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.

There are several types such as WAV, MP3 and FLAC, but what is the difference? Part 4

There are several types such as WAV, MP3 and FLAC, but what is the difference? Part 4

ANALOG vs. DIGITAL AUDIO

There are several types such as WAV, MP3 and FLAC, but what is the difference? Comprehensive research on music file formats

analog audio disc

Data and music
Does the boom from the analog discs come back?

In recent years, the world boom of analog discs has arrived. According to the Association of the Recording Industry of the Public Corporation in General of Japan, the national disk market is the production number of 2017 1063000 sheets. In terms of Amount, it was 1,916 million yen, the highest of the last 10 years.

You may have heard that sound quality is generally better than that of a CD, but what really differs is the recorded frequency band.

It is said that the frequency band that can be stored on a CD is up to about 22,000 Hz, while the analog record contains information of up to about 100,000 Hz. However, it is said that the audible human range is approximately 20Hz to 20,000Hz, so it does not make sense unless you notice the difference in sound. It seems that the parties other than the audible human range, the vibration of the air due to the sound and the force caused by it, are transmitted by other routes other than sound.

This is a great merit that can only be experienced with analog discs, and it can be said that it is the true emotion of the discs.

However, the care of the equipment, the deterioration of the plate, the difficulty of handling and the size can be disadvantages compared to the CDs and the data. (In the youngest generation of these days, this effort is quite new and many people enjoy it).

abstract

There are several formats for musical data files and each one has its own personality. Which of the music services and distribution sites that I have used casually so far?

It can also be good to listen and compare the differences with data such as CD and analog discs.

I want to take me well with musical data wisely according to my style!

There are several types such as WAV, MP3 and FLAC, but what is the difference? Part 3

There are several types such as WAV, MP3 and FLAC, but what is the difference? Part 3

Audio Formats

Relationship between the depth of bits, the sampling frequency and the frequency of bits

Audio File Formats

The musical data has numbers such as the depth of bits and the sampling frequency indicating the amount of musical data per second.

And the product of the two is the “bit rate”.

· Sampling rate
Also known as sampling frequency. It shows how many tens of thousands of sounds are collected per second.

The higher the value, the greater the number of divisions, which translates into a softer sound and an improved sound quality.

By the way, the CD is 44100Hz.

· Bit depth
Also known as quantification bits, bid reduction, sample bits count.

This shows how much capacity is given to divided data.

The greater the sound, the better the sound will be and the quality of the sound will be improved.

The CD is 16 bits.

· Bit rate
It is shown as BPS and shows the amount of data per second.

It is the product of the “sampling frequency” and the “bits depth” mentioned above.

In the case of a stereo file, there are two sounds, so if you formulate it …

Sampling rate (Hz) x Bit depth (bits) x 2 = Bit rate (BPS)
A large “bit rate” means a “sampling rate” and a large large bits depth, which means that sound quality is good.

By the way, in the case of CD,

44100 (Hz) x 16 (bits) x 2 = 1411200 (BPS)
This means that.

In this article, I specifically compared the difference in the file size.

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Update: 2020.07.15 Published: 2018.08.14
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There are several types such as WAV, MP3 and FLAC, but what is the difference? Comprehensive research on music file formats
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Data and music
INDEX

I compared file sizes
So, what is the call frequency?
Is “dead mp3”?
Why are there so many formats in the first place?
I compared file sizes
Then, I compared what kind of difference is made from the point of view of the file size and if there is a difference in Hz that sounds depending on each file format. In comparison, Tucson Repertory Orchestra and Sierra Vista Symphony Orchestra were listening to the opinion of Japanese Director Toru Tagawa, who serves as musical director and director of the (Sierra Vista Symphony Orchestra), is the ninth of Beethoven is good advised me to play The Berlin Philharmonic directed by Karajan, one of the most famous recordings.

I compared file sizes

So, what is the call frequency?
Is “dead mp3”?
Why are there so many formats in the first place?
I compared file sizes
Then, I compared what kind of difference is made from the point of view of the file size and if there is a difference in Hz that sounds depending on each file format. In comparison, Tucson Repertory Orchestra and Sierra Vista Symphony Orchestra were listening to the opinion of Japanese Director Toru Tagawa, who serves as musical director and director of the (Sierra Vista Symphony Orchestra), is the ninth of Beethoven is good advised me to play The Berlin Philharmonic directed by Karajan, one of the most famous recordings.

Then, here is the CD used for this comparison.

Symphony n. ° 9 by Beethoven (choir) from director Herbert von Karajan released by Universal Music. In fact, it is said that the Ninth of Beethoven was the origin of the unit of a CD. (There are several theories about this).

When I really verified it, there was still a remarkable difference in the size of the file.

OLA 701.5 MB.
ALAC 308.6 MB.
MP3.
160 kbps 79.4 MB
256 Kbps 127 MB
320 kbps 158.8 MB
CAA.
160 kbps 80.2 MB
256 Kbps 127.8 MB
320 kbps 159.5 MB
However, for “MP3” and “AAC”, none of the bit rates appeared around 1 MB.

So, what is the call frequency?

With respect to the frequency, I tried to verify showing the waveform. The image above is in WAV format.

Compared to “WAV”, there were almost no changes in the frequency of acute and only a slight change in the bass was observed.

Comparing “MP3” and “AAC”, which have almost the same file size, you can see that “AAC” has a lower tone. In terms of frequency, “AAC” seems to have a better sound quality. In other words, the result of the verification shows that AAC, which is a more recent compression technology, is higher.

There are several types such as WAV, MP3 and FLAC, but what is the difference?

There are several types such as WAV, MP3 and FLAC, but what is the difference?

Music File Formats

Comprehensive research on file formats
Do they like music to all?

audio file formats

I think many people enjoy music by downloading or playing streaming instead of CD these days, but what kind of format music is stored as data?

I researched the differences, advantages and disadvantages of each format.

Types of audio compression

There are three types of music file formats: “Not compressed”, “compressed with loss” and “compressed without loss”.

File-based compression can reduce the size of the file and reduce the download time and storage capacity.

“Uncompressed format”
As its name indicates it, it is an uncompressed file. The point are the original data.

The advantage is the accuracy of the data. However, it also has the disadvantage of a large file, which uses about 10 MB for a 1-minute audio file.

The most used are “WAV” and “AIFF”. It is common to use “WAV” for Windows and “AIFF” for Macintosh.

“Compression format with loss”
This compression format is probably the one that most uses.

Although there are individual differences, it is said that the human audible range is 20 Hz to 20000 Hz. This file format has the advantage that the file size can be deleted while maintaining a certain level of sound quality when it is removed and compressed Other parts difficult to identify.

Even so, the disadvantage is that the sound quality is lower than the original data. It is not exaggerated to say that “MP3” is the best-known file format. As successors, “AAC” is often used, which was created to achieve higher sound quality. In addition, “WMA”, “Vorbis”, etc. They are also in this format.

“Format of compression without loss”
This format compresses the original data while preserves them.

During playback, you can decompress and return to the original uncompressed format, so the sound quality is the same as that of the original data. Although the file size can be reduced compared to the uncompressed format, it is still about half, so the size of the file is greater than that of the compressed format with loss and takes more time coding and decoding.

In addition, it is currently not handled by the main music distribution sites, and the number of devices that can be reproduced is less than that of uncompressed formats. The most common of these formats is “FLAC”, and Apple uses a single format called “ALAC”.

What is the difference between MP3 and AAC? Part 3

What is the difference between MP3 and AAC? Part 3

aac vs mp3

Finally, let’s review the important MP3 and AAC compatible devices.

 

MP3 o AAC

MP3s are compatible with almost all music-playing devices, such as personal computers, smartphones, and audio devices. Therefore, it is generally better to save the file in MP3 format.

As for AAC, it is a recommended storage format for iPad / iPhone users and those who use iTunes, Apple’s official music player, because it is compatible with Apple devices. Even if you import the sound source from a CD with iTunes or purchase paid music content from iTunes, it will be saved in AAC format.

Which is better, MP3 or AAC?

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In this article, I explained about MP3 and AAC music file storage formats. Finally, if you do not know what is the storage format that I should use, to leave and save the music files in MP3 format, it can be said that it is the best. MP3s have many playable devices and the sound quality is not that different from AAC.

Also, files saved in MP3 format can be easily converted to AAC files using iTunesw. When saving as MP3, it can also support post file conversion, so if you have problems with the save format, it is better to select the MP3 format. Also, if you’re targeting Apple devices, try saving music by choosing an AAC format that doesn’t need to be converted.

What is the difference between MP3 and AAC? Part 2

What is the difference between MP3 and AAC? Part 2

AAC Vs. MP3

The disadvantage of the “lossy compression format” used by MP3 / AAC is that the compressed data file cannot be restored to its original size (the original sound quality of music content).

aac vs mp3

There is a music content compression format called “lossless compression format”, which has a relatively large data size and can restore the original sound quality when playing music files.

There is not much difference between the two compression formats, but if you want better sound quality, you should use the “lossless compression format”. In the next chapter, we will further compare the differences between MP3 and AAC formats.

Comparison of MP3 and AAC

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We will compare MP3 and AAC in terms of sound quality and compression rate (bit rate).

Sound quality

As mentioned above, MP3 and AAC are compression methods that use the “lossy compression format”, so there is not a big difference in sound quality between the two formats. The sound quality of MP3 and AAC differs depending on the compression rate (bit rate) of the music content file. So what exactly is the compression rate (bitrate)? The next section describes (compression bit rate).

Compression rate (bit rate)

format Compression rate (bit rate)
64kbbp 96kbbp 128 kbbp 160 kbp 192 kbbp 256 kbbp 320kbbp

MP3 Upper Limit Frequency 8.3 kHz 11.7 kHz 15.2 kHz 18.6 kHz 21.3 kHz 22.0 kHz 22.0 kHz

MP3 size 123kB 184kB 245kB 308kB 372kB 494kB 616kB

AAC upper limit frequency 13.5 kHz 15.2 kHz 18.7 kHz 19.1 kHz 19.6 kHz 20.0 kHz 20.0 kHz

AAC size 127kB 188kB 249 KB 310kB 368kB 490kB 613kB

The comparison table above shows the compression rate (bit rate) of MP3 and AAC, and the upper limit of frequency and data size (capacity). The higher the value of the compression rate (bit rate), the higher the upper limit for frequency and data size (capacity), and the better the sound quality.

Although the compression rate (bit rate) of MP3 and AAC is the same, the data size (capacity) and the upper limit frequency are different, so please compare the sound quality using the table above as a guide.

Proper use of MP3 and AAC

In this chapter at the end of this article, we will introduce how to use MP3 and AAC correctly. Even if you read the comparative explanation of MP3 and AAC presented so far, many people may not get it right. How to use MP3 and AAC correctly should be judged by the compression rate (bit rate).

Bit rate

As discussed in the previous chapter, the higher the value expressed in “kbbs” called the compression rate (bit rate), the better the sound quality. However, MP3 and AAC have the same compression rate (bit rate) but different upper limit frequencies.

128 kbps to 160 kbps is adopted for general MP3 / AAC music files. This is because you can watch various music genres like J-POP and Jazz with high sound quality. You can fully enjoy music with your PC speakers and audio equipment.

Then I will explain the characteristics of the compression rate (bit rate) of 128 kbps or less and the compression rate (bit rate) of 160 kbps or more, and which file format should be used, MP3 or AAC.

Less than 128 kbps

A compression rate (bit rate) of less than 128 kbps does not improve the sound quality of music, etc., and is not suitable for the music content storage file format. Suitable as a conversation-focused radio sound source. Also, if it is less than 128 kbps, the AAC format has a higher frequency upper limit, so the sound quality is said to be better than MP3.

192 kbps or higher

The compression rate (bit rate) of 192 kbps or higher reproduces even delicate sounds like classical music. If you have a good ear, you can clearly tell the difference in sound quality.

When the compression rate (bit rate) is 192 kbps or higher, the MP3 format has a higher upper limit frequency and is said to have a higher sound quality. The data size (capacity) is almost the same as that of AAC, so it is recommended to save it in MP3 format.