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Multi-function video coding (VVC,Versatile Video Coding) is the latest international video coding standard jointly developed by the Telecommunication Standardization Department of the International Telecommunication Union (ITU-T) and the International Organization for Standardization / International Electrotechnical Commission (ISO / IEC). Compared with the previous generation of efficient video coding (HEVC), the VVC codec can reduce the video data size by about 50% while ensuring the same video quality. In the era of growing network video traffic, video compression is becoming more and more important. With the coming tide of video content production using generative artificial intelligence (AI) and the accelerating pace of video content production and content consumption, reducing the number of bits of multimedia content is still an important issue.

Let's take a look at the fundamental innovations that distinguish VVC from the video encoders currently in use, and Qualcomm's efforts to create a vibrant VVC ecosystem.

Optimize video coding for common user experience

In addition to significantly reducing data size, VVC codecs introduce a variety of particularly useful intelligent tools in specific video scenarios such as video conferencing, screen sharing, and panoramic video.

Videoconferencing

The COVID-19 epidemic has had a profound impact on the way people work, causing people to telecommute tools (especially

The demand for video conferencing software (videoconferencing software) has increased dramatically, and video calls have become an important means of communication for personal and professional uses.

In a video call, the network bandwidth at both ends is continuously monitored, and the inbound and outbound video quality is adjusted accordingly to adapt the video data to the available bandwidth. For previous video codecs, such as efficient video coding (HEVC) and advanced video coding (AVC), when the video resolution changes to accommodate the available network bandwidth, the server needs to send a special type of frame called instant decoding refresh (IDR) frame. This interrupts time prediction, meaning that data estimates from previous and subsequent frames cannot be referenced.

VVC provides a special feature called reference Image resampling (RPR), which can make up for the shortcomings of the current generation of video codecs. When decoding, RPR can change the resolution of the video without the need for IDR frames. This avoids the surge in data volume caused by a large number of IDR frames, resulting in a smoother video call experience without stutters.

Resampling of reference images in VVC enables a smoother video call experience

Screen sharing

Screen sharing is becoming more and more popular in team collaboration, especially in the era of telecommuting. With screen sharing, team members can easily showcase their work and collaborate on projects in real time. With the growing demand for screen sharing, the demand for graphic data that is rendered, mixed or superimposed with camera-generated content is also growing.

From the beginning, VVC has been a codec designed to support the encoding of screen-shared content. The VVC codec includes five main underlying tools related to screen content coding: transform Skip residual coding (TSRC), Block-based differential Pulse Code Modulation (BDPCM), intra Block copy (IBC), Adaptive Color Transformation (ACT), and palette mode.

By reducing the amount of data that needs to be transmitted, these tools help improve the color accuracy and overall data efficiency of encoding screen content. Previous video codecs have added some screen coding improvements, but these are not efficient enough and are not supported by all terminals. By contrast, the encoding tool for screen sharing content defined by VVC is supported by default in the main tier (Main Profile) and should be available on most VVC-enabled devices.

Compared with the efficiency shown by other video codecs, it can be said that VVC will be the mainstream choice for applications with all or part of the screen shared content.

VVC improves color accuracy and overall data efficiency of screen sharing

Panoramic video

Panoramic video has gone beyond the passive paradigm of traditional video to provide a higher degree of immersion and interaction. This revolutionary technology enables users to interact with the scene or environment and feel the sense of participation and presence in the virtual space. Virtual reality (VR) is an example of immersive technology that has been realized in our daily life. In addition to entertainment, it has an impact on important economic areas such as electronic health care, audio-visual education and cultural heritage display.

VVC introduces intelligent tools for panoramic video: bitstream extraction and merging, sub-images, virtual boundaries and horizontal surround motion compensation. Panoramic video usually needs to process multiple basic bitstreams at the same time in the way of time synchronization. For previous video codecs, an instantiated video decoder is required for each basic stream. However, the extraction and merging of bitstreams defines a way to splice and clip video in the compressed domain, decoupling the number of basic bitstreams required for video applications and the number of video decoder instances required to run on the terminal.

Sub-image is a new image partition scheme introduced in VVC. It is a rectangular coding region, which is encoded independently of the adjacent region, so the image can be extracted independently. The sub-image can correspond to an area of interest, such as the area seen by the consumer through the VR header. Based on the user orientation, it can support priority processing and send higher fidelity sub-images to the head display terminal.

VVC supports sub-images to improve the 360-degree video experience

In a 360-degree video, when we convert it to a two-dimensional representation, there may be discontinuity points on the unaligned face boundaries of some projections, such as the cube map cubemaps. However, these artifacts can be reduced by disabling loop filtering at the edge. With VVC, we can control loop filtering through horizontal or vertical virtual boundaries, and the configuration of virtual boundaries will also be marked and transmitted in the code stream.

Orbit motion compensation enables motion compensation to be performed outside the left boundary of the image, orbit prediction is made horizontally, and pixel values from the right side of the image are used, and vice versa. This new flexibility helps to encode panoramic video using an isometric cylindrical projection format.

Leading basic video technology

For more than 20 years, Qualcomm has played a crucial role in the development of important video technologies that have revolutionized the way visual content is filmed, transmitted and consumed on smartphones, tablets, PC, televisions and other terminals. These innovations result in better video quality and richer content, while reducing bandwidth and storage space, creating huge benefits for consumers and companies in the ecosystem. Our inventors are widely recognized, and the impact of our technological inventions is not limited to mobile ecosystems, but also to a wider range of areas. Video technologies powered by Qualcomm Technologies are widely deployed in the industry, including leading video codecs, streaming protocols (streaming protocol) and multimedia file formats.

In promoting the development of VVC technology is no exception. Like HEVC, Qualcomm Technologies is a major contributor to the VVC standard introduced in this article.

Drive the ecosystem forward through smartphone VVC demos

VVC has a strong development momentum in the ecosystem and has been added to the core specification of DVB (Digital Video Broadcasting Project / International Digital Video Broadcasting Organization) for video coding in broadcasting and broadband applications. ISDB-T International (also known as SBTVD), the Brazilian technical standard for digital television broadcasting, also uses VVC as the main video codec, which is expected to be adopted by other broadcasting standards.

At Qualcomm, we are excited about how VVC codecs can enhance the current video experience. To this end, we have begun to work with partners in the ecosystem and look forward to bringing VVC technology to consumers.

Recently, we have joined hands with Tencent to optimize its VVC software decoder on the second-generation Snapdragon 8 mobile platform integrated with Adreno GPU. The pre-discussion achieved more than 30% performance improvement with the prototype and was able to play 4K 10-bit 60 frames per second (FPS) ultra high definition VVC content stably and fluently in real time. On July 28-31, China International Digital Interactive Entertainment Exhibition (ChinaJoy 2023) was held in Shanghai, and we demonstrated this optimized decoder for the first time. We believe that optimized software decoders, such as this one from Tencent, will help accelerate the adoption of VVC codecs in video content services.

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