Video reader node doesn't want to play the file

Copied from the old Lightact Answerhub.


I’ve connected a video reader node to Render to canvas node and it all seems to be connected as it should, but I don’t see any video playing. The only thing that appears under the render to canvas node is a black texture.


Sometimes this happens on computers that don’t have any audio outputs while the video includes audio. This causes the video reader node to stop playback because it doesn’t know where to send the audio stream.

Is this the case with you?

I am having this issue as well – my videos worked fine until today. I am working on a computer with an output device (built-in speakers). In fact, when playing back videos with audio, I can hear the audio, but still see no video, only a black texture as described above.


is there a way for you to share the video with me? What codec are you using, if i may ask?


Hi Mitya,

Thanks for the reply… I got it working temporarily on a second PC, but then it stopped after I changed some of the connections (plugging in a different display, resetting my router accidentally, unplugging an external digital audio interface, plugging in an arduino via usb). I’m not sure if any of those could’ve caused the issue? I am still able to hear audio from the video playback, but no video previews appear under the Video Reader or Render to Canvas nodes, and the Canvas will not display the video. I can still render colors and textures from other non-video nodes, such as Voronoi Noise.

I tried with a number of different video files, both mp4 (h264) and mov. I will PM you with a video link.


Hi Mitja,

I was able to more reliably reproduce the issue today, and wanted to send along some info. I am not sure if its a bug, or something related to the external displays or computer audio devices.

My setup:
Workstation: Lenovo Thinkpad P51 laptop
OS: Microsoft Windows 10 Home 64 bit
CPU: Intel Core i7-7820HQ (running at 3.5 GHz)
RAM: 64 GB
GPU: NVIDIA Quadro M2200

External monitor
ASUS 1080p monitor, HDMI (for working)
ProDisplay 42" TLCD display case, HDMI (where I am trying to display video textures)

eDMX Lights
neoPixel strip connected to Enttec Pixel Octo, Art-Net via ethernet

I found that when I was connected to my ASUS monitor via HDMI, the video textures display perfectly. However, when plugged into the TLCD, or when the HDMI is not connected to my computer, I got no preview or playback of the video texture in the target canvas. If I plug the ASUS monitor back in, and toggle the audio device radio buttons in the Video Reader sidebar options, the video preview and display would return.

I have a workaround for now – I found that I can set up the Video Output and start playback while connected to my ASUS monitor, and then unplug the HDMI from the ASUS and plug it into the TLCD. As long as I don’t fully stop playback, I can see the content on the TLCD.

Wanted to share in case this is a bug others have seen. Also, I am working on an exhibition where we’re hoping to use LightAct for 7x 4K TLCDs and a ton of Art-Net LEDs, so wanted to see if there are best practices or fixes here.

Thanks! Appreciate how responsive you’ve been on these forums as I get my hands dirty in LightAct!



Would it be an option to play audio separately? So the video file wouldn’t have any embedded audio?


Hi Mitja,

In the test I talked about above, the video does not have an audio channel. I do not need to handle audio through LightAct for my application, but this issue still happened, even with no audio in the video file.