Google Flow API v1 R2V (Reference-to-Video) now supports portrait aspect ratio with Veo 3.1 models.

Veo 3.1 Ultra Fast Relaxed - Portrait R2V Demo

Reference image: Lady

curl -X POST "https://api.useapi.net/v1/google-flow/videos" \
  -H "Authorization: Bearer user:12345-..." \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "dancing cha-cha",
    "model": "veo-3.1-fast-relaxed",
    "aspectRatio": "portrait",
    "referenceImage_1": "user:...-email:...-mediaGenerationId:..."
  }'

Result:

R2V mode now works with both landscape and portrait aspect ratios using veo-3.1-fast and veo-3.1-fast-relaxed models.