---
sidebar_position: 4
title: Scrobble Modification
toc_max_heading_level: 4
---

Multi-scrobbler configs support the ability to modify scrobble data in an automated fashion by matching and replacing strings in **title, artists, and album** at many different times in multi-scrobbler's lifecycle.

### Why?

You may need to "clean up" data from a Source or before sending to a scrobble Client due to any number of reasons:

* ID3 tags in your music collection are dirty or have repeating garbage IE `[YourMusicSource.com] My Artist - My Title`
* A Source's service often incorrectly adds data to some field IE `My Artist - My Title (Album Version)` when the title should just be `My Title`
* An Artist you listen to often is spelled different between a Source and a Client which causes duplicate scrobbles

In any scenario where a repeating pattern can be found in the data it would be nice to be able to fix it before the data gets downstream or to help prevent duplicate scrobbling. Multi-scrobbler can help you do this.

## Overview

### Journey of a Scrobble

First, let's recap the lifecycle of a scrobble in multi-scrobbler:

**Sources** are the beginning of the journey for a **Play** (song you've listened to long enough to be scrobblable)

* A Source finds a new valid **Play**
* The Source **compares** this new Play to all the other Plays it has already seen, if the Play is unique (title/artist/album/listened datetime) then...
* The Source **discovers** the Play, adds it to Plays it has seen already, and broadcasts the Play should be scrobbled to all Clients

Scrobble **Clients** listen for discovered Plays from Sources, then...

* A Client receives a **Play** from a Source
* The Client **compares** this Play to all the other scrobbles it has already seen, if the Play is unique (title/artist/album/listened datetime) then...
* The Client **scrobbles** the Play downstream to the scrobble service and adds it as a Scrobble it has seen already

### Lifecyle Hooks

You'll notice there is a pattern above that looks like this:

* **Before** data is compared
* Data is **compared**
* **After** data is compared

These points, during both Source and Client processes, are when you can hook into the scrobble lifecycle and modify it.

#### TLDR

In more concrete terms this is the structure of hooks within a configuration (can be used in any **Source** or **Client**):

```json5 title="lastfm.json" {10-14}
[
  {
    "name": "myLastFm",
    "enable": true,
    "configureAs": "source",
    "data": {
      // ...
    },
    "options": {
      "playTransform": {
        "preCompare": {/* ... */},
        "compare": {/* ... */},
        "postCompare": {/* ... */}
      }
    }
  }
]
```

##### Hook

For **Sources**:

* `preCompare` - modify Play data immediately when received
* `compare` - temporarily modify Play data when it is being compared to see if Play was already discovered
* `postCompare` - modify Play data before sending to scrobble **Clients**

For **Clients**:

* `preCompare` - modify Play data immediately when received
* `compare` - temporarily modify Play data when it is being compared to see if it was already scrobbled
* `postCompare` - modify Play data before scrobbling it to downstream service and adding to already seen scrobbles

:::tip

Keep in mind that modifying Scrobble/Play data earlier in the lifecycle will affect that data at all times later in the lifecycle.

For example, to modify the track so it's the same anywhere it is processed in multi-scrobbler you only need to modify it in the **Source's** `preCompare` hook because all later processes will receive the data with the modified track.

:::

### Modification Parts


Each [**hook**](#hook) (`preCompare` etc...) is an object that specifies what part of the **Play** to modify:

```json5
{
    "title": [/* ... */],
    "artists": [/* ... */],
    "album": [/* ... */]
}
```

##### Expression

and then a **list** what pattern/replacements (expressions) to use for the modification by using either simple strings or `search-replace` objects:

```json5
[
  "badTerm", // remove all instances of 'badTerm'
  {
    "search": "anotherBadTerm", // and also match all instances of 'anotherBadTerm'
    "replace": "goodTerm" // replace with the string 'goodTerm'
  }
]
```

Putting it all together:

```json5 title="lastfm.json"
[
  {
    "name": "myLastFm",
    "enable": true,
    "configureAs": "source",
    "data": {
      // ...
    },
    "options": {
      "playTransform": {
        "preCompare": {
          "title": [
            [
              "badTerm",
              {
                "search": "badTerm",
                "replace": "goodTerm"
              }
            ]
          ]
        },
      }
    }
  }
]
```

:::note

If the value of the field (title, an artist, album) is an empty string after transforming then the field is **removed.**

:::

:::tip

Modifications can also be applied to **all Sources** or **all Clients** when using the [AIO Config](./configuration.mdx?configType=aio#configuration-types) `config.json` by setting `playTransform` in `sourceDefaults` or `clientDefaults`:

<details>

    <summary>Example</summary>
```json5 title="config.json"
{
  "sourceDefaults": { // will apply playTransform to all sources
    "playTransform": {
      "preCompare": {
        "title": [
          "(Album Version)"
        ]
      }
    }
  },
  "sources": [/* ... */],
  "clients": [/* ... */]
}
```
</details>

:::

#### Compare Hook

The `compare` [hook](#hook) is slightly different than `preCompare` and `postCompare`. It consists of an object where you define which side(s) of the comparison should be modified. It also **does not modify downstream data!** Instead, the modifications are made only for use in the comparison.

```json5 title="lastfm.json"
[
  {
    "name": "myLastFm",
    // ...
    "options": {
      "playTransform": {
        "compare": {
          "candidate": {/* ... */}, // modify the "new" Play being compared
          "existing": {/* ... */}, // modify all "existing" Play/Scrobbles the new Play is being compared against
        },
      }
    }
  }
]
```

#### Regular Expressions

In addition to plain strings [expressions](#expression) that are matched and removed you can also use Regular Expressions. Write your regex like you normally would, but as a string, and it'll automatically be parsed:

```json5
[
  "/^\(\w+.com)/i", // matches any string that starts with '(YourMusic.com)' and removes it
  {
    "search": "/^\(\w+.com)/i", // matches any string that starts with '(YourMusic.com)'
    "replace": "[MySite.com]" // replace with the string '[MySite.com]'
  }
]
```

The `replace` property uses javascript's [`replace()` function and so can use any special string characters.](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace#specifying_a_string_as_the_replacement)

## Examples

### Remove phrase from Title in all new Plays

Removes the phrase `(Album Version)` from the Title of a Play


<details>

    <summary>Example</summary>
```json5 title="config.json"
{
  "sourceDefaults": {
    "playTransform": {
      "preCompare": {
        "title": [
          "(Album Version)"
        ]
      }
    }
  }
}

```
</details>

### Remove all parenthesized content from the end of a title

<details>

    <summary>Example</summary>
```json5 title="lastfm.json"
[
  {
    "name": "myLastFm",
    // ...
    "options": {
      "playTransform": {
        "compare": {
          "candidate": {
          "title": [
              "/(\(.+\))\s*$/"
            ]
          },
          "existing": {
          "title": [
              "/(\(.+\))\s*$/"
            ]
          },
        },
      }
    }
  }
]
```
</details>

### Rename misspelled artist in all new Plays

<details>

    <summary>Example</summary>
```json5 title="config.json"
{
  "sourceDefaults": {
    "playTransform": {
      "preCompare": {
        "artists": [
          {
            "search": "Boz Skaggs",
            "replace": "Boz Scaggs"
          }
        ]
      }
    }
  }
}
```
</details>

### Remove "Various Artists" albums in all new Plays

<details>

    <summary>Example</summary>
```json5 title="config.json"
{
  "sourceDefaults": {
    "playTransform": {
      "preCompare": {
        "album": [
          {
            "search": "Various Artists",
            "replace": ""
          }
        ]
      }
    }
  }
}
```
</details>
