Video Coding Algorithms and Standards

Digital video coding integrates algorithmic techniques and standardised frameworks to reduce the volume of raw pixel data while preserving perceived visual quality. Most contemporary systems employ a hybrid block-based approach combining spatial prediction, transform coding, quantization and entropy coding. Spatial prediction divides frames into coding units within a Group of Pictures (GOP), applying intra-prediction for spatial redundancy and inter-prediction for temporal coherence. Transforms such as the discrete cosine transform concentrate energy into a limited set of coefficients, which are then quantised and losslessly compressed using context-adaptive entropy methods. Partitioning structures, ranging from quadtrees to nested multi-type trees, adaptively select block sizes to match local texture complexity. In-loop filtering techniques further refine reconstructed frames to reduce artefacts. International standardisation bodies have developed successive generations of codecs—from H.264/AVC to High Efficiency Video Coding (HEVC) and the more recent Versatile Video Coding (VVC)—achieving successive 50% bit-rate reductions. Parallel efforts have led to royalty-free formats such as AV1, optimised for open-source deployment. These standards support a broad spectrum of applications, including streaming, broadcast, immersive media, screen content and high dynamic range displays. The interplay between algorithmic innovation, complexity management and hardware feasibility continues to shape the global adoption of efficient coding solutions.

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Video Coding Algorithms and Standards publication trend

The graph below shows the total number of articles in video coding algorithms and standards across all publications each year (not limited to Nature Index journals).

Technical terms

Bitrate: The quantity of data transmitted or stored per unit of time, typically expressed in kilobits or megabits per second.

Group of Pictures (GOP): A sequence of video frames that includes key reference frames (I-frames) and predicted frames (P- and B-frames) used to exploit temporal redundancy.

Intra-prediction: A method of predicting pixel values within the same frame by referencing neighbouring samples to reduce spatial redundancy.

Inter-prediction: A technique that predicts pixel values based on previously decoded frames to exploit temporal redundancy.

Transform coding: The process of converting spatial domain data into a transform domain (such as using the DCT) to concentrate signal energy into fewer coefficients.

Entropy coding: A lossless compression step that assigns shorter codewords to more frequent symbols, often using context adaptation to maximise efficiency.

Codec: An encoder–decoder system that implements a complete chain of prediction, transform, quantisation and entropy coding to compress and decompress video data.

References

1. Impact of Video Motion Content on HEVC Coding Efficiency. Computers (2024).
2. Developments in International Video Coding Standardization After AVC, With an Overview of Versatile Video Coding (VVC). Proceedings of the IEEE (2021).
3. A Fast QTMT Partition Decision Strategy for VVC Intra Prediction. IEEE Access (2020).
4. Transform Coding in the VVC Standard. IEEE Transactions on Circuits and Systems for Video Technology (2021).
5. Quantization and Entropy Coding in the Versatile Video Coding (VVC) Standard. IEEE Transactions on Circuits and Systems for Video Technology (2021).
6. VVC Complexity and Software Implementation Analysis. IEEE Transactions on Circuits and Systems for Video Technology (2021).
7. Overview of the Screen Content Support in VVC: Applications, Coding Tools, and Performance. IEEE Transactions on Circuits and Systems for Video Technology (2021).
8. A Technical Overview of AV1. Proceedings of the IEEE (2021).