ffmpegmakefileffmpeg-wasm

FFmpeg WASM Custom build : defining custom flags

I wish to create custom ffmpeg.wasm build

Now the official GUIDE show four commands "make dev" "make prd" etc

So I cloned THE REPO and ran "make prd". It did build, but obviously, this build was with default settings, whatever exactly they made be.

So pardon my stupidity, as I cannot figure out how / where / what do I edit to set the custom flags about what I want to be included / excluded in the build?

Solution

  • For anyone else wondering about this, I got my custom build. Here is what I did

    1. This is more of a prerequisite but just in case : Im on windows so I have Docker Desktop running and WSL 2 enabled and running. I boot up my Ubuntu installation and run commands there. (Tried directly from windows but was a headache and I did not get it to work)

    2. I only needed webm muxers. 0 encoders / 0 decoders

    3. I removed most of the stuff from Dockerfile

    this is my Dockerfile

    # syntax=docker/dockerfile-upstream:master-labs

# Stage 1: Base Emscripten environment
FROM emscripten/emsdk:3.1.40 AS emsdk-base
ARG EXTRA_CFLAGS
ARG EXTRA_LDFLAGS
ENV INSTALL_DIR=/opt
ENV FFMPEG_VERSION=n5.1.4
ENV CFLAGS="-I$INSTALL_DIR/include $CFLAGS $EXTRA_CFLAGS"
ENV CXXFLAGS="$CFLAGS"
ENV LDFLAGS="-L$INSTALL_DIR/lib $LDFLAGS $CFLAGS $EXTRA_LDFLAGS"
ENV EM_PKG_CONFIG_PATH=$EM_PKG_CONFIG_PATH:$INSTALL_DIR/lib/pkgconfig:/emsdk/upstream/emscripten/system/lib/pkgconfig
ENV EM_TOOLCHAIN_FILE=$EMSDK/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake
ENV PKG_CONFIG_PATH=$PKG_CONFIG_PATH:$EM_PKG_CONFIG_PATH
RUN apt-get update && \
    apt-get install -y pkg-config autoconf automake libtool ragel

# Stage 2: Build zlib
FROM emsdk-base AS zlib-builder
ENV ZLIB_BRANCH=v1.2.11
ADD https://github.com/ffmpegwasm/zlib.git#$ZLIB_BRANCH /src
COPY build/zlib.sh /src/build.sh
RUN bash -x /src/build.sh

# Stage 3: Base FFmpeg image with source code and zlib
FROM emsdk-base AS ffmpeg-base
RUN embuilder build sdl2 sdl2-mt
ADD https://github.com/FFmpeg/FFmpeg.git#$FFMPEG_VERSION /src
COPY --from=zlib-builder $INSTALL_DIR $INSTALL_DIR

# Stage 4: Build FFmpeg with specified configuration
FROM ffmpeg-base AS ffmpeg-builder
COPY build/ffmpeg.sh /src/build.sh
RUN bash -x /src/build.sh \
    --disable-all \
    --enable-protocol=file \
    --enable-avcodec \
    --enable-avformat \
    --enable-avfilter \
    --enable-demuxer=concat,matroska \
    --enable-muxer=matroska \
    --enable-parser=vp8,vp9,opus,vorbis

# Stage 5: Build FFmpeg WebAssembly module
FROM ffmpeg-builder AS ffmpeg-wasm-builder
COPY src/bind /src/src/bind
COPY src/fftools /src/src/fftools
COPY build/ffmpeg-wasm.sh /src/build.sh
RUN mkdir -p /src/dist/umd && bash -x /src/build.sh \
    -o dist/umd/ffmpeg-core.js
RUN mkdir -p /src/dist/esm && bash -x /src/build.sh \
    -sEXPORT_ES6 \
    -o dist/esm/ffmpeg-core.js

# Stage 6: Export the built files
FROM scratch AS exportor
COPY --from=ffmpeg-wasm-builder /src/dist /dist

    4. Needed to also edit ffmpeg.sh and ffmpeg-wasm.sh in the "build" folder

    this is -wasm.sh

    #!/bin/bash
# `-o <OUTPUT_FILE_NAME>` must be provided when using this build script.
# ex:
#     bash ffmpeg-wasm.sh -o ffmpeg.js

set -euo pipefail

EXPORT_NAME="createFFmpegCore"

CONF_FLAGS=(
  -I. 
  -I./src/fftools 
  -I$INSTALL_DIR/include 
  -L$INSTALL_DIR/lib 
  libavfilter/libavfilter.a
  libavformat/libavformat.a
  libavcodec/libavcodec.a
  libavutil/libavutil.a
  -Wno-deprecated-declarations 
  $LDFLAGS 
  -sENVIRONMENT=worker
  -sWASM_BIGINT
  -sUSE_SDL=2
  -sMODULARIZE
  ${FFMPEG_MT:+ -sINITIAL_MEMORY=1024MB}
  ${FFMPEG_MT:+ -sPTHREAD_POOL_SIZE=32}
  ${FFMPEG_ST:+ -sINITIAL_MEMORY=32MB -sALLOW_MEMORY_GROWTH}
  -sEXPORT_NAME="$EXPORT_NAME"
  -sEXPORTED_FUNCTIONS=$(node src/bind/ffmpeg/export.js)
  -sEXPORTED_RUNTIME_METHODS=$(node src/bind/ffmpeg/export-runtime.js)
  -lworkerfs.js
  --pre-js src/bind/ffmpeg/bind.js
  src/fftools/cmdutils.c 
  src/fftools/ffmpeg.c 
  src/fftools/ffmpeg_filter.c  # For filter function definitions
  src/fftools/ffmpeg_hw.c      # For hardware functions
  src/fftools/ffmpeg_mux.c 
  src/fftools/ffmpeg_opt.c 
  src/fftools/opt_common.c 
  src/fftools/ffprobe.c        # Added for ffprobe functionality
)

emcc "${CONF_FLAGS[@]}" $@

    and this is ffmpeg.sh

    #!/bin/bash

set -euo pipefail

CONF_FLAGS=(
  --target-os=none              # Disable target specific configs
  --arch=x86_32                 # Use x86_32 arch
  --enable-cross-compile        # Use cross compile configs
  --disable-asm                 # Disable asm
  --disable-stripping           # Disable stripping as it won't work
  # --disable-programs          # Removed to allow building programs like ffprobe
  --disable-doc                 # Disable doc build
  --disable-debug               # Disable debug mode
  --disable-runtime-cpudetect   # Disable cpu detection
  --disable-autodetect          # Disable env auto detect
  --enable-avcodec              # Enable avcodec
  --enable-avformat             # Enable avformat
  --enable-avfilter             # Enable avfilter

  # Assign toolchains and extra flags
  --nm=emnm
  --ar=emar
  --ranlib=emranlib
  --cc=emcc
  --cxx=em++
  --objcc=emcc
  --dep-cc=emcc
  --extra-cflags="$CFLAGS"
  --extra-cxxflags="$CXXFLAGS"

  # Disable thread when FFMPEG_ST is NOT defined
  ${FFMPEG_ST:+ --disable-pthreads --disable-w32threads --disable-os2threads}
)

emconfigure ./configure "${CONF_FLAGS[@]}" $@
emmake make -j

    Now to say that I completely understand whats going on would be a lie :D
    I did some notorious "vibe-coding" with Grok to reach this.

    By the end, after running "make prd" I got my .wasm and .js
    Original 30mb now 1.06mb

    Everything works on the frontend.