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What is the standard bitrate for smartphone videos? Part 3

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What is the standard bitrate for smartphone videos? Part 3

Smartphone

Estimated audio bit rate
In the case of audio bit rate, “128 kbps” is basically a guide.

Smartphone bit rate

Generally, for lossy codecs like MP3, AAC, WMA, AC3, Vorbis, a voice bit rate of around 128 kbps is sufficient. On the other hand, if the video is geared towards sound quality, it should be around “192-320kbps”.

Three Points to Consider When Considering the Bitrate of Smartphone Videos

There are a few things to keep in mind when considering the bitrate of your smartphone video.

When creating a video, you should use the appropriate bitrate for factors like size, but when considering bitrate, you need to keep three points in mind.

Here, we will introduce three points to keep in mind when considering the bitrate of smartphone videos, so why not refer to what kind of points to keep in mind?

Bit rate notes 1: The numbers are just a guide.
The proper bitrate for smartphone videos is just a guide.

The bitrate of a video involves multiple factors, not just the size of the image. For example, if you want to save a video with a lot of movement in high quality and a video with little movement that you want to save in medium quality, the appropriate bit rate will be different even if the image size is the same.

So, consider the bitrate you need as a guide only.

Bit rate note 2: consider the resolution according to your purpose
Let’s decide the optimal resolution according to the purpose of the smartphone video.

Even if you call it a smartphone video, it does not mean that a video with almost no motion and a video with high motion should have the same resolution. It is important to select the one that suits your purpose, such as high resolution for videos showing precise movements and low resolution for videos with little movement.

Therefore, when considering the resolution of a video, consider what the video is about.

For seminar videos
Since the seminar video is almost motionless, no high resolution is required.

The seminars and training videos aren’t particularly poignant videos, so lower resolutions won’t be a problem. For example, there is not a big difference between a low image quality of about 300 kbps and a high image quality of about 1500 Kbps, so it is recommended to make a light and low quality video.

For promotional videos
For promotional videos, it is a good idea to have a certain resolution.

It is not attractive that the resolution is low and that the video does not look beautiful in the video for internal promotion. However, it depends on the content of the video itself, so if you are not sure about the resolution, it is recommended to prepare a higher resolution and a slightly lower resolution and compare them.

For sports videos
High resolution is best for sports videos.

The bit rate has the characteristic that it is required since the difference with the previous frame is greater, and it is necessary to set it higher for videos with a lot of movement.

Therefore, if the resolution of the sports video is low, the outline will be broken and the color will fade, resulting in a stressful video.

Bit rate note 3: consider file size
The higher the bit rate, the larger the file size.

Of course, it depends on the content of the video, but as the bitrate increases, so does the file size, so this needs to be taken into account.

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What is the standard bitrate for smartphone videos? Part 2

smartphone bit rate

Video Terms to Remember 1: Resolution
Resolution is the number of vertical and horizontal pixels in a video.

Smartphone BITRATE

The higher the resolution, the better the image will look. For example, if you prepare the same image with the same resolution of “640 x 360” and “2560 x 1440”, the latter will be clearer in detail.

Also, both the resolution and the pixel refer to vertical and horizontal pixels, but in the case of the number of pixels, it is expressed by the total number, so if the resolution is “1980 x 1080”, the number of pixels will be “2,138,400”.

Video term 2: frame rate to remember
Frame rate is the number of still images per second of video.

The frame rate unit is “FPS (Frames Per Second)”. Since a video is made up of a collection of continuous still images, the higher the frame rate, the smoother the video. However, the amount of data will increase accordingly.

Therefore, it is important to set the frame rate to the appropriate size according to the purpose of the video.

Video Term 3: Codec to Remember
A codec is a codec that compresses and decompresses audio and video data.

The larger the size of the video, the greater the amount of data, and the higher the quality, the larger the file size. Therefore, it is necessary to compress the data with a codec.

For example, there are types such as “MPEG-4” and “MPEG-2” for video codecs and “MP3”, “AAC” and “FLAC” for audio codecs.

Estimated bit rate suitable for smartphone videos

For smartphone videos, the standard bit rate is “300 kbps” or “600 kbps”.

Taking as an example the frame size that is often used for inline distribution, if the frame size is 480 x 270 px, 360 x 270 px, the bit rate is “300 kbps” and if the frame size is 640 x 360 px, 480 x 360 px, the bit rate is “600 kbps” will be a guide.

What is the standard bitrate for smartphone videos?

Bitrate

In this article, we’ll give you an overview of bit rates, guidelines for suitable bit rates for smartphone videos, and points to keep in mind when considering bit rates for smartphone videos, so check them out.

smartphone bit rate

What is the important bitrate for smartphone videos?
Bit rate is a term that refers to the amount of data per second.

The amount of data that can be sent and received in one second, and the unit is “bps (bit per second)”. For example, at 1 bps, 1 bit of data can be sent and received per second, and the higher the bit rate, the more data can be transferred.

Therefore, when making smartphone videos, it is necessary to consider the bit rate that viewers can comfortably watch.

Relationship to screen size
The larger the screen size, the greater the amount of data required and, conversely, the smaller the screen size, the less the amount of data.

Therefore, there is a reference bit rate for each screen size. If the screen size is 480 x 360, the bit rate is 500 to 700 Kbps, if it is HD 1280 x 720, it is around 2000 Kbps, and if it is full HD 1920 x 1080, it is around 4000 Kbps It is a guideline for the bit rate.

Three video terms to remember in advance

When creating a video, be aware of the video terminology.

In recent years, there have been many cases of video distribution in companies. However, there are many technical terms in the video, so you need to know the meaning of the terms in order to understand the video properly.

Here are three video terms to remember beforehand, so why not take a look at what they are?

What if the bit rate is high?

Bitrate

High bit rate = a lot of data can be transferred per second

bitrate
.

Sounds like a good thing.

The network cameras managed by my company send the captured video data to a personal computer for viewing over the network.

If you want to see the video, you want to see a beautiful video that moves sharply with high image quality, right?
However, the amount of data in a beautiful image is surprisingly large …

In such case, if the bit rate is high, a lot of data can be transferred per second, so you can deliver beautiful images to your computer. On the other hand, if the bit rate is low, the amount of data that can be transferred per second is small, resulting in choppy and poor quality moving images.

“Then the bitrate should be high anyway!”

… That is not the case.
In fact, in a surveillance camera system, there are the following disadvantages to increasing the bit rate.

Disadvantages of high bit rate!
Transferring a large amount of data increases the load on the network line and equipment.

There is an upper limit to the bit rate that can be transferred depending on the network environment. This depends on the LAN cable you are using, the performance of the hub, etc., but it will be difficult so I will skip it. Just think that there is an upper limit for the bit rate depending on the environment.

“So what happens if it exceeds the upper limit?”

In the case of video from a network camera, the connection often drops. If you exceed the upper limit, the line will be punctured and you will lose connection with the camera. The image may be interrupted for a moment, but if it is too bad, you will not be able to see the image from the camera at all.
If this happens, it will be very troublesome …

Also, if the bit rate is high, a large amount of data will reach the browsing computer and the recording NVR. When a lot of data arrives, the computer or NVR will not be able to process the data, which may cause abnormal operation (reboot, etc.).

Therefore, the System Kay NVR defines the maximum bit rate that can be supported as a specification. The bit rate that the entire NVR can process such as performance and bandwidth limit per channel are described in the specifications.

Video distribution Advantages and disadvantages of a high bit rate

The video bit rate is calculated separately for video and audio and added together.

Bit Rate

The sum of the video and audio bit rates is called the oval bit rate (total bit rate).

Expressed in the formula
Oval bit rate = video bit rate + audio bit rate

Will be.

High bit rate benefits
The higher the bit rate, the better the picture and sound quality, and the lower the bit rate, the worse the picture and sound quality.
However, note that if the video bit rate is high, there are cases where the video bit rate is high and the image quality is good, but the audio bit rate is low and the sound quality is poor. On the contrary, there may be cases where the image quality is poor and the sound quality is good.

High bit rate video basically has the advantage of improving image quality and sound quality, but you also need to understand the disadvantages.

Disadvantages of high bit rate
The higher the bitrate, the more net bandwidth is consumed and the more playback load is applied.
For example, increasing the bit rate from 500 Kbps to 1000 Kbps doubles the net bandwidth usage and doubles the playback load or more.

It is easy to increase the bit rate for high image quality, but if you increase the bit rate too much, the CPU will become overloaded and you may not be able to reproduce it well, so be careful.

Especially when the radio wave of the smartphone is bad or the band is limited, it may not play smoothly at a high bit rate.

Even if the bit rate is increased, the image quality and sound quality do not improve above a certain level.
In fact, increasing the bit rate does not mean that the image quality and sound quality will increase without an upper limit.

For example, if the image quality of the original video material shot by the camera is 100, even if it is converted at a high bit rate by video editing software or encoding software, a high-quality video with a quality of 100 or more image of the original video will be created. You can not.

No matter how high the bit rate is, if the quality of the original video material is poor, the quality will not be better.

Let’s think about the optimal bitrate for each video.
When creating a video, you need to think about how to set the optimal codec, resolution, frame rate, and bit rate yourself.

Then
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 the bit rate is increased, the picture quality and sound quality should not be higher than that of the original video material.
It is useful to remember that.

Also, almost all video editing software, encoding software, YouTube, and other free video publishing services commonly used when creating and publishing videos have preset settings with preset codecs, resolutions, frame rates, and bit rates.

However, the image quality of the presets is not always optimal, so use this bit rate knowledge when you need to make fine adjustments.

Difference between CBR (fixed), VBR (variable) and ABR (average) [bit rate]

constant vs variable bit rate

CBR (constant bit rate)
VBR (variable bit rate)
ABR (average bit rate)
There are three types.

I will present the differences between them.

See the following article for the “bit rate”.

Reference: What is a bit rate? Relationship between image quality and sound quality [Video / Audio]
Related: Difference Between VFR (Variable) and CFR (Fixed) [Frame Rate]

Every feature
I will briefly explain each feature.

CBR (constant bit rate)
CBR (constant bit rate) is

A video with a constant video bit rate.

for instance,

Scenes with intense movement
Scenes with complex audio
Even in “scenes that require a large number of bit rates”, for example, the bit rate to be assigned is constant and

Motionless scene
Scene without audio
Even in “scenes that do not require a lot of bit rate”, the bit rate to be assigned is constant.

In this way, a video that assigns a constant bitrate to “Assign a constant bitrate!” In any scene it is called CBR (constant bit rate) video.

The following are the characteristics of CBR.

(○) Search (fast forward / rewind) is fast
Since the transfer rate is the same, you can search instantly.
(○) File size can be predicted
If you decide beforehand to “encode at XX bit rate”, you can predict the file size from resolution, frame rate, video length, codec, and so on.
(○) Easy to use as a material
In the case of video, there is no need to worry so much, but in the case of the sound source, various problems can occur such as drift of sound with VBR or ABR (so if there is a possibility that it will be used later to video edit material, etc. Better to encode with CBR)
(○) Fast encoding speed
It doesn’t change much, but unlike VBR and ABR, you don’t need to “predict” it, so encoding is faster.
(X) Image quality and sound quality are not very good for the file size
Even a monotonous scene that does not require a lot of bit rate allocation may be assigned a certain number, or a scene that requires a large bit rate may not have enough bit rate, so the image quality and sound quality for the file size. Cospa is bad
VBR (variable bit rate)
VBR (variable bit rate) is

A video whose bit rate varies depending on the scene.

VBR_figure

for instance,

Scenes with intense movement
Scenes with complex audio
In “scenes that require many bit rates”, such as assigning many bit rates and

Motionless scene
Scene without audio
For “scenes that do not require a lot of bit rate”, assign a lower bit rate.

In this way, a video that assigns only the required bitrate according to the scene, “You need this bitrate, don’t you?” It’s called VBR (Variable Bit Rate) video.

The following are the characteristics of VBR.

(○) Image quality (sound quality) by file size is the best
Compared to CBR and ABR, the image quality (sound quality) by file size is the best.
(△) Unpredictable file size after encoding
The file size cannot be predicted because the bit rate fluctuates extremely depending on the content of the material to be encoded. (However with the x264 encoder etc it is possible to predict because it puts an upper limit on the file size and allocates the maximum bit rate within that range)
(X) Old MP3 players may not play well
If you have an old MP3 player, the playing time display may be strange, the bit rate display may be strange, or you may not be able to play from beginning to end.
(X) When used as video editing material, it may cause sound drift.
For more information, see the following article
Reference: Causes and countermeasures for sound deviation [Encoding]
If you want to encode video with high image quality and low capacity, VBR is your choice.

By the way, in VBR, it is common to determine video quality by “quality standard” (CRF value in x264 encoder) rather than by “bit rate standard”.

For example, instead of saying “Encode at 192bps!”, Specify something like “Encode at

What is a bit rate?

Audio Bit rate

The bit rate in a video is “how much information is packed in one second”.

BIT RATE

What if the bit rate is high?
Basically, the higher the bit rate, the better the picture and sound quality.

* Although it is closely related to the “codec” described later, it will basically improve.

There are two types of bit rates
Bit rates are assigned separately for “video” and “audio”.

The higher the bit rate assigned to “video”, the better the “image quality”.
The higher the bit rate assigned to “voice”, the better the “sound quality”.
Also, the sum of the two bit rates is “is called the oval bit rate (total bit rate)”. (This oval bit rate is called “video bit rate”)

▲ If you open the video file properties and open the “Details” tab, you can see “What is the bit rate?”

(However, this Windows function is unreliable, so it is better to use video analysis software like MediaInfo)

soon,

Oval bit rate = video bit rate + audio bit rate
It becomes the calculation formula.

So even if it says “bit rate is high!”, It may mean “video bit rate is high” and “audio bit rate is not high”.

In other words, in such a case, the video will be “Image quality is good, but sound quality is not good …”.

Basically, the file size of “audio” is much smaller than that of “video”, so even if you increase the bitrate of “audio” significantly, the overall size of the file will not change as much.

Therefore, “speech” is often encoded uncompressed (linear PCM).

Relationship to image quality
The higher the “video” bit rate, the more accurate the color information that can be assigned to all pixels.

as a result

High bit rates improve image quality and
If the bit rate is low, the image quality will deteriorate.

▲ High bit rate (12 Mbps, 2.57 MB) ▲ Low bit rate (90 kbps, 20 KB)
* Actually, it is a gif video, so the bitrate is not accurate.

Bit rate difference

Also, in the case of a low bitrate, if you allocate bits evenly to all pixels, you will run out of bits, so in scenes where similar colors are continuous (such as a scene where the blue sky stretches without end), etc. Try to reduce the bits preferably.

As a result, “block noise” ↓ is likely to occur in such scenes.

Block noise
▲ Example of block noise (block noise)

Relationship to sound quality
The audio bit rate is

Sampling rate (Hz) x bit depth (bit) = bit rate (bps)
It can be expressed by the formula.

For example, when recording sound as digital data

How often do you record (= sample rate)
How much data is stored per interval (= bit depth)
Decide and register.

for instance,

Sampling frequency: 44000 Hz
Bit depth: 24 bit
If so, the sound is divided and recorded 44,000 times per second, and the sound is recorded using 24 bits for every 44,000 times.

In other words, if you want to improve the sound quality, you can increase the “sample rate” or “bit depth”.

Increase the sample rate → Soft sound
Increase the bit depth → Increase the expressiveness of the sound, such as finesse and volume
Reference: Meaning and Relationship of Sample Rate, Bit Depth, and Bit Rate

Relationship to codec
I mentioned earlier that “the higher the bit rate, the better the image quality and sound quality”, but the image quality and sound quality are “codecs”. they are closely related to the “.

A “codec” is something like a “compression algorithm” for compressing “video” and “audio”.

Reference: What is video format? Codec difference

for example, “the H.264 video codec” It is a very famous codec that is also used on Youtube and Nico Nico Douga,

(Addendum: Not used now …)

“H.265” which improved the “image quality by file size” from “H.264” There is a codec called “which.

“H.265” is “H.264 at about half the bit rate of”, “H.264 will get the equivalent of image quality and”. (The compression rate is double)

for instance,

Using “2Mbps” video bit rate with “H.264 codec”
Video using “2Mbps” bit rate with “H.265” codec
If there are two videos, the image quality of “H.265” is twice as beautiful even though the bit rate (file size) is the same.

The difference between progressive download and streaming delivery

Streaming

When a business or organization publishes a video on the web or operates a video service, it is important to select a video distribution method.

streaming

On this occasion, we will explain the characteristics and differences between the two distribution methods, “progressive download” and “streaming distribution”.

What is progressive download?
Progressive download is a delivery technology that downloads data such as video and audio and plays them at the same time.

Sometimes referred to as “pseudo-streaming,” the video data is played back as it is saved as a temporary file on a terminal such as a PC or smartphone.

Thus, once the video data is downloaded, it can be freely viewed offline without having to go through the internet.

What is streaming distribution?
Streaming is a technology that transfers audio and video data, plays it back in sequence, and distributes the data to terminals such as PCs and smartphones without saving it.

Streaming distribution uses a dedicated streaming server for video and audio distribution and transfers only the data required for playback, making it suitable for distribution of long duration video such as movies.

Due to the technology to play while data is transferred, if the communication environment is poor, the data reception cannot be maintained and the video may stop in the middle.

Advantages and disadvantages
Let’s take a look at the pros and cons of “progressive download” and “streaming”.

Progressive discharge
merit
Even if the communication environment is bad, smooth playback is possible after the data download is complete.
Since the video data is saved as a temporary file in the terminal, the saved video data can be played repeatedly as long as the cache remains.
Operation is possible without preparing a dedicated streaming server
* Recently, streaming servers are becoming more common.
Demerit
Since the entire video file is downloaded to the terminal and distributed, it is easily copied and no copyright action can be taken.
* Recent video data security
Large video files put a strain on your bandwidth, so they take time to play.
As the number of concurrent viewers increases, the server will become overloaded and viewing will become difficult.
Transmission delivery
merit
Only the video being played is transferred to the user, so if the communication environment is stable, you can comfortably watch long and large-capacity videos.
Since there is no data left on the device, copyright-related measures such as data redistribution and falsification are higher than progressive downloads.
* Recent video data security
By using a CDN, a stable distribution is possible even if the number of concurrent viewers increases.
Reference: What is a CDN that is often used for video distribution?

Demerit
Stable playback is not possible unless the communication environment is protected.
A dedicated streaming server needs to be set up, which requires upfront and running costs.

Video Distribution Advantages and Disadvantages of High Bitrate Part 2

Bitrate

Let’s think about the optimal bitrate for each video.
When creating a video, you need to think about how to set the optimal codec, resolution, frame rate, and bit rate yourself.

Bitrate

However, the image quality of the presets is not always optimal, so use this bit rate knowledge when you need to make fine adjustments.

Video distribution Advantages and disadvantages of a high bit rate

Bitrate

The video bit rate is calculated separately for video and audio and added together.

Bit Rate

The sum of the video and audio bit rates is called the oval bit rate (total bit rate).

Expressed in a formula
Oval bit rate = video bit rate + audio bit rate

High bit rate video basically has the advantage of improving image quality and sound quality, but you also need to understand the disadvantages.

It is easy to increase the bit rate for high image quality, but if you increase the bit rate too much, the CPU will become overloaded and you may not be able to reproduce it well, so be careful.

Especially when the radio wave of the smartphone is bad or the band is limited, it may not play smoothly at a high bit rate.

No matter how high the bit rate is, if the quality of the original video material is poor, the quality will not be better.