Recent comments in /f/MachineLearning

Glitched-Lies t1_j3r89e2 wrote

I just bought one from Brainchip. They seem pretty good. I asked them some of their use cases, they have some videos on their YouTube on classification tasks of images of beer bottles, but they seem to be the same kind of tasks you can do on a regular GPU.

Brainchip PCI chip is interesting because you can code for them like regularly, and then send the built neural network to the chip and convert it from a CNN into a SNN, but there doesn't seem to be a great reason to use it this way. It seems like the main use case would be to run a native SNN on it. NPUs don't seem to scale the way GPUs do though either.

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benanne OP t1_j3r3stl wrote

DiffWave and WaveGrad are two nice TTS examples (see e.g. here https://andrew.gibiansky.com/diffwave-and-wavegrad-overview/), Riffusion (https://www.riffusion.com/) is also a fun example. Advances in audio generation always tend to lag behind the visual domain a bit, because it's just inherently more unwieldy to work with (listening to 100 samples one by one takes a lot more time and patience than glancing at a 10x10 grid of images), but I'm pretty sure the takeover is also happening there.

If you're talking about text-to-audio in the vein of current text-to-image models, I'm pretty sure that's in the pipeline :)

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LetGoAndBeReal t1_j3r0p45 wrote

Thank you for this. It seems this paper could surely help answer my question, if only I could understand it!

A challenge I keep coming up against in my quest to quickly learn about ML/NN is that almost everything I read is either too high level to provide meaningful explanation or too technically dense for me to follow. I guess I will just take note of this paper for now and circle back to it when I'm a bit further along.

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benanne OP t1_j3qzbcr wrote

If you were to graph the weighting that ensures the training loss corresponds to likelihood, you would find that it looks roughly like exp(-x). In other words, the importance of the noise levels decreases more or less exponentially (but not exactly!) as they increase. So if you want to train a diffusion model to maximise likelihood (which can be a valid thing to do, for example if you want to use it for lossless compression), your training set should have many more examples of low noise levels than of high noise levels (orders of magnitude more, in fact).

Usually when we train diffusion models, we sample noise levels uniformly, or from a simple distribution, but certainly not from a distribution which puts exponentially more weight on low noise levels. Therefore, relative to the likelihood loss, the loss we tend to use puts a lot less emphasis on low noise levels, which correspond to high spatial frequencies. Section 5 of my earlier blog post is an attempt at an intuitive explanation why this correspondence between noise levels and spatial frequencies exists: https://benanne.github.io/2022/01/31/diffusion.html#scale

"Variational diffusion models" is another paper that focuses on optimising likelihood, which you might find more accessible: https://arxiv.org/abs/2107.00630

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