> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/mpv-player/mpv/llms.txt
> Use this file to discover all available pages before exploring further.

# Audio Filters

> Apply audio filters for encoding, resampling, and processing

Audio filters let you modify the audio stream before it reaches the audio output. The filter chain syntax is identical to [video filters](/av/video-filters).

```bash theme={null}
mpv --af=<filter1[=param1:param2],filter2,...> audio.flac
```

<Tip>Run `mpv --af=help` to list all available audio filters. Most filters are available via the `lavfi` wrapper, which exposes all of libavfilter's audio filters.</Tip>

## Filter chain syntax

The syntax for `--af` is the same as `--vf`. See [video filters](/av/video-filters) for full details on labels, the `!` prefix for disabled-by-default filters, and runtime toggling.

```bash theme={null}
# Single filter
mpv --af=scaletempo2 audio.flac

# Filter chain
mpv --af=scaletempo2,lavfi=loudnorm audio.flac

# Add to an existing filter list
mpv --af-add=rubberband audio.flac
```

Filter list management options: `--af-add`, `--af-pre`, `--af-clr`. See `--vf` group of options for their behavior.

## Available filters

### lavcac3enc — AC-3 encoding

Encodes multi-channel audio to AC-3 at runtime using libavcodec. Supports up to 6 channels. Output is big-endian for raw AC-3, or native-endian for S/PDIF. Input is resampled to 48 kHz, 44.1 kHz, or 32 kHz if needed.

```bash theme={null}
# Encode to AC-3 and output via S/PDIF (default)
mpv --af=lavcac3enc audio.flac

# Raw AC-3 stream output
mpv --af=lavcac3enc=tospdif=no audio.flac

# Set bitrate to 384 kbps
mpv --af=lavcac3enc=bitrate=384 audio.flac
```

| Parameter           | Description                                                                                                                                                                        |
| ------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `tospdif=<yes\|no>` | Output via S/PDIF passthrough (`yes`, default) or raw AC-3 stream (`no`)                                                                                                           |
| `bitrate=<rate>`    | Bitrate in kbps (default: 640). Valid values: 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, 448, 512, 576, 640. Use `auto` to select based on channel count. |
| `minch=<n>`         | Detach filter if input has fewer than `n` channels (default: 3)                                                                                                                    |
| `encoder=<name>`    | libavcodec encoder to use (must be an AC-3 encoder)                                                                                                                                |

**Auto bitrate by channel count:**

| Channels | Bitrate  |
| -------- | -------- |
| 1        | 96 kbps  |
| 2        | 192 kbps |
| 3        | 224 kbps |
| 4        | 384 kbps |
| 5–6      | 448 kbps |

### format — audio format control

Forces a specific audio format, sample rate, or channel layout. Does not perform conversion itself; it instructs the filter system to insert necessary conversion filters.

```bash theme={null}
# Force 48000 Hz sample rate
mpv --af=format=srate=48000 audio.flac

# Force stereo output
mpv --af=format=channels=stereo audio.flac

# List available formats
mpv --af=format=format=help
```

| Parameter  | Description                                          |
| ---------- | ---------------------------------------------------- |
| `format`   | Force a specific sample format (e.g. `s16`, `float`) |
| `srate`    | Force a specific sample rate (e.g. `48000`)          |
| `channels` | Force a specific channel layout                      |

<Note>To control audio output format (as opposed to mid-chain format), use `--audio-format`, `--audio-samplerate`, and `--audio-channels` instead.</Note>

### scaletempo — tempo scaling (legacy)

Scales audio tempo without altering pitch, optionally synced to playback speed. Uses a time-domain WSOLA-like algorithm.

```bash theme={null}
# Play at 1.2x speed with normal pitch
mpv --af=scaletempo --speed=1.2 audio.flac

# Sync tempo to speed, but don't respond to speed changes
mpv --af=scaletempo=scale=1.2:speed=none --speed=1.2 audio.flac
```

| Parameter                          | Default | Description                                                                                                                |
| ---------------------------------- | ------- | -------------------------------------------------------------------------------------------------------------------------- |
| `scale=<amount>`                   | 1.0     | Additional tempo scale factor                                                                                              |
| `stride=<ms>`                      | 60      | Output stride length in milliseconds                                                                                       |
| `overlap=<factor>`                 | 0.20    | Overlap fraction of stride                                                                                                 |
| `search=<ms>`                      | 14      | Search length for best overlap position                                                                                    |
| `speed=<tempo\|pitch\|both\|none>` | `tempo` | How to respond to speed changes: `tempo` (scale tempo), `pitch` (scale pitch instead, loses video sync), `both`, or `none` |

### scaletempo2 — tempo scaling (recommended, default)

Scales audio tempo without altering pitch using the WSOLA (Waveform Similarity Overlap-and-Add) algorithm, ported from Chromium. Higher audio quality than `scaletempo` and `rubberband` R2 engine.

This filter is inserted automatically when `--audio-pitch-correction` is enabled (the default) and playback speed changes.

```bash theme={null}
mpv --af=scaletempo2 --speed=1.5 audio.flac
```

| Parameter              | Default | Description                                         |
| ---------------------- | ------- | --------------------------------------------------- |
| `min-speed=<speed>`    | 0.25    | Mute audio below this playback speed                |
| `max-speed=<speed>`    | 8.0     | Mute audio above this playback speed (0 = disabled) |
| `search-interval=<ms>` | 40      | Length in ms to search for best overlap position    |
| `window-size=<ms>`     | 12      | Length in ms of the overlap-and-add window          |

### rubberband — high-quality pitch correction

High-quality pitch correction using librubberband. Can replace `scaletempo` and `scaletempo2`, and supports pitch adjustment independent of speed.

```bash theme={null}
mpv --af=rubberband --speed=1.5 audio.flac

# Adjust pitch upward by a musical semitone
mpv --af=rubberband=pitch-scale=1.059463 audio.flac
```

| Parameter                | Description                                                                                               |
| ------------------------ | --------------------------------------------------------------------------------------------------------- |
| `pitch-scale=<amount>`   | Pitch scaling factor; frequencies are multiplied by this value (default: 1.0)                             |
| `engine=<faster\|finer>` | Rubberband engine: `faster` (R2, less CPU) or `finer` (R3, higher quality — default if librubberband ≥ 3) |

List all available rubberband sub-options:

```bash theme={null}
mpv --af=rubberband=help
```

**Runtime commands** (via `af-command`):

* `set-pitch <value>` — Change `pitch-scale` dynamically at runtime
* `multiply-pitch <factor>` — Multiply the current `pitch-scale` dynamically

**Example `input.conf` for semitone pitch stepping:**

```ini theme={null}
[ multiply speed 0.9438743126816935
] multiply speed 1.059463094352953
```

### lavfi — libavfilter wrapper

Filters audio using FFmpeg's libavfilter. Provides access to all of libavfilter's audio filters.

```bash theme={null}
mpv --af='lavfi=loudnorm' audio.flac

# EQ: boost bass by 5 dB below 200 Hz
mpv --af='lavfi=equalizer=f=200:width_type=h:width=200:g=5' audio.flac

# Normalize loudness
mpv --af='lavfi=loudnorm=I=-16:TP=-1.5:LRA=11' audio.flac
```

<Warning>Quote libavfilter graphs to avoid conflicts with mpv's own syntax. Use the same quoting strategies as described in the [video filters lavfi section](/av/video-filters#lavfi--libavfilter-wrapper).</Warning>

Additional options:

| Parameter           | Description                                                                                                                 |
| ------------------- | --------------------------------------------------------------------------------------------------------------------------- |
| `o=<string>`        | AVOptions passed to the filter graph                                                                                        |
| `fix-pts=<yes\|no>` | Compute PTS from sample count instead of relying on libavfilter (default: no). Use for filters that reset or recompute PTS. |

### drop — frame dropping for SPDIF

Drops or repeats audio frames to adapt to playback speed. Operates on full audio frames, designed for S/PDIF (compressed audio passthrough). Used automatically with `--video-sync=display-adrop`.

<Warning>This filter is extremely low quality. Do not use it unless you have a specific need for S/PDIF with `display-adrop`.</Warning>

## Common use cases

<AccordionGroup>
  <Accordion title="Tempo-correct playback at 1.5x speed">
    ```bash theme={null}
    # scaletempo2 is used automatically, but you can be explicit:
    mpv --speed=1.5 audio.flac

    # Or force rubberband for higher quality:
    mpv --af=rubberband --speed=1.5 audio.flac
    ```
  </Accordion>

  <Accordion title="Encode multi-channel audio to AC-3 for S/PDIF">
    ```bash theme={null}
    mpv --af=lavcac3enc audio.mkv
    ```

    This is useful when your audio output device requires AC-3 but the source file is in a different multichannel format.
  </Accordion>

  <Accordion title="Loudness normalization with EBU R128">
    ```bash theme={null}
    mpv --af='lavfi=loudnorm=I=-16:TP=-1.5:LRA=11' audio.flac
    ```
  </Accordion>

  <Accordion title="Parametric EQ">
    ```bash theme={null}
    # 5 dB boost at 100 Hz with 50 Hz bandwidth
    mpv --af='lavfi=equalizer=f=100:width_type=h:width=50:g=5' audio.flac
    ```
  </Accordion>

  <Accordion title="Change audio pitch without changing speed">
    ```bash theme={null}
    # Shift pitch up by one semitone
    mpv --af=rubberband=pitch-scale=1.059463 audio.flac
    ```
  </Accordion>
</AccordionGroup>

## Filter help

```bash theme={null}
# List all available audio filters
mpv --af=help

# Show parameters for a specific filter
mpv --af=scaletempo=help
```

For libavfilter audio filters, refer to the [FFmpeg filter documentation](https://ffmpeg.org/ffmpeg-filters.html).