vPrism Tutorials: Macroblock Analysis

To perform a macroblock analysis, disable hardware acceleration in the App Menu under Settings. The blocks will not display while it is enabled.

Then, load a video, click Analyze, and select Macroblock.

In prediction mode, vPrism overlays the frame with colors that show how each macroblock was coded.

Check Block Type in the Display Section to see I, P, and B blocks by color, and use the Legend below to identify what each color means.

An I-block is encoded entirely from itself with no reference to other frames.

A P-block references a single prior frame.

B-blocks can reference a prior frame, a future frame, or both.

The transparent Skip type is reserved for blocks that carry no residual or motion data. The block is copied directly from the reference frame.

Navigate the video to see how the blocks change throughout.

Switch to Quantization to examine how aggressively each macroblock was quantized.

Check colors to see a heatmap of quantization levels over the frame; higher values indicate stronger compression and more potential loss of detail.

Check "Values" to print the actual quantization index inside each block.

Use this view to quickly spot how specific regions were compressed, to understand why some blocks might be softer or noisier than others, and to explain artifacts.

Together, these tools let you look past the pixels and see how the encoder really built each frame, so you can interpret compression and artifacts with confidence.