WebAssembly build

[FluorescentHallucinogen]

What about compiling FFMPEG to WebAssembly?

There are experimental native WebAssembly implementations for Google Chrome, Mozilla Firefox, Microsoft Edge and Apple Safari.

[Kagami]

I'll look into this, thanks. Though I don't think this will give big speedup compared to asm.js since it's just another format for the same thing. The really promising feature would be SIMD.js.

[FluorescentHallucinogen]

I mean compile FFMPEG directly to WebAssembly.

It is possible to compile any (LLVM-based) programming language other than JavaScript (initially mainly C/C++) to WebAssembly. See http://2ality.com/2015/06/web-assembly.html for more info.

[Kagami]

There is no real difference between compiling to asm.js or compiling to wasm. Most important advantage is load time, in terms of speed Firefox uses AOT compilation for asm.js anyway, so it shouldn't be faster.

I don't mean wasm is bad, just trying to say that pros are mostly related to initial loading/better browser support/standartization/etc.

[amilajack]

Judging by the wasm demo, it seems like there is a big performance difference.

[jfizz]

This might be a useful read: https://hacks.mozilla.org/2017/03/why-webassembly-is-faster-than-asm-js/. It highlights the performance differences between asm.js and WebAssembly.

[jfizz]

I am attempting to to give this a try (compiling to WebAssembly). First I built "ffmpeg-worker-webm.js" without any modifications to make sure I could successfully build on my machine. I was able to build and run that in my browser without any issues. To convert to WebAssembly, I took a look at https://github.com/kripken/emscripten/wiki/WebAssembly. I concluded that I needed to add the flag: -s WASM=1. Trying that in the browser leads to the following output in the console:

ffmpeg version n3.1.2 Copyright (c) 2000-2016 the FFmpeg developers
  test:66:13
  built with emcc (Emscripten gcc/clang-like replacement) 1.37.10 (commit 4ee1557a8f2473405971d4872bf71199174a2776)
  test:66:13
  configuration: --cc=emcc --enable-cross-compile --target-os=none --arch=x86 --disable-runtime-cpudetect --disable-asm --disable-fast-unaligned --disable-pthreads --disable-w32threads --disable-os2threads --disable-debug --disable-stripping --disable-all --enable-ffmpeg --enable-avcodec --enable-avformat --enable-avutil --enable-swresample --enable-swscale --enable-avfilter --disable-network --disable-d3d11va --disable-dxva2 --disable-vaapi --disable-vda --disable-vdpau --enable-decoder=vp8 --enable-decoder=vp9 --enable-decoder=theora --enable-decoder=mpeg2video --enable-decoder=mpeg4 --enable-decoder=h264 --enable-decoder=hevc --enable-decoder=png --enable-decoder=mjpeg --enable-decoder=vorbis --enable-decoder=opus --enable-decoder=mp3 --enable-decoder=ac3 --enable-decoder=aac --enable-decoder=ass --enable-decoder=ssa --enable-decoder=srt --enable-decoder=webvtt --enable-demuxer=matroska --enable-demuxer=ogg --enable-demuxer=avi --enable-demuxer=mov --enable-demuxer=flv --enable-demuxer=mpegps --enable-demuxer=image2 --enable-demuxer=mp3 --enable-demuxer=concat --enable-protocol=file --enable-filter=aresample --enable-filter=scale --enable-filter=crop --enable-filter=overlay --disable-bzlib --disable-iconv --disable-libxcb --disable-lzma --disable-sdl --disable-securetransport --disable-xlib --disable-zlib --enable-encoder=libvpx_vp8 --enable-encoder=libopus --enable-encoder=mjpeg --enable-muxer=webm --enable-muxer=ogg --enable-muxer=null --enable-muxer=image2 --enable-filter=subtitles --enable-libass --enable-libopus --enable-libvpx --extra-cflags=-I../libvpx/dist/include --extra-ldflags=-L../libvpx/dist/lib
  test:66:13
exception thrown: RuntimeError: integer overflow,wasm-function[5914]@http://localhost:9001/ffmpeg-worker-webm.js:7049272:1
wasm-function[5297]@http://localhost:9001/ffmpeg-worker-webm.js:7012313:1
wasm-function[1336]@http://localhost:9001/ffmpeg-worker-webm.js:5172982:1
wasm-function[4434]@http://localhost:9001/ffmpeg-worker-webm.js:6896029:1
wasm-function[2360]@http://localhost:9001/ffmpeg-worker-webm.js:6081367:1
ab/d._main@http://localhost:9001/ffmpeg-worker-webm.js:166:255
ab/d.qf@http://localhost:9001/ffmpeg-worker-webm.js:179:497
b@http://localhost:9001/ffmpeg-worker-webm.js:18:170
Sa@http://localhost:9001/ffmpeg-worker-webm.js:19:74
b@http://localhost:9001/ffmpeg-worker-webm.js:179:234
la@http://localhost:9001/ffmpeg-worker-webm.js:12:144
d@http://localhost:9001/ffmpeg-worker-webm.js:41:413
n/<@http://localhost:9001/ffmpeg-worker-webm.js:42:420
  ffmpeg-worker-webm.js:26:351
failed to asynchronously prepare wasm: RuntimeError: integer overflow  ffmpeg-worker-webm.js:26:351

@Kagami Do you happen to have any advice? I will admit, I am not terribly familiar with WebAssembly/asm.js, so I might be completely off the mark. I am just interested in the performance benefits that WebAssembly (potentially) offers.

[Elite]

@jfizz Here you go https://github.com/jonasof/videoconverter.js-wasm-demo/tree/master/wasm :)

[PaulKinlan]

That is interesting... I was suprised that WASM is considerably slower...

[mityok]

I'm getting more than twice the processing duration:

• about 6s video to snapshots on asm

• about 12s video to snapshots on wasm

very strange...

[shortercode]

I've been running tests on a fork of audioconverter.js and wasm doesn't seem to be giving much of an improvement, I haven't been able to create a proper benchmark for it yet but I've put some console.time calls in preRun and postRun. These are the results:

 [
  "File: Blink WASM: 13338.362426757812 ASM.js: 16333.235107421875 Diff: 82%",
  "File: Bad Seed WASM: 15875.986450195312 ASM.js: 18935.072998046875 Diff: 84%",
  "File: Dare WASM: 16816.656127929688 ASM.js: 19954.324462890625 Diff: 84%",
  "File: Cut Glass WASM: 17789.992553710938 ASM.js: 20735.35205078125 Diff: 86%",
  "File: sfx5 WASM: 110.224609375 ASM.js: 88.295166015625 Diff: 125%",
  "File: zelda_hey WASM: 31.7159423828125 ASM.js: 28.7606201171875 Diff: 110%",
  "File: zelda_item WASM: 218.906005859375 ASM.js: 171.7296142578125 Diff: 127%",
  "File: zelda_laugh WASM: 114.4654541015625 ASM.js: 85.4129638671875 Diff: 134%",
  "File: oglseby7 WASM: 11469.507934570312 ASM.js: 8620.97802734375 Diff: 133%",
  "File: zelda_menu WASM: 177.5545654296875 ASM.js: 87.14990234375 Diff: 204%",
  "File: zelda_shock WASM: 29.5728759765625 ASM.js: 20.3790283203125 Diff: 145%",
  "File: Phantom Lover WASM: 17242.292846679688 ASM.js: 15581.1845703125 Diff: 111%",
  "File: Simple Pleasures WASM: 15349.696533203125 ASM.js: 14238.008544921875 Diff: 108%"
]

Tests were converting wav files to webm opus ( audio only ), and each one was run twice.

Obviously needs more iterations and using something a little more accurate than console.time but it demonstrates the point. WASM proves to be fairly disappointing thus far in terms of performance improvements. Also chrome seems to crash occasionally with the WASM version, which is less than ideal.

[picitujeromanov]

Anybody still interested? Managed to compile it with O2 optimization. Compiling to wasm reduced size to 7mb, I have slight performance increase in some scenarios on Chrome and really nice performance boost on firefox ... my only remaining issue is that even with ALLOW_MEMORY_GROWTH=1 i still manage to crash chrome tab if I render 9 minute video with ultrafast preset and some filters

this build has added concat filter and mjpeg and image2 support for mp4_build as well
ffmpeg-wasm3.zip

[XIAZY]

@picitujeromanov thank you for your build, it works! (and faster than asm.js with -O3 on my machine)
do you have any advice on compiling it to wasm? thanks a lot