WebM is a video format designed to be a royalty-free alternative to the H.264 codec used in the MP4 format.

The added functionality, first spotted by The 8-Bit, allows users to play WebM videos in Safari for the first time. As you can see libx265 does not yet support alpha.Safari features support for WebM video playback in the second beta of macOS Big Sur 11.3 Beta, indicating that Apple's browser will finally support the format after failing to do so for almost 11 years. If it supported alpha it would have pixel format with an a in the name, such as yuva420p or rgba.

Supported pixel formats: yuv420p yuvj420p yuv422p yuvj422p yuv444p yuvj444p gbrp yuv420p10le yuv422p10le yuv444p10le gbrp10le yuv420p12le yuv422p12le yuv444p12le gbrp12le gray gray10le gray12le Checking if an encoder supports alpha / transparency $ ffmpeg -h encoder=libx265 This answer may become outdated due to continuous developments, so make sure to research the current situation. See ffmpeg -h encoder=hevc_videotoolbox for more info. The 'HEVC Video with Alpha' profile will only be used when the -alpha_quality value is not 0 (default is 0, range 0-1.). This has been updated after FFmpeg 4.3 was released, so you'll have to use a build from the current git branch, or wait for 4.4.Įxample command adapted from the relevant commit: ffmpeg -i input%03d.png -c:v hevc_videotoolbox -allow_sw 1 -alpha_quality 0.75 -vtag hvc1 output.mov

This is a hardware accelerated encoder for Apple hardware. It supports 7 HEVC/H.265 external encoders (most are hardware based) including libx265 which does not currently support alpha.Īs of now only the VideoToolbox HEVC Encoder ( -c:v hevc_videotoolbox) supports alpha. VideoToolbox supports alpha / transparencyįFmpeg does not have its own HEVC/H.265 encoder.

Webm codec after effects