Essential Video Coding

Description

Essential Video Coding (EVC), standardized as MPEG-5 Part 1, is a video codec specification incorporated by 3GPP for multimedia services. Its architecture is designed with two distinct profiles: a Baseline profile, which is royalty-free and uses only technologies that are over 20 years old or freely licensed, and a Main profile, which incorporates additional advanced coding tools for higher efficiency but may be subject to licensing. The codec works by employing a hybrid block-based approach, similar to predecessors like AVC and HEVC, but with improved algorithms for prediction, transform, and entropy coding.

The encoding process begins by dividing each video frame into blocks. For each block, the encoder performs intra-frame prediction (using pixels from the same frame) or inter-frame prediction (using motion-compensated pixels from previously encoded frames). The difference between the original block and its prediction, called the residual, is then transformed (e.g., using an integer cosine transform) and quantized to reduce data. The quantized transform coefficients, along with prediction mode information and motion vectors, are entropy coded into a compressed bitstream. EVC introduces several enhanced tools, such as more flexible block partitioning, improved intra prediction directions, and advanced motion vector prediction, which collectively reduce the bitrate required for a given visual quality.

Within the 3GPP ecosystem, EVC is specified as a supported codec for Multimedia Broadcast/Multicast Service (MBMS), streaming, and conversational services. It is defined in the media codec specifications (26-series) alongside other codecs like AVC, HEVC, and VVC. Its role is to provide an efficient, high-quality video compression option for service providers, enabling them to deliver 4K, HDR, and immersive video experiences over mobile networks while managing network congestion and data costs. The specification details the bitstream syntax, decoding process, and compliance points to ensure interoperability between encoders and decoders from different vendors.

Purpose & Motivation

EVC was created to address the market need for a more efficient and commercially viable video coding standard amidst complex patent licensing landscapes surrounding HEVC. The rapid growth of mobile video traffic, driven by streaming services and social media, demanded continual improvements in compression efficiency to conserve scarce wireless spectrum and reduce data delivery costs. However, the adoption of HEVC was hampered by perceived licensing uncertainty and costs, creating a barrier for widespread implementation, especially in royalty-sensitive segments.

The primary problem EVC solves is providing a next-generation compression technology with clear licensing terms, particularly through its Baseline profile. It offers a substantial bitrate reduction—approximately 30-40% over HEVC for similar quality—which directly translates to lower bandwidth consumption and improved quality of experience for users on congested or limited-capacity networks. This efficiency is crucial for emerging applications like 4K/8K streaming, 360-degree video, and augmented reality over 5G.

3GPP's adoption of EVC in Release 16 was motivated by the desire to give the industry a choice of advanced codecs with different trade-offs between performance and intellectual property (IP) considerations. By standardizing EVC, 3GPP ensures it is a fully specified and interoperable option within the media delivery framework, allowing mobile operators and content providers to deploy it for broadcast, multicast, and unicast video services. It represents a strategic effort to future-proof mobile media services with efficient, high-quality compression while attempting to navigate the challenges of codec licensing.