Extend & cover — transform an existing track

Both build on a finished clip rather than starting from a prompt: extend continues a track to make it longer, cover re-renders it in a new style. Both run through the generation endpoint with a task_type, so they inherit the same async flow, credit handling, refunds, and CDN-proxied output. Full schema is in the interactive API reference.

| Operation | task_type | Credits | |---|---|---| | Extend | extend_music | 15 | | Cover | cover_music | 15 |

Both take a continue_clip_id (the source clip from a prior generation), return a task_id, and complete asynchronously — poll GET /api/v1/sonic/task/{id} for the finished tracks.

Extend — make a track longer

Continue a clip into a longer arrangement (e.g. turn a 60-second hook into a full track by chaining extends).

curl -X POST https://api.musicapi.ai/api/v1/sonic/create \
  -H "Authorization: Bearer $MUSICAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "task_type": "extend_music",
    "continue_clip_id": "YOUR_CLIP_ID",
    "mv": "sonic-v5"
  }'

Deep dive: Extend an AI music clip.

Cover — re-render in a new style

Keep the musical idea but re-render it with new tags/prompt — a different genre, mood, or instrumentation.

curl -X POST https://api.musicapi.ai/api/v1/sonic/create \
  -H "Authorization: Bearer $MUSICAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "task_type": "cover_music",
    "continue_clip_id": "YOUR_CLIP_ID",
    "tags": "lo-fi, acoustic, mellow",
    "mv": "sonic-v5"
  }'

Deep dive: Cover music with AI. For swapping a section of a track instead of the whole thing, see Replace a section of an AI song.

Notes

  • Output audio is served from our CDN with stable URLs — upstream provider URLs are never exposed.
  • Failed upstream tasks are auto-refunded; polling task status is free.
  • Related transforms also live on /sonic/create: remaster, add_instrumental, and add_vocals (10 credits each) — see the reference.