transparent background video

Most of the confusion around transparent background video comes from conflating two different things: removing the background (a keying or masking operation that produces a matte) and storing the transparency (an export format with alpha support). You can have a perfect key and still lose it by exporting to the wrong format. This page is about the second part: which formats carry alpha, how to set up the export, and what to check when the result comes back with a solid background instead of a transparent one.

What "transparent background video" actually means

A standard video frame has three colour channels: red, green, and blue. Every pixel has an RGB value, and the background is whatever colour was shot or keyed. A transparent background video adds a fourth channel: alpha. Alpha measures how opaque each pixel is, from 0 (fully transparent, nothing visible) to 255 (fully opaque). When the background pixels have an alpha of 0, the viewer sees through them to whatever is behind the video, whether that is a web page, a lower-third graphic, or another video layer in a compositor.

The alpha channel is not a visual effect. It is data stored in the file. If the format does not support alpha, the data is discarded on export, and the player fills the empty areas with black. This is why exporting a keyed clip as MP4 produces a black background: H.264 has no field for alpha, so the encoder writes 0 for RGB on the keyed pixels and no transparency information at all.

Formats that carry alpha vs formats that do not

Codec support changes over time. HEVC with Alpha is an Apple extension, not part of the standard HEVC specification. VP9 alpha support depends on the encoder and the player. Verify with your specific toolchain before committing to a format for a production pipeline.

PNG sequences vs single-file transparent video

A PNG image sequence is not a video file. It is a folder of numbered PNG files, one per frame, each storing RGBA data with a full alpha channel. When you import the sequence into a video editor or compositor, the software treats the numbered files as consecutive frames and plays them back as a clip. The advantage is universal alpha support, every tool that reads PNG can read the transparency, and no codec negotiation. The disadvantage is file count: a 10-second clip at 30 fps is 300 PNG files, and a 60-second clip is 1,800.

A true transparent video is a single container file. WebM with VP8/VP9 alpha stores the transparency inside the bitstream, so one file contains both colour and alpha for every frame. MOV with ProRes 4444 does the same in a QuickTime container. These are easier to handle, transfer, and play, but they depend on the player supporting the alpha codec.

The practical split: if you are delivering to a web page or an app that supports WebM alpha, export WebM. If you are handing off to another editor or a VFX pipeline, export ProRes 4444 or a PNG sequence. If you are delivering to social media or a platform that does not support alpha, composite the new background before exporting, because you cannot deliver a transparent video to a platform that flattens alpha.

How to export a transparent WebM

WebM with alpha is the format most people want when they search for transparent background video, because it plays in modern browsers and produces a single file. The export path depends on your editor:

DaVinci Resolve (free): On the Deliver page, set the format to WebM and the codec to VP9. In the video tab, check "Export Alpha" if the option is available for your version. If your version does not expose the alpha toggle for WebM, export a PNG sequence and convert it to WebM with alpha using FFmpeg: ffmpeg -i frame_%04d.png -c:v libvpx-vp9 -pix_fmt yuva420p -auto-alt-ref 0 -b:v 1M output.webm

Adobe Premiere Pro: Install the WebM plugin (not bundled by default), or use the Export Settings to match the WebM VP9 format with alpha. Without the plugin, Premiere does not export WebM with alpha natively. The alternative is to export ProRes 4444 from Premiere and convert to WebM with alpha in FFmpeg or Adobe Media Encoder.

After Effects: Add the composition to the Render Queue, set the output module to WebM (if the plugin is installed) or use the built-in ProRes 4444 option with RGB+Alpha channels. For direct WebM export, third-party plugins like Fnord Software's WebM plugin for After Effects enable alpha in the output module.

FFmpeg (command line): If you have a keyed clip or a PNG sequence, FFmpeg is the most reliable path to a transparent WebM. The key flags are -pix_fmt yuva420p (pixel format with alpha) and -auto-alt-ref 0 (disables the alternate reference frame mechanism that strips alpha in some VP8/VP9 encoder configurations).

How to export a transparent MOV (ProRes 4444)

ProRes 4444 is the standard alpha-carrying format for post-production. It is supported natively by Final Cut Pro, Premiere Pro, After Effects, and DaVinci Resolve Studio. The file sizes are large, roughly 100 to 200 MB per minute at 1080p, because ProRes uses minimal compression to preserve quality for editing rather than delivery.

To export: in your editor's export or deliver settings, choose QuickTime (MOV) as the container, ProRes 4444 as the codec, and set the colour space to include alpha (RGB+Alpha or RGBA). If the option says "millions of colours" instead of "trillions of colours," you are exporting ProRes 422 (no alpha), not 4444. The number after ProRes matters: 422 and 422 HQ do not carry alpha; 4444 does.

How to export a PNG image sequence with alpha

Every editor that supports video export supports PNG sequences. Set the export format to Image Sequence or PNG Sequence, choose a destination folder, and the editor writes numbered PNG files (frame_0001.png, frame_0002.png, and so on). Each PNG contains RGBA data with a full alpha channel, so the transparency is preserved per pixel, per frame.

The sequence can be reassembled into a video in any editor or compositor by importing the folder as an image sequence. FFmpeg can also convert the sequence to a transparent WebM or ProRes 4444 MOV, as described above. The downside is storage: PNG sequences are uncompressed or lightly compressed, so a 30-second 1080p clip at 30 fps is about 900 files and 2 to 5 GB.

Why your transparent video has a black background

This is the most common failure, and it has three causes:

1. Wrong format. You exported as MP4 (H.264 or H.265), which has no alpha channel. The keyed pixels are written as RGB 0,0,0, and the player shows black. Fix: export as WebM with alpha, ProRes 4444, or a PNG sequence.

2. Alpha disabled in export settings. You chose a format that supports alpha but the editor's export panel has alpha turned off by default. In Premiere Pro, the Video tab has a "Render at Maximum Depth" and "Include Alpha" toggle that must be checked. In DaVinci Resolve, the Deliver page has an "Export Alpha" checkbox. In After Effects, the Output Module must be set to RGB+Alpha, not RGB only.

3. Player does not support alpha. The file has alpha, but the player ignores it. Windows Media Player does not render WebM alpha. QuickTime Player on Windows does not render ProRes 4444 alpha. To verify alpha is present, open the file in a Chromium-based browser (drag the file into the browser window) or in VLC with the transparent background option enabled.

How to verify transparency before delivery

Before you deliver a transparent video, verify that alpha is actually present. The fastest method: open the file in a Chromium browser by dragging it into a new tab. If the background is transparent, the browser's default background (white or dark grey, depending on theme) shows through. If the background is solid black, alpha is missing or the player does not render it.

For a per-pixel check, use FFmpeg to extract one frame as PNG: ffmpeg -i transparent.webm -vframes 1 -pix_fmt rgba frame_check.png. Open the PNG in an image editor that shows alpha (such as the browser-based green screen remover tool on this site, which displays a checkerboard where alpha is 0). If the checkerboard appears behind the subject, the alpha channel is intact.

Transparent video for web pages (HTML5)

If you are embedding a transparent video on a web page, use the <video> element with a WebM source. The browser renders the alpha channel natively in Chromium and Firefox. Safari support depends on the version and codec: HEVC with Alpha works on Apple devices, and recent Safari versions (14+) also support WebM with VP9 alpha, but older versions do not.

For cross-browser coverage, provide both WebM and HEVC-with-Alpha sources using the <source> tag. The browser picks the first one it can decode:

<video autoplay loop muted playsinline>
  <source src="overlay.webm" type="video/webm">
  <source src="overlay.mov" type="video/quicktime">
</video>

The muted and playsinline attributes are required for autoplay on mobile browsers. Without them, the video will not start playing without user interaction.

Starting from a green screen

If your source footage is a green screen shoot, the path to a transparent video is shorter and cleaner than AI removal. Key the green in your editor to produce a matte, then export to WebM with alpha, ProRes 4444, or a PNG sequence. The key produces the alpha, the format preserves it. A green screen key produces cleaner edges than AI segmentation on most footage, because the background colour is known and uniform, which makes the matte boundary deterministic rather than inferred.

If you do not have green screen footage, the path goes through AI background removal first, then the same export step. The AI tool produces a matte that may be less clean at the edges, but the export format and verification steps are identical.

Quick answers

Related reading: removing a green screen from video (the keying settings that produce the matte), removing a video background without a green screen (AI and manual methods), the 12-point quality check before export (verifying your key before committing to a format), and choosing a green screen editor (which editors support alpha export).