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Introduction
Advanced Video Coding (AVC), also referred to as H.264 or MPEG-4 Part 10, is a video coding standard developed collaboratively by the Video Coding Experts Group (VCEG) of ITU-T and the Moving Picture Experts Group (MPEG) of ISO/IEC. Compared to prior standards, AVC provides significantly better compression while maintaining high visual quality and its increased use has begun driving down video bitrates and bandwidth requirements. AVC has seen widespread adoption across various streaming, broadcast and storage applications.
History and Development
AVC development began in 2001 with the creation of a Joint Video Team (JVT) comprising members from VCEG and MPEG. The goal was to develop a video compression standard capable of twice the compression efficiency of prior standards like MPEG-2 and H.263. Over a period of 4 years, the JVT evaluated numerous compression tools and algorithms before finalizing the AVC standard in 2003.
Some key technical contributions included the use of larger macroblock sizes, motion compensation with quarter pixel precision, context-based adaptive variable length coding (CABAC) of transform coefficients, in-loop deblocking filter and constrained intra prediction. These new tools allowed AVC to achieve 50% better compression relative to MPEG-2 at similar perceptual quality levels. With continued refinements, the compression gains of AVC over prior standards have grown significantly over time.
Technical Overview
The AVC compression scheme uses a block-based hybrid video coding approach with motion compensation and transformed residuals. Videos are divided into coded picture frames comprising of macroblocks, which are further divided into smaller square blocks.
Motion Compensation and Estimation
Motion estimation finds the best matching block within a search area in the reference frame to remove temporal redundancies. Motion vectors pointing to the reference blocks are encoded. Advanced prediction modes like quarter pixel motion estimation further improve compression.
Transform and Quantization
DCT is used to convert spatial domain residual blocks into frequency domain coefficients, which are then quantized. Quantization involves discarding less visible frequency components to achieve higher compression ratios.
Entropy Coding
CABAC provides context-based encoding of quantized transform, motion and other syntax elements. It performs exceptionally well for low bitrate applications compared to universal variable length coding.
In-loop Deblocking Filter
An adaptive filter applied to block boundaries removes blockiness artifacts introduced during compression without increasing bitrate.
Intra Prediction
Angular predictive coding reduces spatial redundancies within intra coded blocks by predicting pixel values of current block from neighboring reconstructed pixels.
Applications and Deployment
Due to the significant compression capabilities of AVC, it has been widely adopted across various applications where bandwidth efficiency is critical:
– Digital Television Broadcasting
AVC is the compression standard powering digital television broadcasting across standards like DVB, ATSC and ISDB. It has allowed switchover to HDTV broadcasts.
– Video Streaming
Nearly all OTT video services like Netflix, Amazon Prime Video, YouTube, Hotstar use H.264/AVC for streaming content over constrained networks.
– Video Conferencing
Solutions from Cisco, Polycom, Lifesize and others rely on AVC for high quality telepresence over limited uplinks.
– Video Surveillance
IP cameras preferentially use AVC to transmit multiple high resolution video streams over narrow connections.
– Blu-ray Disc
High definition optical discs employ AVC/MVC to store up to 50 GB content on a single layer BD.
– Professional Video Production
Non-linear editing solutions from Apple, Adobe and Avid now natively support AVC import/export.
Future Alternatives
While AVC remains the dominant standard, its successors like High Efficiency Video Coding (HEVC), Versatile Video Coding (VVC) and upcoming standards promise even better compression efficiency. HEVC achieves around 50% additional data savings over AVC at the cost of higher computational complexity. VVC targets further 30-50% improvement over HEVC. As hardware support improves for newer codecs in coming years, they are expected to gradually supplant AVC in applications where bandwidth savings outweigh implementation costs. However, AVC will continue serving existing deployments and low complexity use cases for many more years.
Conclusion
In conclusion, Advanced Video Coding (AVC) has had an immense impact on technologies relying on efficient video delivery since its introduction in 2003. Its capabilities enabled the transition to HDTV, facilitated online streaming and enabled new applications requiring high resolution video. Going forward, it will retain importance for legacy systems even as successors like HEVC and VVC start gaining ground where their additional compression benefits outweigh deployment costs. Overall, AVC has been hugely successful in meeting its goal of significantly enhancing compression efficiency of digital video.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
