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@ffmpeg/core

To build @ffmpeg/core, make sure your docker is version 23.0+ as buildx is adopted. Also You will need to install make to run build scripts.

Build​

Dev Build (single thread):

$ make dev

Dev Build (multithread):

$ make dev-mt

Prodution Build (single thread):

$ make prd

Prodution Build (multithread):

$ make prd-mt

Each build might take around 1 hour depends on the spec of your machine, subsequent builds are faster as most layers are cached.

The output file locates at /packages/core or /packages/core-mt.

Custom Build / Reduce Build Size​

You can customize your build to include only the libraries you need, which can significantly reduce the final build size. This is done by modifying the Dockerfile.

Step-by-Step Example: Removing WebP Support​

Here's how to remove libwebp (WebP image support) from the build. The same principle applies to other libraries.

You need to make changes in 4 places in the Dockerfile:

1. Remove the library builder stage​

Find the stage that builds the library you want to remove and delete the entire block:

# Remove this entire block
FROM emsdk-base AS libwebp-builder
COPY --from=zlib-builder $INSTALL_DIR $INSTALL_DIR
ENV LIBWEBP_BRANCH=v1.3.2
ADD https://github.com/ffmpegwasm/libwebp.git#$LIBWEBP_BRANCH /src
COPY build/libwebp.sh /src/build.sh
RUN bash -x /src/build.sh

2. Remove the COPY instruction​

In the ffmpeg-base stage, remove the line that copies the built library:

# Remove this line
COPY --from=libwebp-builder $INSTALL_DIR $INSTALL_DIR

3. Remove the configure flag​

In the ffmpeg-builder stage, remove the corresponding --enable-lib... flag:

# Remove this line from the ffmpeg-builder stage
--enable-libwebp \

4. Remove the linker flags​

In the ffmpeg-wasm-builder stage, remove the library from FFMPEG_LIBS:

# Remove these lines from FFMPEG_LIBS
-lwebpmux \
-lwebp \
-lsharpyuv \

💡 Pro Tip: Start by removing just the main library flag (e.g., -lwebp). If the build fails with "undefined reference" errors, those errors will tell you exactly which additional libraries to remove.

5. Build and test​

# Run the build command
make prd

# Output will be in packages/core/dist/

Additional Build Size Optimization:

You can sometimes play around with build/ffmpeg-wasm.sh and build/ffmpeg.sh to disable things you are not using to make the size smaller.

More Advance Customization Example: Creating a Minimal Build​

For more advanced customization, you might want to create a minimal build that only includes the features you need. A good example is creating a build that can create a video from a sequence of images (e.g., from an HTML canvas), handle MP4 encoding/decoding, and support audio.

A community member, @Kaizodo, shared an approach that resulted in a build size of only 4.80MB. You can find the full details and a discussion in GitHub Issue #866.

The general strategy is to:

  1. Start with a minimal configuration: Instead of removing libraries one by one, a more effective approach is to start with a minimal ffmpeg configuration. This can be achieved by using flags like --disable-everything in the ffmpeg configuration step within the Dockerfile.
  2. Enable specific components: After disabling everything, you can selectively enable only the encoders, decoders, muxers, demuxers, and protocols you need for your specific use case. For example: --enable-encoder=libx264, --enable-decoder=png, --enable-muxer=mp4, etc.
  3. Include only necessary libraries: Make sure your Dockerfile only builds and links the external libraries that correspond to the features you enabled (e.g., libx264). You can remove the build stages for any other libraries.

This approach gives you control over the build content and its final size.

We would like to thank @Kaizodo, @harkdawg and other community members for sharing their knowledge!

Publish​

Simply run npm publish under packages/core or /packages/core-mt.