Improve text to vid (#1678)

Got text to video working, because I really wanted to play with it. It
works, well enough for now.
When I have some more time I plan to look into how to change the UI so I
can add a field for choosing FPS.
Please feel free to critique my changes, I'm still early in the learning
to code process.

# Description
* FPS defaults all changed to 30
* Change the way total_frames is calculated (now just FPS * duration) -
not sure if this is ideal but it works
* Generation now stops when it reaches total_frames value

Closes: #1676 

# Checklist:

- [x] I have changed the base branch to `dev`
- [x] I have performed a self-review of my own code
- [x] I have commented my code in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation

scripts/txt2vid.py

@@ -946,6 +946,7 @@ def diffuse(
         num_inference_steps,
         cfg_scale,
         eta,
+        fps=30
         ):
 
     torch_device = cond_latents.get_device()
@@ -1055,8 +1056,8 @@ def diffuse(
                 speed = "it/s"
                 duration = 1 / duration
 
-            #
-            total_frames = (st.session_state.sampling_steps + st.session_state.num_inference_steps) * st.session_state.max_duration_in_seconds
+            # perhaps add an option to set fps within the ui eventually
+            total_frames = st.session_state.max_duration_in_seconds * fps
             total_steps = st.session_state.sampling_steps + st.session_state.num_inference_steps
 
             if i > st.session_state.sampling_steps:
@@ -1195,13 +1196,13 @@ def load_diffusers_model(weights_path,torch_device):
                 st.session_state["progress_bar_text"].error(e)
 
 #
-def save_video_to_disk(frames, seeds, sanitized_prompt, fps=6,save_video=True, outdir='outputs'):
+def save_video_to_disk(frames, seeds, sanitized_prompt, fps=30,save_video=True, outdir='outputs'):
     if save_video:
         # write video to memory
         #output = io.BytesIO()
         #writer = imageio.get_writer(os.path.join(os.getcwd(), st.session_state['defaults'].general.outdir, "txt2vid"), im, extension=".mp4", fps=30)
         #try:
-        video_path = os.path.join(os.getcwd(), outdir, "txt2vid",f"{seeds}_{sanitized_prompt}{datetime.now().strftime('%Y%m-%d%H-%M%S-') + str(uuid4())[:8]}.mp4")
+        video_path = os.path.join(os.getcwd(), outdir, "txt2vid",f"{seeds}_{sanitized_prompt}{datetime.datetime.now().strftime('%Y%m-%d%H-%M%S-') + str(uuid4())[:8]}.mp4")
         writer = imageio.get_writer(video_path, fps=fps)
         for frame in frames:
             writer.append_data(frame)
@@ -1482,9 +1483,9 @@ def txt2vid(
                         #)
 
         # old code
-        total_frames = (st.session_state.sampling_steps + st.session_state.num_inference_steps) * st.session_state.max_duration_in_seconds
+        total_frames = st.session_state.max_duration_in_seconds * fps
 
-        while second_count < max_duration_in_seconds:
+        while frame_index+1 <= total_frames:
             st.session_state["frame_duration"] = 0
             st.session_state["frame_speed"] = 0
             st.session_state["current_frame"] = frame_index
@@ -1506,7 +1507,7 @@ def txt2vid(
                 #init = slerp(gpu, float(t), init1, init2)
 
                 with autocast("cuda"):
-                    image = diffuse(server_state["pipe"], cond_embeddings, init, num_inference_steps, cfg_scale, eta)
+                    image = diffuse(server_state["pipe"], cond_embeddings, init, num_inference_steps, cfg_scale, eta, fps=fps)
 
                 if st.session_state["save_individual_images"] and not st.session_state["use_GFPGAN"] and not st.session_state["use_RealESRGAN"]:
                     #im = Image.fromarray(image)
@@ -1914,6 +1915,7 @@ def layout():
                                                    beta_schedule=beta_scheduler_type, starting_image=None)
 
         if video and save_video_on_stop:
+            if os.path.exists(video): # temporary solution to bypass exception
             # show video preview on the UI after we hit the stop button
             # currently not working as session_state is cleared on StopException
                 preview_video.video(open(video, 'rb').read())