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ffmpeg.wasm uses transpiled FFmpeg C source code to WebAssembly code, it is for certain that ffmpeg.wasm won't perform as good as FFmpeg as it is not fully optimized at the moment. (Even in ffmpeg.wasm multithread version). In this section we provide a short comparison, so that you can make decision based on your needs:


  • CPU: 8 × 11th Gen Intel® Core™ i5-1135G7 @ 2.40GHz
  • Memory: 15.6 GiB of RAM
  • OS: Manjaro Linux 6.1.44-1-MANJARO (64-bit)
  • Browser: Google Chrome Version 116.0.5845.96 (Official Build) (64-bit)
  • FFmpeg: n5.1.2



  • Each command is executed 5 times.
  • Only ffmpeg.exec() time is measured.
  • Candidates
    • FFmpeg: native FFmpeg, considered as baseline.
    • core: ffmpeg.wasm single thread version.
    • core-mt: ffmpeg.wasm multi thread version.

$ ffmpeg -i input.webm output.mp4

#FFmpegcore v0.12.3core-mt v0.12.3
Avg5.2 sec128.8 sec (0.04x)60.4 sec (0.08x)
Max5.3 sec130.7 sec63.9 sec
Min5.1 sec126.6 sec59 sec