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What are the factors that affect video quality?

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What are the factors that affect video quality?

The “image quality” of a video is actually a very complicated topic.

Whether it is the fluidity of the image, the size of the image or the clarity of the image, it can be counted in the criteria of “image quality”.

Here we must first clarify some more important parameters

1. Bitrate

The bitrate affects the volume of the video, which is proportional to the final size of the video file. That is, the higher the bitrate, the larger the video file size. The lower the bitrate, the smaller the video file size. What role does the code rate play? In simple terms, bitrate size is the amount of data contained in one second of video. That is the sample rate. In this way, the higher the bitrate, the richer the content of the video file, the richer the image details, and the closer the overall image quality to the original material.

2. Frame rate

The frame rate affects the smoothness of the image. Under normal circumstances, if the video exceeds 24 frames per second, the human eye may assume that it is smooth by default. In most cases, the frame rate does not affect “image quality”, because the frame rate standards that can be selected are “scientific” and “effective”. Whether it is film (23.976), PAL (25), or NTSC (29.97), in these common formats, the frame rates shown in parentheses are the frame rates that can give people a good viewing experience. .

3. Resolution

The definition of resolution should be very familiar to everyone. N*M resolution essentially refers to the number of pixels. The resolution determines how fine the video is. If the original material can be guaranteed. The higher the resolution, the better the video content.

With that said, we can start to infer the image and video quality factors.

first priority

quality of original materials

The quality of good footage trumps everything, and the quality of footage can be hidden. That is, I have a 1920 x 1280 video in hand and downscale it to a 1280 x 720 video. If other parameters are reasonable, the image quality of this video can be guaranteed. For example, I only have a PAL material (720*576), I want to convert it to a 1920*1080 video, if the resolution of this material in this new video exceeds 720*576 (i.e. its original resolution), the quality of the video starts to drop off sharply and there is no way to compensate for this process.

Second, the code rate should be selected within a reasonable range. Under normal circumstances, the original 25M/s video material can still be viewed if it is compressed to 8M/s, but only if your display device is a common home device or general projector. Specific discussions are also required in the high definition environment.

The last and most problematic is the video format.

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What are the factors that affect video quality?

Bit rate

Resolution

encoding type

frames per second

The “image quality” of a video is actually a very complicated topic. Whether it is the fluidity of the image, the size of the image or the clarity of the image, it can be counted in the criteria of “image quality”.

Here we must first clarify some more important parameters

1. Bit rate (also called bitrate)

2. Frame rate

3. Resolution

With that said, we can start to infer the image and video quality factors.

first priority

quality of original materials

The last and most problematic is the video format.

There are endless video formats, and we are also dazzled in the process of practical application.

How to achieve high-quality videos with low bandwidth

How to achieve high-quality videos with low bandwidth

Video Bandwidth

The bit rate can be reduced, in particular, due to noise reduction. Noise is quite a damaging factor causing clogging of the encoding process. It leads directly to an increase in the bit rate.

Video bandwidth

Optimize bitrate to reduce streaming

The classic noise reduction systems are of two types. Spatial noise reduction techniques are applied within the frame to help reduce noise, while temporal noise reduction averages the pixels over multiple frames. These are very effective techniques for still images, but they can cause problems when there is movement. In the event that temporary noise reduction is applied to a moving image, a ghost image may appear.

By combining spatial and temporal noise reduction with the ability to dynamically adjust them based on lighting levels and the detection of moving objects, we obtain images with low noise, maximum detail and low bit rate. The bit rate can be optimized by adjusting the amount of noise reduction based on the analysis of important moving objects in the surveillance camera’s field of view. When there is no movement, the bit rate is kept to a minimum. If an important object is detected, the bit rate increases, allowing you to capture as much detail as possible. The result is that the network bandwidth requirements remain low until something major happens in the frame.

Other ways to reduce the bit rate
For some megapixel surveillance cameras, the bit rate is limited by default. Constant bit rate is often used for this. The constant bit rate is kept at a fixed level. This can result in a consistently high bit rate, and setting a low bit rate can result in poor image quality.

In contrast, a variable bit rate preset a certain level of image quality that is maintained regardless of whether there is movement in the frame or not. The bit rate will change depending on the shooting conditions and the presence of motion.

Dynamic noise reduction, as described above, works on the same principle as variable bitrate, but with the addition of intelligent decision-making capabilities based on the presence or absence of motion. This can reduce the bit rate by 50 percent over the standard variable bit rate in non-motion scenes.

Priorization
In addition to reducing noise, prioritization can help lower bit rates. By setting priority areas, you adjust the level of compression for different parts of the image. Multiple areas can be marked on the image, each of which is assigned compression level parameters. A less important area can be configured to use a higher compression rate and therefore a lower bit rate, while important areas can be assigned a lower compression rate to display in more detail.

Take video surveillance at the entrance of a building, for example. Some parts of the image showing the sky can be considered unimportant for better compression. The area of the entrance to the building can be marked as important and assigned a lower compression ratio to ensure recognition of facial features and other identifying details. Finally, the driveway can be defined as a zone with normal compression.

Reduce costs with dynamic noise cancellation
The combination of noise reduction and image area prioritization produces measurable results. The key benefit of this combination is that you get a significantly lower bit rate without losing image quality. A lower bitrate, in turn, reduces bandwidth and memory usage.

Take, for example, a shopping center with a video surveillance system with 200 surveillance cameras installed throughout the premises inside and outside the facility. Let’s say the mandatory requirement for 1080p HD video surveillance cameras is to record continuously for 12 hours a day and once the mall closes, they can only record when motion is detected. In this case, storing video recorded at a rate of 10 frames per second will require almost 70 TB, allowing you to store it for 30 days. The introduction of surveillance cameras that use dynamic noise reduction can save more than 7 TB of required storage capacity. This translates to over $ 10,000 depending on the storage devices used …. Additional savings can also be achieved by adding priorities in certain areas, which will further reduce the bitrate.

3D, HD, 1080p, 1080i, Blue-Ray, DVD … Everything you need to know about video

3D, HD, 1080p, 1080i, Blue-Ray, DVD … Everything you need to know about video

Part 1. Video quality

How do we celebrate the new year? That’s it, on the table! However, television is usually the most integral part of this table. New Years greetings, favorite shows, movies, shows, concerts, without this, the New Year would not be the holiday we are used to.

But the vacation itself lasts only one night, and there are many more vacations and weekends. And how else to decorate the cold days of the week in January that we spend at home, if not watching good movies in high quality? No way! What do we do when we want to see a movie? We turn on the TV … But there they impose a program on us, what if nothing relevant and interesting comes at the moment?

So a video player of any kind or a computer, in combination with the Internet or various discs, comes to our rescue. But, we already said that downloading from the internet is illegal. And time goes by, for example, you can’t download a 3D movie in such a modern format from the Internet. You’ll need a special monitor, special glasses, and for the sake of a movie, you really don’t want to pump out 30 gigabytes. What to do? And how do we understand what and how we see ourselves? How to get the most out of your film?

Or how not to spoil the impression of a canvas that has just been published, which has already been seen, but which you did not like at all due to the quality of the image? And it is not surprising, because this copy was filmed in an underground cinema, on a cheap video camera with shaking hands …

Everything can be solved! For the last time this year, I will open your eyes to the accessible, simple, but often hidden from the eyes of a normal man on the street!

Let go of ignorance. What is video quality?

Today, in 2012, already a year, let’s not mention the subject of videotapes. They have already outlived their own. Let’s see what video quality it is in general. What does it consist of? As measured? Various parameters:

Source. It is the most important. Without a high quality source you can do whatever you want with the video, record it wherever and however you want, it can’t be of better quality anymore. Worse please, but in the opposite direction, never. A simple example: take a movie from a DVD with 10 of them and burn it in Blue-Ray. Will the quality of this change? No…

Under the good quality source, or rather the one from which the countdown comes, we take the film edited in the film studio in the way it was assembled on the editing table in the final version. This is the source of all kinds of licenses and the video quality standard. Everything else can only be WORSE.

Resolution. No, not to see a movie! Video resolution measured in horizontal and vertical pixels. Have you often noticed that licensed DVD movies still look awfully “blurry” on modern “flat” TVs? And the television itself doesn’t look as “sharp” and “bright” as it used to? Many even complain that they bought expensive equipment, but everything has gotten even worse … And few people think that this process is roughly comparable to driving a Zaporozhets, buying a Mercedes, pumping gas from the first tank to the second tank and Undisguised surprise that this “gasoline” is enough for Mercedes for a very short time. Of course, Mercedes needs to fill its own full tank, not a full tank of Zaporozhets!

Do you remember the source? Therefore, it is already insufficient for comfortable viewing. Because standard television has a slightly worse transmission format than DVD. But even this is not enough for a clear display! So what kind of permissions are there?

480p: TV broadcast format. The letter p is responsible for the parameter of displaying the entire image at once, that is, at 24 frames per second, all the pixels in each frame are displayed. The resolution is 640×480 pixels (width x height ratio).

576p: widescreen DVD format, resolution 720X576.

720p – the youngest of the HD formats (high definition, high quality), most often used in games on modern XBOX360 and SONY PLAY STATION 3 consoles. Some modern TV channels also broadcast on it, so the picture looks a lot best. It has a resolution of 1024X768.

1080i: The format designated in technology as HD-Ready (not to be confused with Full-HD!). The letter i is responsible for the interlaced display method. That is, out of 24 (this is just an example, modern video has 60 frames per second), half of the frames will show all pixels across a line, in odd order, and the other half in even order. With this clever method, we have a high resolution, but in fact, although it is not noticeable with the naked eye, we get 12 frames per second, instead of 24. The resolution here is 1920X1080 pixels.