are not perceptible to the human ear. As the book “The Art of Digital Audio” explains, “Psychoacoustic modeling is a technique that takes advantage of the limitations of human hearing to remove sounds that are not perceptible to the listener.”
In my experience, understanding these techniques and how they work together is essential for optimizing audio quality and reducing file size. By using the right combination of techniques, you can achieve excellent audio quality while minimizing file size.

Audio Compression Trade-offs

One of the key trade-offs of audio compression is the balance between audio quality and file size. As the book “The Audio Programming Book” explains, “The more you compress an audio file, the smaller it becomes, but the more audio quality you lose.”
In my experience, this trade-off is particularly important for musicians and sound engineers. By understanding the trade-offs between audio quality and file size, you can make informed decisions about how to compress your audio files for different applications.
Overall, dissecting audio lossy formats is essential for anyone working with audio. By understanding the technical mechanisms and trade-offs of audio compression, you can optimize your audio quality and file size, making it ideal for a wide range of applications.
Final words:
In conclusion, audio compression is a powerful technology that offers excellent audio quality at reduced file sizes. By understanding the techniques and technologies behind audio compression, you can optimize your audio quality and file size, making it ideal for streaming and other bandwidth-limited applications. And if you’re looking for a powerful tool to help you normalize and convert your audio and video files, be sure to check out mp4gain.

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The audio formats with the best sound quality

First of all, divide all types of music files into three parts as follows:

Uncompressed file formats: .WAV, .AIFF

Lossless compression formats: .FLAC, .ALAC (Apple Lossless)

Destructive compression formats: .MP3, .AAC, .WMA, .OGG

Below are their respective advantages and disadvantages.

1. Uncompressed file format
Uncompressed music files are just like the concept of Raw files. Essentially no compression will of course have the best sound quality. (The sample rate and bit rate of the original recording are also very important. If the compressed music file is converted to an uncompressed file, the music won’t magically improve the sound quality.)

The most common disadvantage of uncompressed files is the file size. Generally, the file size of a song is around 25 ~ 40 MB. While that capacity is no longer an issue for cloud hard drives, it is still an issue for email. Also big (25MB max for Gmail attachments). Also, some portable music players or devices may not be able to play such music files.

Advantages: original sound reproduction, no compression, lossless, easier to use in post production

Disadvantages: large file format, fewer supported devices

2. Lossless compression format
The term “compressed and lossless” seems contradictory, but compression does not necessarily affect sound quality. More precisely, it’s more like “compressed to save space”. It’s like compressing a high quality file into a .ZIP and decompressing it when you want to use it, the quality of the file will not be affected.

Therefore, this type of file has a compressed capacity, but the file will be decompressed during playback to restore sound quality. Although the concept of reducing capacity without affecting sound quality is great, the downside is that support for this format is extremely low and in order to decompress the file during playback, an additional codec is required to use it, and it will. also take some performance.

Advantages: small file capacity (about 1/2 ~ 1/3 lossless files), good sound quality

Disadvantages: Decompression can eat performance when used, and support from hardware or software is extremely low

3. Destructive compression format
The destructive compression format is currently the most common music file format, the main reason is that it has the greatest compatibility with portable devices (mobile phones, MP3 players, etc.), and the files are small and have a space of limited storage. , users can store more music (compressed capacity is about one-tenth of lossless sound quality), and most of the music provided by today’s streaming media is files in this format. There is always a price to pay for smaller files. Compared to lossless formats, this destructive compression will affect the audio range that the original sound can present and will cause some distortion. So, to be safe, keep the compression rate above 320 kbps as much as possible.

About Lossy

About Lossy

Lossy

We all love good music. More recently, the audio CD was good digital music. This is 44100 Hz, stereo, 16 bits (linear) per channel, not compressed in any way, which means, according to Wikipedia, 1411.2 kbps.

Lossy

But at the end of the 20th century, in the era of the birth of multimedia, when music began to be played not only on players, but also on computers, it turned out that the audio CD (that is, naked PCM) is even better. . compress. There was, for example, Microsoft ADPCM, which compressed this case a bit, without losing quality, in WAV files. But generally speaking, the original 44 kHz stereo would still require a lot of space this way. Hence, the quality dropped to 22 kHz mono. One of the first multimedia albums of that time: “Immersion” from the group “Nautilus Pompilius”, is still around, and I did.

So MP3 won. To store and distribute compressed music. At 128 kbps “CD Quality”.

MP3 came up strangely. Technically, this is MPEG-1 Audio Layer 3. A layer for compressing audio data into a modern, progressive standard for storing video data on Video CDs. Just packed in its own .mp3 file format. The video CD is no longer interesting to anyone. The following MPEG-2 standard is used in DVD and digital television broadcasts (not HD). And the next MPEG-4 standard is now used for HD video and continues to evolve.

MP3 was revolutionary. It was (almost) the first lossy compression format. When we don’t try to preserve everything that was in the original signal, but, based on some psychoacoustic model, we cut out what a person is not going to hear anyway, and compress the rest. Like JPEG.

Then I tried digitizing the accumulated audio collection. Compact cassettes (just “cassettes”, but more correctly “compact cassettes”) turned out to be complete shit. The frequency range is such that it makes no sense to sample with more than 22 kHz. There were no reel-to-reel recorders in the house. But vinyl records shook the sound quality. With good equipment, you can draw better quality than a CD. You just need to get rid of the clicks.

And then I realized that MP3 is shit too. At these same 128 kbps, the sound quality suffers greatly. And the scariest thing is that vile metallic hues appear where they shouldn’t be. My ears need at least 192 kbps, and the more the better.

Let’s take a hint from a famous punk rock band in the past. Like FLAC. It is such a modern lossless compression standard that it has successfully replaced WAV. Because it is free.

The original is CD quality, so frequencies up to 22 kHz are present as expected.

Original flac

We are going to harvest with FFmpeg, or rather with LAME.

At 320 kbps and 256 kbps, the spectrogram looks almost like the original.

At 192 kbps, there are signs of a 16 kHz cutoff. The spectrogram “darkens”, apparently, the psychoacoustic model has cut something out. By ear, the higher frequency “bursts” really disappeared.

MP3 192 kbps

At the notorious 128 kbit / s, everything is already specifically cut off at 16 kHz. Background sounds are “fuzzy” and begin to bubble. Nothing to do with the original in terms of enjoying the musical details.

MP3 128 kbps

But you can do 64 kbps in MP3. The stereo is gone. Everything gurgles terribly and irritates with completely strange sounds.

The best popular audio formats

The best popular audio formats

I looked around the forest of audio formats for normal use and chose the 5 most important ones. It is true that, in part, a bit simplified, a bit rough in presentation. I refrain from differentiating the exact settings of the respective codecs, that would be too complex.

I also don’t want to get into the nasty topic of DRM. The most important one I dropped is probably Vorbis. . Of course, I assume that the correct settings are used when encoding and that a high quality level is selected.

1st place:
MP3 (MPEG-1 Audio Layer 3)

The most widespread digital format, with good encoding (for example, with LAME) in high bit rates, a format of the highest quality and transparency.

Quality (4.5 / 5 points)
Popularity (5/5 points)
Compression (4/5 points)
Total: 13.5

2nd place:
AAC (advanced audio coding)

It became famous especially for its use in the Apple iPod, a codec that has small advantages over MP3 at low bit rates due to technical developments.

Quality (4/5 points)
Popularity (4.5 / 5 points)
Compression (4.5 / 5 points)
Total: 13

3rd place:
WMA (Windows Media Audio)

Windows proprietary format. Of course, Microsoft has the reins here, so variable format doesn’t run on all playback devices. Otherwise, no major strengths and weaknesses and, for example, the standard format with Napster.

Quality (4/5 points)
Popularity (4/5 points)
Compression (4/5 points)

Total: 12

4th place:
FLAC (Free Lossless Audio Codec) !!

As the only lossless codec on this list. FLAC works in something like a ZIP program: the original can be restored from the compressed file by approximately 50% without restrictions. In times of low hard disk space, a real alternative, especially since many playback devices can play this format. My winner of hearts, the popularity will certainly increase in the future.

Quality (5/5 points)
Popularity (3.5 / 5 points)
Compression (3/5 points)

Total: 11.5

5th place:
Wav

The original format of the normal audio CD data. Impeccable quality and still widespread thanks to the well-known compact disc. It actually started out of the competition because it’s completely unzipped.

Quality (5/5 points)
Popularity (5/5 points)
Compression (0/5 points)
Total: 10

All about all audio file formats

Dematerialized music has evolved considerably for almost 15 years and has played an important role in the daily life of every individual. We’ve all heard more or less about FLAC, MP3, WAV, etc.! Few people really know the difference between each size, its pros and cons …

This article is intended to enlighten you to make the best possible choice for extracting and compressing your audio files.

There are different types of layouts that can be grouped into several large families:

– uncompressed files

-lossless compressed files

– Lossy compressed files

audio formats

-Uncompressed files

WAV: WAV (Waveform Audio File Format) is an audio file format created by Microsoft for Windows. This format is usually an uncompressed container. Therefore, an audio CD with a duration of about 80 minutes in WAV weighs plus or minus 800 MB

Advantages: the file remains in its original form, no loss of information (no loss)

Disadvantages: The WAV file is an uncompressed format that gives it a large size and therefore takes up more space in the storage space.

AIFF – Audio Interchange File Format (AIFF) is the Mac OS equivalent of the WAV format. Therefore, it has the same characteristics as this. The pros and cons of this format are the same as for WAV.

– Lossless compressed files

FLAC: The FLAC (Free Lossless Audio Codec) format is without doubt the most beneficial file for the user. Firstly, in terms of WAV and AIFF, this format is a lossless format, ie the digitization of the file does not imply any loss of information from the audio spectrum. The file is scanned and returned as is. The second advantage of this format is the size it occupies in the storage space. Nondestructive compression is applied to this type of format as a ZIP file, making the scanned file about 2 times less space than a WAV file. Therefore, for 80 minutes of music on CD, the occupied space will be approximately 400 MB. Finally, this format is universal, compatible with most multimedia players, it is compatible with all operating systems except iOS,

Advantages: file size, identical reproduction of the original file during scanning, free and compatible with almost all media players and operating systems

– Disadvantages: none

ALAC: The ALAC (Apple Lossless Audio Codec) format is simply the Apple equivalent of the FLAC file.

– Lossy compressed files

MP3: The MP3 format (Mpeg Layer 3) is a well-known format. It is a format with destructive compression, that is, a recording from which musical information has been removed thanks to the so-called psychoacoustic compression algorithm (taking into account the peculiarities of the human ear), so that less scanning is needed to create a lighter file to obtain . This format is most commonly used for dematerialized music, as it allows a significant space saving in the storage space with a size of about 150 MB for an 80 minute CD. Compression can be more or less destructive depending on the speed used, which can range from 4: 1 (320 Kbits / sec) to 12: 1 (128 Kbits / sec).

-Advantages: it takes up little space on the hard disk and does not affect the quality of the songs with a dynamic range and a limited variety of timbres

– Disadvantages: paid MP3 license, destructive compression for “richer” songs.

AAC: The AAC (Advanced Audio Coding) format is a format close to the MP3 format, but provides additional definition with an identical compression rate. Apple uses this specific format in the iTunes Store, but also on YouTube. the extension can be written in various forms, such as .AAC, .M4A or MP4

-Advantages: better compression quality than MP3

-Cons: compressed file format at a loss

What is the best audio format for listening to music?

Although the MP3 format is the most popular of all available audio formats, it is not the only one, some such as FLAC, WMA, OGG and others, have features that, depending on what you want, can be very useful in certain occasions

Here I show you a summary of what to expect when you are looking for the best audio format to listen to music.

As a general rule, we can classify audio formats into two categories: those that retain all quality and those that lead to loss of quality in sound or information.

Those who retain all audio quality come from pure sources such as CDs, while those who lose quality sacrifice this information to save space.

Formats that preserve audio quality:

FLAC: Free Lossless Audio Codec or FLAC, for its acronym in English, is one of the formats that best preserves audio quality. Its compression algorithm is excellent and does not generate quality losses, it is open source and the file size when compressed is much smaller
Apple Lossless: known as ALAC is very similar to FLAC, but not as efficient as this, so these files are larger, although they have the unconditional support of iOS, which FLAC does not have

APE: The problem with this format is that it is not very compatible with the vast majority of players, but it is similar to the FLAC or ALAC format in terms of audio quality. Being very compressed makes the computer’s processor work faster so it is not recommended in low power computing equipment
WAV and AIFF: they are not compression formats, but exact copies of the original content, differing in the way they save the data. While AIFF was created by Apple, WAV is more universal, but both take too much disk space.

Formats with loss of audio quality:

MP3: MPEG Audio Layer III or MP3, as we all know them, is the most common format you can find
ACC: is more efficient than MP3, files in this format are smaller and is very popular on iTunes
OGG Vorbis: it is a free and open source alternative to MP3 and ACC, it is not restricted by patents but not supported by many players
WMA: this is the proprietary format of Microsoft very similar to MP3, without great advantages over the others
Which audio format to choose
You may be interested: «It’s proven: classical music modifies your genes and makes you smarter»
It is more recommended to choose MP3 or AAC, since many players support them, in addition, if they are encoded with a high bitrate they are almost indistinguishable from the original source. However, if what you want is to burn your music, I recommend formats like FLAC, then you can convert everything to other formats without losing audio quality.