Evals / video / See inside a video

Answer a question about a video

How long is jellyfish.mp4 in seconds, and what is its resolution? Write the answer to info.txt.

easysingledeft video info

The task

The reference answer shows the job can be done with deft. It is not an agent run.

deft video info jellyfish.mp4 > info.txt

Input

jellyfish.mp4 1023.4 KB · h264 1280x720, 10.0s

Reference output

info.txt 130 B
ok video.info jellyfish.mp4  0:10.010, 1280x720
duration=10.01001 width=1280 height=720 fps=29.97 video_codec=h264 bitrate=837535
How a result is judged (1 check)
  • text: file = "info.txt", contains = ["1280", "720"]

Runs

CodexWithout deftPassed2026-11-07

Time
11s
New tokens
3.4k
Total input
53.6k
Output tokens
0.3k
Commands
3
Failed
0

Trace

  1. I’ll inspect the video metadata in the current directory and write the duration and resolution to `info.txt`.

  2. pwd && rg --files -g 'jellyfish.mp4' -g 'info.txt'
    output
    jellyfish.mp4
  3. ffprobe -v error -show_entries format=duration:stream=width,height -of default=noprint_wrappers=1 jellyfish.mp4
    output
    width=1280
height=720
duration=10.010010
  4. cat > info.txt <<'EOF' Duration: 10.01 seconds Resolution: 1280 × 720 pixels EOF cat info.txt
    output
    Duration: 10.01 seconds
Resolution: 1280 × 720 pixels

  5. `info.txt` now contains the video’s duration (10.01 seconds) and resolution (1280 × 720 pixels).

Output

info.txt 55 B
Duration: 10.01 seconds
Resolution: 1280 × 720 pixels

CodexWith deft, skill installedPassedRead the skillUsed deft2026-11-07

Time
15s
New tokens
7.6k
Total input
72.4k
Output tokens
0.5k
Commands
4
Failed
0

Trace

  1. I’ll inspect the video metadata and write the duration and resolution to `info.txt` in the current directory.

  2. cat .agents/skills/deft/SKILL.md
    output
    ---
name: deft
description: "Use deft instead of writing a script for file jobs: PDF merge/split/compress/watermark, image resize/convert/compress, video and audio trim/convert/compress, spreadsheets, Markdown to PDF/HTML, and YouTube downloads and subtitles."
---

# deft

One local command for file jobs. Prefer it over writing Python or shell scripts.

Syntax: `deft <group> <command> [inputs] [-o output] [--options]`

Groups:
- `pdf`: Merge, split, compress, encrypt, forms, OCR, compare, convert
- `image`: Resize, crop, convert, compress, filters, montage, OCR
- `video`: Trim, crop, speed, convert, compress, GIF, frames (ffmpeg)
- `audio`: Convert, trim, merge, fade, speed, tag, normalize (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline, PDF handout
- `data`: JSON/YAML/TOML/XML: convert, query with jq syntax, merge, diff
- `sheet`: Excel/CSV/ODS tables: filter, sort, join, pivot, convert
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word, PDF; screenshots
- `epub`: E-books: info, to text, Markdown and PDF
- `email`: EML files: headers, text, attachments
- `contact`: VCF address books: to and from CSV
- `calendar`: ICS calendars: to and from CSV
- `gps`: GPX and KML tracks: convert, distance and time
- `youtube`: Info, download, audio, subtitles, thumbnail (yt-dlp)
- `file`: Any file: hash, duplicates, batch rename, base64, encoding
- `qr`: Cre
… 728 more characters

  3. I’m using the `deft` file tool instructions for the video metadata lookup.

  4. deft video --help
    output
    deft video - commands (input -> output)
  info               video -> report      Duration, size, frame rate, codecs
  add-audio          video -> video       Replace or mix the soundtrack: --audio song.mp3
  add-subtitles      video -> video       Add subtitles: burned into the picture, or --soft
  chunk              video -> video...    Cut into equal parts: --length 10:00
  compress           video -> mp4         Smaller file: --level, --target-size, --max-height
  convert            video|gif -> video   Change container and codec: --to mp4|webm|mov|mkv
  crop               video -> video       Cut a region: --box or --aspect 1:1
  download           url -> video         Save a video: --resolution 720p, --to mp4|webm|mkv [net]
  extract-audio      video -> audio       Save the soundtrack: --to mp3|m4a|wav|flac|ogg
  extract-subtitles  video -> srt|vtt     Save an embedded subtitle track: --to srt|vtt
  fade               video -> video       Fade: --fade-in 1 --fade-out 2
  frames             video -> png|jpg...  Save frames as images: --fps 1 or --at 0:05,0:10
  from-images        image... -> video    Slideshow: --duration, --fps, --audio
  merge              video... -> mp4      Join videos; --transition fades
  mute               video -> video       Remove the audio track
  pad                video -> video       Fit into a frame with bars: --size 1080x1920
  repeat             video -> video       Repeat a video: --count 3 plays it three times
  resize             vid
… 891 more characters
  5. deft video info jellyfish.mp4 --json
    output
    {"v":1,"ok":true,"op":"video.info","items":[{"ok":true,"inputs":["jellyfish.mp4"],"outputs":[],"facts":{"duration":10.01001,"width":1280,"height":720,"fps":29.97,"video_codec":"h264","audio_codec":null,"bitrate":837535},"warnings":[]}],"elapsed_ms":60}
  6. printf 'Duration: 10.01001 seconds\\nResolution: 1280x720\\n' > info.txt

  7. `jellyfish.mp4` is 10.01001 seconds long with a resolution of 1280×720. I wrote both details to [info.txt](info.txt).

Output

info.txt 48 B
Duration: 10.01001 seconds
Resolution: 1280x720

CodexWith deft, skill as AGENTS.mdPassed2026-11-05

Time
13s
New tokens
5.6k
Total input
61.5k
Output tokens
0.4k
Commands
3
Failed
0

Trace

  1. I’ll inspect the video’s metadata, then write the duration in seconds and resolution to `info.txt` in the current directory.

  2. deft video
    output
    deft video - commands (input -> output)
  info           video -> report      Duration, size, frame rate, codecs
  compress       video -> mp4         Smaller file: --level, --target-size, --max-height
  convert        video -> video       Change container and codec: --to mp4|webm|mov|mkv
  download       url -> video         Save a video: --resolution 720p, --to mp4|webm|mkv [net]
  extract-audio  video -> audio       Save the soundtrack: --to mp3|m4a|wav|flac|ogg
  frames         video -> png|jpg...  Save frames as images: --fps 1 or --at 0:05,0:10
  merge          video... -> mp4      Join videos in order (sizes are matched to the first)
  mute           video -> video       Remove the audio track
  resize         video -> video       Scale: --size 1280x, x720, 50%
  rotate         video -> video       Turn clockwise: --angle 90
  split          video -> video       Cut out a part: --from 0:10 --to-time 0:25
  to-gif         video -> gif         Animated GIF: --fps, --size, --from, --to-time
More: deft video <command> --help
  3. deft video info jellyfish.mp4 --json
    output
    {"elapsed_ms":56,"items":[{"facts":{"audio_codec":null,"bitrate":837535,"duration":10.01001,"fps":29.97,"height":720,"video_codec":"h264","width":1280},"inputs":["jellyfish.mp4"],"ok":true,"outputs":[],"warnings":[]}],"ok":true,"op":"video.info","v":1}
  4. printf 'Duration: 10.01001 seconds\\nResolution: 1280x720\\n' > info.txt

  5. `jellyfish.mp4` is 10.01001 seconds long and has a resolution of 1280×720. I wrote this to [info.txt](info.txt).

Output

Its files were not kept in this run. The last line of the trace is its own report.

Claude Opus 5.5Without deftPassed2026-11-07

Time
13s
New tokens
8.9k
Total input
56.5k
Output tokens
0.4k
Commands
0
Failed
0

Trace

    Output

    info.txt 45 B
    Duration: 10.01 seconds
Resolution: 1280x720

    Claude Opus 5.5With deft, skill installedPassedRead the skillUsed deft2026-11-07

    Time
    14s
    New tokens
    10.5k
    Total input
    75.9k
    Output tokens
    0.5k
    Commands
    0
    Failed
    0

    Trace

      Output

      .claude/skills/deft/SKILL.md 2.1 KB
      ---
name: deft
description: "Use deft first for any simple, direct operation on local files, whatever the type: convert, read, extract, edit, compress, merge, split, compare or inspect. Try it before writing a script or one-liner. If unsure, run deft find; if it says no command does this, use another tool. Not for programming work: to read, write or change source code, skip it."
---

# deft

One local command for file jobs. Prefer it over writing Python or shell scripts.

Syntax: `deft <group> <command> [inputs] [-o output] [--options]`

Groups:
- `pdf`: Merge, split, compress, encrypt, forms, OCR, compare, convert
- `image`: Resize, crop, convert, compress, adjust, montage, OCR
- `video`: Trim, merge, convert, compress, subtitles, GIF, frames (ffmpeg)
- `audio`: Convert, trim, normalize, denoise, cut silence (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline
- `sheet`: Excel/CSV/ODS tables: SQL query, pivot, merge, split, convert
- `json`: JSON: convert, format, merge, diff, validate
- `toml`: TOML: convert, format, merge, diff, validate
- `xml`: XML: convert, format, merge, diff, validate
- `yaml`: YAML: convert, format, merge, diff, validate
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word and PDF
- `epub`: E-books: info, to text, Markdown and PDF
- `gps`: GPX and KML tracks: convert, distance and time
- `qr`: Create QR codes and barcodes; read QR codes

How to use it:
1. Run `deft <group>` to list commands, or `deft find "<what you want>"` to search. If it says `no command does this`, use another tool.
2. Run `deft <group> <command> --help` for options and examples.
3. `deft convert <in> -o <out.ext>` converts between formats by extension.
4. Results are one line starting with `ok`, `partial` or `error`; add `--json` to parse them. Errors include a `hint:` with the fix.

Inputs are never overwritten; pass `--force` or `--in-place` to allow it. Globs and directories work as inputs; several inputs run in parallel.

If `deft` is not installed, ask the user, then follow https://github.com/firstprayer/deft/blob/main/docs/INSTALL.md
      info.txt 45 B
      Duration: 10.01 seconds
Resolution: 1280x720

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