Although streaming media platforms such as Youku and iQiyi have now become one of the mainstream ways to watch movies, whenever an action blockbuster they want to see is released, many people will still buy tickets to enter the cinema for the first time.
Some hardcore movie fans say that in addition to enjoying the visual enjoyment brought by the big screen, you don't have to worry about the characters on the screen.
▲ "Justice League" 1080P H.264 partial enlargement
The "paste" mentioned here is not a black word between rice circles, but a literal meaning - once the fight scene becomes violent on streaming media, the originally clear picture will appear some "mosaic" color blocks at an inopportune time.
Obviously, the highest-end 4K image quality has been selected in the streaming media, but the 1080P original disk resources that have not been downloaded have been downloaded to play it, is this the so-called "genuine victim"?
Does high resolution really mean HD?
Before we can figure this out, we must first know what the 1080P and 4K that we often talk about are.
Both 1080P and 4K are common video display formats, but they refer to different display units.
1080P refers to the vertical direction of the screen has a 1080P horizontal scan line, usually the picture resolution is 1920 * 1080, where 1080P refers to the "width" behind.
4K refers to reaching 4000 pixels in the horizontal direction of the screen, the common projection resolution of movies is 4096 * 2160 (DCI 4K), and 4K refers to the "long" in front.
Therefore, to accurately describe the resolution of a picture, we need to use both, for example, the DCI 4K mentioned above will be labeled as 4K 2160P on YouTube.
High-resolution video is like a larger canvas, when you display on large-size devices, you often need content corresponding to the size, otherwise there will be pixel particles due to insufficient resolution, making you feel blurry.
When you switch resolutions on a streaming site, you can clearly feel that the same video is very different in 480P and 1080P resolutions.
In order to facilitate the audience's understanding, some streaming websites also label these resolutions with the words HD, ultra-clear, and ultra-clear.
However, the resolution of a video is not the only criterion that determines the clarity of a video.
As mentioned earlier, resolution only describes the size of the "canvas", when a stamp with the Mona Lisa (480P) and the original (1080P) are compared together, the stamp will naturally appear less delicate than the original when it is stretched to the size of the original, but it is still vivid when it is restored to the size of the stamp.
That is to say, in addition to the size of the canvas affecting the clarity, the quality of the painting is also very important, corresponding to the video, including a series of encoding parameters such as bitrate, frame rate, motion estimation parameters, etc.
This is also why the 1080P raw disk resources of tens of GIGabytes will be more than some streaming media 4K film sources, the former's bit rate (the amount of data transmitted per unit time) may be dozens of times larger than the latter, and the picture is naturally more refined.
Usually, the higher the bitrate of the video, the higher the video quality, but for streaming platforms, a high bitrate means high bandwidth, that is, it will burn more money.
▲ Image courtesy of The Verge
If you go through the financial reports of some streaming media platforms, you will find that whether it is Domestic Youku, iQiyi, Tencent Video or foreign YouTube and Netflix, they are in a state of loss to varying degrees, of which servers and bandwidth account for the majority of their costs.
Therefore, high bitrate is destined to belong to only a few content, such as the "1080P high bitrate" clarity option launched by Station B, which is only supported by specific content and only open to large members.
If you want to see a more accurate video, changing the encoding is king
Is there a magic that allows us to see more high-definition video at the same or even lower bandwidth?
As a result, the encoding and decoding compression efficiency of the video is crucial, and the higher the efficiency, the higher the quality of the video seen by the audience.
We all know that the video is played continuously by many frame pictures, but when the phone loads the video, it does not accept these frames of pictures, but a "compression package", the phone to do is to use the decoder to unravel these packages, restored to the video that can be played correctly.
This is because in the production process of digital video, each video will go through a certain lossy data compression, in order to control the volume of the video file at a certain size, easy to store, transfer and edit.
▲ If the video is not compressed, the volume will be astronomical
If digital video is not compressed, at 20 megapixels, 24 frames per second, the image taken in one second is larger than 1GB, and a memory card may only be enough to shoot 2-3 short videos, which is obviously not acceptable.
The most successful and widely used codec formats are MPEG-2 and H.264, where H.264 is commonly used on streaming platforms.
According to Encoding's 2019 Global Media Formats Report, H.264 accounted for 84% of all video produced in 2018, compared to 12% of its successor, H.265.
H.264 is like the JPEG of the video world, you can see it in almost any corner of the Internet, and it has good compatibility with the device, whether it is a computer, a mobile phone, a smart watch or a car machine, you can basically open it.
But H.264 also has an unavoidable flaw, that is, it was born in 2003 in terms of efficiency and can not meet the needs of increasingly high-definition video, when the resolution to 4K, H.264 has been unable to process, people urgently need a more efficient codec format.
In 2013, the ITU (International Telecommunication Union) proposed a new encoding format, the name is very straightforward, called High Efficiency Video Coding (HEVC), which is more familiar H.265.
H.265 surpassed its predecessor H.264 in terms of compression rate and compression speed, and indeed met people's demand for high-efficiency codec formats, but only in terms of usage rate, H.265 has never been able to catch up with H.264.
An important reason is that H.264 has only one patent pool, while H.265 has three patent pools, making the royalties of H.265 expensive, and hardware manufacturers or content manufacturers who want to use the new code need to pay a large patent royalty.
Still, most electronic devices are currently gritting their teeth in favor of H.265 encoding.
For example, Apple, which has been leading the promotion of H.265 popularization, has joined the hardware support of H.265 in the A9 processor, and Google has also supported Android 5.0 or above, including Intel, Nvidia, AMD, Microsoft and other companies have also announced support to varying degrees.
But in the content and software industry, H.265 has not been so smooth.
▲ Green is supported
Like YouTube, the world's largest video site, has no intention of supporting H.265, and mainstream browsers except Safari do not support H.265, the reason is because the patent licensing fee of the new standard is too expensive for these companies with a huge number of users and a huge amount of content.
In order to compete with it, Google launched an open source VP9 encoding format in 2012, which was supported by browser manufacturers such as Firefox and Edge, but because Google has a lot of control over VP9, other content manufacturers chose to wait and see and did not actively follow up.
▲ You can find many familiar companies
In 2018, Google no longer chose to go it alone, but jointly formed the Development Media Alliance (AOMedia) with Mozilla, Netflix, Meta, Microsoft, Samsung, Tencent and other technology companies, launched the AV1 encoding technology that aligned with H.265 with various indicators, and did not charge a licensing fee, open source for developers to use.
Hardware vendor support can accelerate AV1 decoding on hardware devices, and can improve battery life and playback performance, which will invisibly attract more content vendors to migrate to new codec formats, in such a virtuous cycle, open source AV1 has a good chance to become the next H.264.
As one of the founding members of AOMedia, Netflix did a lot of testing of AV1 and finally decided to announce the launch of AV1 format streaming services for TVs and PS4 Pro in 2021, revealing that it is exploring AV1 formats with HDR.
At the same time, AV1's appearance rate on the domestic Internet is also getting higher and higher, Tencent announced that Tencent Cloud live broadcast and on-demand products will support THE AV1 standard; iQiyi became the first video website in China to enable av1 format in 2020; Station B recently added AV1 decoding to the player, and can freely choose more efficient AV1 format playback on the desktop side.
On the hardware side, Intel, Nvidia, and AMD have introduced support for AV1 on the latest series of products; mobile Samsung (Exynos 2200) and MediaTek (Tianji 1000 onwards) have also begun to support this new standard, leaving Qualcomm and Apple, a founding member of AOMedia, without announcing a support plan.
According to Protocol, Qualcomm may support AV1 decoding on the Snapdragon 8 Gen 2 launched at the end of this year, allowing AV1 to be further promoted.
At that time, we can consume more high-definition content with less traffic, which is a good thing for content consumers and creators, and all of this is quietly changing.