# How to Use Focused Mode with Start and End Timestamps in Claude Video

> Learn how to use focused mode with start and end timestamps in Claude Video. Enhance frame extraction and filter transcripts for specific video segments efficiently.

- Repository: [bradautomates/claude-video](https://github.com/bradautomates/claude-video)
- Tags: how-to-guide
- Published: 2026-07-29

---

**The `watch` skill enters focused mode when you supply `--start` and/or `--end` flags, automatically increasing the frame extraction density for that specific segment while filtering transcripts and timestamps to match the original video timeline.**

The `claude-video` repository by bradautomates provides a powerful **watch** skill that analyzes video content using Claude's computer vision capabilities. When you need to examine a specific moment rather than process an entire video, **focused mode with start and end timestamps** lets you target precise segments with optimized frame sampling. This mode automatically applies a denser frame budget and constrains all outputs to your specified time window.

## How Focused Mode Works

When you provide either `--start` or `--end` parameters, the script evaluates `focused = start_sec is not None or end_sec is not None` in [`skills/watch/scripts/watch.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/watch.py) (lines 55‑58). This boolean triggers a specialized extraction pipeline that prioritizes detail within your defined boundaries.

### Parsing Timestamps with `parse_time`

User-provided time strings are converted to seconds by the `parse_time` function defined in [`skills/watch/scripts/frames.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/frames.py) (lines 55‑71). This utility handles multiple human-readable formats including `HH:MM:SS`, `MM:SS`, or raw integer seconds.

### Calculating the Effective Range

In [`skills/watch/scripts/watch.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/watch.py) (lines 40‑53), the script computes `effective_start`, `effective_end`, and `effective_duration` based on your provided values. If you omit `--end`, the skill analyzes from your start point to the video's conclusion. If you omit `--start`, processing begins at 00:00.

### Optimizing Frame Density with `auto_fps_focus`

The primary advantage of focused mode lies in the `auto_fps_focus` implementation in [`skills/watch/scripts/frames.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/frames.py) (lines 41‑58). Unlike the standard `auto_fps` function, this specialized routine allocates a denser frame budget for short clips while strictly respecting the global 2 FPS ceiling. This ensures maximum visual detail from your targeted segment without exceeding processing limits.

### Extracting Frames and Filtering Content

The extraction functions in [`skills/watch/scripts/frames.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/frames.py) (lines 86‑92) receive `start_seconds` and `end_seconds` arguments, passing them directly to ffmpeg to process only the requested slice. Simultaneously, [`skills/watch/scripts/watch.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/watch.py) (lines 63‑66) invokes `filter_range` to trim any available transcript segments to the same time window, ensuring textual analysis aligns perfectly with the extracted visual frames.

### Output Reporting

The final report includes a "Focus range" line and preserves timestamps relative to the original video timeline rather than offsetting from the clip start, as implemented in [`skills/watch/scripts/watch.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/watch.py) (lines 78‑84).

## Usage Examples

Here are practical commands demonstrating **focused mode with start and end timestamps**:

```bash

# Analyze the last 10 seconds of a 1-minute video

python3 "$SKILL_DIR/scripts/watch.py" video.mp4 --start 50 --end 60

```

```bash

# Zoom into a 30-second window at maximum 2 FPS

python3 "$SKILL_DIR/scripts/watch.py" "$URL" --start 2:15 --end 2:45 --fps 2

```

```bash

# Extract from 1 hour 12 minutes to the end of the video

python3 "$SKILL_DIR/scripts/watch.py" "$URL" --start 1:12:00

```

## Summary

- **Focused mode** activates automatically when you supply `--start` or `--end` flags to the watch skill.
- The `parse_time` function in [`skills/watch/scripts/frames.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/frames.py) converts human-readable timestamps to seconds.
- `auto_fps_focus` allocates a denser frame budget for short segments while respecting the 2 FPS global limit.
- ffmpeg receives time boundaries directly via `start_seconds` and `end_seconds`, and transcripts are filtered via `filter_range` to match the visual range.
- Output preserves original video timestamps and displays the focused range for verification.

## Frequently Asked Questions

### What timestamp formats does focused mode support?

The `parse_time` function accepts multiple formats including raw seconds (e.g., `50`), minutes:seconds (e.g., `2:15`), and hours:minutes:seconds (e.g., `1:12:00`). All values are normalized to seconds before the `effective_start` and `effective_end` calculations begin.

### Can I use focused mode without specifying both start and end times?

Yes. If you provide only `--start`, the skill analyzes from that point to the video's end. If you provide only `--end`, it processes from the beginning (00:00) up to that timestamp. The logic in [`skills/watch/scripts/watch.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/watch.py) (lines 40‑53) handles these partial ranges by deriving `effective_duration` from the video metadata.

### Does focused mode affect transcript analysis?

Yes. When a transcript is available, the script trims it to match your specified time window using `filter_range` (lines 63‑66 in [`skills/watch/scripts/watch.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/watch.py)). This ensures that any text-based analysis corresponds exactly to the visual frames being extracted and analyzed.

### What is the maximum frame rate in focused mode?

Even in focused mode, the skill respects the global 2 FPS ceiling defined by the selected detail mode. The `auto_fps_focus` function in [`skills/watch/scripts/frames.py`](https://github.com/bradautomates/claude-video/blob/main/skills/watch/scripts/frames.py) optimizes the frame distribution within this hard limit, selecting a higher effective rate for short clips without ever exceeding 2 frames per second.