pika-h3-flex

Pika H3 Flex

Pika H3 Flex is Pika's post-trained H3 model for professional iteration: six sampling steps, synchronized stereo audio (dialogue, ambience, music) in one pass, and shot direction through references and prompts. pika_video calls the hosted Pika API; the open weights are also published on Hugging Face for local ComfyUI use, which is a separate, unverified path.

Route and billing

Item	Value
Tool	pika_video, model: "pika-h3-flex"
Credential	PIKA_API_KEY from https://dev.pika.art (API Keys)
Support	support@pika.art for API, billing and key problems
Billing	Prepaid per output second, charged to the user's own Pika organization. Failed jobs are not charged. A job covered by a Pika promotional allowance settles at $0 and reports data.free_generation.
Price	480p $0.01/s, 768p $0.02/s, 1080p $0.035/s, 2k $0.04/s, 4k $0.08/s. Reference-to-video: 480p $0.03/s, 768p $0.06/s, 1080p $0.075/s, 2k $0.08/s, 4k $0.10/s, plus reference video input seconds at the same rates.
Cost reporting	cost_usd is the settled charge from the job record. data.cost_status is settled, pending or unavailable; only settled is final.

OpenMontage's default budget policy asks the user before any single action over $0.50 and the first time a new paid tool is used. A 768p 15 second clip is $0.30 and runs unprompted; any 4k clip of 7 seconds or more prompts.

Set dry_run: true to validate the request and get the exact quoted price from Pika's free quote endpoint without uploading or generating. For reference-to-video with video references, pass reference_video_seconds so the preflight estimate includes the input-video charge.

Operations

Operation	Inputs	Notes
text_to_video	prompt	Default when nothing else is supplied.
image_to_video	prompt + image_url or image_path (first frame), or last_frame_image_url / last_frame_image_path	Either frame alone is valid. reference_image_url / reference_image_path are accepted as first-frame aliases.
first_last_frame_to_video	prompt + both frames	Describe the motion between the two frames.
reference_to_video	prompt + references	references in Pika's native ordered shape, or reference_image_urls / reference_video_urls / reference_audio_urls and the *_paths equivalents. Local files are uploaded to Pika.

Operation is inferred from the inputs when omitted. Supplying frames with operation: "text_to_video" is an error, not a silent downgrade.

Reference rules

• At most 9 images, 3 videos and 3 standalone audio clips, 12 files total.
• At least one image or video is required; audio alone is rejected locally.
• Each video or audio clip must be 2 to 15 seconds; combined video and combined standalone audio must each fit in 15 seconds. A video's own soundtrack stays with that video and is not counted as a standalone audio reference.
• Order matters. The per-type lists are sent as images, then videos, then audio. Use references when a different order is intended.

Shared parameters

• duration: whole seconds, 3 to 15, default 5. Output rounds up to the model's frame grid (124 frames for a 5 second request at 24 fps), so clips run slightly long. Plan edits on the delivered length, not the requested one.
• resolution: 480p or 768p native; 1080p, 2k, 4k are generated at 768p and upscaled once, preserving audio and frame rate. Draft at 480p, then rerun the approved take at the delivery resolution.
• aspect_ratio: auto, 21:9, 16:9, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 9:16, 9:21. Omitted: auto when rewriting, otherwise the first keyframe's ratio or 16:9. Keyframes are resized and center-cropped.
• seed: integer. Same seed and same request reproduce closely, not exactly.
• rewrite: default true. Pika improves the prompt before generation. Turn it off for exact prompt control, for A/B tests across seeds, or when the prompt already follows the structure below. prompt_optimizer is accepted as an alias.
• Audio is always generated. generate_audio: false is rejected; strip audio in post with video_compose if a silent clip is needed.

Prompting

Write the prompt as a shot list, not a caption. The model follows explicit structure well:

1. Scene: setting, time of day, lighting, lens or style in one sentence.
2. Subjects: who or what, with the one or two details that must hold.
3. Action and camera: what happens, in order, with camera moves named (slow push-in, orbit, handheld follow, whip pan, hard cut to).
4. Audio: dialogue in quotes with the speaker named, then ambience and music intent. Dialogue is lip-synced when the speaker is on screen.
5. Text on screen: exact words, placement, and when they appear, for motion graphics.

Multi-shot stories work in one prompt: separate shots with "Cut to:" and keep each shot's subject and lighting consistent by repeating the locks. For reference-guided work, say what each reference is for ("first image: the product; video: the dance to follow; audio: the track to cut to").

Keep prompts under 8,000 characters. Describe motion that fits the duration; a 15 second request is the ceiling, not a target.

Failure handling

• insufficient_balance or cycle_limit_exceeded: the user's Pika balance is empty. Point them to https://dev.pika.art. Do not switch provider silently.
• rate_limited (HTTP 429): honor data.retry_after, then submit again.
• content_moderation or invalid_input: revise the prompt or inputs; the message names the problem.
• Poll timeout: the result carries data.resume_job. Call pika_video again with that object (and a longer poll_timeout) to keep waiting on the same job instead of paying for a new one. Set job_path to persist the checkpoint.
• The tool never retries a paid submission on its own.

Provenance

Every result records data.request (the exact payload sent), data.job_id, data.usage, data.billing and data.resume_job. Keep these with the clip for reproducibility and cost reconciliation.