Tag: will bitrate affect video quality

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What is the capacity of the high resolution sound source?

High resolution sound source with more information than conventional CDs.

Since the data size is large, you can enjoy high-quality sound with a three-dimensional effect, but the problem is that when managing multiple high-resolution audio sources, the required storage capacity becomes huge.

Then I will introduce what is the capacity of the high resolution sound source, including the management method.

What is the capacity of Hi-Res Audio sources compared to CDs?
In determining the capacity (file size) of a high-resolution sound source, the sampling frequency and bit depth of the sound source are important factors.

The sample rate (sample rate) is a numerical value that is used as an index when converting analog data, such as speech, to a digital signal.

It indicates how many times per second an information sample was measured, and is expressed in “Hz (hertz)”.

If sampling is done every 44,100 seconds, it will be “44.1 kHz”.

On the other hand, the bit depth is a numerical value that indicates how many pieces are recorded in each divided data.

It is represented by “bit”.

Both the sample rate and the bit depth mean that the higher the number, the more information there will be, that is, the higher the resolution.

The amount of music data per second is called the bit rate.

Bit rate is the sample rate multiplied by the bit depth and is expressed in “bps”.

The calculation formula is as follows.

Bit rate (bps) = sample rate (Hz) x bit depth (bit) x 2

For example, the bit rate and sample rate of a CD sound source are generally “44.1 kHz / 16 bits”.

Most so-called “CD sound quality” sound sources are based on this number.

The size of the 5 minute 44.1 kHz / 16 bit / sound source file is about 50 MB.

But what about hi-res audio sources?

High resolution sound source capacity per song (5 minutes) varies depending on the music data format, as shown below.

WAV: 192 kHz / 24-bit: capacity for 5 minutes is 330 MB
FLAC: 192 kHz / 24 bit: capacity for 5 minutes is 200 MB
ALAC: 192 kHz / 24 bits: capacity for 5 minutes is 200 MB
What you can see from this is that the capacity of the high resolution sound source is 4 to 6 times that of the CD sound source in 5 minutes.

Large capacity high resolution music management equipment
If you download 5 high-resolution songs for 4 minutes, it will take up about 700MB (for 96kHz / 24-bit WAV files).

In the case of 10 songs, it exceeds 1400MB, that is, 1GB.

If so, I would like to have enough storage to handle that amount of data.

An effective way to do this is to build a NAS-centric network audio system that incorporates a large-capacity hard drive.

For example, if you can prepare a 4TB (terabyte) hard drive, it can store around 20,000 high-resolution songs.

Next, we will explain what NAS and network audio are like.

NAS
NAS stands for “Network Attached Storage” and it reads like aubergine.

It stands for network attached storage, and it is also called a network hard drive or network compatible HDD.

In other words, it is an external hard drive that is used when connecting to a network (LAN).

A normal external hard drive used when connecting to a PC = PC via USB etc. can basically be used with only one PC.

However, if it is a NAS, it can be used with multiple devices participating in the LAN.

Files saved on the hard drive can also be used and shared from, for example, the personal computers of each family member participating in the home LAN, smartphones connected via Wi-Fi, and TVs in the living room to be.

It is also possible to access the data on the NAS from the outside via the Internet.

The NAS is often used in the home to store and share data for music, video (video / TV recording data), photos (images), etc.

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Meaning and relationship of sample rate, bit depth, and bit rate

Sampling rate
Bit depth
Bit rate

I will present the three meanings and relationships of.

Table of Contents
What is the sampling rate?
What is bit depth?
What is a bit rate?
resume
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What is the sampling rate?
For example, let’s say you say “Ah” for 1 second.

When recording this “Ah” sound on a personal computer, the “Ah” sound is divided into tens of thousands per second, each divided into tens of thousands.

“The height of this section was about this.”
“The length of this section was about this.”
Record it as data like this.

The personal computer continually reads each of this divided data and outputs it as a “voice” called “Ah”.

At this time, “how many tens of thousands of sounds are collected per second” is called the “sample rate.” (Also called “sample rate”)

Sampling rate
▲ Sample rate image

The more divisions you make, the smoother the sound will be, and as a result, you will feel that the sound quality has improved!

What is bit depth?
The sample rate is “how many tens of thousands of sounds are collected per second”.

“How much capacity is given to each divided data (sample)” is called “bit depth”.

Figure_bit depth
▲ Bit depth image

Also called “number of quantization bits”, “number of sample bits”, “bit offset”, and so on.

For example, if the bit depth is “16 bits”, the amount of information is 2 to the 16th power (65536) for one sample.

The higher the bit depth, the greater the expressiveness of the sound’s fineness and volume, and as a result, I feel like the sound quality has improved!

By the way, the bit depth of most of the world’s sound sources is 16 bit.

that’s why

“Import music from CD!”
“Import music downloaded from the Internet!”
In such cases, 16 bits is sufficient.

On the other hand, if you say “What you recorded in your DAW comes out wav!”, It is better to have 16 bits or more.

This is because, for example, when processing audio effects with audio editing software, sound deterioration can be reduced to zero by assigning an additional bit depth (for example, 32-bit). (Although 16 bit is fine for final output)

What’s more,
note that “bit depth” on this page has a different meaning than “bit depth” in video.

Reference: What is Bit Depth (Color Depth)? Differences like 10bit / 24bit / 30bit

What is a bit rate?
Bit rate is the “amount of data per second”.

Reference: What is a bit rate? Relationship between image quality, sound quality and codec [Video / Audio]

The “sample rate” and “bit depth” presented above are

Sample rate: how many tens of thousands of sounds are collected per second
Bit depth: how much to give to each divided data
Therefore, the product of these two values ​​is the “bit rate”.

Audio encoding

I wrote over audio files last time, but if you reduce the file size (code at a lower bit rate), the sound quality tends to deteriorate. How much should it really be? .. ..

When compressing using audio encoding (AAC, MP3, etc.), the compression rate is determined by the bit rate at the time of encoding. Specifically, if you set a low bit rate, the compression rate will be higher and the file size when saved will be smaller, but first of all, what is the bit rate for uncompressed original sound source (PCM) ?
If you save it as PCM, the sound quality will be that of the original sound, but it can be a bit awkward to save without worrying about the file size. Also, depending on the application, I think the memory capacity is sufficient even for the original sound size and the communication speed is fine. Therefore, I would like to write about the sample rate and bit rate that are often heard in digital audio.

The bit rate of digital audio is determined by the sampling frequency, the number of bits assigned to a sample (number of quantization bits), and the number of channels (stereo, monaural, etc.).

PCM bit rate (uncompressed) = sample rate x number of quantization bits x number of channels
As I wrote a bit last time, in file containers like wav and mp4 format, this information is attached as a header, so that the application can see the header and play it back. The compression rate of the encoding is determined by the bit rate specified at the time of encoding for this PCM (uncompressed) bit rate.
For example, as many of you know about music CDs, with 44.1 kHz stereo, this is the next bit rate.

Music CD bit rate: 44100Hz x 16bit x 2ch (stereo) = 1411.2kbps
When encoding this with MP3, AAC, etc., it is natural to specify a bit rate lower than 1,411.2 kbps. For example, when encoding at 256 kbps, the compression rate is around 18% when the original sound is 100% and the file size is 1/5 or less.

Encode a music CD at 256 kbps: 256 kbps / 1,411.2 kbps = about 18%
In general, the sample rates of audio devices connected to PCs are 48 kHz and 44.1 kHz for music, 16 kHz and 8 kHz for audio such as microphones and headphones, and 32 kHz, 24 kHz, 22.05 kHz. , etc.

The bit rate of PCM (uncompressed sound source) with 16-bit quantization bits is as follows.

Stereo (for music) PCM 16-bit bit rate (example)
Sampling frequency Number of quantization bits Number of channels Bit rate Comments
48kHz 16 16 2 1536 kbps
44.1 kHz 16 16 2 1,411.2 kbps Music CD
32kHz 16 16 2 1,024 kbps
24kHz 16 16 2 768 kbps
22.05 kHz 16 16 2 705.6 kbps
Monaural (for audio) PCM 16-bit bit rate (example)
Sampling frequency Number of quantization bits Number of channels Bit rate Comments
32kHz 16 16 1 512 kbps Super Wide Band
24kHz 16 16 1 384 kbps
16kHz 16 16 1 256 kbps broadband
8kHz 16 16 1 128 kbps Narrow band

Sampling rate
If you check the web, there are explanations such as the sampling required to convert analog waveforms to digital conversion. For example, it shows how many samples of an audio signal input from a microphone are taken per second and digitized. The larger the sample, the greater the range that can be recorded. When an analog waveform is digitized, the frequency that can be expressed is half the sampling frequency (sampling theorem). For example, with a sample rate of 48kHz, it is possible to express up to 24kHz. At 8kHz (narrowband) and 16kHz (wideband), which are often used for audio, you can only hear up to 4kHz and 8kHz, respectively. The higher the sample rate, the higher the bit rate.

sampling theorem
It is a very simple explanation, but it can express up to half the sample rate. When sampling a signal, if the interval is small, it can be restored close to the original signal, but if it is too thick, it cannot be restored (I would like to write a little more detail when talking about signal processing or other time ).

What is the bit rate? Simple explanation

Bit rate is a unit of data transfer.

When used in video or audio, as in video editing, it indicates how much data is represented per unit of time, and “bits per second (bps)” is generally used.
A bit is the smallest unit of data that a computer handles.
Two states of “0” and “1” can be expressed by 1 bit. (1 binary digit)
Similarly, a byte representing the size of a file is a unit of data handled by a computer. (1 byte = 8 bits)
Here are some things to keep in mind about bit rates.
In home appliance hard disk recorders, it is sometimes expressed as a recording mode such as XP, SP, LP.
The higher the bit rate value (numerical value), the better the picture and sound quality, but the greater the amount of data (file size).
The unit of bit rate is usually Mbps, which means 10 6 (10 to the sixth power) for video, and kbps, which means 10 3 (10 to the third power) for audio.
When burning a video to DVD, there is a limit to the amount of data that can be burned to DVD, and if you try to burn a long video, you will have to lower the bit rate, resulting in poor image quality. . To record high-quality video, the bit rate must be increased, which increases the amount of data required and shortens the recording time.
Even if the bit rate used is the same, the image quality and sound quality will differ depending on the encoder and compression method used for digitizing.

What are “bit depth” and “sample rate”? Part 2

What is the sample rate?

Next, I will explain the sample rate.

The sample rate is like the “resolution” of the audio.

The higher the sample rate, the more samples per second = you can hear better.

Requires double sample rate

One thing to keep in mind here is that you need twice the sample rate to hear sound at that frequency.

For example, if you want to hear a 1000 Hz (1 kHz) sound accurately and clearly, the sampling frequency must be at least 2000 Hz (2 kHz).

If the sample rate is less than twice the value you want to hear, “aliases” will occur and you will not be able to process the sound accurately, such as crackle or noise.

Nyquist frequency

By the way, to use a little technical word, it also means not to exceed the “Nyquist Frequency”.

The Nyquist rate is exactly half the supported sample rate.

For example, if the sampling frequency is 44.1 kHz, the Nyquist frequency will be 22.05 kHz.

If you try to handle this high-pitched sound that exceeds 22.05 kHz, the above-mentioned “aliasing” will occur and you will not be able to reproduce the sound correctly.

Range recognizable by the human ear

The loudest sound that can be recognized by the human ear is said to be 20 kHz, so to hear a 20 kHz sound, you only need to have a sample rate of at least 40 kHz.

After that, to avoid aliasing, apply an anti-aliasing filter until the Nyquist (Transition Band) frequency is reached.

For 44.1 kHz, 2050 samples x 2 are required.

In other words, a sample rate of 44.1 kHz is all that is needed to minimize the limit of sound (20 kHz) that the human ear can hear.

When the sampling frequency is high (96 kHz, 192 kHz)

Recently, it can be set to a high sample rate, such as 96 kHz or 192 kHz.

Unfortunately, even with such a high sample rate, it’s hard to tell the difference.

As shown in the image above, non-human animals can hear higher frequency sounds.

However, it is a level that we do not have to worry about because it is a completely inaudible zone for the human ear.

By the way, many audio interfaces cover up to 192 kHz.

Controversy over sampling rate

In fact, in the 1970s, many media outlets were controversial about sample rates.

At the time, 48 kHz was the audio standard used in radio, television, and video work.

However, broadcasting stations have decided to use 44.1 kHz as a standard to prevent data from being copied to consumers (viewers) by intentionally breaking compatibility (or making conversion difficult) …

It’s difficult to change data from 44.8 kHz to 44.1 kHz, so it prevented the average viewer from converting it to the sample rate used for home devices.

By the way, the article “Comparison of professional versus cheaper audio interface” is summarized here, which is also explained from the point of view of bit rate and sample rate.

What are “bit depth” and “sample rate”?

What are “bit depth” and “sample rate”?
What are “bit rate” and “sample rate”?
I wrote it in the DTM project file settings and audio interface specs, but I don’t understand the meaning …

This time, we will answer those questions.

Here’s a quick rundown of “What is a Bit Rate / Sample Rate ?,” Explained by Professional Drummer / Engineer / Producer Ed Thorne.

Once you know this, you will be able to export the sound source in the appropriate format and you will be able to understand the standards for the equipment that you will buy in the future.

Please take a look to the end!

What is bit-deapth?

Bit depth refers to the range in which the dynamics (inflection) of the sound can be processed.

For example, if the bit depth is “16-bit”, the range of up to 96 dB can be reproduced and processed from the silent state.

96dB is all about the volume when the audience is excited at the live venue.

On the other hand, if the bit depth is “24 bit”, the 144 dB dynamics can be reproduced and processed.

144dB is roughly the volume of a jet airplane.

Dynamics in the age of streaming

Not long ago, there was no volume limit like current streaming services like YouTube and Spotify.

The louder the sound, the better the music itself, which is why the producers always wanted to make the song louder and bigger than any other music.

Today, many platforms where you can listen to music have volume restrictions, so the idea that “the more music you can play loud sounds, the better” has changed, and times have changed.

So, in this age, 16-bit or 24-bit might not make much of a difference.

The amount of data also changes

By the way, if the bit depth is high, the amount of data will change as well.

When recording a lot, it may be better to consider this a bit.

Video bit rate basics

Video bitrate is simply the amount of video data, and in principle the higher the value, the higher the image quality.

The image is like the “effective pixel count” of a digital camera.
For example, the image quality of a camera with 6 million pixels is better than that of a camera with 1 million effective pixels.
Also, the higher the video bit rate, the larger the file size.
This is also the same as the number of pixels.
A camera with 6 million pixels can shoot larger (size here is horizontal length or vertical length) than a camera with 1 million effective pixels, so the file will naturally be larger.
DVD-Video does not support high definition because the video bit rate is determined to be approximately 9.6 Mbps maximum and 720 x 480 pixels in height and width.
Therefore, to save to DVD with high picture quality like HDTV, you need to save to a new standard like AVCHD.
With VideoStudio 12 Plus, you can save to DVD-R with AVCHD, and DVDs created with this software can be viewed on PlayStation 3 and Blu-ray recorders.

Even if the video bit rate is high
However, it should be noted that if the number of effective pixels and the video bit rate are large, the image quality will always be high.
For example, if you compare the image from a camera connected to a mobile phone with 3 million effective pixels to a digital camera with 3 million pixels, it will be completely different.
It is simply the value of the amount of data packed, the performance of the image sensor (Satsuzososhi), which is also a sensor for the light-catching part, a camera with a good lens and a high-performance CPU, etc. It depends on.

This time, I would like to write about what I have researched or understood about video bit rates.

What is the video bit rate?
What makes it difficult
First of all, “bit” is an element that hinders the bit rate of the video.
If it was a video byte rate it would have been a bit easier to understand. When.
In fact, the “bytes” of the size of files and hard drives used in personal computers, etc. they are deeply related to bits, and “1 byte” means “8 bits”.

In the computer world, “a” or “not” Kano binary is there to root.
If you are making a program (especially in C language, etc.), you will feel awkward in this area, but 1 byte is a set of 8 bits. Please understand.

So, let’s go back to bitrate.
In general, no one talks about file size or hard drive size in bits.
“HDD that I bought this time, I am 960G bit”,
the person I say is not.
By the way, 960Gbit becomes 120GB when converted to bytes.

Bps unit
The unit is “bps”.
b = bit (1 byte = 8 bits)
p = even (in Japanese, it means “○ minutes”)
s = second (seconds) In other
words, if you translate it into Japanese, “1” The number of bits per second. ”

When capturing images from Sony HDR-HC3 high definition camcorder By the way, DVD-Videos, such as rental DVDs, have a maximum of 10.08 Mbps (however, the value includes audio, etc.), digital terrestrial transmission is 15 Mbps (higher image quality than DVD?), and mini DV tapes like Handycam. The video camera that records is 25Mbps.
The image on the left is the property of the file created when the image shot by the Sony HDR-HC3 high definition camcorder was imported to a computer.
The video data rate is 25000 kbps or 25 Mbps.
High definition BS digital transmission is approximately 23 Mbps.
Also, I think that Blu-ray discs, which are called Next Generation DVDs, could record up to 36 Mbps.
VHS is said to be 2 Mbps.

If you look at it this way, you can see that the DVD that I thought was high quality is not that high in reality.
However, from the point of view of older standards such as VHS, the image quality is very high.

By the way, 100 Mbps or 8 Mbps, which is used for the speed of ADSL and fiber optic lines, is also a bit rate.

[YouTube] Here’s how to check the bitrate of videos!

Have you ever had a problem with choppy YouTube playback? Checking the video bit rate can improve the playback environment. This time, I will show you how to check the bitrate of videos posted on YouTube.

Table of Contents

What is a bit rate?
How to find out the bitrate of YouTube videos
resume

What is a bit rate?

Regarding the “bitrate (bitrate)”, I think some people say, “I heard the name, but I don’t know what it means …”.

Generally speaking, the bit rate is “the amount of information (amount of data) sent and received every second”.

The unit is expressed as “bps”. For example, 1 second is displayed as 1 bps.

I don’t think there are many opportunities to be aware of this, but when you watch a video on the Internet, you may see it in a beautiful state in terms of image quality and sound quality due to the difference in each bit rate. or it may be spasmodic.

Is it better to have a higher bit rate?

A high bit rate means that you can send a large amount of data at one time.

As you can see by comparing raw video and beautiful video in terms of image quality and sound quality, the higher the image quality, the higher the bit rate.

On the other hand, the higher the bit rate, the better, and the server and electronic media used can be overloaded when doing a large amount of communication.

If you’re having trouble with choppy video, it’s a good idea to check the video playback player settings once.

How to find out the bitrate of YouTube videos
This time, I will show you how to check the bitrate of videos posted on YouTube.

The procedure to check it is very simple.
Go to the page of the video whose bit rate you want to check and right-click on the video.

Basic knowledge of video files.

.
The terms codec, resolution, frame rate, and bit rate you often see when creating videos.

This is essential basic knowledge for creators whose livelihood is video-related work.

Basic terms frequently used in video creation
1. Image quality (unit: px)
Video quality means the number of pixels.

The next four are the overall image quality. The numbers represent the number of pixels. (Number of pixels: number of pixels (points) that make up the image)

SD image quality: 720 x 480
HD image quality: 1280 x 720
Full HD: 1920 x 1080
4K: 4096 x 2160
8K: 7680 x 4320
The higher the number of pixels, the more beautiful the image will be, but the heavier the data will be. Considering the number of pixels and the amount of data, HD image quality is standard at the moment.

YouTube displays 1080p, which is Full HD, as standard. Since 1080p is compatible with the progressive 1920 x 1080 high definition picture quality used in other TV receivers, it is said to take progressive p.

YouTube provides images with different resolutions depending on the viewer’s device. Also, if you play a video in an environment with a slow line, the image quality will automatically decrease.

Bit rate (unit: bps)
Bit rate means the amount of data per second. Since the amount of data includes video and audio, the higher the bit rate, the higher the image quality and sound quality. Also, the higher the frame rate (explained below), the higher the bit rate.

The higher the bit rate, the better the picture and sound quality.
If the bit rate is high, the network and the playback terminal will be overloaded.
Even if you increase the bit rate, the image quality and sound quality will not be higher than the original video material.
The bit rate unit is as follows.

Kilobits per second (kbps, kb / s, 10 bps at third power)
Megabits per second (Mbps, Mb / s, 10 bps to the sixth power)
Gigabit per second (Gbps, Gb / s, 10 bps to the 9th power))
Terabit per second (Tbps, Tb / s, 10 bps to 12)

Frame rate (unit: fps)
Frame rate means how many still images are used in one second video. For example, 30 fps means “30 still images are used per second”. Recently, 60fps has been added to cameras. If you duplicate the image taken, the image that is comparable to the general 30fps will have the image quality that you can see if the image is stable even in slow motion. The higher the frame rate, the more still images will be used per second and the smoother the movement will be when viewed in video.

On the iPhone 6S, it’s 30fps when shooting in 4k and 60fps when shooting in Full HD. In the case of a movie, 24 frames per second are played, making it 24 fps.

The higher the frame rate, the higher the data, but since the frame rate of the screen playing the video is fixed, even if you increase the frame rate of the video itself, it will not be drawn at that rate.