Even out loudness

Normalize the loudness of music.mp3 to about -16 LUFS and save it as level.mp3.

The task

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

deft audio normalize music.mp3 -o level.mp3

Input

music.mp3 96.2 KB · mp3, 6.1s

Reference output

level.mp3 102.4 KB · mp3, 6.1s

How a result is judged (1 check)

media: file = "level.mp3", duration = 6.1, tolerance = 0.5

Runs

CodexWithout deftPassed2026-11-07

Time: 16s
New tokens: 4.9k
Total input: 55.4k
Output tokens: 0.5k
Commands: 3
Failed: 0

Trace

I’ll check the available audio tools, then normalize `music.mp3` and save the result as `level.mp3` in this directory.

pwd && ls -l music.mp3 && command -v ffmpeg && command -v ffprobe

output

-rw-r--r--@ 1 user  staff  98472 Nov  5 21:11 music.mp3
/opt/homebrew/bin/ffmpeg
/opt/homebrew/bin/ffprobe

ffmpeg -hide_banner -nostats -i music.mp3 -af loudnorm=I=-16:TP=-1.5:LRA=11:print_format=json -f null -

output

Input #0, mp3, from 'music.mp3':
  Metadata:
    encoder         : Lavf61.7.100
  Duration: 00:00:06.14, start: 0.025057, bitrate: 128 kb/s
  Stream #0:0: Audio: mp3 (mp3float), 44100 Hz, stereo, fltp, 128 kb/s
      Metadata:
        encoder         : Lavc61.19
Stream mapping:
  Stream #0:0 -> #0:0 (mp3 (mp3float) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, null, to 'pipe:':
  Metadata:
    encoder         : Lavf61.7.100
  Stream #0:0: Audio: pcm_s16le, 192000 Hz, stereo, s16, 6144 kb/s
      Metadata:
        encoder         : Lavc61.19.101 pcm_s16le
[Parsed_loudnorm_0 @ 0x7b8c88600] 
{
	"input_i" : "-32.43",
	"input_tp" : "-17.16",
	"input_lra" : "3.80",
	"input_thresh" : "-42.43",
	"output_i" : "-17.14",
	"output_tp" : "-2.75",
	"output_lra" : "3.00",
	"output_thresh" : "-27.14",
	"normalization_type" : "dynamic",
	"target_offset" : "1.14"
}
[out#0/null @ 0x7b8c88180] video:0KiB audio:4578KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: unknown
size=N/A time=00:00:06.20 bitrate=N/A speed=30.5x

ffmpeg -hide_banner -y -i music.mp3 -af loudnorm=I=-16:TP=-1.5:LRA=11:measured_I=-32.43:measured_TP=-17.16:measured_LRA=3.80:measured_thresh=-42.43:offset=1.14:linear=true:print_format=summary -c:a libmp3lame -b:a 128k level.mp3

output

Input #0, mp3, from 'music.mp3':
  Metadata:
    encoder         : Lavf61.7.100
  Duration: 00:00:06.14, start: 0.025057, bitrate: 128 kb/s
  Stream #0:0: Audio: mp3 (mp3float), 44100 Hz, stereo, fltp, 128 kb/s
      Metadata:
        encoder         : Lavc61.19
Stream mapping:
  Stream #0:0 -> #0:0 (mp3 (mp3float) -> mp3 (libmp3lame))
Press [q] to stop, [?] for help
Output #0, mp3, to 'level.mp3':
  Metadata:
    TSSE            : Lavf61.7.100
  Stream #0:0: Audio: mp3, 48000 Hz, stereo, fltp, 128 kb/s
      Metadata:
        encoder         : Lavc61.19.101 libmp3lame
[Parsed_loudnorm_0 @ 0xacb44c600] 
Input Integrated:    -32.4 LUFS
Input True Peak:     -17.2 dBTP
Input LRA:             3.8 LU
Input Threshold:     -42.4 LUFS

Output Integrated:   -16.0 LUFS
Output True Peak:     -1.6 dBTP
Output LRA:            3.0 LU
Output Threshold:    -26.0 LUFS

Normalization Type:   Dynamic
Target Offset:        -0.0 LU
[out#0/mp3 @ 0xacb44c180] video:0KiB audio:96KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: 0.435384%
size=      96KiB time=00:00:06.20 bitrate= 127.4kbits/s speed=22.5x

Normalized `music.mp3` to **-16.0 LUFS** and saved it as [level.mp3](level.mp3). The output true peak is **-1.6 dBTP**.

Output

level.mp3 96.4 KB · mp3, 6.1s

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

Time: 15s
New tokens: 4.6k
Total input: 56.6k
Output tokens: 0.4k
Commands: 3
Failed: 0

Trace

I’ll check which local media tool is available, then normalize `music.mp3` and save `level.mp3` in this directory.

cat .agents/skills/deft/SKILL.md && pwd && rg --files -g 'music.mp3' -g 'level.mp3' -g 'AGENTS.md' -g 'package.json' -g 'pyproject.toml' -g 'requirements.txt'

output

---
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; r
… 711 more characters

deft audio normalize --help

output

deft audio normalize - Even out loudness (EBU R128)

Usage: deft audio normalize <audio>... [-o <audio|dir>] [options]
In: audio (each handled separately)   Out: audio (default <name>.normalized.<ext>)

Options:
  --loudness <number>          Target loudness in LUFS (default -16)
Common: -o --force --dry-run --json -j   (deft help common)

Examples:
  deft audio normalize tone.mp3 -o level.mp3
Needs: ffmpeg, ffprobe

deft audio normalize music.mp3 -o level.mp3 --loudness -16
output
```
ok audio.normalize music.mp3 -> level.mp3  102KB  0.65s
```
Normalized `music.mp3` to about −16 LUFS and saved the result as [level.mp3](level.mp3).

Output

level.mp3 102.4 KB · mp3, 6.1s

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

Time: 11s
New tokens: 5.6k
Total input: 61.2k
Output tokens: 0.3k
Commands: 3
Failed: 0

Trace

I’ll use the provided `deft` workflow to normalize the MP3 and save the result in the current directory.

deft audio

output

deft audio - commands (input -> output)
  info        audio -> report  Duration, codec, sample rate, channels
  compress    audio -> mp3     Re-encode as MP3 at --bitrate (kbps)
  convert     audio -> audio   Change format: --to mp3|m4a|wav|flac|ogg|opus
  from-video  video -> audio   Save the soundtrack: --to mp3|m4a|wav|flac|ogg
  merge       audio... -> mp3  Join audio files in order
  normalize   audio -> audio   Even out loudness (EBU R128)
  split       audio -> audio   Cut out a part: --from 0:10 --to-time 0:25
More: deft audio <command> --help

deft audio normalize --help

output

deft audio normalize - Even out loudness (EBU R128)

Usage: deft audio normalize <audio>... [-o <audio|dir>] [options]
In: audio (each handled separately)   Out: audio (default <name>.normalized.<ext>)

Options:
  --loudness <number>          Target loudness in LUFS (default -16)
Common: -o --force --dry-run --json -j   (deft help common)

Examples:
  deft audio normalize tone.mp3 -o level.mp3
Needs: ffmpeg, ffprobe

deft audio normalize music.mp3 -o level.mp3 --loudness -16
output
```
ok audio.normalize music.mp3 -> level.mp3  96KB  0.29s
```
Normalized `music.mp3` to about -16 LUFS and saved it as [level.mp3](level.mp3).

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: 21s
New tokens: 10.3k
Total input: 57.4k
Output tokens: 1.2k
Commands: 0
Failed: 0

Trace

Output

level.mp3 144.5 KB · mp3, 6.1s

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

Time: 11s
New tokens: 10.0k
Total input: 74.7k
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

level.mp3 102.4 KB · mp3, 6.1s

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