Vocal Isolator API

About Vocal Isolator

Vocal Isolator can provide the separation stage in an audio review or editing application. Submit an existing MP3 or WAV recording and receive voice and background tracks for further listening or editing. The full-song separation example offers a completed fixture for a paired-track review interface. This endpoint processes audio that already exists; your application should not present it as script synthesis or lyric transcription.

Call it with the model name popnow/vocal-isolator-v1/audio-separation on POST /jobs/createTask, from $0.0012.

Introduction

Vocal Isolator separates an existing audio recording into a vocal track and a background track. Send the mixed recording through audio_url; no prompt or previously generated music task is needed. This endpoint is for working with sound you already have, such as a song rehearsal, a narrated clip or a podcast recording with music underneath.

Key features

Two stems from one recording

The task is intended to return both parts of the same source: vocals first and the remaining background second. In music, the background is the instrumental accompaniment. In a spoken recording, it can include music and environmental sound. These are related stems from one processing job, rather than two alternative generations to choose between. Separation can leave audible leakage or remove details that overlap between the two parts.

Request parameters

Pricing

Prices are in USD. The API uses a separate USD balance. Website credits cannot be used or transferred to it, and API funds cannot be transferred to website credits. When a task is accepted, we reserve the maximum quoted amount from your API balance. On completion, we charge for actual usage, never more than the hold, and release the remainder. If the task fails, the hold is released.

Input duration is rounded up to whole seconds, with a 1-second minimum.

Send the same request body to POST /jobs/quote to see the estimated and maximum USD charge before running. A quote does not run the task or charge your balance.

Use cases

Prepare a music practice track

Use the background stem to rehearse against your own backing track, and keep the vocal stem for checking phrasing. Listen through pauses as well as loud passages: reverberation and backing vocals can remain in the accompaniment. Compare at similar listening levels before deciding whether a stem is suitable for the rehearsal.

Separate narration from an existing mix

For a clip with speech over music, audition the vocal result before placing it into a new edit. The background stem can be useful as an editing reference, but it is not guaranteed to contain only music. Keep both stems aligned to the same source start when comparing them in your editor.

Prompt guide & pro tips

Prepare the source recording

There is no prompt to tune. Upload the clearest version of the mixed recording you have, rather than a recording of loudspeaker playback or an extra compressed copy. Use MP3 or WAV through the upload control. This endpoint handles the complete supplied file; prepare a separate source clip first if only part of a longer recording is needed. Preserve the original and give the derived stems distinct names.

Review both tracks before using them

Check speech consonants, sustained notes, silence between phrases and the left and right channels. Listen for musical sound leaking into the vocals and voice remaining in the background. Do not assume that adding the stems back together reconstructs the original exactly. Measure their actual lengths before editing long sequences, and verify alignment in the target editor. Output format, sample rate and separation quality still require validation with your material.

API quick start

Call the Vocal Isolator API in three steps

1. Create an API key. Sign in to PopNow and create a key in the API console. Keys start with sk-popnow-. API calls use your separate USD balance.
2. Send the request. POST /jobs/createTask with model popnow/vocal-isolator-v1/audio-separation and an input object that follows the parameter table. The response returns a task ID straight away.
3. Get the result. Poll GET /jobs/recordInfo with the task ID, or pass a callBackUrl and we post the result to it. Download the output links when the task succeeds.

# 1. Create the task. Keep the Idempotency-Key if you retry after a network error.
export IDEMPOTENCY_KEY="$(uuidgen)"
curl -X POST https://api.popnow.ai/api/v1/jobs/createTask \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $IDEMPOTENCY_KEY" \
  -d '{
  "model": "popnow/vocal-isolator-v1/audio-separation",
  "input": {
    "audio_url": "https://media.popnow.ai/shortfilm/voices/Aoede-46e4c427.mp3"
  }
}'

# 2. Copy data.taskId from the response, then poll until state is succeeded, failed, canceled or expired.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $POPNOW_API_KEY"

Replace the prompt and any links with your own. The API tab has the response, polling and callback reference.

What to build with the Vocal Isolator API

• Create a paired listening view that lets an editor audition the voice and background independently. Keep both outputs associated with the same source recording, making it easy to compare them with the original before adding either to a project.
• Add a separation queue to an audio asset library. Save the source segment and its task state together, then attach the returned components as related assets rather than overwriting the original recording.

Vocal Isolator parameter notes

• audio_url is the required input and the only exposed property. Use a direct MP3 or WAV asset and validate the actual audio type. A webpage with an embedded player is not itself an audio source file.
• Recordings must fit the published duration range. If your editor allows trimming, measure the resulting segment before quotation and submission. Sending the original longer file while displaying a shorter selected region would process the wrong material.
• There is no prompt, separation strength, voice identifier or output encoding field. Keep the form focused on source selection and your own pre-processing choices. A generic audio settings object should be filtered out rather than passed through as unsupported properties.
• The source accepts standard audio media rather than a video container. Do not substitute a clip URL from a video timeline without first producing an appropriate audio asset in your application. Retain the relationship between that audio segment and its original project for later editing.

How Vocal Isolator API pricing adds up

Separation is metered from input recording duration in billable second blocks with the catalog minimum and accepted cap. It is not charged by lyric length or by treating each returned component as a separate synthesis request. Obtain the live USD quote for the chosen audio segment, confirm its maximum hold and read final costUsd from the completed task.

• Separate voice and background, 5-second clip: $0.006 each, $0.60 for 100 clips

Async jobs, webhooks and rate limits

Every Vocal Isolator request is asynchronous: createTask returns a taskId straight away, and the result arrives when the job finishes. Poll GET /jobs/recordInfo every few seconds, or pass a public https callBackUrl and verify the X-Webhook-Signature header (HMAC-SHA256 over taskId, timestamp and the body hash) before trusting the payload. Each account gets 1,000 write requests per 10 seconds; a 429 carries Retry-After. Send an Idempotency-Key with createTask so a retried request for popnow/vocal-isolator-v1/audio-separation never runs or bills twice.

Common Vocal Isolator API errors

Vocal Isolator API questions

More about Vocal Isolator

Try it

Try in PlaygroundVideo Editor · Separate voice and background

Docs

Vocal Isolator model ID and input schema in the API docsPopNow API quickstart: send your first requestWebhooks: get Vocal Isolator results without polling