fix(txt2vid): callback kwargs are nested into get_timesteps_arr instead of make_clip_frames

[Anai-Guo]

Problem

In StableDiffusionWalkPipeline.walk, callback= and callback_steps= are indented one level too deep — they land inside the get_timesteps_arr(...) sub-expression that computes T, instead of staying on the enclosing self.make_clip_frames(...) call:

            self.make_clip_frames(
                ...
                skip=skip,
                T=get_timesteps_arr(
                    audio_filepath,
                    offset=audio_offset,
                    duration=audio_duration,
                    fps=fps,
                    margin=margin,
                    smooth=smooth,
                    callback=callback,               # <-- belongs to make_clip_frames
                    callback_steps=callback_steps,   # <-- belongs to make_clip_frames
                )
                if audio_filepath
                else None,
            )

get_timesteps_arr accepts neither:

def get_timesteps_arr(audio_filepath, offset, duration, fps=30, margin=1.0, smooth=0.0):

while make_clip_frames declares both (callback=None, callback_steps: int = 1).

This breaks the progress callback on both paths:

• audio_filepath set → the get_timesteps_arr(...) call is evaluated and raises TypeError: get_timesteps_arr() got an unexpected keyword argument 'callback'. Every audio-driven walk() dies before the first frame.
• no audio_filepath → the ternary short-circuits, so nothing raises, but make_clip_frames is called without callback/callback_steps. They fall back to None/1 and the caller's progress callback silently never fires.

The same block is duplicated verbatim in the streamlit copy, so both are fixed here.

• scripts/txt2vid.py:964
• webui/streamlit/scripts/txt2vid.py:959

Fix

Dedent the two kwargs by one level so they close on make_clip_frames(...) instead of get_timesteps_arr(...). No other change — 2 lines per file.

Verification

No Stable-Diffusion runtime on this box, so I checked it structurally: parse the live file with ast, build stubs carrying the real signatures of get_timesteps_arr and make_clip_frames, and replay every call site through inspect.Signature.bind, before and after the patch.

##### scripts/txt2vid.py
  master:
    make_clip_frames   line 949   OK        callback forwarded=False
    get_timesteps_arr  line 964   TypeError got an unexpected keyword argument 'callback'
  patched:
    make_clip_frames   line 949   OK        callback forwarded=True
    get_timesteps_arr  line 964   OK        kwargs=['offset', 'duration', 'fps', 'margin', 'smooth']

##### webui/streamlit/scripts/txt2vid.py
  master:
    make_clip_frames   line 944   OK        callback forwarded=False
    get_timesteps_arr  line 959   TypeError got an unexpected keyword argument 'callback'
  patched:
    make_clip_frames   line 944   OK        callback forwarded=True
    get_timesteps_arr  line 959   OK        kwargs=['offset', 'duration', 'fps', 'margin', 'smooth']

Both halves of the bug show up and both clear: the TypeError goes away, and callback forwarded flips False → True, which is the silent half that the crash was masking.

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