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Observer daleye
Registered: ‎11-13-2014

AXI4-Stream Broadcaster to Video out halting

I am working through a project to split an AXI4-Stream to 6 different outputs. The pipeline is as follows:


  • VDMA
  • AXI4-Stream Broadcaster
    • OSD x 6
    • VTC x 6
    • AXI to Video Out x 6

The issue I'm having is depending on the build, the VTC/AXI to Vide out  instances are not asserting TReady together; therefore, the AXI Broadcast does not assert TReady and the VDMA does not pass data.


What is the most reliable way to configure the AXI to Video out and Timing Controller to yield 6 duplicate outputs? In slave mode, as detailed below, we have had success, but a rebuild may result in halted video streams.


Topolgies to consider:

  • AXI to Video output - Slave mode
    • Each AXI to Vid controls its own VTC through gen_clken
  • AXI to video output - Master mode
    • Each AXI to vid has its own VTC free running
  • AXI to Video output - Master w/ Gen lock
    • A single AXI to vid is in Slave mode with FSYNC Output from its VTC
    • The remaining 5 instances are in Master mode with their VTC's External FSYNC IN Enabled

 Is there another way to achieve this? Some example designs seem to utilize a VDMA for each output. We'd like to avoid this if possible. Is there something that can be done to better constrain the design/initialze the cores to ensure they assert Tready together?

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2 Replies
Xilinx Employee
Xilinx Employee
Registered: ‎08-02-2011

Re: AXI4-Stream Broadcaster to Video out halting

Hmmm, I'd use the 3rd option with slave mode+genlock. This is one of the main purposes of the fsync_in pin on the VTC is to keep multiple independent streams in sync. This should result in the same tready behavior across all axis2vid out cores (when tvalid behavior is the same too).
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Registered: ‎08-26-2017

Re: AXI4-Stream Broadcaster to Video out halting

Hi @daleye


Am trying something very similar to this. A VDMA followed by broadcaster with two out ports. One of the out port is connected to AXI-S to Video out instance (with a VTC of its own) . The other is connected to a resampler->YCC2RGB->AXI-S to video out instance (with a VTC of its own).


I do see the same problem. I do not get a video output on any of the video out ports. 


Were you able to fix this? If so can you please suggest on the changes that you made in the setup that fixed the issue.


Thanks and Regards,

Ajay Kumar G

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