What is the key difference between the H.264 and H.265 video codecs in terms of compression efficiency at the same quality level?

The key difference between the H.264 and H.265 video codecs, in terms of compression efficiency at the same quality level, is that H.265 (also known as High Efficiency Video Coding or HEVC) can achieve the same video quality as H.264 at approximately half the bitrate. Bitrate refers to the amount of data used per second to encode a video; a lower bitrate means a smaller file size and less bandwidth required for streaming. This means that H.265 can deliver higher quality video at a lower bandwidth, or the same quality video at a significantly reduced bandwidth, compared to H.264. This improved efficiency is achieved through more advanced compression techniques, such as more sophisticated motion prediction, more flexible block partitioning, and improved entropy coding. For example, a 1080p video stream that requires 6 Mbps with H.264 might only require 3 Mbps with H.265 to achieve similar visual quality. This makes H.265 particularly beneficial for streaming high-resolution video (4K or higher) or for streaming to users with limited bandwidth.