Converting Video to a Transparent Format - Windows

This article explains how to convert MOV/MP4 files (for example, videos with a green/blue/black background or footage) into transparent video files suitable for FMX for Windows.
The workflow includes two parts:

1. After Effects – remove the background and export a video with an alpha channel.

2. FFmpeg – compress the transparent file to reduce size while keeping quality.

1. Create the Transparent Video in After Effects

Step 1: Open and Import

• Launch Adobe After Effects.

• Import your video into the Project panel.

Step 2: Create a Composition

• Drag the video onto the New Composition button to create a comp with matching settings (typically 1080×1920 for vertical videos).

Step 3: Apply Keying to Remove the Background

1. Open Effects & Presets.

2. Go to Keying → Linear Color Key.

3. Drag the effect onto your video layer.

4. In Effect Controls, use the Eyedropper next to Key Color and click the black background.

5. Adjust the matching tolerance until the background is fully removed and clean.

Step 4: Export With Transparency

1. Go to Composition → Add to Render Queue.

2. In the Render Queue, click Output Module (Lossless).

3. Set Format to QuickTime.

4. Under Video Output → Channels, choose RGB + Alpha.

5. Select one of the transparency-supported codecs:

   • Animation

   • Apple ProRes 4444

6. Render the file.

This exported MOV now contains transparency and is ready for compression.

2. Install FFmpeg (Windows)

Option A: Recommended — Official Static Build

1. Go to https://ffmpeg.org/download.html

2. Under Windows Builds, choose a reliable provider (e.g., gyan.dev).

3. Download ffmpeg-release-essentials.zip.

4. Extract it to a folder such as C:\FFmpeg.

5. Inside the bin folder, you'll find ffmpeg.exe.

Option B: Adding FFmpeg to PATH (Optional)

To run FFmpeg from any folder:

1. Open System Properties → Environment Variables.

2. Edit Path and add:
   C:\FFmpeg\bin

3. Restart CMD.

Otherwise, place your video files inside the bin folder and run commands there.

3. Compress the Transparent Video With FFmpeg

Since FMX workflows standardize at 1080×1920, we keep the original resolution. No resizing is applied.

Step 1: Prepare

Copy your exported transparent .mov into the FFmpeg bin folder.

Step 2: Run CMD

Open Command Prompt:

cd C:\FFmpeg\bin

Step 3: Run the Conversion Command

Replace input.mov with your file name:

ffmpeg -i input.mov -c:v png -pix_fmt rgba output_transparent.mov

Command Explanation

• -c:v png
  Uses PNG video encoding, which preserves transparency while reducing file size significantly compared to uncompressed exports.

• -pix_fmt rgba
  Ensures the output contains an alpha channel.

• No scale filter
  The output remains at 1080×1920, which is recommended for FMX.

Final Notes

• FMX supports transparent MOV files encoded in PNG or ProRes 4444.

• If transparency is missing, verify:

  • After Effects export uses RGB + Alpha.

  • FFmpeg output uses -pix_fmt rgba.

• PNG is preferred for FMX because it balances quality, file size, and compatibility.