Sampler Animated Preview - Not Working with Latest ComfyUI

[ricklove]

After I updated ComfyUI, video sampler previews are no longer working with the KSampler (Advanced) using WanVace.

They were working great with comfy v0.3.39, but not after update to v0.3.42

I tried updating ComfyUI-VideoHelperSuite but still no animated preview. Also, I checked the settings menu and animated previews are enabled.

[AustinMroz]

I'm afraid I haven't had any luck replicating this. v0.3.39 with associated frontend v1.23.4 works just fine for me. I've spent about an hour now trying different perfmutations of versions and workflows, but everything seems to be working fine.

[ricklove]

ok, thanks! Must be unique to my setup - if I discover the problem, I'll let you know.

[ricklove]

Wait, did you test v0.3.39 - that was working fine for me. It is v0.3.42 which is not working

[AustinMroz]

Sorry, this was a mistype on my part. I was testing with v0.3.42, yes.

A couple more questions I'd appreciate

• Any insight on how previews fail? Does it just display the static first frame preview?
• Do you get previews if you launch ComfyUI v0.3.39 with --frontend-version v1.20.6?

[ricklove]

• It shows the first frame only
• I'll test the frontend version flag

[ricklove]

• Still broke after downgrading front end: python_embeded\python.exe -m pip install comfyui-frontend-package==1.20.6

[ricklove]

Also, I will note that I never had previews with SamplerCustomAdvanced. Previews were only working with the KSampler and KSampler (Advanced). Now, they don't work with any sampler (just shows first frame only).

[ricklove]

The only thing I upgraded was ComfyUI and then installed these requirement changes:

I did not update any other custom nodes packages. Though I did update VHS to latest.

[ricklove]

In the network inspector, I see the image previews are blob of type image/jpeg:

[ricklove]

In get_latent_video_previewer is getting a false value for prev_setting (I added log statements).

[ricklove]

manually setting prev_setting=True in the code makes it work. So the bug seems to be when getting the value (probably when trying to parse the extra_pnginfo)

[phazei]

I'm also having issues with this. I'm not sure if it's a larger issue with ComfyUI frontend or this. But in general, a browser will only allow 6 open API connections. When I have the queue window open, it seems to get stuck loading the previews there and in the view. If I hit play on one of the loaded videos from the queue, it seems to unstick the connections and everything starts working again for a short period before it happens again. It's very strange.

Thing is, it doesn't happen right away, only after I've been using it a bit. And then reloading the web page only fixes it for a short while.

[mikheys]

I have the same problem. It only shows the first frame.

[ricklove]

manually setting prev_setting=True in the code makes it work. So the bug seems to be when getting the value (probably when trying to parse the extra_pnginfo)

The bug is this. It is simply not getting the value from the ui metadata correctly (for me).

[phazei]

@ricklove I have a pr to update the metadata here:
#503

But I don't think it's directly related to this ticket.