CBR vs. VBR

ABR, CBR and VBR

CBR (constant bit rate) and VBR (variable bit rate)
Another parameter when compressing video with MPEG is CBR and VBR.
CBR is an abbreviation for Constant Bit Rate, which is one of the encoding methods for converting music and video to data. In the case of MPEG2 video compression, a method that always allocates a fixed number of bits. It’s CBR. On the other hand, there is also a method called Variable Bit Rate, or VBR for short, which allocates a large number of bits to the part where the movement or color changes drastically.

● VBR (variable bit rate)
MPEG generally requires more data to maintain the same image quality in fast moving/changing scenes. If the bitrate is fixed, noise will be more noticeable in a scene with a lot of movement than on a screen with little movement. To fix this, if the bitrate is set high in the scene where the motion is most intense and you normally want to give a lot of information, the amount of data will be excessive in other scenes. With VBR, the amount of data is automatically adjusted according to the scene, as much in a scene with a lot of movement that requires a lot of data, and less in the part where there is almost no movement on the screen, so the quality of the image is reduced. does not degrade. It is generally suitable for long-term recording because it saves space by minimizing file size.

● CBR (constant bit rate)
This is a method of consistently mapping the same data, regardless of how easy or difficult it is to compress the data. The advantage is that the size of the compressed file can be easily predicted (calculated) and if the upper limit of data transmission is limited, it will be of maximum quality in that frame. For example, in the case of DVD, CBR of 9.8 Mbps is the highest image quality in the DVD standard. The downside is that the sound quality and picture quality are not good (quality is not constant) for the amount of data. CBR is common for MP3s.

● ABR (average bit rate)
A type of VBR that is meaningful only when encoded. This is a method of setting the upper bound, average, and lower bound bitrates at encoding time, and encoding so that the final average bitrate is specified while observing the upper bound and lower bound. The overall quality remains the same to some extent, but the quality itself cannot be specified. The advantage is that you can reduce the amount of data while maintaining quality when the data transfer is limited to a certain extent. As an example, a DVD should be burned at an upper limit of 9.8 Mbps, and if it’s a single-sided layer, it should be stored at 4.7 GB, so you also need to specify the average rate (final file size ) .

Notes on MP3/WMA/AAC files

Playable MP3/WMA/AAC files are files with the extension <.mp3>, <.wma> or <.m4a>.

This unit can play MP3/WMA/AAC files created with the following bit rates and sampling frequencies.

Sampling frequency:

8-48kHz

Transfer Rate:

8 to 320kbps

This unit recognizes up to 255 folders and 999 files per USB device.

USB supported file systems are FAT16 and FAT32.

Files with a song larger than 2 GB cannot be played.

Some MP3/WMA/AAC files cannot be played depending on the recording status and recording method. In that case, “Cannot play” is displayed for files that cannot be played.

Playback order of MP3/WMA/AAC files

(Folders that do not contain MP3/WMA/AAC files will be ignored.)

During playback, previously created folders are played in order. In the folder, the songs are played in the order of the created songs.

If you change the folder name or file name (song name) using a computer, the order may change.

The maximum number of characters that can be displayed on this machine is as follows.

Folder name: 64 characters

File name: 64 characters (including extension)

Tag Display (Title/Artist/Album):
ID3 v1.0/1.1: 30 characters
ID3 v2.2/2.3/2.4: 100 characters

For characters that cannot be displayed, “*” is displayed.

Even audio files that conform to the above standards may not play depending on the characteristics of the disc and the recording conditions.

Playback may not be possible depending on the specifications and settings of the encoding software.

Files with DRM (Digital Rights Management) cannot be played.

Audio files encoded with VBR (Variable Bit Rate) may be outside the supported bit rate range. Audio files with bit rates outside the supported range cannot be played.

What is the difference between CBR/VBR/ABR in audio/video conversion [I tried it]

Bitrate is an index that determines the quality of compressed video and audio. Bitrate is the number of bits per second, and in general, the higher the bitrate, the higher the quality. However, the file size will increase accordingly.

The compression method is the behavior of the bitrate at the time of compression, which is the constant bitrate (CBR) method, variable bitrate (VBR), or average bitrate method (Bitrate average, ABR) . be classified.

Constant Bit Rate (CBR) Characteristics
The method of compressing with a constant bit rate is called the constant bit rate (CBR) method. Since the bitrate is fixed, it is not only easy to predict the file size after compression, but also search the playback position at high speed. However, there are problems with videos, such as the quality changing between scenes with little movement and scenes with lots of movement.

WAVE and uncompressed AIFF can also be called CBR.

advantage
It is possible to predict the file size after compression
High-speed playback position search possible
Disadvantage
Quality tends to vary

Variable Bit Rate (VBR) Features
The method of compressing by changing the bit rate is called the variable bit rate (VBR) method. In the VBR method, the bit rate is high where the data jitters sharply, and the part where the jitter is gradual is low and compressed, so the quality can be kept constant as a whole and can be compressed with higher quality than CBR. .It is said that. However, the size of the compressed file is unpredictable because the bitrate changes from moment to moment. Also, it takes more time to search for playback position than CBR .

advantage
Easy to control quality
high quality
Disadvantage
Difficult to predict the size of the compressed file
It takes time to search for the playback position
Average Bit Rate (ABR) Features
Although the bit rate is variable, the method of compressing with a constant average bit rate is called the average bit rate (average bit rate, ABR) method. Although the bitrate fluctuates with this method, the final size of the file can be predicted to some extent because it is compressed so that the average bitrate of all data is constant. This allows you to maintain quality like VBR and predict file size like CBR. However, it takes longer to process than other methods because the data must be scanned at least once before compression.

advantage
It is possible to maintain quality up to a certain point.
File size can be predicted to some extent
Disadvantage
The compression process takes time
Bitrate method of major audio compression formats
MP3
CBR, VBR
WMA
CBR, VBR
CAA
VBR, ABR
Ogg Vorbis
VBR, ABR

VBR

VBR is a compression coding method for audio and video data that changes the amount of data (bit rate) transferred per unit of time.

With VBR , it is possible to reproduce data while maintaining picture quality and sound quality by transferring at a high bit rate in places where the data changes drastically in the file to be transferred. On the contrary, if the bit rate is lowered in a monotonous place where there is little movement, the amount of transfer can be suppressed without waste and the transfer efficiency can be improved.

VBR can be used with MP3, WMA, AAC, etc. among the major file compression encoding methods and can be used with MPEG-2, etc. as video method.

Of the VBRs, the method that adjusts the amount of data to be transferred to be close to the average of the whole is called ABR (Average Bitrate). For VBR, the method where the bit rate is predetermined by a fixed value is called CBR (constant bit rate).

Audio recording bit rate

One measures speed. They both show quality.

Bringing the musical experience to digital music items, including a career as a music producer and composer.

The terms bit depth and bit rate in digital audio are so similar that many people think they mean the same thing. It is easy to confuse them, but they are two different concepts.

You may need to know the bitrate when choosing the best audio format for your portable device or when converting to MP3 format with an audio conversion tool or other program such as iTunes.

Bit depth is important when digitizing an analog music collection or when you need the best possible sound quality.

Audio recording bit rate
Bitrate is a unit of measurement expressed in kilobits per second (Kbps), which is thousands of bits per second. Kbps is a measure of the bandwidth of data transmission equipment. Shows the amount of data flowing through the network at a given time.

For example, recording at a bit rate of 320 Kbps is processed at 320,000 bits per second.

Bit rate per second can also be expressed in other units of measurement, such as megabits per second (Mbps) or gigabit per second (Gbps), but these are 1000 Kbps per second or bit. Only used if 1000 Mbps is met.

In general, high bitrate recordings provide higher quality audio and take up more space on your computer or mobile device. However, unless you’re using high-quality headphones or speakers, you won’t notice any improvement over low-quality headphones or speakers.

For example, if you’re listening with a standard pair of headphones, you probably won’t notice the difference between a 128 Kbps file and a 320 Kbps file.

For more information on bitrates, see the additional information, including their relationship to audio compression.

bit depth
At first, bit depth may seem like a complex topic. The simplest form is a measure of how accurately a sound is represented in digital audio. The higher the bit depth, the more accurate the digital sound.

You’ve probably already come across songs sent at specific bitrates from MP3 download services or music streaming sites, but let’s not talk too much about bit depth. However, if you want to digitize your vinyl record or analog tape collection and save them as high-quality digital audio files, you need to know about bit depth.

Increasing the bit depth will give you a more detailed recording. If the bit depth is low, quiet sound will be lost.

High resolution CD and sound sound. PART 3

Is not it possible to feel the difference in format (difference between CD and high resolution) purely by sound?

As explained above, the “suspicion that sound content in each format is different” can not dissipate from the music files sold.
(It should be the same, but it is difficult to identify unless indicated explicitly).

In that case, I have no choice but to record it and touch it myself.
If you record the same sound source in different formats and play it, you can see if you may feel that the sound is different depending on the format.
The important thing is to record the same sound source in different formats with the same configuration of the equipment.
(Do not convert the recorded file to a different format).

However, even with this method, it is possible that you are listening to the habits of the equipment, not the format difference, so you should be careful, you must compare several recording equipment in the same way to extract points in common.

Teams that can be recorded at home are the UA-3FX (~ 48kHz / 24bit) and the FA-66 (~ 192KHz / 24bit).

Since there is only one for each, it is not possible to record the same sound source in several formats at the same time.
Then we must do. ..

That’s it! We are going to bend an analog disc! (Hahaha)

In modern terms, it is a digital file of analog records. .. (Smile bitter)
If you record an analog disk with the same configuration but with different sampling frequencies and bits depths, you can achieve “almost the same sound source”, “same device settings” and “different formats”, so I tried it.
I mean, half of the reason why I bought a used FA-66 was “dubbing disc”, so I experienced it a long time ago. (Hahaha)

From this moment, we are in the world of
“Individual opinions”,
“There are individual differences in how we feel the effects” and
“Compared to our company”
.
(Given that we have not confirmed the similarity between several devices, half-talks).

I certainly felt the difference in sound when I changed the sampling frequency, but I felt the difference when I changed the depth of bits was greater than that.
Expressed in words, increasing the sampling frequency made it feel smooth and courteous, and lower it made it sound more vigorous and dense.
The depth of 24-bit bits is more realistic and I felt that the feeling of location and space became clearer.

By the way, when folding analog discs, I feel that I prefer 48 kHz / 24 bits to the highest specification of 192 kHz / 24 bits.
Therefore, at present, in the analog record file (for playback purposes in NW players, etc.), the recording is made at 48 kHz / 24 bits, and the level is not altered and saved only by adjusting the Input / output reading.
In order to move to a CD, it is recorded at 44.1 kHz / 24 bits and, after adjusting the level, etc., it becomes 16 bits.

In any case, the taste is different from the feeling of “oh! Weird” that you feel when you change from the CD version of the same song on sale to the high resolution version, and the difference is very small.