AAC Format


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AAC Format

AAC Format
AAC Format
AAC Format
AAC Format

What is AAC Format?

The Advanced Audio Codec, commonly abbreviated as ACC, is a standardized digital audio compression scheme. It has been designed to achieve better sound quality than MP3 at similar bit rates. Born out of the necessity to enhance audio quality in the era of digital technology, ACC has since become a prominent format in various multimedia applications.
Every format has its unique attributes, and ACC stands out for its efficiency and versatility. Its architecture allows it to retain more sound detail, thereby promising richer audio experiences.

Audio formats play a crucial role in defining the essence of digital media. Choosing the right format can determine the balance between quality and size, a factor paramount to the digital age.
“In the realm of sound, ACC shines bright amidst the myriad of formats.” – The Sound Almanac

Benefits of using ACC audio.

The superiority of ACC over some other traditional formats lies in its myriad advantages. Firstly, it offers a wider frequency range, meaning listeners can hear more details in both the low and high ends of the audio spectrum.
Moreover, it provides a more efficient compression algorithm, allowing for smaller file sizes without sacrificing quality. This makes ACC an excellent choice for streaming services and other platforms where bandwidth and storage are of concern.

Lastly, ACC’s adaptability ensures it can be used across various platforms, ensuring consistent audio quality regardless of the device.
“A great audio format is like a symphony; it brings out the best in every note.” – Digital Media Chronicles

How does AAC compare to MP3?

When one draws a comparison between ACC and MP3, the former often comes out on top in terms of technical prowess. While MP3 revolutionized the music industry in the 90s, ACC has taken the reins in the 21st century by providing enhanced audio clarity.
A key distinction lies in their bit rates. ACC can deliver similar or even better quality than MP3 at a reduced bit rate, making it more efficient and versatile.

However, it’s essential to understand that while ACC might hold technical advantages, MP3’s widespread adoption ensures its presence in most audio applications.
“While MP3 paved the way, ACC refined the path.” – Echoes of the Digital Age

Historical background of AAC format.

Delving into the history, ACC was introduced in 1997 as part of the MPEG-2 standard. Designed to be the successor of MP3, its development was driven by the goal of surpassing the existing audio formats in quality and efficiency.
Throughout its journey, ACC has undergone various enhancements. Each iteration aimed at refining its performance, making it a stalwart in the realm of digital audio.

Today, it stands as a testament to the advancements in audio technology, bridging the past and the present.
“History isn’t just about dates; it’s about innovation, especially in the digital world.” – Auditory Odyssey

Technical specifications of AAC.

ACC’s brilliance is underscored by its technical underpinnings. It supports up to 48 channels, as opposed to MP3’s two channels. Additionally, it boasts a wider frequency range, extending from 8Hz to 96kHz.
Its sampling rates and enhanced compression algorithms ensure a superior audio experience, setting ACC apart from its counterparts.

It’s these technical attributes that allow ACC to retain audio fidelity even at lower bit rates, a hallmark of its design.
“In technology, the devil is in the details, and ACC mastered them all.” – The Digital Revolution

How is AAC used in the modern era?

Today, ACC is ubiquitous. From streaming services to podcasts, its presence can be felt across various multimedia platforms. Its efficiency makes it ideal for applications where bandwidth is paramount, ensuring listeners receive top-tier audio quality.
Moreover, as devices evolve, ACC’s adaptability ensures its seamless integration, cementing its position in the digital realm.

The digital landscape is ever-evolving, and ACC continues to remain at its forefront, owing to its versatility and excellence.
“Modern challenges require modern solutions, and ACC is the answer to today’s audio challenges.” – Tales of the Technological Era

What devices support AAC playback?

Most modern devices, ranging from smartphones to home entertainment systems, support ACC playback. Its widespread acceptance is a testament to its superiority and the industry’s confidence in its capabilities.
Manufacturers realize the importance of sound quality for consumers. By incorporating ACC compatibility, they ensure that listeners get the best audio experience possible, regardless of the device they use.

As technology marches forward, the list of devices that support ACC is only expected to grow.
“In a world filled with noise, it’s the clarity of ACC that shines through.” – Rhythms of the Modern World

Future prospects of AAC technology.

The trajectory of ACC appears promising. As audio requirements become more demanding and listeners more discerning, AAC’s attributes position it as the format of the future.
Developments in audio technology might bring about new formats, but the foundational principles of ACC will likely remain relevant. Its adaptability ensures it can evolve with the times, making it a lasting presence in the audio world.
“The future is but a canvas, and ACC has already painted its masterpiece.” – Soundscapes of Tomorrow

Is AAC the best audio format?

While it’s tempting to label AAC as the best, it’s essential to understand that the “best” is subjective. AAC holds undeniable advantages in terms of efficiency and quality. However, the right format often depends on specific use cases and personal preferences.
That said, in many scenarios, ACC does emerge as the top contender, balancing quality with efficiency like few other formats can.
“Perfection isn’t an end but a journey, and ACC’s journey is nothing short of remarkable.” – The Audio Anthology

Potential drawbacks of AAC.

No technology is without its shortcomings. Some critics argue that while AAC is efficient, it may not always deliver the best quality for audiophiles at higher bit rates compared to other lossless formats.
Additionally, older devices might not support ACC, leading to compatibility issues.

Despite these drawbacks, AAC’s merits often outweigh its limitations, making it a favorite in many applications.
“Every coin has two sides, but it’s the shine that often catches the eye.” – Digital Dilemmas

Final words

The AAC format, with its rich history and technical brilliance, stands as a beacon in the realm of audio technology. Its journey from its inception to its widespread adoption today underscores its significance. As we continue to evolve in the digital age, ACC’s role in shaping our auditory experiences cannot be overstated.


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What are the differences in audio quality between various MP4 audio codecs, such as AAC, MP3, and AC3?

What are the differences in audio quality between various MP4 audio codecs, such as AAC, MP3, and AC3?

What are the differences in audio quality between various MP4 audio codecs, such as AAC, MP3, and AC3?
What are the differences in audio quality between various MP4 audio codecs, such as AAC, MP3, and AC3?
What are the differences in audio quality between various MP4 audio codecs, such as AAC, MP3, and AC3?
What are the differences in audio quality between various MP4 audio codecs, such as AAC, MP3, and AC3?

Lossy Audio Compression: Understanding the Basics

As a music lover, I’ve always been interested in the technical aspects of audio compression. When it comes to digital audio, there are two main types of compression: lossless and lossy. Lossless compression is used to reduce the size of audio files without sacrificing any quality, while lossy compression is used to achieve smaller file sizes by discarding some of the audio data.

Lossy compression is the most common type of compression used in digital audio, and it’s what we’re talking about when we discuss MP4 audio codecs like AAC, MP3, and AC3. The basic idea behind lossy compression is to remove parts of the audio that are less important to the overall sound, while keeping the parts that are most important.

For example, a lossy audio codec might remove some of the high-frequency sounds that are outside the range of human hearing, or it might reduce the bit rate of the audio to achieve a smaller file size. The result is a file that sounds almost identical to the original, but is much smaller in size.

The Differences Between AAC, MP3, and AC3

When it comes to MP4 audio codecs, there are several options to choose from, including AAC, MP3, and AC3. Each of these codecs has its own strengths and weaknesses, and the one you choose will depend on your specific needs.

AAC (Advanced Audio Coding) is a popular codec that’s used in a wide range of applications, from streaming audio to mobile devices. It’s known for its high-quality sound and efficient compression, which makes it a great choice for music lovers who want to store large collections of music on their devices.

MP3 (MPEG-1 Audio Layer III) is one of the oldest and most widely used audio codecs. It’s known for its compatibility with a wide range of devices and software, and it’s still a popular choice for music lovers who want to store their music in a digital format. However, MP3 is not as efficient as some of the newer codecs, and it can produce lower-quality sound than AAC or AC3.

AC3 (Dolby Digital) is a codec that’s commonly used in movie theaters and home theater systems. It’s known for its high-quality sound and support for surround sound, which makes it a great choice for movie lovers who want to experience their favorite films in the best possible way. However, AC3 is not as widely supported as AAC or MP3, and it can produce larger file sizes than some of the other codecs.

Choosing the Right Codec for Your Needs

When it comes to choosing the right MP4 audio codec, there are several factors to consider. If you’re looking for the best possible sound quality, AAC is probably your best bet. It’s known for its high-quality sound and efficient compression, which makes it a great choice for music lovers who want to store large collections of music on their devices.

If you’re looking for compatibility with a wide range of devices and software, MP3 is still a solid choice. It’s one of the oldest and most widely used codecs, and it’s still supported by most devices and software. However, if you’re looking for the best possible sound quality, you may want to consider AAC or AC3 instead.

Finally, if you’re a movie lover who wants to experience your favorite films in the best possible way, AC3 is probably your best bet. It’s known for its high-quality sound and support for surround sound, which makes it a great choice for home theater systems.

Final Words

In conclusion, the differences in audio quality between various MP4 audio codecs like AAC, MP3, and AC3 are largely a matter of personal preference. Each codec has its own strengths and weaknesses, and the one you choose will depend on your specific needs. Whether you’re a music lover, a movie lover, or just someone who wants to store their audio in a digital format, there’s a codec out there that’s right for you. And if you’re looking for a great tool to help you normalize and convert your audio files, be sure to check out MP4Gain.

What is the difference between AAC and MP3 audio?

What is the difference between AAC and MP3 audio?

AAC vs MP3
AAC vs MP3
AAC vs MP3
AAC vs MP3

Introduction

As a music lover, I am always interested in the different audio formats that are available. In this article, we will discuss the differences between AAC and MP3 audio formats. We will explore their similarities, differences, advantages, and disadvantages.

Similarities

Both AAC and MP3 are audio codecs that compress audio files to reduce their size while maintaining a reasonable level of audio quality. They are both widely used and supported by many devices and media players. AAC and MP3 are both lossy audio formats, which means that they remove some audio data during compression, resulting in a smaller file size.
However, AAC is considered to be a more advanced codec than MP3. AAC offers better audio quality at the same bit rate as MP3, and it is also more efficient at lower bit rates.

Differences

The main difference between AAC and MP3 is the way they compress audio files. MP3 uses a method called “perceptual coding,” which discards some audio data that is not noticeable to the human ear. AAC, on the other hand, uses a more advanced method called “spectral band replication,” which analyzes the audio signal and replicates the missing audio data.
Another significant difference is that AAC is a newer and more advanced codec than MP3. AAC was introduced in 1997, while MP3 was introduced in 1993. AAC is also the default audio format for Apple devices, while MP3 is more widely used in other devices and media players.

Advantages and Disadvantages

AAC offers better audio quality than MP3 at the same bit rate, and it is more efficient at lower bit rates. AAC also supports more channels than MP3, which makes it a better choice for surround sound and other multi-channel applications.
However, MP3 is still more widely supported than AAC, especially in older devices and media players. MP3 also has a larger user base and a more extensive library of available audio files.

Final Words

In conclusion, both AAC and MP3 are popular audio formats that have their advantages and disadvantages. AAC offers better audio quality and is more efficient at lower bit rates, while MP3 is more widely supported and has a larger user base. If you are looking for a high-quality audio format for your music collection, AAC is an excellent choice. However, if compatibility and availability are more important to you, then MP3 may be a better option.

Quote:

“As technology advances and the demand for higher quality audio increases, newer and more advanced audio codecs like AAC are becoming more popular.” – John Doe, Audio Engineer

10 Common Audio Formats: Which Format Should I Choose?

10 Common Audio Formats: Which Format Should I Choose?

Audio Formats
Audio Formats

Audio files come in various formats and sizes, in addition to our common MP3, there are AAC, FLAC, OGG, WMA, etc.

Audio Formats
Audio Formats

Why are there so many different audio standards? What format is the best? What should you choose when saving audio files?

In fact, all audio formats can be divided into 3 categories, and once you understand the characteristics of each of these 3 types, you can choose one of the three, and then choose a further subdivided category according to your specific needs.

Comparison of audio formats – operation, equipment – Introduction to 10 common audio formats: which format should I choose?
uncompressed audio format
The uncompressed format preserves the original audio waveform. The so-called original audio waveform refers to the result after the sound is captured and converted to a digital signal for storage. Raw audio waveforms are stored without any post processing. From the results, such an audio file will consume a lot of space. For 24-bit (24-bit) 96 KHz audio, you need about 34 MB of storage space per minute.

Uncompressed audio format: PCM
PCM is short for Pulse-Code Modulation, which is a technical method of simulating sound using digital signals. The sounds that we can hear in nature exist in the form of physical sound waves, and in order to simulate this sound wave with a digital signal, scientists decided to sample it and record it with another wave, which is what we call a pulse.

Therefore, digital audio has two basic concepts: sample rate and bit depth. The so-called sampling rate refers to the speed of how many times the sound is sampled. The so-called bit depth refers to the space occupied by a single sample. In uncompressed formats, the product of the sample rate, bit depth, and audio duration is the space occupied by the digital signal that represents the audio content.

PCM is a format commonly used on CDs and DVDs, but its derivative LPCM is often used in practice. LPCM is short for Linear PCM, which is Linear Pulse Code Modulation. Most PCM files in use today are actually LPCM files, so there is no need to differentiate between them.

Uncompressed audio format: WAV
WAV is short for Waveform Audio File Format, which is a standard audio format developed by Microsoft and IBM in 1991.

Many people think that WAV is an uncompressed audio format, but this is not entirely true. In fact, WAV is a “wrapper” type format, a common format developed by Microsoft to use audio for various platforms. So it is possible for WAV to contain compressed audio, but this is rarely the format of choice when using compression these days.

All the Audio Format Differences: Which One Should You Use?

All the Audio Format Differences: Which One Should You Use?

All the Audio Format
All the Audio Format

Three classifications of audio formats

All the Audio Format
All the Audio Format

Characteristics and differences of different audio formats

Which audio format is right for you?

You already know MP3, but what about AAC, FLAC, OGG or WMA? Why are there so many audio file formats and is there any best audio format?

Comparison of audio formats

Audio files come in various types and sizes. While we’re all probably familiar with MP3, what about AAC, FLAC, OGG, or WMA? Why are there so many audio standards? Is there a better audio format? Which ones are important and which ones can be ignored?

All audio formats are divided into three main categories, and once you know what the categories mean, you can choose the format within the categories that best suits your needs.

uncompressed audio format

Uncompressed audio consists of actual sound waves that have been captured and converted to digital format without any additional processing. So uncompressed audio files tend to be the most accurate, but take up a lot of disk space: about 34MB per minute for 24-bit 96KHz stereo.

Audio file format: PCM

PCM stands for Pulse Code Modulation, a digital representation of the original analog audio signal. Analog sounds exist as waveforms. To convert a waveform into digital bits, the sound must be sampled and recorded at specific intervals (or pulses).

This digital audio format has a “sample rate” (how often the samples are made) and a “bit depth” (how many bits are used to represent each sample). There is no compression involved. Digital recordings are almost accurate representations of analog sounds.

Digital Audio Quality

Digital Audio Quality

Digital Audio Quality
Digital Audio Quality

Data rate refers to the data flow used by a video file in a unit of time, also called bit rate or bit stream rate.

Digital Audio Quality
Digital Audio Quality

The popular interpretation is the sampling rate, which is the most important part of image quality control in video encoding. Generally, the units we use are kb/s or Mb/s. Generally speaking, at the same resolution, the higher the code stream of the video file, the lower the compression ratio and the higher the image quality. The higher the code stream, the higher the sampling rate per unit time, the higher the data stream, the higher the accuracy, the closer the processed file is to the original file, the better the image quality, the clearer the image quality and the higher the decoding capability of the playback device is required.

Of course, the larger the code stream, the larger the file size. The calculation formula is file size = time X code rate/8. For example, a 720P RMVB file with a 1 Mbps stream of 90 minutes is common on the Internet and its volume is = 5400 seconds × 1 Mb/8 = 675 MB.

Generally speaking, a video file includes images and sounds, just like an RMVB video file, which contains video information and audio information. Audio and video have their own sampling methods and different bit rates, that is, the same video Audio and video file bit rate is not the same. And what we’re talking about is the bitrate of a video file, which generally refers to the sum of the bitrate of the audio and video information in the video file.

Taking the most popular and familiar RMVB video file in China as an example, VB in RMVB refers to VBR, which is short for Variable Bit Rate. The Chinese meaning is variable bit rate, which means that RMVB adopts dynamic encoding. In this way, a higher sample rate is used for complex dynamic images (singing and dancing, flying cars, wars, actions, etc.), while a lower sample rate is used for static images, and the resources are use rationally to achieve image quality and volume .Effect.

The most fundamental difference between code rate and sample rate is that the code rate is for the source file.

 

2. Sampling rate

Sample rate (also called sample rate or sample rate) defines the number of samples per second taken from a continuous signal to form a discrete signal, and is expressed in hertz (Hz). Sampling rate refers to the sampling frequency when converting an analog signal to a digital signal, i.e. how many points are sampled per unit of time. How many bits are in the data for a sample point? Bit rate refers to the number of bits (bits) transmitted per second. The unit is bps (bit per second). The higher the bitrate, the more data transmitted and the better the sound quality. Bit rate = sample rate x number of bits used x number of channels.

The sample rate is similar to the number of frames of moving images. For example, the sampling rate of movies is 24 Hz, the sampling rate of PAL format is 25 Hz, and the sampling rate of NTSC format is 30 Hz. When we play back the still images sampled at the same rate as the sampling frequency, we see a continuous image. In the same way, when a CD recorded at a sampling rate of 44.1 kHz is played back at the same rate, a continuous sound can be heard. Obviously, the higher the sample rate, the more coherent the sound will be heard and the picture will be seen. Of course, the sampling rate that human auditory and visual organs can distinguish is limited, which is basically higher than sound sampled at 44.1 kHz, and most people haven’t noticed the difference.

The number of digits in the sound is equivalent to the number of colors on the screen, indicating the amount of data per sample. Of course, the larger the amount of data, the more accurate the playback sound, so as not to confuse the sound. of the teapot with the train whistle. In the same way, it is more clear and precise for the image, so as not to confuse blood and ketchup. However, limited by the function of human organs, 16-bit sound and 24-bit image are basically the limits of ordinary humans, and the highest digits can only be distinguished by instruments.

Detailed Music Format Part 2

Detailed Music Format Part 2

Music Format
Music Format

Music CD

Music Format
Music Format

 

That is, CD records. A CD can play sound files of approximately 74 minutes. The Windows system comes with a CD player. Also, the software that comes with most sound cards provides CD playback functionality, and even some CD-ROM drives are offline. from computer Can be used as a stand-alone CD player when powered on.

WMA with unlimited potential

In developing its own network media service platform, Microsoft primarily promotes ASF (Audio Streaming Format), which is an open standard that supports data transmission over various networks and protocols. It supports audio, video, and a variety of other types of multimedia. And WMA is short for Windows Media Audio, which is equivalent to an ASF file that contains only audio.
The compression ratio of WMA files can be as high as 1:18 in 80kbps 44kHz mode, which is basically the same as VQF. And the compression speed is doubled compared to MP3. So it should be more competitive than VQF.

Vorbis free music format

To avoid rising royalties charged by MP3 music companies, programmers at GMGI’s iCast company developed a new free music format, Vorbis, that rivals or even exceeds MP3 in sound quality. And it will be released over the internet and can be downloaded for free without worrying about infringement issues. But MP3 has become very popular on the Internet, and Microsoft’s Windows Media technology has also started to spread, and Vorbis’s outlook is still not optimistic.

Other audio formats

AIF/AIFF: A sound file format developed by Apple, supported by the MAC platform, and supports 16-bit stereo at 44.1 kHz.
AU: SUN’s AU Compressed Sound File Format, which only supports 8-bit sound, is a commonly used sound file format on the Internet, mainly created by SUN workstations.
CDA: CD audio track file.
CMF: A MIDI-like sound file developed by CREATIVE.
DSP: Abbreviation for digital signal processing. By improving the signal processing method, sound quality will be greatly improved and songs will be more pleasing to the ear.
S3U: MP3 playback file list
RMI: MIDI Instrument Sequence

Lossy compression:

AAC – Sound quality is second only to MPC at high bit rates and looks good at both high and low bit rates. The encoding speed is too slow!
MPC: Performance is average at low bitrate, not as good as MP3 and OGG encoded by Mp3Pro, sound quality is best at high bitrate, and encoding speed is
fast.OGG: The sound quality is better at a low bitrate, and the same is true at a high bitrate. Encoding is slightly slower.
MP3 (MP3Pro): Sound quality is lower than OGG at low bit rate and other aspects are the same as MP3
WMA: High and low bit rates are average, VBR is not supported and the highest is 192Kbit/s

lossless compression:

FLAC – Worst compression ratio of the four, decent encoding speed, good platform support.
PAC: Slightly slower encoding speed, third in compression ratio, good platform support.
APE: The fastest encoding speed, the best compression rate, and the platform is generally supported.
WV: The encoding speed is very fast, the compression rate is second among the four types, and it is only supported by the Windows platform.

Detailed music format

Detailed music format

Audio File Formats
Audio File Formats

classic wave

Audio File Formats
Audio File Formats

As the most classic Windows media audio format, the WAVE file is widely used, which uses three parameters to represent sound: the number of sampled bits, the sample rate, and the number of channels.
The channels are divided into mono and stereo, and the sample rates are generally 11025 Hz (11 kHz), 22050 Hz (22 kHz), and 44100 Hz (44 kHz). The capacity occupied by the WAVE file = (sampling frequency × sampling bits × channel) × time/8 (1 byte = 8 bits).

traditional mod

MOD is a wavetable-like music format, but its structure is similar to MIDI, it uses real samples, and the volume is small. In the earlier DOS era, MOD was often used as background music for games. Modern mods can contain many audio tracks in many formats, such as S3M, NST, 669, MTM, XM, IT, XT, and RT.

midi music computer

MIDI is short for Musical Instrument Data Interface. Records the sound played by the instrument digitally (each note is recorded as a number), and then synthesizes these records via FM or wavetable during playback: FM synthesis is the sound of the instrument is simulated by mixing the multi-frequency sounds; wavetable synthesis consists of storing the sound samples of the instrument in the wavetable of the sound card and extracting the sound from the wavetable as you play.

Boss Boss MP3

It can be said that MP3 is famous, it uses MPEG Audio Layer 3 technology to compress the sound with a compression ratio of 1:10 or even 1:12, with a sampling rate of 44kHz and a bit rate of 112kbit/s. .
MP3 music is music stored in digital form. If you want to play it, you must have a corresponding digital playback and decoding system. Generally, MP3 digital music is decoded by special software and then restored to a waveform sound signal for playback output. This type of software is called For MP3 players, such as Winamp, etc.

Overlord RA series online

RA, RAM, and RM are Real’s mature network audio formats, using “streaming audio” technology, making them well suited for network streaming. Information such as copyright, singer, producer, mail and song title can be added during production.
RA can be called the supreme lord of multimedia communication on the Internet. It is suitable for streaming on the Internet and is currently the best format for listening to online music online.

VQF with high compression ratio

VQF or TwinVQ is an audio compression technology developed by Nippon Telegraph and Telephone and Yamaha Corporation.
The audio compression rate of VQF is almost twice that of standard MPEG audio and can reach approximately 1:18 or even higher. And popular compression formats like MP3 and RA are usually only around 1:12. But it still won’t affect the sound quality, when VQF compress music at 44kHz-80kbit/s audio sampling rate, its sound quality will be better than 44kHz-128kbit/s MP3, when compress at 44kHz-96kbit/s , the music is close to 44kHz-256kbit/s MP3.

MD minidisc

MD (ie MiniDisc) is a comprehensive portable music format released by SONY in 1992. The compression algorithm it uses is ATRAC technology (the compression ratio is 1:5). MD is divided into Recordable MD (Recordable, with two heads of magnetic head and laser head) and Single Play MD (Prerecorded, only laser head).
The powerful editing function is the strong point of MD. You can quickly select tracks, move tracks, merge, split, delete and edit track titles. It is more personalized than CD and you can have your own MD album at any time. MD products include MD Walkman, MD bedside audio, MD car audio, MD recording deck, MD camera gun and MD driver, etc.

AAC: Lossy Encoding Is Getting Better – AAC Format Summary

AAC: Lossy Encoding Is Getting Better – AAC Format Summary

AAC Music File Format

At the time of writing this article, the MP3 codec is over 23 years old. So as not to repeat myself with the article (its most recent version), which already describes the OGG Vorbis codecs (and again hello to the Xiph organization, this is also its development), MPC (Musepack), WMA (Windows Media Audio) and AAC, I will briefly describe the format here. AAC in terms of technologies that until recently were at the forefront of lossy coding.

AAC Format

In my humble opinion, AAC (Advanced Audio Codec) is one of the most advanced formats in the field of data encoding. I will describe the main features of this format, starting with the popular profiles that can be represented by a matryoshka (see the figure below):

– Low Complexity Advanced Audio Coding (LC-AAC)

Low decoding complexity is great for implementing a hardware codec; The hardware requirements for CPU and RAM are also low, which has gained a lot of popularity for this profile. It encodes the 96 kbps signal efficiently.

– High Efficiency Advanced Audio Coding (HE-AAC).

The HE-AAC profile is an extension of LC-AAC and is complemented by patented SBR (Spectral Band Replication, thick – “spectral repetition”) technology. It is spectral repetition technology that allows you to “preserve” high frequencies by encoding at low bit rates.

Why is “save” in quotes? Because the king is not real: the codec leaves room for additional information that is used by the codec synthesizer to restore the high frequencies, but since these frequencies are synthesized, that is, they are recreated by the codec, they are, in fact, a rough copy of the high frequencies that existed in the original file. … In practice, a signal encoded at 48 kbps will sound, for example, as mp3 at 98 kbps if it is supported by the decoder; otherwise, the file will simply be played without restoring the high frequencies and its bit rate will correspond to its mp3-like quality.

– High Efficiency Advanced Audio Coding Version 2 (HE-AACv2)

This profile is relatively young (described in 2006), it was created for a more efficient audio coding in low bandwidth conditions.
The second version of the profile is an extension of the first profile, the changes are in the addition of PS (Parametric Stereo) technology. The principle is somewhat similar to SBR technology: the codec also makes room for recovery information from the stereo base, sacrificing precision.

The operating conditions for this profile are the same as for the HE-AAC described above; The lack of profile support from the decoder will make the recording sound in mono.

– AAC-LD (advanced audio coding – low delay)

The AAC-LD profile has advanced coding algorithms to reduce delays (up to 20 ms);

– AAC-ELD (Advanced Audio Coding – Enhanced Low Delay)

This profile, which inherits all the capabilities of HE-AACv2 (analogous SBR and PS technologies are used, but designed for low latencies);

– AAC main profile

This profile was introduced as MPEG-2 AAC or HC-AAC (High Complexity Advanced Audio Coding). Not compatible with LC-AAC;

– AAC-LTP (Advanced Audio Coding – Long Term Prediction)

This profile is more complex and resource intensive (but also of higher quality) than all the others. It is also not compatible with LC-AAC.

That’s all I wanted to write about this codec. I put the greatest emphasis on the technologies that are used in various AAC profiles (which, by the way, generate a lot of abbreviations: AAC, LC-AAC, eAAC +, aacPlus, HE-AAC, etc.), as I will compare them with the from Opus, but the codec does its job: it is widely used in Internet radio, as well as in digital radio transmission technologies: DRM (Digital Radio Mondiale) and DAB (Digital Audio Broadcasting) (you can see these technologies here), YouTube , as an audio track for many videos in mp4, mkv, etc.

2. Introduction to Opus: description of the format

On December 21, 2017, Xiph announced the beta version of the Opus audio codec version 1.3. I will not go into important matters when I describe this codec, since such information is freely available (for example, here, here, and for those who know English, here and here). The release notes for this beta version can be found here. Here I will point out that this codec is an excellent candidate to replace other codecs. It has many advantages:

bit rate from 6 to 510 Kbit / s;
sampling frequency from 8 to 48 KHz;
support for constant bitrates (CBR) and variables (VBR);
support for narrowband and wideband audio;
support for voice and music;
support for stereo and mono;