# eac3to

Canonical URL: https://encode.wiki/tools/utilities/eac3to/
Content version: ca42e61ede0a24f789d7287a0001244ad22f4abf
Status: current
License: CC BY-SA 4.0
Checksum (SHA-256): 026a3a6eb534155d96b794e63feab71ed200f1a57617eb93bb665492a185a3e3

eac3to is a command-line tool for Windows, originally written by madshi, for working with Blu-ray (and HD DVD) content and its audio. It lists the titles on an unencrypted disc folder, demuxes the video, audio, subtitle and chapter tracks of a chosen title, and converts audio between formats: decoding DTS-HD MA, TrueHD and LPCM to FLAC or WAV, extracting the DTS core from a DTS-HD track, applying delays and gain, and fixing frame-rate (speed-up/slow-down) conversions.

For most remuxing work, [FFmpeg](/tools/utilities/ffmpeg/) and [MKVToolNix](/tools/utilities/mkvtoolnix/) are simpler and run on every platform; MKVToolNix opens Blu-ray playlists directly. eac3to is still used when you want its title listing for a disc folder or its audio handling in one step.

## Get it

madshi stopped development at version 3.36. The code was handed over to the DG tools developers (DGDecNV), who publish new builds at [rationalqm.us/eac3to](https://www.rationalqm.us/eac3to/) and support it on their forum. It is a portable archive: extract it to a folder and add that folder to `PATH`. Some conversions (for example AAC or DTS encoding) depend on external encoders that are not bundled; `eac3to -test` reports which are found.

## Usage

The general form is:

```text
eac3to source [title)] [track: destination ...] [options]
```

List the titles of a disc folder, then the tracks of one title:

```text
eac3to "D:\Movie\BDMV"
eac3to "D:\Movie\BDMV" 1)
```

A number followed by `)` selects a title (playlist); a number followed by `:` selects a track in it. Extract several tracks of title 1 in one pass:

```text
eac3to "D:\Movie\BDMV" 1) 1: chapters.txt 2: video.mkv 3: audio.flac 4: subs.sup
```

The output extension decides what happens to each track: `.flac` or `.wav` decodes audio losslessly, while a matching extension (`.dts`, `.thd`, `.ac3`) copies the stream. `-demux` extracts the main video track and all audio tracks in their original formats.

Other common jobs:

```text
eac3to input.dts output.dts -core          # keep only the DTS core of a DTS-HD track
eac3to input.ac3 output.ac3 +200ms         # delay audio by 200 ms
eac3to input.dts output.flac -slowdown     # 25 fps PAL audio to 23.976 fps
```

| Option                       | Effect                                                                         |
| ---------------------------- | ------------------------------------------------------------------------------ |
| `-core`                      | Extract the DTS core of a DTS-HD track, or the AC3 core of a TrueHD track.     |
| `+100ms`, `-100ms`           | Delay or advance audio.                                                        |
| `+3dB`, `-3dB`               | Change the gain.                                                               |
| `-slowdown`, `-speedup`      | Undo PAL speed-up (25 to 23.976 fps), or apply it (23.976 to 25 fps).          |
| `-down16`                    | Reduce decoded audio to 16-bit.                                                |
| `-downStereo`, `-downDpl`    | Downmix to plain stereo or Dolby Pro Logic II.                                 |
| `-keepDialnorm`              | Keep dialogue normalisation, which eac3to otherwise removes when decoding.     |
| `-demux`                     | Extract the main video track and all audio tracks in their original formats.   |
| `-log=file.txt`              | Write the log to a specific file.                                              |

Read eac3to's output before trusting the result: it reports problems such as gaps or overlaps in the source and what it did about them.

## Related pages

- [Handle audio and subtitles](/guides/audio-and-subtitles/)
- [MKVToolNix](/tools/utilities/mkvtoolnix/) and [FFmpeg](/tools/utilities/ffmpeg/)
- [FLAC](/codecs/audio/flac/) and [Dolby audio formats](/codecs/audio/dolby/)