Tag: does youtube accept audio formats

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Choosing the best format to compress audio data: MP3, AAC or WavPack?

If not lossless, who? MP3, AAC, what else? Previously, we have already studied music compression algorithms several times, it is time to compare the most valuable ones.

Amicably, one should give up lossy codecs entirely, but it’s always interesting to draw a line where quantity turns into quality. Also, even a lossy codec can surprise you with something, you’ll see. In this review, we decided not to fool ourselves with different VBR modes, but to immediately stop at the maximum bitrate with a constant value of 320 kb / s. Today, with modern laptop capacity, asking for an extra 10MB for album capacity at the risk of losing quality? So that? In general, even with older codecs, the 320 kb / s stream ensures the absence of characteristic artifacts with nasty jingles. The first part of the review will be devoted to comparing the growth of artifacts using RMAA software, in the second part, the subjective experience of the listener in real phonograms is presented.

Comparison frequency response of three lossy formats relative to original WAV

If the last time the iPad Mini was used as a sound source, now, to improve the accuracy, we take any influence of the iron out of the brackets, and then all the distortion analysis will be done exclusively in the digital domain, without conversion to analogical. , since RMAA provides that opportunity.

To do this, we generate a test sample in WAV in RMAA, then we alternately handle it in various lossy codecs. Then we will convert WAV from them again, so that the program can “recognize” the file and evaluate deviations from the original template. Now we look at how the high frequencies are cut off and the distortion grows, giving the sound an unpleasant color. By the way, there won’t be that many. In general, at a bit rate of 320 kb / s it will not be so easy to detect something harmful by ear. It’s not even artifacts, but maybe a bit of a “dull” sound compared to the original. The phonogram seems to fade a bit, it loses its mobility due to the alteration of transient processes after psychoacoustic processing. But it will not always be possible to clearly record this difference, it depends on the specific track.

MP3: avalanche distortion
Let’s start with the most popular format. MP3 is a monster from the Fraunhofer Institute that has taken over the Earth. Because of this, nowadays it doesn’t occur to anyone to use pure WAV for sound recording. Even if they rip out the defaced YouTube audio, they still shred it back to MP3, and even at an obscene 128kb / s bit rate. We will not do this, and for testing we will use the latest version of the LAME 3.100 encoder with an insane preset and a 320 kb / s bit rate.

In the first figure, it was seen that the spectrum in MP3, as expected, undergoes oscillations in the HF region and finally filters at the 20 kHz limit. Of course, this is the limit of the synthetic test; in a real music signal, it will probably be even lower. The size of the dynamic range in the MP3 file has not changed compared to the original. Those. The LAME 3,100 encoder at 320 kb / s does not add any intrinsic noise to the recording.

1 kHz waveform distortion when encoded in MP3 compared to original WAV

Converting a single 1 kHz signal to MP3 showed the appearance of many small harmonic distortions. And although formally their participation is small (0.0009%), that is, one and a half to two times less than in the exhaust of a good DAC: in the dynamic spectrum of a real phonogram, their number will grow in an avalanche and in an unpredictable order. Furthermore, the “thickening” of the base of the strait at the original 1 kHz peak indicates certain problems, tainted by parasitic oscillations. This characteristic is clearly illustrated by the 100 Hz “square” wave after conversion to MP3. As you can see, its outline loses its definition along the horizontal axis. All of this ultimately has a negative effect on hearing fatigue when listening to MP3s, unfortunately even the highest bit rates.

100 Hz “square” wave after conversion to MP3 (top) and AAC (bottom)

AAC: increase the noise, but keep it clean
A more precise way operates the AAS algorithm, which is actively used by Apple, and not only by it. Digital TV broadcasters work with this audio codec, and AAC is also included in the MPEG-4 container package.

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What is the best audio format for my portable device?

Does it matter what audio format you use?

Check the format of your laptop
Choose the level of sound quality you want
Consider the bit rate
Is the music service you are using adequate?
Video: In what format to download music, FLAC or mp3? Chenfec C01 MP3 MP4 Player Review with Bluetooth 4.0 16Gb Memory and Pedometer with MicroSD Voice Recorder 2021, March

He brings musical experience, including experience as a music producer and composer, to articles on digital music.

If you have a portable device that can play digital music, have you ever wondered what specific audio format you should use?

After all, it’s not always clear which format is best for music. Some services like Amazon sell digital music in MP3 format. While Apple offers song downloads from its iTunes Store in AAC format.

The question then is what formats can your device actually play. If it is relatively new, it can play lossless formats like FLAC and older ones like MP3 and AAC.

And to add even more confusion, there is also a listening factor. How important is sound quality to you?

To help you decide, here are some things you can do.

Check the format of your laptop
Before choosing an audio format, the first thing to do is check its compatibility. This can usually be found on the manufacturer’s website or in the specifications section of the user manual (if provided, of course).

Here are articles that can help if you own one of the following Apple devices:

Choose the level of sound quality you want

If you are not going to use high quality audiophile equipment in the future, a lossy audio format may be sufficient if you only intend to use your laptop. For wide compatibility, the MP3 file format is the safest option. This is an old algorithm, but it works well. In fact, it is still the most compatible audio format of all.

However, if, for example, you rip tracks from a music CD, it may be wise to save a lossless copy on your computer / external hard drive and convert it to a lossy format for your laptop as well. This will keep your music safe in the future, even if new formats and hardware appear later.

Consider the bit rate
Bit rate is an important factor to become familiar with, especially when looking for the best quality music playback. However, the actual bit rate setting you need will depend on the audio format you are using.

For example, the MP3 (MPEG-1 Audio Layer III) format has a bit rate range of 32 to 320 Kbps. You can also choose two encoding methods, namely CBR and VBR. In this case, instead of encoding using the default CBR (constant bit rate), it is much better to use VBR (variable bit rate) encoding. This is because VBR will give you the best quality-to-file size ratio.

The encoder you use is also an important factor.

If you are using an audio file converter that uses, for example, the MP3 Lame encoder, then the recommended preset for high-quality audio is “extreme fast”, which corresponds to the following:

Lameness Sensor Switch: -V0
Average bit rate: approx. 245 kbps.
VBR working range: 220-260 kbps.
Is the music service you are using adequate?
It is best to choose the music service that works best for you and your portable device.

For example, if you own an iPhone or other Apple product and exclusively use the iTunes Store for your music, then it makes sense to stick with the AAC format, especially if you’re going to stay in the Apple ecosystem. This is a lossy compression scheme, but it is ideal for the average listener.

However, if you have a mix of hardware and want your music library to be compatible with everything, then choosing a music download service that offers MP3 is probably the best option; after all, it is still the de facto standard.

But if you are a music lover who wants only the best and your laptop can handle lossless audio files, then choosing an HD music service is easy.

What audio format should I choose? Highest quality music format Part 3

Audiophiles versus compressed music

Most audiophiles who value the best possible sound quality tend to avoid MP3, AAC, and other digital audio formats because these formats use compression to create smaller files. The trade-off is that the upper and lower limits of the audio range are lost. Loss is not noticed by most average listeners, but for sound enthusiasts it can be a barrier. If you are used to listening to music on your iPhone or Android device, you will probably be satisfied with AAC or MP3.

Lossy audio compression
I’ll start with the well-known and widely used MP3 format (although not always the favorite). This audio format is actively used everywhere and everywhere, where it is needed and where it is not needed. But this does not mean that it is not worthy of the place it occupies in its niche. Very worthy. Although he has been “sitting” in his niche for about two decades, no one has “kicked” him out of there yet. And there were many who wanted to say it. And the main favorite of them is WMA (Windows Media Audio), which was conceived by Microsoft as an alternative to MP3. As a result, it is an alternative and it is, despite the best efforts of the developers. The next character is OGG. Despite the broader possibilities than MP3, for example, it never received widespread acceptance. Although it is compatible with many operating systems. Perhaps, it is worth mentioning the AAC audio format, which was supposed to replace MP3 in the relay. It has improved encoding quality and reduced compression loss. But Ay.

The main advantage of these formats is their small size. The downside is the loss of quality.

What audio format should I choose? Highest quality music format Part 2

AAC or MP3: audio quality and file size

To explore the differences between formats, let’s compare The Mountain Goats’ Wild Sage song encoded in each format at three different speeds: 128 kbps, 192 kbps, and 256 kbps. The higher the kbps, the larger the file, but the better the quality.

See also: New Year’s discounts of up to 20,000 rubles on Samsung Galaxy smartphones on Beeline
Format Encoding rate file size
MP3 256K 7.8 MB
CAA 256K 9.0 MB
MP3 192 thousand 5.8 MB
CAA 192 thousand 6.7 MB
MP3 128K 3.9 MB
CAA 128K 4.0 MB
256KBIT / S AAC or MP3
The MP3 and AAC versions sound pretty much the same. The MP3 version is 1.2 MB smaller.

AAC vs. MP3 at 192 Kbps
These versions sound a bit confusing compared to the 256 Kbps versions. However, there is no clear distinction between AAC and MP3. MP3 is almost 1MB less.

MP3 or AAC A 128KBIT / S
The AAC file is a bit cleaner and brighter than the MP3 file, which suffers from a bit of haze and some mixing of sounds. The file sizes are almost the same.

In what format does the music sound with the best quality?
The most popular is the lossless FLAC format, and one of the most widely used CD to FLAC conversion programs is EAC (Exact Audio Copy).

Of all the parameters of digital audio, it is necessary to pay attention first of all to the following indicators:

sample rate (precision of digitizing an analog signal in time), bit rate (the amount of information contained in the file in terms of one second).

Sample rate is the rate at which digital audio is processed. The most common sample rate for quality audio formats is 44.1 kHz.

It is generally accepted that a high bit rate guarantees the best quality; this is true, but only if the source file is of good quality. A high-quality MP3 should have a bit rate of 320 kbps, but a high-quality FLAC format generally has a bit rate of 900 kbps or more.

What audio format should I choose? Highest quality music format

audio format

The audio format is usually a measure of the quality of a track. There is a lot of controversy over which is the best format for music. So I recently witnessed a similar dispute. Not virtual, but real In general, I decided to write an article on audio formats and try to explain in human language which is the best audio format. I’ll try to avoid abstruse terms and feature descriptions, so as not to hurt the brains of readers again.
Immediately, I admit that I am not going to sing praises in honor of any particular audio format, nor am I going to “skip” anyone. Let everyone decide for themselves. I will not go into the “jungle” and review the most famous formats of high quality music.

I believe that these disputes are led by people, to put it mildly, not well versed in this matter. Because professionals (that is, people who know what they are doing and why they are doing it) will not do it. With today’s abundance of audio formats, anyone who needs it will find what they need. Agree, a dispute between a tractor driver and a driver about which is better – a tractor or a car will look stupid. For some purposes a tractor, for others a machine. Here it is the same.

WAV is rightly considered the highest quality music format. This audio format is uncompressed and without quality loss. Used for recording and processing sound, this is the highest quality sound as the WAV recording is not compressed. Encoded to any other audio format. Well, as a result, it “weighs” quite a bit, which is why it is mainly used for sound recording.

What are the different audio formats?

What are MP3, WMA, WAV and FLAC and how are they different? How to convert?
About audio formats

There are many different audio formats. The most used formats are MP3 (MPEG-2 Audio Layer III) and WAV. The type of format is generally determined by the file extension (what comes after the period in the file name .mp3, .wav, .ogg, .wma)

A codec is a specific algorithm for encoding and compressing data in an audio format. For some file types, the codec is uniquely defined. For example, in the mp3 format, the MPEG Layer-3 codec is always used, and in the mp4 format, different codecs can be used.

Often the concepts of codec and format are used in the same sense. Especially when the format always uses the same codec. But sometimes it is important to distinguish between the concepts of formats and codecs. For convenience, the format can be considered a kind of container in which an audio or video signal can be recorded using a specific codec.

Some formats, such as mp4 or flv, may contain audio and video streams, but chkinger’s CD emulator streams AUDIO STREAMS ONLY.

Codecs are divided into two types, depending on the type of compression:

Lossless sound quality

This group of formats records and encodes audio in such a way that it can be accurately reconstructed by decoding.

The most popular lossless encoding formats are:

FLAC (Free Lossless Audio Codec)

APE (mono audio)

ALAC (Apple Lossless Audio Codec)

Lost

Lossy compression modifies the sound. For example, frequencies inaudible to the human ear are eliminated. The decoded file will differ from the original in terms of the information recorded on it, but it will sound more or less the same.

Popular lossy formats:

MP3

WMA

OGG

CAA

Learn more about popular audio formats

WAV is one of the first audio formats. Typically used to store uncompressed audio (PCM) recordings that are identical in sound quality to CD (audio-CD) recordings. On average, a minute of sound in wav format takes about 10 megabytes. Often an audio CD is ripped onto it and then converted to mp3 using an audio converter.

MP3 (MPEG Layer-3) is the most popular audio format in the world. MP3, like many other lossy formats, truncates audio that the human ear cannot hear, reducing file size. At the moment, mp3 is not the best format in terms of the relationship between file size and sound quality, but due to its prevalence and compatibility with most devices, many people store their recordings on it.

WMA (Windows Media Audio) is a proprietary format of Microsoft. Initially, this format was introduced as a replacement for MP3, which, according to Microsoft, has higher compression characteristics. But this fact has been questioned by some independent tests. Furthermore, the WMA format supports data protection through DRM.

OGG is an open format that supports encoding of audio with various codecs. The most used codec in ogg is Vorbis. In terms of compression quality, the format is comparable to MP3, but less common in terms of media player and audio player.

AAC is a proprietary audio format that has more capabilities (number of channels, sample rates) compared to mp3 and offers slightly better sound, with the same file size. At the moment, aac is one of the highest quality lossy audio encoding algorithms. The format is compatible with most devices. A file of this format can have the extensions aac, mp4, m4a, m4b, m4p, m4r.

FLAC (only Gromaudio USB 3 can play it from CD changer emulators) is a popular lossless compression format. It does not change the audio stream and the sound encoded with it is identical to the original. It is often used for listening to sound in high-end sound systems. It has limited support for devices and players, so usually for listening to flac on the player, it is pre-converted.

Audio Formats

Main formats

AAC
Advanced audio coding
The format is a further development of the MP3 format.
A THE C
Apple lossless audio codec
Apple Lossless (also known as Apple Lossless Encoder, ALE or Apple Lossless Audio Codec, ALAC) is an audio codec developed by Apple Inc for lossless compression of digital music.
ALS
MPEG-4 audio lossless encoding
MPEG-4 ALS is an efficient and fast codec for a variety of applications.
AMR
Adaptive multiple rate
The AMR compression format was developed specifically for use in cellular systems. Its field of application is voice audio content compression.
BOW
Monkey Audio
Monkey’s Audio (Windows only) is considered one of the best lossless audio codecs for storing music due to its effective ratio of output file size to speed.
ATTRAC
Adaptive Transformation Acoustic Coding
ATRAC is a lossy compression system based on psychoacoustic principles. Compresses an audio CD to approximately 1/5 of the original with a slight loss in sound quality.
Asao
Nellymoser audio codec
Nellymoser Asao is a proprietary codec that was designed for low bit rates.
CELTIC
Overlapping Energy Constrained Transformation
The CELT codec is an algorithm for compressing audio data. Like MP3, Vorbis, and AAC, it is suitable for high-quality music streaming. Unlike these formats, CELT also has a very low latency, lower even than Speex, GSM or G.729.
Dolby
Dolby has developed many audio sound formats. Among them there are also compression formats.
FLAC
Free Lossless Audio Codec
FLAC is possibly the most popular lossless audio compression format.
LossyWAV
LossyWAV is a free lossy compression format. But, in essence, it is a preprocessor for PCM audio stored in WAV containers.
MP1
MPEG-1/2 Audio Layer I
MPEG-1 Audio Layer I (abbreviated as MP1) is one of the three formats included in the MPEG-1 standard. Even though it is compatible with many media players, the codec is already very outdated and has been superseded by the MP2 and MP3 codecs.
MP2
MPEG-1/2 Audio Layer II
MP2 is still used in the broadcasting industry for satellite transmission of digital video transmission and digital audio transmission.
MP3
Audio Layer III MPEG-1/2
The format is sometimes confused with MPEG-3, but MP3 is designed to compress only audio information and the full name sounds like MPEG Audio Layer-3.
MP3 surround sound
In 2004, Fraunhofer IIS released a backward compatible extension for MP3. MP3 Surround files provide high quality 5.1 sound with new decoders.
MP4
MPEG-4 Part 14
These are file extensions for the MPEG-4 container format, which can include all types of multimedia (video, natural and synthetic audio, 2D and 3D graphics, animated avatars, etc.).
MPC
Musepack
Musepack is a lossy compression scheme invented by the German programmer Andree Buschmann.
MT9
A new multitrack waveform data storage format that claims to be MP3.
Ogg Vorbis Audio
The Ogg vorbis format was developed by Xiphophorus. On the same site you can find the source codes of the project. It is part of the Ogg project to create a completely open multimedia system.
OptimFROG
OptimFROG is a lossless compression algorithm whose main goal is to reduce the size of audio files as much as possible. This is somewhat similar to ZIP compression, but is highly specialized for audio data.
Opus
Opus is a highly versatile, royalty-free, open source audio codec.
RealMedia
RealMedia is a proprietary streaming and multimedia file format owned by RealNetworks products and services.
SND
Sound
SND (SouND) is a digital audio file format created by Apple.
Speex
Speex is a patent-free audio compression format developed for voice transmission, as well as for use in open source software (eg VoIP).
TAK
Tom’s lossless Audio Kompressor
TAK is lossless audio compression that provides APE efficiency and FLAC decoding speed.
VQF
TwinVQ
A proprietary format that was created to replace MP3, but was never fully developed due to its proprietary nature.
Wav
Wave audio file format
The WAV format is perhaps the most common audio storage format. It is the easiest to use to process and is compatible with almost all audio players.
WMA
Windows Media Audio
WMA is a compression format developed by Microsoft.
WavPack
WavPack is a completely open, lossless, high quality, lossy audio compression format with a unique hybrid mode.

What audio formats do you need? Part 3

 

.flac

Advantage:
– The best sound quality
– lossless compression
– additional features (built-in markup for tracks, any resolution, stream, etc.)
– free license, open source

Disadvantages:
– average file size (more than “lost”, but less than “uncompressed” formats)
– On older operating systems, you may need to download and install the player program beforehand.

To know what to use:
to listen to high-quality music, create a music library, phono archive

ogg Vorbis

A lossy compression format with slightly better sound quality than mp3, free license and additional features. The gg format was created for sound and video, in addition, it is possible to use different sound coding systems (the so-called container format). Usually ogg is used with the Vorbis encoder, which provides better sound quality than mp3 at the same bit rate. All audio examples on Wikipedia are presented in this format, as it takes up little space and follows the ideology of free software. Compatible with most Internet browsers and many players. It has proven itself at both high and low bit rates, which is important for voice transmission.

Recently, the manufacturer, the Xiph.org foundation, suggested using the new free Opus encoder instead of Vorbis, which is already supported in many browsers. If you generalize further, common users will not notice the “substitution” as the file will likely have the same extension. ogg (although there is a separate .opus extension). However, while this is a matter for the future.

ogg (Vorbis)

Advantage:
– Better quality / size ratio
– Small file size
– Free license
– Additional functions (built-in markup for tracks, any sample rate, stream, etc.)

Disadvantages:
– Average sound quality (better than mp3, but worse than “lossless” formats)
– not all players are supported yet (but almost all browsers)

What to use for:
Internet: audio samples on free sites, podcasts, broadcasts, networking projects; computer games, voice recording

wav (and aiff)

The oldest audio format that contains uncompressed audio, similar to an audio campaign disc. wav was developed by Microsoft in the early 90’s (and the aiff format was Apple in 1988). The wavyaiff formats are identical to each other, except for some technical details that are only of interest to specialists. Both formats are now compatible with Windows and Mac OS, so in general, there is absolutely no difference in their use. The only difference is that aiff allows you to store additional information. Of course, WAV and AIFF files take up a lot of disk space, so it’s not worth storing your music library in these formats or using them to send them over the Internet.

However, wav (and aiff) have an advantage over compression formats. The fact is that when compressed formats are played, the player decompresses them on the fly, which requires additional processor resources. While listening to music, it does not matter, the processor load is still very low. But when working with sound in real time (complex sound processing, creating sound collages, improvisation, sampling, etc.), this can be significant. Therefore, it makes sense to store short sounds in uncompressed formats, intended to continue working with them, for example, sound effects.

.wav (and .aiff)

Advantage:
– The best sound quality
– the most economical use of the processor during playback
– compatible with most programs and devices

Disadvantages:
– large file size

What to use for:
processing, real-time sound manipulation, storing short sounds

How to play all these files and how to convert music to them?

play

As mentioned above, now there is no problem to play any of these formats on a computer and phone. Windows Media Player and iTunes play flac, wav, mp3; Chrome, Firefox, Safari, Opera (including their mobile versions) and many other browsers support all four formats in some way.

However, for convenience, versatility, and to avoid any pitfalls, we recommend installing a proven (and, of course, free) player that plays all formats correctly.

What audio formats do you need? Part 2

Hence, mankind started looking for a way to reduce file size without reducing sample rate and bit depth.

Compression with loss of sound quality

As a result of the research, it was found that human perception “skips” some sounds and their individual components, and if they are removed from the sound stream, the listener will not notice anything. Thanks to an algorithm that discards the “unnecessary”, it was possible to achieve impressive file size compression rates: 10 times and more! However, it turned out that the human brain “is not dumb” and understands that something is wrong with sound. Lossy compression gives a flatter, “cardboard” sound, lost transparency, sound details, a sense of space.

The bit rate, which is set by the creator of the sound file, plays an important role. For lossy compression, the higher the bit rate, the better the sound quality, but also the larger the file size. About 15 years ago, most music listeners were satisfied with the bit rate of MP3 files – 128-192 kbps (ten times) compression. Recently, there has been a tendency to prefer higher bit rates (256-320 kbps) or other formats (.ogg, .opus). Advanced compression algorithms use a variable bit rate: more bits are allocated for more complex musical pieces and less for lighter pieces, maintaining more or less the same quality at different moments of the sound.

Lossless compression

To avoid quality degradation, lossless audio compression methods have been developed as an alternative to lossy compression. Such compression is similar to archiving: when the data is packed into an archive, a file in zip, rar, etc. format, the size of which is smaller than the original data. It can then be unpacked and the original data will be accurately restored to the last bit. But conventional archiving methods produce very little compression of the audio data. Therefore, special algorithms for sound began to be developed, based on the idea of ​​predictability, self-similarity of sound waves. These algorithms usually compress a file 2 to 3 times. The resulting file size is larger than lossy compression, but still fully retains the original quality.

Lossless audio files (such as .flac) can be played without first unpacking – the audio player unzips the file during playback (the same is true for lossy files, however).
Unlike “lossy” formats, the bit rate isn’t that important here: it changes all the time depending on how much you’ve managed to compress a particular piece of sound, and of course it doesn’t affect the quality.

Audio file formats

To reiterate our original thesis, you only need four audio formats for all possible purposes. Consider them!

mp3

The most popular audio format with the worst sound quality. Lossy compression format.

As a step?

mp3 is historically the first audio compression format. It appeared and spread in those distant times, when the memory of computers was scarce and the Internet was accessed by telephone calls. Digital sound as such was still a novelty and existed alongside analog cassettes. The alternative to mp3 was just uncompressed sound (wav …), which takes up large amounts of data. Users were inspired by the very ability to burn all of their favorite artist’s albums to CD-ROM or send a song via email. At the time, undemanding consumers paid no heed to the voices of skeptics. So mp3 soon became the most widely used audio storage format.

[“I don’t hear the difference between mp3 and non-mp3 quality.” ]

.mp3

Advantage:
– Support for the maximum number of programs and devices
– Small file size

Disadvantages:
– Poor sound quality
– Limited technical capabilities

What to use for:
to listen to “drafts”, for preliminary screenings, “fast” delivery of demos over the Internet, rehearsals, official purposes, for voice recording

flac

flac is a lossless audio compression format, the most popular among its “siblings”. Compresses the file size, depending on the complexity of the audio information, between 1.4 and 4 times (the bit rate varies from 350 to 1010 kbps). Its prevalence was facilitated by open source code, which made it possible to create a large number of programs that work with it on all operating systems. Flac spread it so widely that even “brontosaurs” like Apple and Microsoft resigned themselves to its existence.

What audio formats do you need?

You are a music lover or a professional musician, or you simply use music for some of your own purposes (performances, dances, videos …), but you are not well versed in all these “computer” things: formats, files, bitrates, extensions … This article is for you …

The content is brief: of all the variety of audio formats, you need four:
1) for high-quality listening, a music library;
2) for “fuzzy” listening service purposes;
3) “for Wikipedia”;
4) for real-time audio processing.

Which ones, why and what to do about it – read below!

Digital sound
Audio Pixels Audio
compressed and uncompressed

To understand how one format differs from another, let’s briefly understand what
it is digital sound.

Sound “pixels”

You have surely seen an image of a sound wave (for example, in a sound editing program). Like any image, a sound graphic can be recorded digitally by dividing it into many small “pixel” parts. The smaller the pixels, the more horizontally and vertically, the better the image.

Only in the case of sound, horizontally, we plot the time axis and vertically, the value of the signal (in real sound propagating through the air, the value of the signal is the change in air pressure). Each second of sound is divided into many smaller identical time intervals, in each of which a signal value is recorded. The number of these segments per second is called the sampling frequency …. And the number of possible gradations of the signal value is determined by the bit depth; This parameter indicates how many bits are used to record a signal value: the more bits that are used, the more gradations of the value can be recorded. For example, our figure shows a bit width of 4 bits, which gives 2 4 = 16 value gradations.

Digital recording of a sound wave. The green curve is the original sound, the purple bars are its digital recording as separate signal values.

As a result of digital rendering, the sound wave looks like this:

Digital-sound-image__presentation_2.png

Digital representation of a sound wave.

This is of course a very rough “drawing”, but if you use a higher sample rate and bit depth you can make the “pitch” invisible to our ears (just like very small pixels are invisible for the eye).

The sample rate of an audio CD is 44,100 hertz (signal values ​​per second) = 44.1 kHz (kilohertz). This is sufficient to encode all frequencies audible to the human ear. And its capacity is 16 bits, which allows to transmit 2 16 = 65,536 gradations of signal values.

Experts discuss whether you need a higher resolution for high-quality sound. Indirect evidence suggests yes. Hence, there is digital sound with higher sample rates (48, 96, 192, 384 kHz) and bit depths (24, 32 bits). This high resolution supports DVD Audio, many types of files (flac, wav, aiff …), some cinema sound formats (Dolby TrueHD, DTS-HD Master Audio …).

Uncompressed and compressed audio bit rate

However, even an audio CD takes up a lot of space. This is shown by the bit rate parameter (bit rate, data rate, kbit / s): it indicates how many bits (kilobits) are required to record 1 second of sound. For uncompressed “normal” sound, it is very easy to find out the bit rate: you need to multiply the bit depth (number of bits times 1 signal value) by the sample rate (number of values ​​per second) and by the number of sound channels (let’s not forget that stereo sound has two sound channels, left and right, in each of which the sound wave is recorded separately).

Using our figure, the bitrate can be represented symbolically as follows:

Digital-sound-image__presentation_3.png

Uncompressed audio bit rate (blue area)

It is easy to calculate that the bit rate of an audio CD is

16 bits × 44 100 Hz × 2 channels = 1,411,200 bps = 1,411.2 kbps.

This is usually true for uncompressed audio file formats (wav, aiff).
So one second of uncompressed sound takes approx. 172 KB, one minute – 10 MB, one hour of music occupies 606 MB, the total sound volume of an audio CD is 74 minutes, ie approx. 750 MB.

[How do we calculate this? ]

Hence, mankind started looking for a way to reduce file size without reducing sample rate and bit depth.