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What are lossy and lossless audio formats, and what are common audio formats? Part 2

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What are lossy and lossless audio formats, and what are common audio formats? Part 2

Audio Formats:

2. WAVE is a sound file format developed by Microsoft, it is used to save the audio information resources of the WINDOWS platform, and is compatible with the WINDOWS platform and its applications.

3. AIFF format (Audio Interchange File Format) and AU format, AIFF is the English abbreviation for Audio Interchange File Format. It is an audio file format developed by APPLE and supported by the MACINTOSH platform and its applications. Many compression techniques are supported.

4.MPEG is the English abbreviation for Motion Picture Experts Group Currently, MP3 is the most common music format on the Internet. Although it is lossy compression, its biggest advantage is a higher compression ratio in exchange for very little sound distortion.

5. MP3 MPEG audio file compression is lossy compression. MPEG3 audio encoding has a high compression ratio of 10:1~12:1, while basically keeping the low audio part undistorted, but at the expense of the high 12KHz to 16KHz. in the sound file. The quality of the audio part is changed by the size of the file. Music files of the same length are stored in *.mp3 format, usually only 1/10 of *.wav file, so the sound quality is lower than CD or WAV format.

6. MPEG-4 Adopts object-based compression coding technology. Before encoding, the video stream is first analyzed, and each video object is segmented from the original image, and then the shape information, motion information, texture information is encoded separately, and temporal redundancy between consecutive frames is eliminated thanks to better motion prediction and compensation than MPEG-2. Its core is content-based scalability, which can assign priorities to each object in the image, express the most important objects with high spatial and temporal resolution, and express the less important objects (such as surveillance systems, background) are rendered. with a lower resolution. or even not displayed. Therefore, it has the ability to adaptively allocate resources and can perform low-speed, high-quality video transmission and image communications. It occupies less resources, has great flexibility, good network performance, and has a wider range of applications.

7. The MIDI (Musical Instrument Digital Interface) format is used by people who often play music, MIDI allows digital synthesizers and other devices to exchange data.

8. WMA (Windows Media Audio) format is a heavyweight player from Microsoft. The background is harsh, the sound quality is stronger than MP3 format, and it is much better than RA format. It is the same as the VQF format. developed by the Japanese company YAMAHA. However, the method to maintain sound quality can achieve higher compression ratio than MP3. The compression ratio of WMA can generally reach around 1:18. Another advantage of WMA is that content providers can use DRM (Digital Rights Management) like Windows Media. Rights Manager 7 adds copy protection.

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What are lossy and lossless audio formats, and what are common audio formats?

We often hear some terms like MP3, lossless, CD sound quality, and even come into contact with them. So what are lossy and lossless audio formats? What are their differences? Apart from the ones I heard above, what other common audio formats exist? Next, I will share with you the relevant knowledge of audio formats and answer your questions.

First, let’s briefly popularize the audio format:

The audio format is the music format. Audio format refers to the process of digital and analog conversion of audio files for playback or processing on a computer. At present, music file playback formats are divided into two types: lossy compression and lossless compression. When using different music file formats, there is a big difference in sound quality performance.

Difference Between Lossy and Lossless Compression:

Lossy compression is to reduce the audio sample rate and bit rate, and the output audio file will be smaller than the original file. Lossless compression, on the premise of saving 100% of all the data in the original file, can compress the audio file to a smaller size, and after restoring the compressed audio file, it can achieve the same size and code. than the source file. Speed.

Here are the common audio formats:

1. CD The standard CD format is the sampling frequency of 44.1K, the rate is 1411K/second, and the quantization number is 16 bits. Since the CD track can be said to be approximately lossless, its sound is basically faithful to the original sound.

Lossy vs Lossless, Audio Quality

Much is said and has been said about the difference between the formats that generate a loss of information (lossy) versus those that do not generate any loss (lossless).

What is Lossy?

To compress a file, so that it occupies less space on the disk, we must necessarily use two techniques, the first is pure compression, which does not lose quality and which we will explain later PLUS compression by discarding information.

It is omitting information that we know, after studies, that the human ear will hardly perceive. At least the average human ear.
Younger people listen to more frequencies than from the age of 30, when we listen to fewer frequencies.

But not only does age count, but other phenomena also enter, for example what is called masking and which could be summarized by saying that if two frequencies occur with similar frequencies, and one occurs an instant before the other, in general the second that masked… that is, it is not audible to the human ear, so we could discard it and save space.

There are also all the frequencies that the human ear does not perceive, there we have more information that we can discard without damaging the quality or at least maintaining a very similar quality of perception.

LossLess

There are other formats that do not lose quality because they only use mathematical methods to save space. Imagine the following line:

1111111000001110000000

This consumes a space, but this information could be summarized, for example as follows:

1(7)0(5)1(3)0(7)

This second way of storing information takes up much less space WITHOUT discarding anything. It simply explains that from the number 1 there are 7, followed by 5 zero numbers, then 3 from the number 1 and finally 7 zeros.

It’s the same, we just tried to save space by finding a compressed way to write it, but we didn’t rule anything out.

This is exactly how the zip and lossless music methods work.

Is there a difference in the human ear when listening to one and the other?
We will answer that in another article.

Data compression: lossless or lossy

To be able to store large amounts of data, a huge amount of storage space is required. When the space is at some point full, a new storage space is usually made available. Mainly in the form of new hard drives, server systems or the like. But there is another way to store more data: data compression.

Lossless vs Lossy

Data compression works like a pillow you squeeze
Figuratively speaking, data compression works the same way as when you squeeze a pillow. Not all air is required between the pillowcase and the feathers. By squeezing the pillow, you compress it by removing the air (as much as you can); the pillow becomes smaller, that is, more compressed than before.

It is similar with data compression. Here also items that are not absolutely necessary, in this case data, are removed and the storage space still required by the remaining data is reduced.

Lossy vs Lossless Compression

Different lossless compression encoding methods.

When it comes to data compression, a distinction is made between lossless compression and lossy compression, so it can be further subdivided into different types of compression.
Lossless compression is generally only done with text files. If the text is saved as a character string and not as an image or the like, the storage space can be saved using the dictionary method, for example. Recurring parts of the string are simply replaced by abbreviations.

Text: Hello world. Hello user
Encoding: world X5. X5 users.

With the help of Run Length Encoding (RLE), identical text components that are placed one after the other are only saved once. This can also save storage space.

Text: Today was beautiful, beautiful, beautiful and tomorrow will be more beautiful.
Coding: Today was / 3 / beautiful, / and tomorrow will be more beautiful.

In entropy encoding, as is the case with Huffman code or arithmetic encoding, for example, text elements are sorted in binary and encoded according to their frequency, and the most frequently occurring element is given the binary number smaller.

With these numbers, the text elements are stored in a separate dictionary.

Text: IF YOU FLY BACK, FLY, FLY, FLY, FLY AFTER.
Coding: 10100 1 1 1101 1 1 1 11

Difference between lossless and lossy compression

The benefit of lossless encoding is clear: it ensures that all “compressed” data in the compressed data packet can be accessed and restored.

In addition to lossless compression, there is also lossy compression. Irrelevant information is not encoded here, but is directly removed. Therefore, we speak of a reduction in irrelevance.

Lossy compression: the MP3 format

Of course, this procedure can lead to extremely high compression rates. However, this irrelevant information is irrevocably deleted. This means that the original state cannot be restored after compression.

Lossy compressions are often used for image, audio, and video files, as they often have to handle large volumes. The MP3 format is a classic example in this context. Here, frequency patterns are removed from an audio file that are almost inaudible to the human ear. This saves storage space.

If you compress data packets, you can use your own data storage capacity better than uncompressed data packets. However, you should always consider the type of compression you are using. Because lossy compression is not always desirable.

Uncompressed and compressed formats

Popular audio formats

Uncompressed formats

There are audio formats that do not have compression and are the best in terms of sound quality. On the other hand, they take up much more memory space and a lower transmission speed than compressed formats. With professional software such as Pro Tools, SuperCollider or Max, you generally work with files of this type. The two main formats are:

WAV (wave). Audio format developed by Microsoft and IBM for compatible IBM PCs. In this format, musical instruments feel the same regardless of the PC on which the file is played (with the same acoustic quality of the hardware components, of course).

AIFF (Audio Interchange File Format). The format developed by Apple is also called the Apple Interchange File Format.

Audio formats

Lossy compression

It allows for more compression, but at the expense of sound quality. Lossy compression methods generally tend to discard information considered useless, keeping only the essential ones and arise from the idea that not all frequencies contained in a sound spectrum are perceived by the human ear. Then the high frequencies are cut off, which are believed to be the least distinct in our hearing. Obviously, the more frequencies you cut, the more the space occupied by the audio track decreases and with this also the quality of the result as a reconversion process. It does not allow the complete restoration of the cut-off frequencies. Let’s see what are the main audio formats of this type:

MP3 (MPEG-1/2 Audio Layer 3). Audio compression algorithm capable of drastically reducing the amount of data required to reproduce a sound, compromising obtaining an almost faithful reproduction of the original uncompressed file. The best codec for compression is Lame. maximum achievable bit rate 320 Kbps.

WMA (Windows Media Audio). Audio file standard invented by Microsoft. Audio compression format very similar to an MP3.

OGG (Vorbis). It is an open source algorithm and with the same perceived quality, it allows greater compression than the MP3 format, obtained through advanced psychoacoustic research.

AAC (advanced audio coding). It is an audio compression format officially included in MPEG-4. Provides superior audio quality to MP3 format with more compact encoding. Currently it is used mainly by Apple, which in the variant that manages copyright has a compression of 128 Kbps (the standard of the iTunes Store) and corresponds to that of an MP3 at 192 Kbps at constant bitrate. Conversion times are a bit slower than other formats.

AC3 (Dolby Digital). Dolby Digital is a multi-channel audio coding system developed by Dolby Laboratories Inc and used in film, digital TV, laser discs, DVDs, and other digital audio streaming or playback media. It works from a minimum of 96 kbps to a maximum of 640 kbps. In cinema, Dolby Digital is used with only 320 kbps of bandwidth, as it prints in the limited space available between the slide holes of the films. Generally, in DVD it is used with a bit rate of 192 kbps to encode stereo signals (2.0, 2.1) or stereo surrounds, and with a bit rate between 384 and 448 kbps for 5.1 signals.

Lossless compression

These compression methods try to reduce the space occupied by the track without going to touch the sound. The compression rate is much lower than with lossy methods, but there is no loss of quality and the sound is identical to the original when converting. Let’s see what are the main audio formats of this type:

FLAC (Free Lossless Audio Codec). The widespread open source audio codec is currently well supported by various audio software. Unlike most lossless compression algorithms (like ZIP and gzip, for example) that only achieve 10-20% compression, it achieves significant compressions, on the order of 30-50%.

APE (Monkey’s Audio). No lossy format that allows us to reduce the space our music occupies by approximately 50% (in some cases even more). Currently it is no longer developed.

ALAC (AApple Lossless Audio Codec). The format developed by Apple stores data in an MPEG-4 container with the extension .m4a. It does not have Digital Rights Management (DRM) and is now deprecated.

Files without compression, lossless and lossy formats

Files without compression, with compression but without loss and with compression and with loss … what does that mean?

There is currently a huge confusion in most people about audio formats and that is why we are going to give an explanation that is as simple and clear as possible so that most of the people who read can understand enough to be able to make decisions about it. .

We will not try to get into technicalities or knowledge What are for specialists or connoisseurs or programmers, such as those who developed the mp4gain, but rather we will talk about general concepts at the beginner level but that can allow a correct understanding of the matter.

So the first thing we must understand is that the quality of an audio file depends on the amount of details it contains and for it to contain many details, it takes up a lot of space on the hard disk.

We could say that there are three groups of audio file formats:

– audio formats that do not have compression such as WAV, AIFF, etc.

– formats that compress audio but do not have a loss of information. FLAC, MPEG-4 SSL, WAV PACK, etc.

– There are also the formats that the audio compresses but that do have a loss of information, for example MP3, Ogg, HERE, ETCÉTERA

Now let’s clarify what it means that some formats do have compression but do not have loss of information while others also have compression but do have loss of information.

The formats that are compressed but have no loss of information what they do is something very similar to zip the file. In other words, they simply compress.

The original information but they do not discard anything, therefore when unzipping the file the original file is obtained again that had all the details and therefore is of very high quality.

On the other hand there are files such as MP3 that are compressed but also to achieve greater compression what they do is that they get rid of some part of the information. For example, those frequencies that are not audible to the human ear also get rid of that information that is redundant and they also use the method called masking which part of the idea that a sound that is very loud and is very forward It will be able to mask other sounds and the human brain will not perceive those other sounds. Therefore, according to this theory, they can get rid of these sounds that have been masked and the file will sound more or less the same to the human ear.

This concept of sound masking was one of the great milestones that made MP3 become so popular because it could compress files a lot, at a time when disk space was not superfluous, and yet they sounded pretty good to that ear. era and those people.

Also the programs that made the normalization of the audio volume, achieved results that at that time sounded good, but at this time the listening ear as a has become much more demanding and sophisticated. And so we need much more modern normalizers with much more algorithms. more powerful like mp4gain.

Guide to fully understand lossless formats

They end with a period followed by three or four letters. It is what happens with absolutely all the files of a computer or a smartphone. These last letters represent the format in which said file is. Today we are going to focus on one type of format, the lossless format.

What is a lossless format?

Any element in a computer has to have some kind of format, or so to speak, some kind of structure that is known by that computer so that it can work with the file. In a parallel with the world of physical objects, the format would be something like the material with which the object is constructed.

Just as there are different materials with different properties, there are also different formats with different characteristics. Most of the files we use today have a compressed format, so they take up less space on our computer and are easier to send via the Internet, or upload to a social network. However, these formats are not the highest quality, since this position would be occupied by lossless formats. These formats retain the original quality of the file, and are the ones that offer the best results.

If we talk about images, the lossless formats are RAW, BMP and PNG, among others. Meanwhile, the compressed formats are JPG and GIF. However, there are certain differences with some of them. RAW, for example, stores all the light data captured by the camera’s sensor. It is a perfect format for photographers. But it would not even be for photographers who want to share a particular photograph on a social network. A RAW photo can easily occupy 25 MB, depending on the resolution of the camera. A high quality JPG photo would be a photograph that would occupy two or three megabytes, although it would have less quality.

If we talk about audio, there are three main formats without loss: WAV, FLAC and ALAC. The latter is the one used by Apple in iTunes. They are formats that do not lose any quality with respect to the original audio. Yes we would be losing quality with MP3 and OGG.

And if we talk about video, there are few lossless formats that we can talk about. In fact, there is a problem, and storing videos without loss would be an impossible task for anyone who did not have a storage server nearby. That is why we usually opt for the MKV, WMV, and H.264 formats. Of course, the latter is much better, because the compression process is much more intelligent.

Compression, how does it work?

Now, what is this about compressed formats? As the name implies, we are talking about formats that reduce files, and we can rely on it to perfectly understand how these formats work. Surely we have all seen ourselves in the situation of having to pack a suitcase with just the right space, finish choosing all the clothes we are going to take on a trip, and finally have to decide what we can do without being able to close the suitcase, because we had too many clothes. For that is the compression of each of the formats. They remove items from that file, and thus make them weigh or occupy less.

Why are there different formats? Returning to the case of the suitcase, each person will make different decisions regarding those things that he can do without for his trip. It will vary from one person to another. The same goes for formats. The developers of these reduce the space occupied by a file, but each of the formats deletes data in a different way, so that a file compressed to JPG, can be different from one GIF, even if the two are compressed. Each of them has followed a different procedure to delete the data, and that the song, image, or video, continue to play almost the same as the original version.

When to convert from compression to lossless?

The question that heads this paragraph is especially important for all those who at some point have converted a file from a compressed format to a lossless format. And, in fact, it goes with a trap, because you should never convert a file from a compressed format to a file without loss. In reality, nothing happens if we do, but we will not improve the quality of that file, although it will now be available in a format in which the files are not compressed.

Of course, it is also not a good idea to convert a file into a compressed format, to a different compressed format. Let’s keep in mind that each compression process is different depending on the format chosen. That is, each format eliminates the data it deems appropriate to maintain image quality. If we have a file in a compressed format, that will mean that it no longer retains all data.