Generate Social Clip

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What this workflow does

1. Trim — in_point / out_point on the video element
2. Crop to vertical — crop_left / crop_right center-crop for 16:9 → 9:16 (auto-computed when omitted)
3. Transcribe — POST /v1/tasks/transcribe with word-level timestamps
4. Segment — group words into caption lines (sentence breaks or pauses > 0.8s)
5. Style — optional opening title with difference blend motion; caption lines cycle color → box → glow (the first two paint with the text element’s background_color, which is required for them)
6. Render — POST /v1/renders at 1080×1920 using the TikTok Captions recipe as the composition template

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Example user prompt

Take the section from 00:22:43 to 00:44:56, crop to vertical, add an opening title with Difference blend, then burn in word-timed captions — mix color, box, and glow styles across different fonts.

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Inputs

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Output

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Timecode conversion

00:22:43 → 22×60 + 43 = 1363
00:44:56 → 44×60 + 56 = 2696
duration → 2696 − 1363 = 1333 seconds

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Vertical crop (16:9 → 9:16)

keep_fraction = (9/16) / (source_width / source_height)
crop_each_side = (1 − keep_fraction) / 2

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Caption line rules

1. Converts each word’s start/end from milliseconds (the transcript’s clock) to seconds by dividing by 1000, then filters words to [start_seconds, end_seconds] and offsets to composition time (0 = clip start)
2. Groups words into lines — split on . ? ! or a gap > 0.8s between words
3. Skips words inside opening_title_duration when a title is set
4. Creates one text element per line, each with its own unique id (cap-0, cap-1, …) — duplicate element ids are a blocking DUPLICATE_ELEMENT_ID error
5. Sets each line’s time to the first word’s start and duration to last_word.end − time
6. Cycles word_animation.style: color → box → glow → color … . color and box paint with background_color, so that field is required on those two — omit it and the request 422s (an absent value resolves to opaque black on the renderer, i.e. an invisible highlight). glow does not need it.

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Render composition template

{
  "width": 1080,
  "height": 1920,
  "duration": 1333,
  "frame_rate": 30,
  "elements": [
    {
      "type": "video",
      "id": "vid1",
      "source_url": "https://cdn-user.framelane.io/uploads/.../podcast.mp4",
      "in_point": 1363,
      "out_point": 2696,
      "crop_left": 0.342,
      "crop_right": 0.342,
      "volume": 50
    },
    {
      "type": "text",
      "id": "title",
      "text": "Albert",
      "font_family": "Alfa Slab One",
      "text_color": "#FFFFFF",
      "font_size": 260,
      "x": "50%",
      "y": "70%",
      "time": 0,
      "duration": 3,
      "motion": [{ "type": "difference", "time": 0, "duration": 3 }]
    },
    {
      "type": "text",
      "id": "cap-0",
      "text": "When I came to you with those calculations",
      "time": 4.496,
      "duration": 2.493,
      "background_color": "#e8734a",
      "word_animation": {
        "style": "color",
        "words": [
          { "text": "When", "start": 4.496, "end": 4.577 }
        ]
      }
    }
  ]
}