> ## Documentation Index
> Fetch the complete documentation index at: https://gccai.heqingsong.uk/llms.txt
> Use this file to discover all available pages before exploring further.

# Generate mashup (mashup)

>  - Remix a song into a new creation.
- Referencing source tracks: requires **exactly 2**, specified via `task_ids` (an array of length 2) + optional `audio_indexes`
- Async task: submitting returns a `task_id`; poll `GET /v1/music/tasks/:task_id` for the result 

<Info>
  **Referencing source tracks**: mashup requires **exactly 2 source tracks**—specify them via `task_ids` (an array of exactly 2 of your `task_id`s), with optional `audio_indexes` (a parallel array selecting which item in each task's `music[]`, 1-based, default `1` for both).
</Info>

<Warning>
  `custom` determines which fields take effect: fields written under the wrong mode are **silently ignored** by the upstream (no error). With `custom=true`, `prompt` (lyrics), `title`, `tags`, `negative_tags`, `auto_lyrics`, `style_weight`, `weirdness_constraint`, `audio_weight`, and `persona_id` take effect and `gpt_description` is ignored; with `custom=false`, only `gpt_description` is read (**required** in that case — if missing, a 400 is returned at submission time). `vocal_gender` works in both modes. If `custom` is omitted, the backend infers it in this order: `prompt` present → `true`; no `prompt` but `gpt_description` present → `false`; otherwise `tags`/`title` present → `true`.
</Warning>

<RequestExample>
  ```bash cURL theme={null}
  curl -X POST https://gccai.heqingsong.uk/v1/music/generations/mashup \
    -H 'Authorization: Bearer <token>' \
    -H 'Content-Type: application/json' \
    --data '{
      "model": "suno",
      "task_ids": ["task_01ABC", "task_01DEF"],
      "audio_indexes": [1, 2],
      "custom": true,
      "prompt": "upbeat mashup of the two tracks"
    }'
  ```

  ```python Python theme={null}
  import requests

  url = "https://gccai.heqingsong.uk/v1/music/generations/mashup"

  payload = {
      "model": "suno",
      "task_ids": ["task_01ABC", "task_01DEF"],
      "audio_indexes": [1, 2],
      "custom": True,
      "prompt": "upbeat mashup of the two tracks"
  }

  headers = {
      "Authorization": "Bearer <token>",
      "Content-Type": "application/json"
  }

  response = requests.post(url, json=payload, headers=headers)

  print(response.json())
  ```

  ```javascript JavaScript theme={null}
  const url = "https://gccai.heqingsong.uk/v1/music/generations/mashup";

  const payload = {
    model: "suno",
    task_ids: ["task_01ABC", "task_01DEF"],
    audio_indexes: [1, 2],
    custom: true,
    prompt: "upbeat mashup of the two tracks"
  };

  const headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
  };

  fetch(url, {
    method: "POST",
    headers: headers,
    body: JSON.stringify(payload)
  })
    .then(response => response.json())
    .then(data => console.log(data))
    .catch(error => console.error('Error:', error));
  ```

  ```go Go theme={null}
  package main

  import (
      "bytes"
      "encoding/json"
      "fmt"
      "io/ioutil"
      "net/http"
  )

  func main() {
      url := "https://gccai.heqingsong.uk/v1/music/generations/mashup"

      payload := map[string]interface{}{
          "model": "suno",
          "task_ids": []string{"task_01ABC", "task_01DEF"},
          "audio_indexes": []int{1, 2},
          "custom": true,
          "prompt": "upbeat mashup of the two tracks",
      }

      jsonData, _ := json.Marshal(payload)

      req, _ := http.NewRequest("POST", url, bytes.NewBuffer(jsonData))
      req.Header.Set("Authorization", "Bearer <token>")
      req.Header.Set("Content-Type", "application/json")

      client := &http.Client{}
      resp, err := client.Do(req)
      if err != nil {
          panic(err)
      }
      defer resp.Body.Close()

      body, _ := ioutil.ReadAll(resp.Body)
      fmt.Println(string(body))
  }
  ```

  ```java Java theme={null}
  import java.net.http.HttpClient;
  import java.net.http.HttpRequest;
  import java.net.http.HttpResponse;
  import java.net.URI;

  public class Main {
      public static void main(String[] args) throws Exception {
          String url = "https://gccai.heqingsong.uk/v1/music/generations/mashup";

          String payload = """
          {
            "model": "suno",
            "task_ids": ["task_01ABC", "task_01DEF"],
            "audio_indexes": [1, 2],
            "custom": true,
            "prompt": "upbeat mashup of the two tracks"
          }
          """;

          HttpClient client = HttpClient.newHttpClient();
          HttpRequest request = HttpRequest.newBuilder()
              .uri(URI.create(url))
              .header("Authorization", "Bearer <token>")
              .header("Content-Type", "application/json")
              .POST(HttpRequest.BodyPublishers.ofString(payload))
              .build();

          HttpResponse<String> response = client.send(request,
              HttpResponse.BodyHandlers.ofString());

          System.out.println(response.body());
      }
  }
  ```

  ```php PHP theme={null}
  <?php

  $url = "https://gccai.heqingsong.uk/v1/music/generations/mashup";

  $payload = [
      "model" => "suno",
      "task_ids" => ["task_01ABC", "task_01DEF"],
      "audio_indexes" => [1, 2],
      "custom" => true,
      "prompt" => "upbeat mashup of the two tracks"
  ];

  $ch = curl_init($url);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
  curl_setopt($ch, CURLOPT_POST, true);
  curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload));
  curl_setopt($ch, CURLOPT_HTTPHEADER, [
      "Authorization: Bearer <token>",
      "Content-Type: application/json"
  ]);

  $response = curl_exec($ch);
  curl_close($ch);

  echo $response;
  ?>
  ```

  ```ruby Ruby theme={null}
  require 'net/http'
  require 'json'
  require 'uri'

  url = URI("https://gccai.heqingsong.uk/v1/music/generations/mashup")

  payload = {
    model: "suno",
    task_ids: ["task_01ABC", "task_01DEF"],
    audio_indexes: [1, 2],
    custom: true,
    prompt: "upbeat mashup of the two tracks"
  }

  http = Net::HTTP.new(url.host, url.port)
  http.use_ssl = true

  request = Net::HTTP::Post.new(url)
  request["Authorization"] = "Bearer <token>"
  request["Content-Type"] = "application/json"
  request.body = payload.to_json

  response = http.request(request)
  puts response.body
  ```

  ```swift Swift theme={null}
  import Foundation

  let url = URL(string: "https://gccai.heqingsong.uk/v1/music/generations/mashup")!

  let payload: [String: Any] = [
      "model": "suno",
      "task_ids": ["task_01ABC", "task_01DEF"],
      "audio_indexes": [1, 2],
      "custom": true,
      "prompt": "upbeat mashup of the two tracks"
  ]

  var request = URLRequest(url: url)
  request.httpMethod = "POST"
  request.setValue("Bearer <token>", forHTTPHeaderField: "Authorization")
  request.setValue("application/json", forHTTPHeaderField: "Content-Type")
  request.httpBody = try? JSONSerialization.data(withJSONObject: payload)

  let task = URLSession.shared.dataTask(with: request) { data, response, error in
      if let error = error {
          print("Error: \(error)")
          return
      }

      if let data = data, let responseString = String(data: data, encoding: .utf8) {
          print(responseString)
      }
  }

  task.resume()
  ```

  ```csharp C# theme={null}
  using System;
  using System.Net.Http;
  using System.Text;
  using System.Threading.Tasks;

  class Program
  {
      static async Task Main(string[] args)
      {
          var url = "https://gccai.heqingsong.uk/v1/music/generations/mashup";

          var payload = @"{
              ""model"": ""suno"",
              ""task_ids"": [""task_01ABC"", ""task_01DEF""],
              ""audio_indexes"": [1, 2],
              ""custom"": true,
              ""prompt"": ""upbeat mashup of the two tracks"""
          }";

          using var client = new HttpClient();
          client.DefaultRequestHeaders.Add("Authorization", "Bearer <token>");

          var content = new StringContent(payload, Encoding.UTF8, "application/json");
          var response = await client.PostAsync(url, content);
          var result = await response.Content.ReadAsStringAsync();

          Console.WriteLine(result);
      }
  }
  ```

  ```c C theme={null}
  #include <stdio.h>
  #include <curl/curl.h>

  int main(void) {
      CURL *curl;
      CURLcode res;

      curl_global_init(CURL_GLOBAL_DEFAULT);
      curl = curl_easy_init();

      if(curl) {
          const char *url = "https://gccai.heqingsong.uk/v1/music/generations/mashup";
          const char *payload = "{"
              "\"model\":\"suno\","
              "\"task_ids\":[\"task_01ABC\",\"task_01DEF\"],"
              "\"audio_indexes\":[1,2],"
              "\"custom\":true,"
              "\"prompt\":\"upbeat mashup of the two tracks\""
          "}";

          struct curl_slist *headers = NULL;
          headers = curl_slist_append(headers, "Authorization: Bearer <token>");
          headers = curl_slist_append(headers, "Content-Type: application/json");

          curl_easy_setopt(curl, CURLOPT_URL, url);
          curl_easy_setopt(curl, CURLOPT_POSTFIELDS, payload);
          curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

          res = curl_easy_perform(curl);

          if(res != CURLE_OK) {
              fprintf(stderr, "curl_easy_perform() failed: %s\n",
                      curl_easy_strerror(res));
          }

          curl_slist_free_all(headers);
          curl_easy_cleanup(curl);
      }

      curl_global_cleanup();
      return 0;
  }
  ```

  ```objectivec Objective-C theme={null}
  #import <Foundation/Foundation.h>

  int main(int argc, const char * argv[]) {
      @autoreleasepool {
          NSURL *url = [NSURL URLWithString:@"https://gccai.heqingsong.uk/v1/music/generations/mashup"];

          NSDictionary *payload = @{
              @"model": @"suno",
              @"task_ids": @[@"task_01ABC", @"task_01DEF"],
              @"audio_indexes": @[@1, @2],
              @"custom": @YES,
              @"prompt": @"upbeat mashup of the two tracks"
          };

          NSError *error;
          NSData *jsonData = [NSJSONSerialization dataWithJSONObject:payload
                                                            options:0
                                                              error:&error];

          NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
          [request setHTTPMethod:@"POST"];
          [request setValue:@"Bearer <token>" forHTTPHeaderField:@"Authorization"];
          [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
          [request setHTTPBody:jsonData];

          NSURLSessionDataTask *task = [[NSURLSession sharedSession]
              dataTaskWithRequest:request
              completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                  if (error) {
                      NSLog(@"Error: %@", error);
                      return;
                  }
                  NSString *result = [[NSString alloc] initWithData:data
                                                          encoding:NSUTF8StringEncoding];
                  NSLog(@"%@", result);
              }];

          [task resume];
          [[NSRunLoop mainRunLoop] run];
      }
      return 0;
  }
  ```

  ```ocaml OCaml theme={null}
  (* Requires cohttp and yojson libraries *)
  open Lwt
  open Cohttp
  open Cohttp_lwt_unix

  let url = "https://gccai.heqingsong.uk/v1/music/generations/mashup"

  let payload = {|{
    "model": "suno",
    "task_ids": ["task_01ABC", "task_01DEF"],
    "audio_indexes": [1, 2],
    "custom": true,
    "prompt": "upbeat mashup of the two tracks"
  }|}

  let () =
    let headers = Header.init ()
      |> fun h -> Header.add h "Authorization" "Bearer <token>"
      |> fun h -> Header.add h "Content-Type" "application/json"
    in
    let body = Cohttp_lwt.Body.of_string payload in

    let response = Client.post ~headers ~body (Uri.of_string url) >>= fun (resp, body) ->
      body |> Cohttp_lwt.Body.to_string >|= fun body_str ->
      print_endline body_str
    in
    Lwt_main.run response
  ```

  ```dart Dart theme={null}
  import 'dart:convert';
  import 'package:http/http.dart' as http;

  void main() async {
    final url = Uri.parse('https://gccai.heqingsong.uk/v1/music/generations/mashup');

    final payload = {
      'model': 'suno',
      'task_ids': ['task_01ABC', 'task_01DEF'],
      'audio_indexes': [1, 2],
      'custom': true,
      'prompt': 'upbeat mashup of the two tracks'
    };

    final response = await http.post(
      url,
      headers: {
        'Authorization': 'Bearer <token>',
        'Content-Type': 'application/json',
      },
      body: jsonEncode(payload),
    );

    print(response.body);
  }
  ```

  ```r R theme={null}
  library(httr)
  library(jsonlite)

  url <- "https://gccai.heqingsong.uk/v1/music/generations/mashup"

  payload <- list(
    model = "suno",
    task_ids = c("task_01ABC", "task_01DEF"),
    audio_indexes = c(1, 2),
    custom = TRUE,
    prompt = "upbeat mashup of the two tracks"
  )

  response <- POST(
    url,
    add_headers(
      Authorization = "Bearer <token>",
      `Content-Type` = "application/json"
    ),
    body = toJSON(payload, auto_unbox = TRUE),
    encode = "raw"
  )

  cat(content(response, "text"))
  ```
</RequestExample>

<ResponseExample>
  ```json 200 theme={null}
  {
    "code": 200,
    "data": [
      {
        "status": "submitted",
        "task_id": "task_01K8SGYNNNVBQTXNR4MM964S7K"
      }
    ]
  }
  ```

  ```json 400 theme={null}
  {
    "error": {
      "code": 400,
      "message": "Invalid request parameters",
      "type": "invalid_request_error"
    }
  }
  ```

  ```json 401 theme={null}
  {
    "error": {
      "code": 401,
      "message": "Authentication failed, please check your API key",
      "type": "authentication_error"
    }
  }
  ```

  ```json 402 theme={null}
  {
    "error": {
      "code": 402,
      "message": "Insufficient account balance, please top up and try again",
      "type": "payment_required"
    }
  }
  ```

  ```json 403 theme={null}
  {
    "error": {
      "code": 403,
      "message": "Access forbidden, you do not have permission to access this resource",
      "type": "permission_error"
    }
  }
  ```

  ```json 429 theme={null}
  {
    "error": {
      "code": 429,
      "message": "Too many requests, please try again later",
      "type": "rate_limit_error"
    }
  }
  ```

  ```json 500 theme={null}
  {
    "error": {
      "code": 500,
      "message": "Internal server error, please try again later",
      "type": "server_error"
    }
  }
  ```

  ```json 502 theme={null}
  {
    "error": {
      "code": 502,
      "message": "Gateway error, the server is temporarily unavailable",
      "type": "bad_gateway"
    }
  }
  ```
</ResponseExample>

## Authorizations

<ParamField header="Authorization" type="string" required>
  All endpoints require authentication using a Bearer Token

  Get an API Key:

  Visit the [API Key management page](https://gccai.heqingsong.uk/keys) to get your API Key

  Add the following to the request headers when using it:

  ```
  Authorization: Bearer YOUR_API_KEY
  ```
</ParamField>

## Body

<ParamField body="model" type="string" default="suno">
  Audio model. Currently pass `suno` (defaults to `suno` if omitted).
</ParamField>

<ParamField body="task_ids" type="string[]" required>
  Array of your `task_id`s for the 2 source tracks (must be **exactly 2**; any other count returns `400` directly at submission time).
</ParamField>

<ParamField body="audio_indexes" type="integer[]">
  Array parallel to `task_ids`, selecting which item in each task's result `music[]` (1-based, default `1` for both).
</ParamField>

<ParamField body="instrumental" type="boolean" default="false">
  Whether purely instrumental (`true`=no vocals). If omitted, defaults to `false` (with vocals).
</ParamField>

<ParamField body="version" type="string" default="v5.5">
  Generation version: `v3.5` / `v4` / `v4.5` / `v4.5+` / `v4.5-all` / `v5` / `v5.5`, affects audio quality and billing; defaults to `v5.5` if omitted, and an invalid value returns `400` directly at submission time.
</ParamField>

<ParamField body="custom" type="boolean">
  `true`=custom mode (`prompt` used as lyrics); `false`=inspiration mode (uses `gpt_description`); if omitted, inferred from the content (see the Warning above).
</ParamField>

<ParamField body="prompt" type="string">
  Lyrics. Takes effect when `custom=true` (ignored in inspiration mode).
</ParamField>

<ParamField body="gpt_description" type="string">
  Inspiration prompt. **Required when `custom=false`** — if missing, the request fails with `400` at submission (the upstream is not called, nothing is charged).
</ParamField>

<ParamField body="title" type="string">
  Title. **Only takes effect when `custom=true`**.
</ParamField>

<ParamField body="tags" type="string">
  Style tags. **Only takes effect when `custom=true`**.
</ParamField>

<ParamField body="negative_tags" type="string">
  Style tags to exclude. **Only takes effect when `custom=true`**.
</ParamField>

<ParamField body="auto_lyrics" type="boolean">
  `true`=rewrite the provided lyrics creatively. **Only takes effect when `custom=true`**.
</ParamField>

<ParamField body="style_weight" type="number">
  Style weight, `0.00`–`1.00` (out-of-range values return `400` directly at submission time). **Only takes effect when `custom=true`**.
</ParamField>

<ParamField body="weirdness_constraint" type="number">
  Creativity weight, `0.00`–`1.00` (alias `weirdness`). **Only takes effect when `custom=true`**.
</ParamField>

<ParamField body="audio_weight" type="number">
  Audio weight, `0.00`–`1.00`. **Only takes effect when `custom=true`**.
</ParamField>

<ParamField body="vocal_gender" type="string">
  Vocal gender: `Male` / `Female`. **Works in both modes**.
</ParamField>

<ParamField body="persona_id" type="string">
  Persona style id. **Only takes effect when `custom=true`**.
</ParamField>

<Note>
  **Getting the result**: This endpoint is an async task. After submitting you get a `task_id`; poll `GET /v1/music/tasks/{task_id}` at 3–5s intervals until `status` is `completed` or `failed` (music generation typically takes 30–120s; while generating, `status` is `pending` and `progress` goes queued 10 → ready 50 → done 100). On completion take `audio_url` from `data.result.music[]`. On failure `data.error.message` gives the reason and the pre-deducted quota is automatically refunded.
</Note>

## Response

<ResponseField name="code" type="integer">
  Response status code
</ResponseField>

<ResponseField name="data" type="array">
  Returned data array

  <Expandable title="Attributes">
    <ResponseField name="status" type="string">
      Task status

      * `submitted` - Submitted
    </ResponseField>

    <ResponseField name="task_id" type="string">
      Unique task identifier (used to poll `GET /v1/music/tasks/{task_id}` for the result)
    </ResponseField>
  </Expandable>
</ResponseField>