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Bitrate Part 2

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Bitrate Part 2

bitrate

The amount of information transmitted through the channel per unit of time is called the bit rate, and the unit is bits per second (bit/s), called the bit rate.

BITRATE

Bitrate is often used in communications as a synonym for connection speed, transmission speed, channel capacity, peak throughput, and digital bandwidth capacity. The higher the bit rate, the higher the data transfer. Bit rate in video refers to the sampling rate at which an analog signal is converted to a digital signal [4] . Video file quality is often measured in terms of bitrate. [4] .
Distinction of conceptedit transmission
Baud rate is also known as waveform rate or modulation rate. The code for a data unit is represented by a finite combination of numbers, each of which is a symbol (or code point). In electrical communication, an electrical waveform is often used to represent one or more symbols. Waveforms with different characteristics may represent different symbol values or symbol combination values, and the duration of the waveform corresponds to the duration of the symbol or symbol combination it represents. Obviously, the shorter the duration of an electrical waveform, the more waveforms are transmitted in a unit of time, or the more data is transmitted, that is, the higher the data rate. Therefore, we can define the baud rate as follows: In the process of data transmission, the number of waveforms transmitted per unit time on the line is the baud rate, and its unit is “baud” [5] .
“Bit rate” and “baud rate” are speed units defined in two different concepts, and it is often easy to confuse them when you are not careful. When binary waveform is used, baud rate and bit rate have the same value, but their meanings are different [5] .
Difference: Both bit rate and baud rate are units that measure the transmission rate of a modem. In data transmission, data information is represented by binary numbers “0” and “1”, and each binary number is called 1 bit. The number of bits transmitted through the channel per unit of time is called the bit rate, expressed in bits per second, usually abbreviated as bit/s. The number of symbols transmitted through the channel per unit of time is called the baud rate, also called the modulation rate. Bit rate and baud rate are consistent only when modulated with two values. For example, in quadrature modulation, every two bits of the data signal form a symbol, and there are 4 values: 00, 01, 10 and 11, which represent the phase changes of the 4 types of carrier signals respectively, for Therefore, send such a symbol. It is equivalent to transmitting two bits of data, and the baud rate is equivalent to half the bit rate. The usual transmission rates of 300, 600, 1200 and 9600, etc., refer to the baud rate, which indicates that the number of binary numbers transmitted per unit of time is 300, 600, 1200 and 9600 [6] .

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Bit rate

Bit rate refers to the number of bits (bit) transmitted per unit of time, in bps (bit per second).

Bit rate is also known as “binary bit rate”, commonly known as “code rate”. Indicates the number of bits transmitted per unit of time. It is used to measure the transmission speed of digital information, often written as bit/sec. According to the number of bits occupied by each image storage frame and the transmission bit rate, the digital image information transmission speed can be calculated [1].
In modern digital communication, the transmission volume of digitized video and other information is large, so it is often measured in kilobits per second or megabits per second, which are written as kbit/sec (or kbps) and Mbit/sec. (or Mbps respectively). ). For example, the amount of information digitized from an ordinary color TV signal can reach 216 Mbit/sec. A good digital broadcast channel can transmit dozens of color TV programs, and its capacity can reach several gigabits or gigabits per second (written as Gbit/sec or Gbps) [1] .
Bitrate is often used to measure the quality of video files.
Bitrate is often used to measure the quality of video files.
flexibility edit stream
Because each network is unique and each access line has different conditions (such as length, attenuation, crosstalk environment, etc.), access lines from different telephone companies must support different data rates. For ADSL and VDSL modems, it is best to set the data rate to one of many possible data rates. For example, DMT-based ADSL and VDSL can theoretically change the tariff at fine intervals, and CAP-based RADSL (Rate Adaptive ADSL) also provides some flexibility in tariff configuration [2].
However, telephone companies may want to limit xDSL service to a small set of rates sufficient to provide a variety of services. If a limited set of tariffs can be adapted to a wide range of services, then the management of the services in this case is simpler than in the case of variable tariffs. Telephone companies want the choice of modem speed to be under the control of the network, not the user [2] .
In this mode, the selection of the transmission rate set of the xDSL network must be prudent. In this case, there is a possibility that two adjacent systems receive traffic at very different rates and the system must be able to handle such a situation. The other model, the “best match” approach using adaptive rate ADSL (similar to a voiceband modem), is more beneficial to new network operators and Internet Service Providers (ISPs) [2] .
Transmission control method
Most bit rate control schemes consist of two parts. Part of the encoded bit stream output by the encoder is fed into a buffer. For a constant bitrate channel, the data in the buffer is fetched at a constant rate, and if the buffer is large enough, the bitrate variation caused by the MPEG picture type, etc. can be smoothed out. This is necessary for both constant bit rate transmission and variable bit rate transmission in general. However, in practice, the buffer size is always limited. The buffering process will bring a delay to the system, and this delay is proportional to the size of the buffer. Latency is often a serious issue for real-time image communication, so buffers should be kept as small as possible. That is, long-term fluctuations in bitrate due to changes in scene content or changes, etc. they cannot be softened in this way, so another part is needed. This is to send some measure of the output bitrate to the encoder to control the encoding process, thus changing the output bitrate [3] .

Sample rate and bit rate of MP3 Part 2

BIT RATE

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 higher digits can only be distinguished by instruments. For example, the phone has 7-bit sound sampled at 3 kHz and the CD has 16-bit sound sampled at 44.1 kHz, so the CD is clearer than the phone. ]

When you understand the above two concepts, bitrate is easy to understand. Take the phone as an example, 3000 samples per second, each sample is 7 bits, then the phone’s bit rate is 21000. And the CD is 44100 samples per second, two channels, each sample is 13 bit PCM encoded, so the CD bit rate is 44100*2*13=1146600, which means the CD data volume per second is about 144KB. the capacity of a CD is 74 minutes equal to 4440 seconds, which is 639360KB=640MB.

Sound is actually a type of energy wave, so it also has the characteristics of frequency and amplitude, with frequency corresponding to the time axis and amplitude corresponding to the level axis. The wave is infinitely smooth, and the string can be considered to be made up of innumerable points. Since the storage space is relatively limited, in the process of digital encoding, the points of the string must be sampled. The sampling process consists of extracting the frequency value of a certain point. Obviously, the more points that are extracted in one second, the richer the frequency information that can be obtained. To restore the waveform, there must be two sampling points in one vibration. The highest frequency that can be felt is 20kHz, so to meet the auditory requirements of the human ear, at least 40k samples per second, expressed at 40kHz, and this 40kHz is the sample rate. Our common CD has a sample rate of 44.1 kHz. It is not enough to have only frequency information, we must also obtain and quantify the energy value of this frequency to represent the strength of the signal. The number of quantization levels is an integer power of 2, and the sample size of our common CD bit is 16 bits, that is, 2 to the power of 16. Sample size is harder to understand than bit rate. sampling, because it makes it seem abstract. For a simple example: suppose a wave is sampled 8 times, and the energy values corresponding to the sampling points are A1-A8, but we only use 2-bit sampling size, as a result we can only keep the 4 point values in A1-A8 and discard the other 4. If we use the 3bit sample size, all 8 point information is recorded. The higher the sample rate and sample size values, the closer the recorded waveform is to the original signal.

MP3 sample rate and bit rate

Bit Rate

When we listen to mp3 and watch movies, we will notice two parameters.

BIT RATE

The most common ones are 44.1 KHz sample rate and 192 Kbps bit rate. So what is the sample rate and what is the bit rate? What is the relationship between them? Explain:

The process of converting an analog audio signal to a digital audio signal is called sampling. In a nutshell, how many data points does it take to record a 1 second long sound via waveform sampling. For example: the sound sample rate of 44.1 KHz is equivalent to spending 44,000 data points to describe the sound waveform for 1 second. In principle, the higher the sample rate, the better the sound quality; sampling frequency is generally divided into three levels: 22.05KHz, 44.1KHz and 48KHz; 22.05KHz can only achieve FM radio sound quality, and 44.1KHz is the theoretical limit of CD sound quality, 48KHz has reached DVD quality.

Sampling rate refers to the sampling frequency when converting sound (analog signal) to mp3 (digital signal), i.e. how many data points are sampled per unit of time. (The data for a sample point is 8 (or even more) bits long.)

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.

It can be said that the sample rate and bit rate are like the horizontal and vertical coordinates on the coordinate axis. The sampling frequency on the abscissa represents the data points sampled per second. The bit rate on the ordinate represents the precision when quantizing analog quantities with digital quantities.

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 44.1kHZ, and most people haven’t noticed the difference. ]

Quality (bit rate)

In multimedia technology, quality is often used to judge the effect of audio, and quality here is actually bitrate.

1. Introduction
2 sound control
3 encoding mode
Introductionedit transmission
The term quality is widely used.
In multimedia technology, quality is often used to judge the effect of audio, and quality here is actually bitrate.
On WINDOWS it is called “bit rate” and on some players it is described as ” bit rate “.
Quality refers to the bit rate at which digital sound is converted from analog to digital format. The higher the bitrate, the better the quality of the restored sound.
sound control edit stream
16 Kbps = phone quality
24 Kbps = increase phone quality, shortwave transmission, longwave transmission, European standard medium wave transmission
40 Kbps = American standard medium wave transmission
56Kbps=Voice
64 Kbps = boost voice (best bitrate setting for cell phone ringtones, best setting for cell phone mono MP3 players)
112 Kbps = FM stereo broadcast FM 128 Kbps = tape (best setting for mobile phone stereo MP3 player, best setting for low-end MP3 player)
160 Kbps = HIFI high fidelity (best setting for mid to high end MP3 players)
192Kbps=CD (best setting for high-end MP3 players)
256Kbps=Studio Music Studio (for music enthusiasts)
In fact, with the advancement of technology, the quality of music is also getting higher and higher, the highest quality of MP3 is 320Kbps, but some formats can achieve higher sound quality.
For example, the emerging APE audio format can provide real audiophile level lossless sound quality and smaller volume than WAV format, and its quality is usually 550kbps-950kbps.
encoding modeedit stream
VBR (Variable Bitrate) Dynamic Bitrate means there is no fixed bitrate. The compression software immediately determines which bitrate to use based on the audio data being compressed. This is a method that takes quality as a premise and takes file size into account The recommended encoding mode;
ABR Average Bit Rate (Average Bit Rate) is an interpolation parameter of VBR. LAME created this encoding mode in response to the low file volume ratio of CBR and the variable size of files generated by VBR. Within the specified file size, ABR takes every 50 frames (about 1 second for 30 frames) as a segment. High-frequency and insensitive frequencies use relatively low traffic, and low-frequency and large dynamic performance use high traffic, which can be used as VBR and CBR, a compromise option.
CBR (constant bitrate), constant bitrate means the file has one bitrate from start to finish. Compared to VBR and ABR, the compressed file size is very large and the sound quality will not improve significantly compared to VBR and ABR.

What is the optimal bit rate?

What is the optimal bit rate?

To decide what the flow can be, it is necessary to understand how it works, at least in the first approximation.

In the H.264 codec (MPEG-4 Part 10), the construction of the video image is as follows: the camera creates a reference frame (I-frame) and, based on it (therefore, it is called a frame of reference), subtract the still parts of the picture from the frame – a P- frame. The third of this second frame is then subtracted and a modified P-frame is also created. Thus, a series of P-frames is created, which only carry changes between two adjacent frames. Since in the process of “subtracting” frames, errors may occur leading to artifacts, then after a certain number of frames the scheme is repeated, a reference frame is sent again, and then a series is sent of frames with changes across the network. The resulting keyframes and modified P-frames are sent over the LAN to recreate a series of full frames on the display device. It does this by “appending” or “superimposing” P-frames to a reference frame and sending the resulting series of frames to the monitor. This is how codecs work with interframe compression. Of course, in practice everything is more complicated by an order of magnitude (there are also B-frames, which, based on the analysis of a large set of frames, predict where a particular object will move in the field of view of the camera, which allows to significantly reduce the flow when observing the translational movement, for example, that -to the mechanisms).

With a slight change in the observed scene, the changes between adjacent frames will also be minimal, respectively, and the traffic on the network will be minimal. The reverse is also true: if the scene changes significantly, the changes between frames will be significant, consequently affecting the network load.

Do not forget about the peculiarities of codecs with interframe compression, they introduce quite a noticeable delay between the moment of the event itself and the moment it is displayed on the screen. This is due to the work of the codec itself, as the camera needs to receive both frames, then subtract one from the other, send it to the image output device, and overlay it on the reference frame, which takes time and therefore introduces a delay.

There is no point in talking about optimal resolutions without referring to the observed scene, since, for example, when observing an empty corridor at a quality of 1080p / 25 fps, the transmission can be approximately 1 Mbps, and when observing a station of meter at rush hour, an image in the 720p / 25 fps format may take up to 20-30 Mbps

What is the bit rate?

What is the bit rate?

Bitrate, or as they say the width of the sequence

It is the amount of data transmitted or processed in 1 second. The concept mainly applies to multimedia content, for example, video bit rate is nothing more than the amount of video information that is displayed on the screen in one second. To measure the bit rate, the designation “Kbit / s (kbps)” is used, that is, kilobits per second, less frequently Mbit / s, and so on. The more information that is transmitted during a specific period of time, the higher the quality of the image.

When people say “low bit rate video” they are generally referring to low quality video. Blur, opacity, and pixelation are characteristic of such video, while high-bit-rate video has a detailed image with rich colors. Like video, audio also comes with low and high bit rates. Music with a low bit rate loses in the frequency range, words and chords become less distinguishable, and itself takes on an unnatural sound, as if it were an electronic sound.

Bit rate types
When compressing video, you have 3 modes to choose from: constant, variable, and average. Let’s start in order:

Constant Bit Rate (CBR). Sets the desired value and does not change throughout the video. The advantage of this option is that you know in advance what the size of the final file will be. But there is also a downside, especially in relation to sound. It may grow during playback, which may require changing the bit rate. Since you don’t get what you want, quality suffers.
Changes in sound level

Variable (VBR). In this case, you are working in conjunction with a codec. Your task is to set the maximum bitrate and programs must select the required value for each scene. Thus, the “minus” of the previous regime has been eliminated. Also, the file size may be even smaller than expected, but the outcome is impossible to predict.
Average (ABR). From the name it is clear: this is a cross between the first and second mode. Here you set not only the maximum, but also the minimum bitrate, and the codec itself selects it within these limits, based on the dynamics of the video. Its quality is better than that of the variable option, because the bit rate does not fall below the set value.
YI 4K video bit rate increase
Although action cameras have been in our lives for a long time, not everyone understands their true purpose. More than once I have come across the fact that people see them as a compact analog of ordinary consumer camcorders and make corresponding demands on them. First of all, it comes down to the quality of the footage shot. “I just want to take the camera out of my pocket, start recording, and get a picture like on film.”

… This is impossible in principle. And it is doubly impossible in an action camera, since it is a compromise between “action” (a set of characteristics for operation in extreme conditions) and the quality of the shot: improving one thing, the other will deteriorate proportionally.

However, you can do something. For example, replace the lens or increase the video bit rate. What will increase the bit rate? Some improvement in image quality. It should be understood that although the camera shoots at a fairly high bit rate (up to 60 Mbps), the built-in codec uses a fast profile. In other words, video recorded with a 60 Mbps camera will be worse than video recorded on a computer with the same bit rate. First of all, areas of almost uniform color and “jerky” undergo such coding. For example, grass, ripples in the water, or foliage. Increasing the bitrate is not a panacea here, but a tangible step forward. It is true that you need to understand that the developer set a limit of 60 Mbit / s for a reason and that increasing the bit rate is done at your own risk and risk. Also, this increases the requirements for the memory card used and the writing speed on it.

If you use a camera, for example, for video blogs with video uploading to YouTube, you don’t need to change anything, as the video host will recode your video by itself, regardless of the initial parameters. If you’re post-processing the footage, it makes sense to give it a try as there is minimal body movement.
DISCLAIMER OF LIABILITY
In many respects, this article expresses the subjective opinion of the author. Furthermore, the author is not responsible for possible damage to the camera.

What is bit rate and why is it important?

What is bit rate and why is it important?

With today’s technology, we can expect high speed and quality in everything we do on our computers, our smartphones, and any other newer devices. However, although this increase in speed and quality has several factors, many of them have to do with what is called the bit rate.

What bitrate means depends on the context you’re using it in, but it’s very important to know what it is and what benefits it might bring you (or what to expect instead).

What is the bit rate?

Bit rate is a term used to describe the amount of data that is transferred over a period of time. Depending on the context, common bitrate measures include kbps and Mbps, respectively, which means kilobits per second and megabits per second. Regardless of which drives are used, a higher number is usually good, indicating high speed or high quality.

However, it is also important to understand that smaller numbers can reduce the load on your hardware, which can be important for devices such as smartphones and netbooks.

When it comes to internet speed, a higher bit rate is always desirable – it doesn’t overload your own hardware, it just sends you the content you want faster. With higher bit rates, you can do more with an Internet connection – stream HD movies, play online games with minimal latency, and download large files in just seconds.

You can find out what bitrate you are getting by visiting a website like speedtest.net and running your tests. The numbers are good to compare with others, but generally don’t expect the expected number (other than the number your ISP announced). Certain parts of the world and Google Fiber users can get speeds of up to 1 Gbps (1000 Mbps), while typical cable broadband users in the US can get as low as 10 Mbps.

There has been a lot of discussion in online communities like Reddit about high internet prices in the US due to how slow speeds are, and initiatives like Google Fiber are starting to pay off.

When it comes to audio and video, bit rates take on a different definition. In this context, bit rates refer to the amount of data stored per second of multimedia playback. For example, a 320 kbps MP3 audio file has a higher quality than the same file at just 128 kbps, as long as both files were created from the same ideal source. You will have to remember that you cannot improve an audio file that sounds bad by copying it to an audio file with a higher bit rate, as the source was bad from the beginning. So a higher bit rate is a general rule of thumb, but it is not 100% correct.

The same is true for video: a higher bitrate will have a higher quality when comparing the same video with the same resolution. The bit rate is expected to increase as the resolution increases as more data is processed. Consequently, high bit rates for audio and video can provide superior quality, but can also put a lot of pressure on your hardware, which can lead to stuttering.

Also, keep in mind that different file formats use different compression algorithms, which can result in lower bit rates and higher quality. However, for these algorithms, the processing load tends to increase.