Video and Image Processing Suite User Guide

ID 683416
Date 4/04/2022
Document Table of Contents

2.1. Avalon-ST Video Configuration Types

The Avalon-ST video protocol also allows for symbols to be transmitted in sequence. The start of the same transaction transmitted in “symbols in sequence” configuration. The symbols themselves are unchanged, but are transmitted consecutively rather than being grouped together.

Most color spaces require more than one symbol to represent each pixel. For example, three symbols are needed for each of the red, green and blue planes of the RGB color space.

Figure 3. Avalon-ST Video Packet Transmission (Symbols in Series)

Avalon-ST Video allows for multiple pixels to be transmitted in parallel. When the number of pixels transmitted in parallel is greater than one, the optional Avalon-ST empty signal is added to the data transfer interface between the IP cores.

The figure below shows 4 pixels, each comprising 3 symbols (or color planes), being transmitted in parallel.
Figure 4. Avalon-ST Video Packet Transmission (Pixels in Parallel)This figure illustrates the end of a video packet containing 1366 pixels, where the final beat of the transaction is not fully populated with pixel data - because 1366 is indivisible by 4, the number of pixels in parallel being used in the Avalon-ST Video configuration. The Avalon-ST standard handles this situation by populating the empty signal with the number of invalid (or empty) symbols in the final beat of transmission. The number of invalid symbols given in the empty signal must be a multiplication of the number of symbols per pixel in all circumstances.