What is the likely cause of macroblocking in a hybrid fiber/coax (HFC) network when MER measurements are adequate?

In a hybrid fiber/coax (HFC) network, macroblocking typically refers to the visual artifact that occurs in video streams, where large blocks of pixels exhibit distortion, significantly affecting the viewing experience. When the Modulation Error Ratio (MER) measurements are adequate, this indicates that the signal quality is generally good, and other common causes of macroblocking may not be responsible.

Excessive channel multiplexing in the headend can lead to macroblocking as it may place too much data onto the available bandwidth, causing the compression algorithms to work harder to fit all channels. This increased strain can degrade the video quality, resulting in macroblocking. If there are too many channels being transmitted at once, especially in scenarios where high-definition content is being shared, it can result in insufficient bitrates allocated to the video streams. This is particularly problematic for compressed formats where lower bitrates can lead to increased compression artifacts, such as macroblocking during scenes with rapid motion or complex visuals.

In summary, excessive channel multiplexing in the headend is a viable cause of macroblocking in an HFC network when MER is adequate, as it highlights the balance between bandwidth capacity and the demand placed on video compression processes.