AVC, which stands for Advanced Video Coding, is more commonly known as H.264. It’s a widely-used video compression standard that followed H.263 and was developed by the ITU-T Video Coding Experts Group (VCEG) together with the ISO/IEC Moving Picture Experts Group (MPEG). Here’s a brief overview of AVC/H.264:
Purpose: AVC/H.264 was designed to achieve a good video quality at notably lower bit rates than previous standards, making it particularly suitable for a wide range of applications, from low bit-rate Internet streaming to high-definition broadcast and Digital Cinema.
Efficiency: H.264 provides a more efficient video compression method than its predecessors. It’s known to offer around 50% bitrate savings for the same video quality when compared to standards like MPEG-2.
Compression Techniques:
- Intra Prediction: AVC uses various intra prediction modes to estimate block values within a single frame.
- Inter Prediction: It employs motion compensation with multiple reference frames for inter prediction.
- Transform and Quantization: H.264 uses a 4×4 or 8×8 DCT-like transform for frequency conversion.
- Entropy Coding: Two methods are employed – CAVLC (Context Adaptive Variable Length Coding) and CABAC (Context Adaptive Binary Arithmetic Coding). CABAC offers better compression but is more computationally demanding.
Profiles and Levels: AVC/H.264 defines several profiles catering to different application needs, and levels that set maximum parameters for those profiles. For instance, the “Baseline Profile” is tailored for low-cost applications with limited computing resources.
Network Adaptability: H.264 has features that make it adaptable to various network conditions, offering good error recovery for streaming over unreliable networks.
Applications: H.264 is used in a myriad of platforms:
- Video conferencing tools (e.g., Zoom, Skype)
- Streaming services (e.g., YouTube, Netflix)
- Broadcast television
- Blu-ray discs
- Video storage solutions
- And many others.
Licensing: While H.264 provides excellent compression and quality, it is patent-encumbered. This means that using it, especially for commercial purposes, often requires paying royalties.
To sum it up, AVC/H.264 has been a pivotal video compression standard and remains one of the most widely adopted codecs globally, despite the emergence of newer codecs like HEVC/H.265 and AV1. Its balance of compression efficiency, video quality, and computational demands has made it a go-to choice for many applications.