Replace Background

Try out this capability in Bria's sandbox

Description

an asynchronous job that detects the video background and composites a user-provided image or video asset behind the subject. Size and duration mismatches between the input video and the background asset are handled automatically.

behavior:

• Returns HTTP 202 with request_id and status_url

• Check job status by polling status_url or by calling the Status Service with the request_id until a terminal status is returned

foreground input containers:

• .mp4, .mov, .webm, .avi, .gif

*foreground input codecs:

• H.264, H.265 (HEVC), VP9, AV1, PhotoJPEG

background input formats:

• Image: .jpg, .png, .webp, .gif

• Video: .mp4, .mov, .webm, .avi

attributes preserved in output:

• Aspect Ratio and resolution (matches foreground video)

• Frame Rate (matches foreground video)

• Foreground audio if present and preserve_audio is true. Background audio is always discarded.

Limitations:

• Max foreground duration: 60 seconds

• Max background video duration: 60 seconds

• Resolutions: Input resolution up to 16000x16000 (16K) for both foreground and background. Inputs larger than this return 413 Payload Too Large. Output resolution matches the foreground input resolution.

• Video Background spect ratio: provided background video must be of same aspect ratio as the foeground video.

mismatch handling (image bakground):

• Background is scaled to cover the full frame, then center-cropped to exactly match the foreground resolution. Some background edges may be clipped.

mismatch handling (video backgrounds only):

• Background video shorter than foreground: loop from 0s until foreground ends.

• Background video longer than foreground: play from 0s, trim at foreground end.

Output transparency:

• Output is fully opaque (composited).