Pika H3 Flex Reference to Video

Pika H3 Flex reference-to-video with synchronized audio. Guide the video with up to 9 images, 3 videos and 3 audio clips cited as @Image1, @Video1, @Audio1. 3-15s, 480p to 4K.

maker
pika
category
video
input → output
reference → video, image → video, video → video
runs via
api, javascript and python sdk, belt cli, mcp
updated
2026-11-08
price
$0.06/sec 480p, $0.12/sec 768p, $0.15/sec 1080p, $0.16/sec 2k, $0.20/sec 4k (output+input video sec). Stems: $0.001/sec

api reference

about

pika h3 flex reference-to-video with synchronized audio. guide the video with up to 9 images, 3 videos and 3 audio clips cited as @image1, @video1, @audio1. 3-15s, 480p to 4k.

get an api key

create one in settings → api keys. the examples read it from INFERENCE_API_KEY.

bash
1export INFERENCE_API_KEY="inf_your_key"

1. calling the api

install the client

nothing to install. any http client works; the examples use curl, and jq to read responses. every response wraps its result in a data field.

run and get result

send "wait": true to hold the connection until the task finishes. without it the call returns right away with the task still running.

bash
12# "wait": true holds the connection until the task finishes.3# the response is {"data": {"id", "status", "status_text", "output", ...}}4curl -X POST https://api.inference.sh/apps/run \5  -H "Authorization: Bearer $INFERENCE_API_KEY" \6  -H "Content-Type: application/json" \7  -d '{8    "app": "pika/pika-h3-flex-reference",9    "input": {10      "prompt": "@Image1 walks through the rainy street from @Video1, wearing the jacket in @Image2. The voice from @Audio1 says '\''we made it'\''. Sound: rain, footsteps, no music."11    },12    "wait": true13  }'

stream live updates

get real-time progress updates as the task runs. ideal for showing progress bars, partial results, or long-running tasks. send "stream": true and the response is a server-sent event stream that ends when the task does.

bash
12# "stream": true answers with server-sent events until the task finishes3curl -N -X POST https://api.inference.sh/apps/run \4  -H "Authorization: Bearer $INFERENCE_API_KEY" \5  -H "Content-Type: application/json" \6  -d '{7    "app": "pika/pika-h3-flex-reference",8    "input": {9      "prompt": "@Image1 walks through the rainy street from @Video1, wearing the jacket in @Image2. The voice from @Audio1 says '\''we made it'\''. Sound: rain, footsteps, no music."10    },11    "stream": true12  }'

run in the background

start the task and get its id back right away, then check on it later. for long tasks, or when you'd rather be called back, see webhooks.

bash
1# without "wait" the call returns the task right away (status 1, "received")2TASK_ID=$(curl -s -X POST https://api.inference.sh/apps/run \3  -H "Authorization: Bearer $INFERENCE_API_KEY" \4  -H "Content-Type: application/json" \5  -d '{6    "app": "pika/pika-h3-flex-reference",7    "input": {8      "prompt": "@Image1 walks through the rainy street from @Video1, wearing the jacket in @Image2. The voice from @Audio1 says '\''we made it'\''. Sound: rain, footsteps, no music."9    }10  }' | jq -r '.data.id')1112# later: read its state. done when status is 10 (completed), 11 (failed) or 12 (cancelled)13curl -s https://api.inference.sh/tasks/$TASK_ID \14  -H "Authorization: Bearer $INFERENCE_API_KEY" | jq '.data | {status, status_text, output}'

2. authentication

the api uses api keys for authentication. see the authentication docs for detailed setup instructions.

3. files

file inputs are automatically handled by the sdk. you can pass local paths, urls, or base64 data.

automatic upload

pass urls directly or use data uris for inline content.

bash
1# pass URLs or data URIs as input values2curl -X POST https://api.inference.sh/apps/run \3  -H "Authorization: Bearer $INFERENCE_API_KEY" \4  -H "Content-Type: application/json" \5  -d '{6    "app": "pika/pika-h3-flex-reference",7    "input": {8      "image": "https://example.com/image.png",9      "audio": "data:audio/mp3;base64,..."10    },11    "wait": true12  }'

manual upload

you can also upload files manually and use the returned url.

bash
1# 1. create the file: the response has an upload_url and the file's uri2FILE=$(curl -s -X POST https://api.inference.sh/files \3  -H "Authorization: Bearer $INFERENCE_API_KEY" \4  -H "Content-Type: application/json" \5  -d '{"files": [{"filename": "image.png", "content_type": "image/png"}]}')67# 2. PUT the bytes to upload_url8curl -X PUT "$(echo "$FILE" | jq -r '.data[0].upload_url')" \9  -H "Content-Type: image/png" \10  --data-binary @image.png1112# 3. pass the uri as an input value13echo "$FILE" | jq -r '.data[0].uri'

4. webhooks

get notified when a task completes by providing a webhook url. when the task reaches a terminal state (completed, failed, or cancelled), a POST request is sent to your url with the task result.

bash
1curl -X POST https://api.inference.sh/apps/run \2  -H "Authorization: Bearer $INFERENCE_API_KEY" \3  -H "Content-Type: application/json" \4  -d '{5    "app": "pika/pika-h3-flex-reference",6    "input": {7        "prompt": "@Image1 walks through the rainy street from @Video1, wearing the jacket in @Image2. The voice from @Audio1 says 'we made it'. Sound: rain, footsteps, no music."8    },9    "webhook": "https://your-server.com/webhook"10  }'

webhook payload

your endpoint receives a JSON POST with the task result:

json
1{2  "event": "task.completed",3  "timestamp": "2024-01-15T10:30:05Z",4  "data": {5    "id": "task_abc123",6    "short_id": "abc123",7    "status": 10,8    "status_text": "completed",9    "output": { ... },10    "created_at": "2024-01-15T10:30:00Z",11    "updated_at": "2024-01-15T10:30:05Z"12  }13}
eventstringtask.completed, task.failed or task.cancelled
timestampstringiso timestamp of the delivery
data.idstringtask id
data.short_idstringshort task id
data.statusnumberterminal status (10=completed, 11=failed, 12=cancelled, 13=rejected)
data.status_textstringthe status as a word: completed, failed or cancelled
data.outputobjecttask output (when completed)
data.errorstringerror message (when failed, omitted otherwise)
data.session_idstringsession id (when the task ran in a session, omitted otherwise)
data.created_atstringiso timestamp
data.updated_atstringiso timestamp

5. schema

input

promptstring*

what happens in the video. cite references in order as @image1, @image2, @video1, @audio1. describe shots, camera, lighting and sound.

example: "@Image1 walks through the rainy street from @Video1, wearing the jacket in @Image2. The voice from @Audio1 says 'we made it'. Sound: rain, footsteps, no music."minLength:1maxLength:8000
reference_imagesarray

up to 9 reference images (png, jpeg or webp, up to 50 mib each, aspect between 1:4 and 4:1). cite as @image1..@image9.

reference_videosarray

up to 3 reference videos, 2-15s each and 15s combined. input video seconds are billed at the output rate. cite as @video1..@video3.

reference_audiosarray

up to 3 reference audio clips, 2-15s each and 15s combined. free. cite as @audio1..@audio3.

durationinteger

video length in whole seconds, 3 to 15. billed per output second.

default: 5min:3max:15
aspect_ratiostring

output aspect ratio. auto follows the prompt and reference video.

default: "auto"
options:"auto""21:9""16:9""3:2""4:3""5:4""1:1""4:5""3:4""2:3""9:16""9:21"
resolutionstring

480p and 768p are native. 1080p, 2k and 4k generate at 768p and upscale once, keeping audio and frame rate.

default: "768p"
options:"480p""768p""1080p""2k""4k"
rewriteboolean

let pika expand the prompt before generation. turn off to use the prompt verbatim.

default: true
seedinteger

seed. 0 lets pika choose.

default: 0min:0
audio_stemsboolean

also return the soundtrack split into dialogue, music and effect wav stems. billed per stem second on top of the video.

default: false
stems_channel_modestring

audio stems only. mono downmixes before separation; stereo keeps both channels.

default: "mono"
options:"mono""stereo"

output

seedinteger

seed pika used for this video.

stemsarray

dialogue, music and effect wav stems when audio_stems is on.

videostring(file)*

generated mp4 (h.264 + aac, 24 fps).

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