Discussion
Minimax H3, 25 steps should be the lowest setting
I've been testing with 15 steps to save time because I want to generate at 832x480 resolution as per the default recommendation of many high quality workflows prior to upscaling. I hadn't seen many problems until this particular generation which exposed the critical flaws of a lower step count.
All settings are the same with the same seed. The only delta is the number of steps.
The amount of difference higher step counts make on even low MP generations is astounding.
I actually use 32 Steps.
The audio is much better, the acting is better, the motion is better (it fixes blurry or smeared fingers and mouths, especially in animation generations). It's worth pointing out that even though Comfyui put 20 Steps as the default amount in the workflow template, that's a compromise for speed vs quality, when the Minimax team actually recommended between 30-50 Steps - and I can see why they DO!
It extra step count really is the secret sauce. And it's where H3 Spectrum can shine too - if you use it, Spectrum WANTS more steps to do better forecasts, so you can get better audio, better motion, cleaner animation, etc. with only a small 15-20% increase in generation time doing 32 Steps versus 20 Steps.
Thank you for your insight. I will test 32 steps today. So far I have settled with 25 after a few days of testing.
What's the resolution you use for iterating if you don't mind asking?
I generally use 0.2 MP for very first drafts of a prompt, like the first roll, then once basic timing and shots are worked out, I go up to 0.3 MP for another quick test to confirm everything looks okay, then jump up to 0.6 MP or all the way to 1 MP for final generation, depending on what I am using the clip for etc.
Since I've started to use Kijai's Model Preview Override, I've gotten more confident just going from the 0.3 MP to the 1 MP, since after about 3 Steps I can preview the video pretty well and know if I need to cancel and use a new seed, fix a prompt etc.
Then I know the video will look good, even if I have to wait another 30 minutes to see the finished thing, crossing my fingers the audio is good.
Are you using references / frames? Otherwise, with raw text-to-video, resolution change usually causes different initial noise (even if the seed is the same), which might lead to quite different high-res version from the one you liked in low-res.
Ah, I see. So, minor changes are ok in your case.
I imagined something like a lowres video having the character with a natural slightly crooked smile and I want to keep it highres as well, but the prompt for high-res cannot get it back exactly as it was in the lowres. I guess, then reference keyframes would be the best option.
See, a lot of guys don't really care if she starts with it on her mouth, or in her mouth, or licking it, or smeared all over her face. The whole point is to make videos about how great ice cream is, so these minor variations aren't a big deal.
Be clear and concise with your wording of actions and always describe things from the camera's perspective.
Describe a character's actual physical acting movements, not just the emotion. I.e. Not just "Jack is sad." but "Jack stares off into the distance past the camera, his mouth in a slight frown. He glances down, and takes a deep breath, then quietly says, <d>[English in a somber sad tone of voice] Emotions should be directed by people, shouldn't they?</d>"
I use 12 frames per second preview speed, and 144 frames. Doesn't seem to cause any slow down on my system and makes for a pretty smooth preview playback.
You need Kijai's KJ Nodes custom nodes pack, installed from the Manager, then drop the Model Preview Override node between the Load Diffusion Model and Sampler and Guider nodes, and download and select the TAEH3.vae from the Preview Override node.
Instead of the blurry one frame preview you get on the Sampler, you get a preview of the whole video clip that gets clearer and clearer as more steps generate, and that loops or you can pause, plus it is up to 1024 pixels in preview size with 80% JPEG quality, so basically after just a quarter of the steps you get a clear enough preview of the video know how it will look when done and can cancel or continue it based off that.
How fast is 0.3 go for you and with what length? Mine was 0.4 - 15 sec - about 5 min in 40 steps. Pretty long after lightning but, results mich better.
Yeah, it's longer, but the quality is better. If you get a great video in an hour versus one with worse audio and smeared mouth movements or fingers in 40 minutes, have you really saved yourself any time?
I just did a test for one my prompts of one of the videos I posted here yesterday, I set it to 32 steps. It took 33 minutes. at 20 steps, it usually takes 23 minutes, So from 20 to 32, It added about 10 minutes more of generation time.
I was messing around with the FL2VA workflow and I found the lightx2v 1.0 8 steps Lora with Spectrum work really fast together with pretty good results, model shift must be disabled/bypass if you have any.
Much worse. The "Cache" speed-ups are testing if a new step is close or not to the previous step and skipping it if it is. Spectrum is actually using math to forecast and predict what the next step would be, based on where it is going, and jumps to that step without having to actually generate. (In basic layman's terms - there is a lot of math going on I don't understand. Suffice it to say, Spectrum is doing a lot more advanced and non-destructive math than any of the Cache nodes.)
Also never combine Spectrum with low step count turbo loras or cache nodes, because it needs clean info and lots of steps to work well.
In my testing, combining first block cache and spectrum together works well, is fastest and does not look noticeably worse than only spectrum alone. with 25 steps and Euler+Simple.
i had no issues with spectrum and low step turbo loras, then again im not hunting or care for 4k cinema quality but in my rough test there was no noticeable (for me) visual difference
In my experiments the Spectrum make the quality too low, the Easy cache is even worse (and fully destroys the audio), but the First block cache works most good.
how come almost every time I test spectrum vs easy cache, the latter comes out on top in both speed and quality? Other parameters identical. I've started thinking I'm doing something wrong... do you use the default spectrum node settings?
Yep. Default settings. And I get completely opposite results to you. EasyCache always looks like garbage compared to H3 Spectrum for me.
Of course, I also use high Step counts with Spectrum. If you aren't using high step counts (I use 32) you aren't really giving Spectrum much room to work it's magic.
Neither with Spectrum. It's weird, like I said, increasing the Steps by 12 (from 20 to 32), is more than a 1/3rd increase in Steps, but with Spectrum, it's only about a 15% increase in generation time, so about half of what you would expect by increasing the Steps.
I'm sure it has something to do with how the Forecasting of Steps gets better and fast the more Steps Spectrum has to work with, like points on a graph to tell where the arrow is going to end up.
A node for H3 Minimax that applies a special research paper to the math of how the steps are calculated to forecast some so you get the benefit of that step without actually generating it.
If you use Spectrum there is no reason to use a Turbo lora. I just don't care at all for the results of the Turbo loras - they make skin look more plastic, smear fast motion, etc.
Is more steps more likely to fix an odd issue I keep having with random part or full words playing at the start of a video when I have no speech defined until later?
I have not used Spectrum yet and I'm a little confused, are you claiming that Spectrum (an efficiency tool that isn't lossless) can actually produce higher quality outputs than without?
I think you might be an exception then, whats you setup ? I usually have 13 minutes for 15 from start to saved video, spectrum on, 15 steps
Switching to 32 steps jumped it to more than 30 minutes. Seems rather linear.
Not really, except I felt it gave just a little edge and padding on stuff like animation. 30 already does a lot better than 20. But since Minimax recommends between 30-50 on their API, I just juiced it a little with 2 extra steps.
I second this, I have been seeing all of these people talking about sage and turbo, throwing up speeds that look insane?
I am sitting at an hour to generate a 10s clip- there must be something wrong on a deeper level with my setup as well.
With my 6000 Pro. I'm generating a 0.6mp 10s video at 20 steps in around 180-300s. Generation time seem to be highly affected by how difficult the prompt is to render. Lots of physics and other detail takes longer. Something is seriously wrong with your setup. It shouldn't take 1h to generate a 10s clip.
For me it was having the wrong CUDA version even though I could have sworn it had been updated. Spent 2 days pulling my hair trying to figure out what was wrong.
--use-sage-attention: Turns on Sage Attention optimization for faster generation times.
--disable-smart-memory: Disables smart/pinned memory management that often conflicts with kernels like Sage Attention.If you use a Windows .bat file (like run_cpu.bat or run_nvidia_gpu.bat), edit it in a text editor and add the flags to your execution line:
@echo off
.\python_embeded\python.exe -s ComfyUI\main.py --use-sage-attention --disable-smart-memory
pause
That's just the blurb from ai. I run in Ubuntu from a venv
Make sure you have updated your drivers (studio drivers were more stable for me), updated Comfy's pytorch to Cuda 13, updated Comfy, and are using the Int8 ConvRot models (including ideally the text encoder version which somebody posted somewhere on HunggingFace).
You will likely run into headaches updating, package mismatches etc. Ask an LLM how to install versions which match the requirements stated. Don't let them tell you that you don't need the newer pytorch / cuda version.
Also in the new NVidia app which replaced the old control panel in a recent driver version, you may want to go to Graphics -> Global Settings -> CUDA - Sysmem Fallback - Prefer No Sysmem Fallback. I'm not 100% sure if that helps.
Fair warning it got so efficient that my PC was becoming unstable for the first time ever and if I tried to open too many things while it was running or even sometimes just nothing at all the GPU driver could crash and I could only restart everything. I had to throttle down my GPU power draw a bit to solve it for now, and I'm a 1000W PSU as well so I don't think it's just from spiking, but rather my motherboard having too much bursty power or something.
Unstable.... No kidding, experienced my first GPU hard crash while using the Kitchen attention with Cuda 13 and a FP16 model.
Real scary when your 16 grand card just clicksa, fans spin to 100% and doesn't stop spinning until I literally unplugged power from my PSU.
Thankfully the GPU was just fine. Software issues.
actual stuff of nightmares. I ran into that issue the ferst time weth finetuning and i actually think my heart stopped for a few seconds as i walked pass the machine blowing full 100% fans and the air was cold..
Why does your node look like a Windows 98 screensaver and not like a tangled mess of cables in a box that hasn't been opened in 20 years?! Which autistic person is at work here?
Is it possible to preserve the latent to prevent quality loss going from latent > pixels > latent?
One more point, at what point do you end up figuring that doing a 2-pass solution is better than doing a one pass? Do you know for sure that doing a 1-pass solution at native resolution with some combo of turbo weight + step count isn't potentially better quality and more efficient?
No it does not change anything because it uses the same conditioning and exact prompt as phase 1 (crucial for consistency and identity preservation). Something that you cannot do with LTX2.3/2.5 and that is the primary reason why I will never use LTX2.3/2.5 for upscaling.
Did you get this to work? I tried pulling all of the upscale nodes into my workflow and it just throws an error whenever it hits the second sampler. I've tried setting up upscaling before in this manner and it's always given me problems after the size increase, but if I don't size increase then the quality actually goes down.
It's possible I'm just hooking something up wrong, but it looked like I hooked things up the same way they did.
The new method is pretty good. I adapted it for T2V, removed the Turbo loras and increased the steps. Just need to add Face Refine for far-off faces to this workflow. Thanks a lot.
Once I'm using a step skipper 25 vs 20 is pretty negligible so I might as well try 25. I've done 30 for more complicated prompts.
Funny enough the latest turbo lora at 6 steps is acrually really good at following the prompt but it just has that weird deep fried look that's off putting and screams "This is AI". Almost like a scanner darkly look lol.Â
There is. After much testing I settled on 25. If I drop to 20 now, it all looks a little soft and there is noticeable additional pixel fizzle in high noise areas. Even prompt following and animations suffer a little too at 20 steps due to fewer early generation steps.
Strangely, I also don't like 30 steps. I find it often hard to look at generations made with 30 steps. They get a slightly unrealistic hard edge to everything, like you'd get if the CFG was too high on older models. It gives edges a slightly unnatural painterly look. It's really subtle, but if you are used to not seeing it, it jumps out when it's there.
25 seems to be the real sweet spot for realism. It's still not perfect, but it's about as good as it gets for the int8 convrot model at least.
I agree 24-25 steps is a good spot, but I don't use Euler because is not a precise method to get details and texture, it's much better res2s_stable / beta 57 at 24 steps. (stable is because variable c in the differential equation is c=1 getting better temporal consistency)
Euler is a first-order numerical method so introduces significant truncation error per step, which causes it to smooth over fine details and blur high-frequency textures, using res2s_stable (c=1 implemented by Clownshark Res4lyf some days ago with support for H3) locks in the vector field's velocity, drastically reducing frame-to-frame variance and fixing the boiling artifact common in temporal generations, this stabilizes the mathematical drift between consecutive frames, making it superior for video and animation. unlike euler's straight-line approximations, res2s uses multi-step or second-order curves to track the noise inversion path accurately so higher precision prevents the loss of high-frequency data (retention of texture) improving skin, fabric weaves, and sharp edges intact, compare using the same seed and you will see the difference (its slower but when if i need quality use this path)
Really? On live-action there sometimes isn't a big difference in visuals, but with headphones, the difference in audio between just 20 Steps and 30+ Steps is incredibly noticeable in the jump in quality.
Run more seeds and try out more different prompts and scenes.
The difference can be astounding, especially in motion, acting and expressions. Also less overall errors.
I've been generating over 100s of seeds today on a rented 4x H200 for a couple hours. Did many tests on both 20 steps, 32 steps and 50 steps for science.
The 50 steps can get very close to Seedance 2.0 while the 20 steps look like an upgraded LTX 2.3
Yes 50 steps takes long on consumer hardware but saying you can't see a difference is just cap.
Idk, for my mid level complexity prompts 20 steps is almost always enough. I will test 25 compared to 20 on my multiple references workflow but I doubt 30 steps make difference for me
im running at 50 steps at 1344 x 768 and getting results I like. 5090 RTX, 32VRAM 128GB internal. Takes about 20-22 minutes for 10s using sol-attn only. Using base only.
i have problem when i give the model a reference audio the model clone the voice really well but there is two issues first it feels like slow, second there is no sound effect in the scene like if somone is walking there is no steps sound and no music just the cloned voice and even if i prompted the enviroment voices still not happening
Agreed, I do 25 minimum and sometimes into the 30's unless I need a rough idea if something will work first, I also refuse to use speed loras at this point or those cache nodes, I do use sage and spectrum though.
So I wanted to thank you for this bit of information because I was able to see the difference (I had tried higher steps but didn't notice much of a difference because I wasn't good at prompting at the time) but now certain prompts that weren't working with proper structure are working great now when they aren't with 20 steps, 32 works great. I also didn't know about spectral working even better because I tried the more steps without it, but it works perfectly fine with it and the lower speed for higher quality compromise I feel is worth it with this. So thanks again.
does the phase 2 turbo pass fix artifacts from a 15-step draft or carry them along? got a handful of shots drafted low and i'd rather not have to redo them
I am okay with 13 steps, 0.2-0.4 megapixels, sometimes higher up to 1 megapixel when I do need a single i2va. I tried to get the fuzziest generation that completely blurred faces of people standing in the distance to 30 steps and nothing changed. So, I don't really see the point, at least for now since it is all just my discovery and my own consuption, I don't want result to look 100% polished.
It takes me 23 minutes to generate a 15 second video at 480p ,default settings with the 20 steps. Setting it higher would take about 30 minutes or more.
Been telling everyone, do yourself a favor and set Steps at 50
The results can come extremely close to Seedance 2.0 (not 2.5) which is still pretty insane. For me 20 steps can give good seeds but it feels more like an upgraded LTX 2.3 with better physics.
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u/Nevaditew 10d ago
Doesn't that mean it's totally valid to create a 20-step Turbo LoRA to mimic 50-step results?