User guide

11–4 Chapter 11: Clocked Video Output MegaCore Function
Functional Description
Video and Image Processing Suite January 2013 Altera Corporation
User Guide
The Clocked Video Input MegaCore function extracts any ancillary packets from the Y
channel during the vertical blanking. Ancillary packets are not extracted from the
horizontal blanking. The extracted packets are output via the Clocked Video Input’s
Avalon-ST output with a packet type of 13 (0xD).
Separate Synchronization Format
For the separate synchronization format, the MegaCore function outputs horizontal
and vertical syncs and field information via their own signals.
A sample is output for each clock cycle on the
vid_data bus. The vid_datavalid
signal is used to indicate when the
vid_data video output is in an active picture
period of the frame.
Table 11–1 lists five extra signals for separate synchronization formats.
Control Port
If you turn on Use control port in the parameter editor for the Clocked Video Output,
it can be controlled using the Avalon-MM slave control port. Initially, the MegaCore
function is disabled and does not output any video. However, it still accepts data on
the Avalon-ST Video interface for as long as it has space in its input FIFO.
The sequence for starting the output of the MegaCore function is as follows:
1. Write a 1 to
Control register bit 0.
2. Read
Status register bit 0. When this is a 1, the function outputs video.
The sequence for stopping the output of the MegaCore function is as follows:
1. Write a 0 to
Control register bit 0.
2. Read
Status register bit 0. When this is a 0, the function has stopped video output.
This occurs at the end of the next frame or field boundary.
The starting and stopping of the MegaCore function is synchronized to a frame or
field boundary.
Video Modes
The video frame is described using the mode registers that are accessed via the
Avalon-MM control port. If you turn off Use control port in the parameter editor for
the Clocked Video Output, then the output video format always has the format
specified in the parameter editor.
Table 11–1. Clocked Video Output Signals for Separate Synchronization Format Video
Signal Name Description
vid_h_sync 1 during the horizontal synchronization period.
vid_v_sync 1 during the vertical synchronization period.
vid_f
When interlaced data is output, this is a 1 when F1 is being output and a 0
when F0 is being output. During progressive data it is always 0.
vid_h 1 during the horizontal blanking period.
vid_v 1 during the vertical blanking period.