LoudBatch
Loudness checker for CarDSPMusicPlayer (Android)
Measures the loudness of your entire music library on your Mac in one go, and writes a gain value for each song to a CSV file. Import that CSV into CarDSPMusicPlayer, and the time-consuming "Loudness normalization" analysis on your device is finished instantly.
Let your Mac do the heavy analysis
Songs ripped from old CDs and recent, loudly mastered songs sound very different in level at the same volume setting. CarDSPMusicPlayer corrects this automatically, but it analyzes songs a little at a time so as not to disturb playback, so a large library takes a long time.
Analysis on the device only
Days to a week
For about 10,000 songs. A car head unit takes tens of seconds per song.
Analysis with LoudBatch (Mac)
Tens of minutes
Tested with a library of about 14,000 songs. Several songs are analyzed in parallel.
How to use
-
Install
Open the downloaded .dmg and drag LoudBatch into your Applications folder.
-
Analyze your music folder
Launch LoudBatch, choose the folder that contains your music files, and start the analysis. All subfolders are included.
-
A CSV is created
volume_gains.csvis created directly inside the folder you chose. If you stop partway, the results so far are kept. -
Import it on Android
Copy the CSV to your Android device and import it into CarDSPMusicPlayer. Songs are matched by file name, and the gain values take effect immediately.
The LoudBatch app itself is currently in Japanese only.
The exported CSV
LoudBatch never writes to your music files. All results are saved to a separate CSV file (UTF-8).
| file_name | artist | duration_sec | measured_lufs | true_peak_dbfs | gain_db | status | leading_silence_sec | trailing_silence_sec |
|---|---|---|---|---|---|---|---|---|
| 02 Groove On.m4a | Al Turner | 282.0 | −23.1 | −1.2 | +5.1 | ok | 0.3 | 1.8 |
| 01 Marmalade Groove.mp3 | Tatsuro Yamashita | 231.4 | −15.8 | −0.4 | −2.2 | ok | 0 | 2.4 |
| corrupt.mp3 | error:decode_failed | 0 | 0 |
gain_db is the gain for each song (target − measured, limited to ±12 dB). The length of silence at the start and end of each song is also recorded and used by "Trim silence between songs".
A file that can't be read doesn't stop the whole run; only that row is marked error. The actual CSV also has columns for the relative path and the title.
Specifications
- Formats
- MP3 / AAC (M4A) / ALAC / FLAC / WAV / AIFF / Ogg Vorbis / Opus / WavPack
- Measurement
- Integrated Loudness per ITU-R BS.1770 / EBU R128
- Target level
- −18 LUFS (adjustable)
- Gain limit
- ±12 dB (adjustable)
- Re-runs
- Unchanged songs are skipped; only added or updated songs are analyzed
- Music files
- Read-only. No conversion, moving, or tag writing
- Requirements
- macOS 14 Sonoma or later (Apple silicon / Intel)
- Security
- Notarized by Apple. Opens right after download
LoudBatch uses FFmpeg for audio analysis. FFmpeg is distributed under the GNU Lesser General Public License (LGPL) version 2.1 or later. The bundled FFmpeg 9.0.1 is built from the unmodified official source (ffmpeg-9.0.1.tar.xz), and the full license text and build configuration are included in the app at
Contents/Resources/licenses.