Add preview rate option.

After accounting for the loss of in-between frames from their temporal
vae's, both mochi and ltxv have a target frame rate that is close to 8.
Given the difficulty of conveying the discrepancy of in-between frames
and the hard diminishing returns of processing too many previews on
execution rate, it was very tempting to leave this option off entirely.

I have decided to include anyways under the consideration that it would
be easier to explain to a user why changing a setting didn't work the
way they expect than to explain why the setting doesn't exist at all.

videohelpersuite/latent_preview.py

@@ -12,10 +12,11 @@ serv = server.PromptServer.instance
 from .utils import hook
 
 class WrappedPreviewer(latent_preview.LatentPreviewer):
-    def __init__(self, dltp):
+    def __init__(self, dltp, rate=8):
         self.first_preview = True
         self.last_time = 0
         self.c_index = 0
+        self.rate = rate
         self.decode_latent_to_preview = dltp
     def decode_latent_to_preview_image(self, preview_format, x0):
         if x0.ndim == 5:
@@ -24,8 +25,8 @@ class WrappedPreviewer(latent_preview.LatentPreviewer):
             x0 = x0.reshape((-1,)+x0.shape[-3:])
         num_images = x0.size(0)
         new_time = time.time()
-        num_previews = int((new_time - self.last_time) * 8)
-        self.last_time = self.last_time + num_previews/8
+        num_previews = int((new_time - self.last_time) * self.rate)
+        self.last_time = self.last_time + num_previews/self.rate
         if num_previews > num_images:
             num_previews = num_images
         if self.first_preview:
@@ -46,7 +47,7 @@ class WrappedPreviewer(latent_preview.LatentPreviewer):
             sub_image.save(message, format="JPEG", quality=95, compress_level=1)
             serv.send_sync(server.BinaryEventTypes.PREVIEW_IMAGE,
                            message.getvalue(), serv.client_id)
-            self.c_index = (self.c_index +1) % num_images
+            self.c_index = (self.c_index + 1) % num_images
         return None
 
 @hook(latent_preview, 'get_previewer')
@@ -56,9 +57,11 @@ def get_latent_video_previewer(device, latent_format, *args, **kwargs):
     try:
         prev_setting = next(serv.prompt_queue.currently_running.values().__iter__())[3] \
                 ['extra_pnginfo']['workflow']['extra'].get('VHS_latentpreview', False)
+        rate_setting = next(serv.prompt_queue.currently_running.values().__iter__())[3] \
+                ['extra_pnginfo']['workflow']['extra'].get('VHS_latentpreviewrate', 8)
     except:
         #For safety since there's lots of keys, any of which can fail
         prev_setting = False
     if not prev_setting or not hasattr(previewer, "decode_latent_to_preview"):
         return previewer
-    return WrappedPreviewer(previewer.decode_latent_to_preview)
+    return WrappedPreviewer(previewer.decode_latent_to_preview, rate_setting)

web/js/VHS.core.js

@@ -1334,6 +1334,20 @@ app.ui.settings.addSetting({
         }
     },
 });
+app.ui.settings.addSetting({
+    id: "VHS.LatentPreviewRate",
+    name: "🎥🅥🅗🅢 Playback keyframe rate.",
+    type: "boolean",
+      type: 'number',
+      attrs: {
+        min: 1,
+        step: 1,
+        max: 60
+      },
+      tooltip:
+        'When dragging and resizing nodes while holding shift they will be aligned to the grid, this controls the size of that grid.',
+    defaultValue: 8,
+});
 
 app.registerExtension({
     name: "VideoHelperSuite.Core",
@@ -1615,6 +1629,7 @@ app.registerExtension({
                 }
             }
             res.workflow.extra['VHS_latentpreview'] = app.ui.settings.getSettingValue("VHS.LatentPreview", false)
+            res.workflow.extra['VHS_latentpreviewrate'] = app.ui.settings.getSettingValue("VHS.LatentPreviewRate", 8)
             return res
         }
         app.graphToPrompt = graphToPrompt