Asset types and channels. When to pick which
Siren generates six asset types. Each renders to a different output format and suits a different distribution context. The Reasoner picks the type by default from your prompt. You can override in the composer.
Card
A still PNG, painted to your Brand DNA. Cards are the fastest to render (8–15 seconds) and the most flexible. Every template in Siren can generate a card variant. Cards work on every channel: X, LinkedIn, Instagram, YouTube community posts. TikTok is video-only.
When to pick card: single-point announcements, stat callouts, quote graphics, product screenshots with context. Anything where the message is complete in one frame.
Video
A 15-second MP4 with background music. Built by Siren's video engine: your template animates frame by frame, then ffmpeg encodes the sequence. There is no AI-generated video. The motion comes from the template's animation primitives. Consistent, on-brand, every render.
Render time: 60–90 seconds. Videos currently ship with per-archetype background music. Voice narration is coming in v1.5.
When to pick video: launch moments, feature reveals, short demos, any prompt where motion carries the message. Video outperforms cards on reach on X and LinkedIn because both platforms boost native video in the feed.
Slideshow
A narrative MP4 built from a sequence of branded slides. Slideshows are better for sequential arguments (step 1, step 2, step 3). Videos are better for single-moment impact.
Render time: 90–120 seconds, depending on slide count.
Carousel
A multi-image set for swipe-through posts. Each image is its own rendered frame, styled consistently across the set. Carousels are the highest-engagement format on LinkedIn for B2B content, and they are strong on Instagram for educational material.
When to pick carousel: how-to content, multi-step explanations, before/after comparisons, list-based posts that benefit from swipe interaction. Five slides is the default. The Reasoner can go up to ten.
Infographic
A single-image data visualization. Siren's infographics are not chart screenshots. They are styled data stories built to match your brand palette and archetype.
When to pick infographic: research reports, market data, benchmark comparisons, any prompt where the key message is a number.
OG Image. A 1200×630 image for link previews. This is the image that appears when you share a URL on X, LinkedIn, Slack, or iMessage. It is not a social post. Use OG images when you are sharing a link and want the preview designed rather than scraped.
Choosing a channel
Channels set the aspect ratio and pixel dimensions. The same prompt rendered for X (1280×720) and for Reels (1080×1920) produces two different layouts from the same template.
You can override. Type a prompt, click your asset type, then click your preferred channel before hitting Generate. The Reasoner will respect the override and route to a template that supports that channel.