Capability

Extend

Continue an existing song or instrumental from either end. Songs extend in v5, v6, and v7; instrumentals extend in v5 only.

Quickstart (compat)
extend_song
extend_music
Pricing

Compat routes available

POST /v{5,6,7}/extend/song covers extend_song. POST /v5/extend/music (and the alias POST /v1/generate/extend) covers extend_music, v5 only. See Compat Routes.

Quickstart

POST/v7/extend/songcompat route, simplest way to start

curl -X POST https://apiv2.soundverse.ai/v7/extend/song \
  -H "Authorization: Bearer sksoundverse_..." \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: extend-req-001" \
  -d '{
    "audio_url": "https://example.com/my-song.mp3",
    "lyrics": "new verse lyrics here..."
  }'

audio_url is required — omitting it returns 400 {"error": "MISSING_FIELD"}.

extend_song — native payload

POST/v1/generationstool_id for (model, "extend_song")

Field	Type	Required	Default	Description
song	file input	Yes	—	The whole song to extend/continue. mp3/m4a, up to 40MB — a larger cap than other reference fields since this is a full song, not a short clip.
lyrics	string	No	""	Lyrics for the new part. Up to 3000 characters.
extend_at_ms	integer	No	0	Where the new part begins, in ms. 0 continues from the end of the song. Otherwise 8000–420000.
extend_type	string	No	"tail"	'tail' continues from the end (default); 'head' prepends to the start.

extend_at_ms’s 8000–420000 range is enforced by clamping the value at generation time, not by request validation — an out-of-range value is silently clamped, not rejected. An invalid extend_type (anything other than tail/head) fails mid-generation rather than at request validation.

extend_music — native payload

POST/v1/generationstool_id for (model="v5", "extend_music")

Field	Type	Required	Default	Description
music	file input	Yes	—	The instrumental to extend. mp3/m4a, up to 40MB.
prompt	string	No	""	How the new part should sound — style, mood, instruments. Optional.
extend_seconds	float	No	30.0	How many seconds of new music to add. 1.0–120.0.
side	string	No	"tail"	'tail' or 'head'.

Pricing

Version	Royalty-Free	Standard	Distribution	Sync	Master
extend_song v5 / v6 / v7	$0.07	$0.07	$0.07	$0.07	$0.07
extend_music v5	$0.07	$0.07	$0.07	$0.07	$0.07

USD per generation, by license tier.

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