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Video Speed and Quality Problems and Fixes

Frame capture rate under 0.1 fps


You are receiving less than 0.1 fps from the output of the Video Capture HDMI block. Generally, you can expect ~5 fps for 1080p YCbCr 4:2:2 or ~3 fps for 1080p RGB. If you are getting less than 0.1 fps, then there is a problem with the capture system. The socket connections are timing out.

This problem can occur under the following conditions:

  • If the data is zeroes (shows up as green for YCbCr; black for RGB and Y-only), then data is not being successfully captured. This issue may be caused by:

    • Port blocking software

    • Antivirus software

    • Other incompatible setup on the socket

  • If the data contains partial valid data (you can see part of images from the camera or TPG), then the data collection is timing out. Non-optimized socket settings on the host can cause this issue.

Possible Solution

  • For total loss of data (all zeroes): Turn off any antivirus or port blocking software on the host.

  • For partial loss of data: Contact tech support to report the problem.

Frame capture rate between 0.1 fps and 1.0 fps


You are receiving 0.1 - 1.0 fps from the output of the Video Capture HDMI block. Generally, you can expect ~5 fps for 1080p YCbCr 4:2:2 or ~3 fps for 1080p RGB. Non-optimal host socket settings can cause this problem. If you are getting less than 1 fps, check your host socket settings.

Possible Solution

On Linux®, ensure that your socket buffer limits are raised to 10 MB (many distributions have a limit of 128 KB).

sh> sudo sysctl -w net.core.rmem_max=10485760 

HDMI display detects a connection, but has a blank image


You are attempting to get HDMI input from an iPhone, iPad, or iPad mini and the display indicates an active connection (usually with a green light), but the display is blank.

Possible Solution

  • If you have problems getting HDMI input when using HDMI/DVI or HDMI/Dport dongles in the connection to the monitor, try a monitor that has a direct HDMI input.

  • With an older connector, instead of mirroring the iPad display, the HDMI output is driven only from specific applications. Play a movie to see video on the HDMI display; the video does not show on the device display. In this case, although you get a blank screen initially, you can see video on the HDMI display when you run an application that outputs a video signal.

Monitor shows no image with HDMI source connected


The HDMI source is connected to the board but the monitor does not show any image.

Possible Solution

Make sure that the HDMI source and the monitor are compatible. Then try the following steps:

  1. Connect the HDMI source to the monitor directly and try again. If it works, you can continue with your programming.

  2. Change the monitor or the HDMI source.

  3. Connect the HDMI source to the board.

  4. Check the UART console. It shows if the HDMI source is detected or not. If no HDMI source is detected, try another HDMI source.

Video output does not respond to changes on input control ports


If your generated interface model drives the AXI-Lite control inputs using Constant blocks, the data type conversion from the default data type of double can result in this input driving a value of 0 when deployed on the board.

Possible Solution

Set the data type of any constant blocks in the hardware or software interface model to a fixed-point or integer type to avoid this conversion error.

Captured partial frames, remainder of the frame is black or green


If you capture part of the frame, and the rest is green (YCbCr) or black (RGB or Y-only), there is most likely a network issue with the Ethernet connection to your board. Some packets have been dropped.

Possible Solution

Check your host socket settings and network traffic. Your router or a slow Ethernet adaptor may drop packets. Ensure that your Ethernet adapter supports full Gigabit Ethernet throughput.

Captured mosaic frames, with horizontal and vertical discontinuities


The board has lost alignment with the video stream. This problem can occur if you changed the camera settings while a simulation was running, or if the camera connection to the board is loose or damaged.

Possible Solution

Avoid changing the camera settings while a simulation is running. Stop the simulation, and restart to restore alignment. If a restart does not fix the issue, restart the board.