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denoiser.hpp: simplify DPM++ (2S) Ancestral #667

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Merged
merged 3 commits into from
Sep 16, 2025
Merged

denoiser.hpp: simplify DPM++ (2S) Ancestral #667

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denoiser.hpp: simplify DPM++ (2S) Ancestral
vmobilis Apr 30, 2025
077ab16
Merge branch 'master' into patch-1
leejet Sep 16, 2025
8598863
adjust code
leejet Sep 16, 2025
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21 changes: 6 additions & 15 deletions denoiser.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -770,7 +770,6 @@ static void sample_k_diffusion(sample_method_t method,
} break;
case DPMPP2S_A: {
struct ggml_tensor* noise = ggml_dup_tensor(work_ctx, x);
struct ggml_tensor* d = ggml_dup_tensor(work_ctx, x);
struct ggml_tensor* x2 = ggml_dup_tensor(work_ctx, x);

for (int i = 0; i < steps; i++) {
Expand All @@ -785,22 +784,15 @@ static void sample_k_diffusion(sample_method_t method,
auto sigma_fn = [](float t) -> float { return exp(-t); };

if (sigma_down == 0) {
// Euler step
float* vec_d = (float*)d->data;
// d = (x - denoised) / sigmas[i];
// dt = sigma_down - sigmas[i];
// x += d * dt;
// => x = denoised
float* vec_x = (float*)x->data;
float* vec_denoised = (float*)denoised->data;

for (int j = 0; j < ggml_nelements(d); j++) {
vec_d[j] = (vec_x[j] - vec_denoised[j]) / sigmas[i];
}

// TODO: If sigma_down == 0, isn't this wrong?
// But
// https://github.com/crowsonkb/k-diffusion/blob/master/k_diffusion/sampling.py#L525
// has this exactly the same way.
float dt = sigma_down - sigmas[i];
for (int j = 0; j < ggml_nelements(d); j++) {
vec_x[j] = vec_x[j] + vec_d[j] * dt;
for (int j = 0; j < ggml_nelements(x); j++) {
vec_x[j] = vec_denoised[j];
}
} else {
// DPM-Solver++(2S)
Expand All @@ -809,7 +801,6 @@ static void sample_k_diffusion(sample_method_t method,
float h = t_next - t;
float s = t + 0.5f * h;

float* vec_d = (float*)d->data;
float* vec_x = (float*)x->data;
float* vec_x2 = (float*)x2->data;
float* vec_denoised = (float*)denoised->data;
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