greenscreen obs

OBS Studio is free, open-source broadcasting software that supports live chroma keying through its built-in Chroma Key filter. The filter works in real time, which means the key is applied as the video is captured, not as a post-processing step. This has implications for quality: you cannot go back and adjust the key after recording, so the greenscreen OBS setup must be correct before you go live or hit record.

What you need before starting

A green screen setup in OBS requires three physical components and one software component:

• A green screen background. A green muslin or pop-up collapsible screen. The colour does not have to be a specific green paint code, but it should be a saturated, uniform green. Wrinkles and creases create shadows that the keyer cannot remove.
• Even lighting on the green screen. Two lights placed at 45-degree angles to the screen, at equal brightness, aimed to eliminate hotspots and shadows. The screen should be lit separately from the subject. Uneven lighting is the number one cause of partial key failure.
• A camera with manual controls. A webcam or DSLR where you can lock exposure, white balance, and focus. Auto-exposure shifts the image brightness between frames, which changes the green values and causes the keyer to fail intermittently.
• OBS Studio installed. Version 30 or later for current filter behaviour. The Chroma Key filter has been in OBS since early versions, so older versions also work, but the interface may differ slightly.

The subject should be positioned at least 1.5 metres from the green screen to avoid spill (green light reflecting onto the subject). If the subject is too close, no amount of spill suppression in OBS will fully remove the green tint on skin and hair.

Step 1: Add the camera source

In OBS, the Sources panel is where you add video inputs. To add a camera:

1. In the Sources panel (bottom centre of the OBS window), click the + button.
2. Select Video Capture Device.
3. Name it (for example, "Camera" or "Webcam") and click OK.
4. In the properties dialog, select your camera from the Device dropdown.
5. Set the resolution and frame rate to match your camera output. Common settings: 1920x1080 at 30 fps.
6. If your camera driver exposes manual controls, set Exposure to manual, White Balance to a fixed value (not auto), and Focus to manual. This prevents the camera from adjusting mid-stream and breaking the key.
7. Click OK. The camera feed appears in the preview, and the green screen should be visible behind the subject.

If the camera properties do not show manual exposure or focus controls, they may be available in the camera manufacturer's software or in the Video Capture Device properties under "Configure Video." Some webcams (particularly older models) do not expose these controls to OBS at all, and you will need to set them in the manufacturer's app before launching OBS.

Step 2: Add the Chroma Key filter

The Chroma Key filter is applied to the camera source, not as a separate source. To add it:

1. Right-click the camera source in the Sources panel.
2. Select Filters.
3. In the Filters window, under Effects Filters, click the + button.
4. Select Chroma Key.
5. The filter properties appear. Set the following:
   • Key Color Type: Green (this presets the key colour to standard green screen green)
   • Similarity: Start at the default (usually around 100 or 0.4 depending on version) and increase until the green disappears. If parts of the subject start disappearing, you have gone too far. Back off until only the green screen is keyed.
   • Smoothness: Start at 1 (lowest). Increase to 2 or 3 if the edge between subject and background has a hard, jagged line. Higher values soften the edge but can create a visible halo if set too high.
   • Spill Suppression: Start at 0. Increase if you see a green tint on the subject's hair, shoulders, or skin. This removes green spill reflected from the screen onto the subject.
6. Close the Filters window. The preview should now show the subject with the green screen removed (transparent, showing the OBS background colour behind).

The similarity slider is the most critical control. Too low and green patches remain. Too high and the subject begins to disappear, starting with semi-transparent areas like hair and glass. The correct value is the lowest setting that removes all visible green from the screen area. If you cannot find a value that removes green without eating the subject, the problem is almost always uneven lighting on the green screen, not the filter settings.

Chroma Key vs Color Key filter in OBS

OBS includes two keying filters: Chroma Key and Color Key. They look similar but work differently:

Use Chroma Key. Physical green screens are never a single uniform colour because lighting, fabric texture, and camera noise all create variation. Color Key only removes the exact colour you pick, so any pixel that deviates slightly remains visible as a green patch.

Step 3: Add a background source

After the chroma key removes the green, the keyed areas are transparent. To put something behind the subject, add a new source and position it below the camera source in the Sources list. In OBS, the Sources list is a layer stack: sources higher in the list appear in front of sources lower in the list.

Background source options:

• Image: Add a static image (PNG, JPG) as the background. Good for branded backgrounds, virtual offices, or solid colours. This is the simplest and most CPU-efficient option.
• Media Source: Add a video file (MP4, WebM) that plays as the background. Good for animated backgrounds. The video loops by default. CPU usage depends on the video resolution and codec.
• Browser Source: Add a web page URL as the background. Good for dynamic content like animated overlays, clock widgets, or web-based scenes. The browser source renders the page using an embedded Chromium instance.
• Scene: Add another OBS scene as a source. This lets you composite multiple scenes together, which is useful if your background itself has multiple layers.

To layer the background correctly:

1. Add the background source (click + in the Sources panel, select Image or Media Source).
2. In the Sources list, drag the background source so it is below the camera source. The camera (with its chroma key) is on top, the background is underneath.
3. Resize the background to fill the canvas. Right-click the background source, select Transform, then Fit to screen.
4. Resize the camera source so the subject is positioned correctly within the background. Right-click the camera source, select Transform, then Edit Transform to adjust position and scale.
5. Check the preview. The background should show through the areas where the green was keyed out, and the subject should be on top of the background.

If the background is not visible, the most common cause is source order. The background must be below the camera in the Sources list. If it is above, it covers the camera entirely. Right-click and select "Move Source Down" or drag it below the camera source.

The five most common OBS green screen problems and fixes

After the basic setup, these are the problems that occur most often in greenscreen OBS configurations, in order of frequency:

1. Green fringe around the subject's edges

A thin green line along the subject's outline, most visible on hair and shoulders. This is spill, caused by green light from the screen reflecting onto the subject.

Fix in OBS: Increase the Spill Suppression slider in the Chroma Key filter. Start at 0 and increase in small steps until the green tint disappears. Do not over-apply, as high spill suppression can desaturate the subject's natural skin tones.

Fix at the source: Move the subject further from the green screen (at least 1.5 metres). Reduce the brightness of the green screen lights. The spill is physical light, so if the screen is too bright or too close, no software setting will fully remove it.

2. Green patches remaining on the screen

Areas of the green screen that are not keyed out, usually in corners, behind the subject, or in shadow areas. This means the similarity is too low to catch the darker or unevenly lit green.

Fix in OBS: Increase the Similarity slider in small increments. If raising similarity causes the subject to start disappearing, stop and address the lighting instead. The screen is not uniformly lit enough for a single similarity value to key it all.

Fix at the source: Add or reposition the green screen lights. Two lights at 45-degree angles, equidistant from the screen, at equal intensity. The goal is a screen surface where every point reads the same green value to the camera. Use the OBS preview at 100% zoom to look for shadow areas on the screen before adding the filter.

3. Subject disappearing or becoming transparent

Parts of the subject (hair, clothing, skin) are being keyed out along with the green screen. This means the similarity is too high, and the keyer is removing colours that are close to green but are part of the subject.

Fix: Lower the Similarity slider. The correct value is the lowest one that removes all green from the screen. If the subject's clothing is green or green-ish, no similarity value will work: the keyer cannot distinguish green clothing from a green screen. Change the subject's clothing.

This also happens with semi-transparent subject elements: glass, sheer fabric, hair with light behind it. The keyer treats partial transparency as partial green, and removes it. There is no OBS setting that fixes this without also removing the semi-transparent element. A tighter key (lower similarity) preserves more of these elements but may leave more green on the screen.

4. Key flickers or pulses between frames

The key quality changes between frames, with the edge between subject and background shifting or the green screen partially appearing and disappearing. This is caused by the camera auto-adjusting exposure or white balance between frames, which changes the green values the keyer sees.

Fix: Lock the camera's exposure, white balance, and focus to manual. In the Video Capture Device properties, or in the camera manufacturer's software, set all three to manual mode. Once the camera stops adjusting, the green values are stable across frames and the key is consistent.

If the camera does not support manual controls (some basic webcams do not), the flicker is a hardware limitation. Workarounds: add a lamp that keeps the overall brightness constant (so the auto-exposure does not need to adjust), or use a virtual camera app with a fixed exposure before sending the feed to OBS.

5. Background source not visible behind subject

The keyed areas show the OBS default background colour (black) instead of the background source. The background source exists but is not showing through the keyed-out green.

Fix: Check the source order in the Sources panel. The background source must be below the camera source. If it is above, it covers the camera. Right-click the background source and select "Move Down" or drag it below the camera in the list.

If the order is correct and the background is still not visible, check that the Chroma Key filter is actually applied to the camera source (right-click the camera source, select Filters, and verify the Chroma Key is listed under Effects Filters). A filter that was added but not configured will not key anything, so the camera covers the background entirely.

Lighting the green screen for OBS

The quality of the OBS chroma key is determined more by the green screen lighting than by the filter settings. Even lighting produces a uniform green that the keyer can remove with a single similarity value. Uneven lighting produces a range of green values, and no single similarity setting can remove all of them without eating the subject.

The standard setup: two softbox or panel lights placed at 45 degrees to the green screen, on opposite sides, at equal distance and intensity. The lights should hit the screen at an angle that fills the surface evenly without creating hotspots (bright spots where the light is directly aimed). Move the lights further from the screen to spread the light wider and reduce hotspots.

The subject should be lit separately from the screen. Subject lighting should match the intended background: if the background is a bright office, light the subject brightly; if it is a dim scene, dim the subject lights accordingly. The common mistake is lighting the subject and the screen with the same lights, which either overexposes the screen (creating white-green that keys poorly) or underexposes the subject.

For detailed green screen lighting instructions including light placement, intensity ratios, and how to diagnose common lighting problems, see the green screen lighting guide.

Camera settings that affect the key

Three camera settings directly affect the chroma key quality in OBS:

• Exposure: Auto-exposure changes the image brightness as the subject moves, which shifts the green values and causes key flicker. Set to manual. The exposure should be set so the green screen is bright enough to read as a clear, saturated green, but not so bright that it clips to white.
• White balance: Auto white balance shifts the colour temperature, which changes the green hue the keyer targets. Set to a fixed value (typically 5600K for daylight or 3200K for warm lights). If the white balance drifts, the green screen may shift toward yellow or blue-green, and the Chroma Key filter (set to "Green") will not catch the shifted colour.
• Focus: Auto-focus can hunt during the stream, especially if the subject moves toward or away from the camera. When the focus shifts, the green screen edges blur, which changes the key quality. Set to manual focus and lock it on the subject's position.

If the camera does not expose these controls in OBS, check the manufacturer's software. Many webcams (Logitech, Microsoft, Elgato) have a separate camera settings app where manual controls can be locked. Once set in the manufacturer app, the settings persist when the camera is used in OBS.

Recording and streaming settings

The chroma key is applied in real time, so the recording or stream output includes the composited result (subject on background). There is no separate "keyed" file; what you see in the OBS preview is what is recorded.

For recording (not streaming), use these settings in OBS Settings > Output > Recording:

• Recording Format: MKV (not MP4). MKV is crash-safe; if OBS crashes mid-recording, the MKV file is intact. Remux to MP4 after recording using File > Remux Recordings.
• Encoder: Hardware encoder if available (NVIDIA NVENC H.264 or AMD HW H.264). Software x264 if no hardware encoder. Hardware encoders reduce CPU load, which matters because the chroma key filter already uses CPU.
• Rate Control: CBR (Constant Bitrate) for consistency. For recording, VBR is also acceptable if you want smaller files.
• Bitrate: 6000 to 10000 kbps for 1080p at 30 fps. 15000 to 20000 kbps for 1080p at 60 fps. The composited video (subject on background) has more visual complexity than a raw camera feed, so slightly higher bitrate is needed to avoid compression artifacts at the subject edge.
• Keyframe Interval: 2 seconds (every 60 frames at 30 fps). This is the streaming standard and works for recording.

For streaming, the settings are determined by the platform requirements (YouTube, Twitch). Set the bitrate to match the platform's recommended value for your resolution. The chroma key adds no visible overhead at streaming bitrates because the compositing is done before encoding.

CPU and performance impact

The Chroma Key filter is a CPU-based effect (it does not use the GPU). On a system with limited CPU resources, the filter adds load that can cause dropped frames during streaming or recording. The impact depends on the video resolution: 720p keys are lightweight, 1080p keys are moderate, 4K keys are heavy.

To reduce CPU load:

• Use a hardware video encoder (NVENC or AMF) for recording and streaming. This moves encoding off the CPU, leaving more CPU for the key filter.
• Keep the Smoothness slider low (1 or 2). Higher smoothness values require more processing per pixel at the key boundary.
• Stream at a lower resolution than the canvas. Use OBS's scaling filter to downscale from 1080p capture to 720p stream output. The key is applied at full resolution, but the encoded output is smaller.
• Avoid combining the Chroma Key with other heavy filters on the same source. Each effects filter on a source adds CPU load in series.

If OBS is dropping frames (check the Stats window: View > Stats), the chroma key may be the bottleneck for your greenscreen OBS setup. Test by temporarily disabling the filter and checking if the drops stop. If they do, reduce the resolution or smoothness, or switch to a hardware encoder.

Virtual green screen without a physical screen

OBS does not include built-in AI background removal. If you do not have a physical green screen, you have two options to achieve a similar effect:

1. OBS Background Removal plugin. A community plugin that uses a neural network to generate a person mask, which is then used as a key. It installs as an OBS filter and works similarly to the Chroma Key filter, but keys on person detection instead of colour. The quality depends on the model and the footage: it works well for single-person, well-lit shots, and struggles with multiple people, fast motion, or low-contrast backgrounds. It is more CPU-intensive than the colour Chroma Key.

2. Virtual camera app. Run the camera through a separate app that applies background removal, then send the processed feed to OBS as a virtual camera. This offloads the AI processing from OBS. The trade-off is an extra layer of software and potential latency between the physical camera and the OBS preview.

Both methods produce a mask-based key, not a colour key. The mask quality determines the result, and it will not match a well-lit physical green screen for edge quality, especially on hair and semi-transparent areas. For professional streaming, a physical green screen with proper lighting and the OBS Chroma Key filter produces better results at lower CPU cost than any virtual greenscreen OBS alternative.

When OBS chroma key is not the right tool

OBS is designed for real-time compositing during streaming and recording. It is not designed for post-production keying of recorded video files. If you have a pre-recorded video with a green screen and need to key it, use a video editor instead:

• For removing a green screen from a video file: DaVinci Resolve, Premiere Pro, or Final Cut Pro offer non-real-time keying with more controls (multiple matte operations, despill curves, edge refinement) that produce better results than OBS on the same footage.
• For transparent background video formats: OBS records to MP4 or MKV, which do not support alpha channels. If you need a video with transparency, use a video editor that can export WebM with alpha or ProRes 4444.
• For replacing a video background in post-production: a video editor gives you frame-by-frame control over the key and the composite, which OBS does not.
• For choosing a green screen editor for recorded footage: see the editing software comparison guide.

OBS is the right tool when you need live compositing: streaming, video conferencing, live presentation recording. For anything that will be edited after recording, capture the green screen footage raw and key it in an editor. The greenscreen OBS workflow trades post-production flexibility for real-time compositing speed.

Quick answers

Related reading: removing a green screen from video files (for post-production keying in editors), how to light a green screen (the lighting setup that determines OBS key quality), green screen for Zoom (similar setup for video conferencing), video background removal without a green screen (AI alternatives), and choosing a green screen editor (for recorded footage).