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Merged
leejet merged 7 commits into from
Aug 30, 2026
+81 −21
Merged

feat: additional --preview-interval values #1915

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f739158
use `sd_get_preview_interval()`
vmobilis Aug 23, 2026
036b575
Merge branch 'leejet:master' into master
vmobilis Aug 27, 2026
cb2d258
Options for `preview-interval`
vmobilis Aug 27, 2026
1c6b83e
Description of preview options
vmobilis Aug 27, 2026
5a89444
stable-diffusion.cpp: clang-tidy formatting
vmobilis Aug 29, 2026
a287366
Merge branch 'master' into pr1915
leejet Aug 30, 2026
130bd85
fix: handle preview intervals across sampling passes
leejet Aug 30, 2026
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2 changes: 1 addition & 1 deletion examples/cli/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -94,7 +94,7 @@ struct SDCliParams {
options.int_options = {
{"",
"--preview-interval",
"interval in denoising steps between consecutive updates of the image preview file (default is 1, meaning updating at every step)",
"preview interval: in each sampling pass, positive N updates every Nth denoiser step and -N previews only completed logical step N; 0 previews the final completed step of the first pass (base-resolution or high-noise). Default: 1",
&preview_interval},
{"",
"--output-begin-idx",
Expand Down
3 changes: 3 additions & 0 deletions include/stable-diffusion.h
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Expand Up @@ -446,6 +446,9 @@ typedef bool (*sd_graph_eval_callback_t)(struct ggml_tensor* t, bool ask, void*

SD_API void sd_set_log_callback(sd_log_cb_t sd_log_cb, void* data);
SD_API void sd_set_progress_callback(sd_progress_cb_t cb, void* data);
// In each sampling pass, a positive interval previews every Nth denoiser step, while a
// negative interval previews only completed logical step -interval. Zero previews the final
// completed step of the first sampling pass (base-resolution or high-noise).
SD_API void sd_set_preview_callback(sd_preview_cb_t cb, enum preview_t mode, int interval, bool denoised, bool noisy, void* data);
SD_API void sd_set_backend_eval_callback(sd_graph_eval_callback_t cb, void* data);
SD_API int32_t sd_get_num_physical_cores();
Expand Down
45 changes: 45 additions & 0 deletions src/runtime/preview_interval.h
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@@ -0,0 +1,45 @@
#ifndef __SD_RUNTIME_PREVIEW_INTERVAL_H__
#define __SD_RUNTIME_PREVIEW_INTERVAL_H__

#include <cstddef>
#include <cstdint>
#include <limits>

namespace sd::preview {

constexpr std::uint64_t logical_sample_step(int step) {
return step < 0 ? static_cast<std::uint64_t>(-static_cast<std::int64_t>(step))
: static_cast<std::uint64_t>(step);
}

constexpr bool sample_step_is_complete(int step,
std::size_t total_steps,
bool terminal_sigma_is_zero) {
return step > 0 ||
(terminal_sigma_is_zero &&
step < 0 &&
logical_sample_step(step) == static_cast<std::uint64_t>(total_steps));
}

constexpr bool should_preview_sample_step(int step,
std::size_t total_steps,
bool terminal_sigma_is_zero,
int interval,
bool preview_final_step) {
if (interval > 0) {
return step % interval == 0;
}
if (!sample_step_is_complete(step, total_steps, terminal_sigma_is_zero)) {
return false;
}

std::uint64_t logical_step = logical_sample_step(step);
if (interval < 0) {
std::uint64_t requested_step = static_cast<std::uint64_t>(-static_cast<std::int64_t>(interval));
return logical_step == requested_step;
}
return preview_final_step && logical_step == static_cast<std::uint64_t>(total_steps);
}
} // namespace sd::preview

#endif // __SD_RUNTIME_PREVIEW_INTERVAL_H__
52 changes: 32 additions & 20 deletions src/stable-diffusion.cpp
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Expand Up @@ -61,6 +61,7 @@
#include "model/vae/wan_vae.hpp"
#include "runtime/denoiser.hpp"
#include "runtime/guidance.h"
#include "runtime/preview_interval.h"
#include "runtime/sample-cache.h"
#include "upscaler.h"

Expand Down Expand Up @@ -2467,8 +2468,11 @@ class StableDiffusionGGML {
sd_get_preview_mode()};
}

void report_sample_progress(int step, size_t total_steps, int64_t* last_progress_us) {
if (step > 0 || step == -(int)total_steps) {
void report_sample_progress(int step,
size_t total_steps,
bool terminal_sigma_is_zero,
int64_t* last_progress_us) {
if (sd::preview::sample_step_is_complete(step, total_steps, terminal_sigma_is_zero)) {
int64_t now = ggml_time_us();
int showstep = std::abs(step);
float step_seconds = last_progress_us != nullptr && *last_progress_us > 0
Expand Down Expand Up @@ -2530,6 +2534,7 @@ class StableDiffusionGGML {
int audio_length,
float frame_rate,
const sd_cache_params_t* cache_params,
bool preview_final_step,
const sd::Tensor<float>& video_positions = {}) {
struct RunnerDoneOnExit {
GGMLRunner* runner = nullptr;
Expand Down Expand Up @@ -2589,8 +2594,9 @@ class StableDiffusionGGML {
}
}

size_t steps = sigmas.size() - 1;
bool has_skiplayer = (slg_scale != 0.0f || slg_uncond) && !skip_layers.empty();
size_t steps = sigmas.size() - 1;
bool terminal_sigma_is_zero = sigmas.back() == 0.f;
bool has_skiplayer = (slg_scale != 0.0f || slg_uncond) && !skip_layers.empty();
if (has_skiplayer && !sd_version_is_dit(version)) {
has_skiplayer = false;
LOG_WARN("SLG is incompatible with this model type");
Expand Down Expand Up @@ -2639,6 +2645,13 @@ class StableDiffusionGGML {
float c_out = scaling[1];
float c_in = scaling[2];

bool preview_needed = preview.callback != nullptr &&
sd::preview::should_preview_sample_step(step,
steps,
terminal_sigma_is_zero,
sd_get_preview_interval(),
preview_final_step);

std::vector<float> base_timesteps_vec = prepare_sample_timesteps(sigma, shifted_timestep);
std::vector<float> timesteps_vec = base_timesteps_vec;
sd::Tensor<float> audio_timesteps_tensor;
Expand Down Expand Up @@ -2669,21 +2682,17 @@ class StableDiffusionGGML {
if (!denoise_mask.empty()) {
denoised = denoised * denoise_mask + init_latent * (1.0f - denoise_mask);
}
if (sd_should_preview_denoised() && preview.callback != nullptr) {
if (step % sd_get_preview_interval() == 0) {
preview_image(step, denoised, version, preview.mode, preview.callback, preview.data, false);
}
if (preview_needed && sd_should_preview_denoised()) {
preview_image(step, denoised, version, preview.mode, preview.callback, preview.data, false);
}
report_sample_progress(step, steps, &last_progress_us);
report_sample_progress(step, steps, terminal_sigma_is_zero, &last_progress_us);
sd::guidance::GuiderOutput output;
output.pred = denoised;
return output;
}

if (sd_should_preview_noisy() && preview.callback != nullptr) {
if (step % sd_get_preview_interval() == 0) {
preview_image(step, noised_input, version, preview.mode, preview.callback, preview.data, true);
}
if (preview_needed && sd_should_preview_noisy()) {
preview_image(step, noised_input, version, preview.mode, preview.callback, preview.data, true);
}

sd::Tensor<float> cond_out;
Expand Down Expand Up @@ -2896,12 +2905,10 @@ class StableDiffusionGGML {
if (!denoise_mask.empty()) {
denoised = denoised * denoise_mask + init_latent * (1.0f - denoise_mask);
}
if (sd_should_preview_denoised() && preview.callback != nullptr) {
if (step % sd_get_preview_interval() == 0) {
preview_image(step, denoised, version, preview.mode, preview.callback, preview.data, false);
}
if (preview_needed && sd_should_preview_denoised()) {
preview_image(step, denoised, version, preview.mode, preview.callback, preview.data, false);
}
report_sample_progress(step, steps, &last_progress_us);
report_sample_progress(step, steps, terminal_sigma_is_zero, &last_progress_us);
output.pred = denoised;
return output;
};
Expand Down Expand Up @@ -5719,7 +5726,8 @@ SD_API bool generate_image(sd_ctx_t* sd_ctx,
1.f,
0,
static_cast<float>(request.fps),
request.cache_params);
request.cache_params,
true);
int64_t sampling_end = ggml_time_ms();
if (!x_0.empty()) {
LOG_INFO("sampling completed, taking %.2fs", (sampling_end - sampling_start) * 1.0f / 1000);
Expand Down Expand Up @@ -5840,7 +5848,8 @@ SD_API bool generate_image(sd_ctx_t* sd_ctx,
1.f,
0,
static_cast<float>(request.fps),
request.cache_params);
request.cache_params,
false);
int64_t hires_sample_end = ggml_time_ms();
if (!x_0.empty()) {
LOG_INFO("hires sampling %d/%d completed, taking %.2fs",
Expand Down Expand Up @@ -6974,6 +6983,7 @@ SD_API bool generate_video(sd_ctx_t* sd_ctx,
latents.audio_length,
static_cast<float>(request.fps),
request.cache_params,
true,
latents.video_positions);
int64_t sampling_end = ggml_time_ms();
if (x_t_sampled.empty()) {
Expand Down Expand Up @@ -7016,6 +7026,7 @@ SD_API bool generate_video(sd_ctx_t* sd_ctx,
latents.audio_length,
static_cast<float>(request.fps),
request.cache_params,
plan.high_noise_sample_steps <= 0,
latents.video_positions);

int64_t sampling_end = ggml_time_ms();
Expand Down Expand Up @@ -7154,6 +7165,7 @@ SD_API bool generate_video(sd_ctx_t* sd_ctx,
latents.audio_length,
static_cast<float>(hires_request.fps),
hires_request.cache_params,
false,
hires_video_positions);
sampling_end = ggml_time_ms();
if (final_latent.empty()) {
Expand Down
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