Provide Dockerfile, build fixes

Fixes Kagami#44

.gitignore

@@ -1,3 +1,3 @@
 /node_modules/
 /ffmpeg*.js
-/*.wasm
+/ffmpeg*.wasm

Dockerfile

@@ -0,0 +1,7 @@
+FROM ubuntu:rolling
+
+RUN sed -i 's|http://archive.ubuntu.com/ubuntu/|mirror://mirrors.ubuntu.com/mirrors.txt|g' /etc/apt/sources.list \
+ && apt-get update && apt-get install -y git python build-essential automake libtool pkg-config && apt-get clean \
+ && cd /root && git clone https://github.com/emscripten-core/emsdk.git \
+ && cd /root/emsdk && ./emsdk install latest && ./emsdk activate latest \
+ && sed -i 's|\]$|],"getrusage":["memset"]|' /root/emsdk/upstream/emscripten/src/deps_info.json

Makefile

@@ -124,6 +124,9 @@ build/x264/dist/lib/libx264.so:
 		--enable-shared \
 		--disable-opencl \
 		--disable-thread \
+		--disable-interlaced \
+		--bit-depth=8 \
+		--chroma-format=420 \
 		--disable-asm \
 		\
 		--disable-avs \
@@ -165,10 +168,9 @@ FFMPEG_COMMON_ARGS = \
 	--enable-ffmpeg \
 	--enable-avcodec \
 	--enable-avformat \
-	--enable-avutil \
+	--enable-avfilter \
 	--enable-swresample \
 	--enable-swscale \
-	--enable-avfilter \
 	--disable-network \
 	--disable-d3d11va \
 	--disable-dxva2 \

README.md

@@ -133,22 +133,39 @@ ffmpeg({
 ```
 
 ## Build instructions
-Tips, use a [docker](https://www.docker.com/) container (basic ubuntu is good)
+
+It's recommended to use [Docker](https://www.docker.com/) to build ffmpeg.js.
+
+1.  Clone ffmpeg.js repository with submodules:
+    ```bash
+    git clone https://github.com/Kagami/ffmpeg.js.git --recurse-submodules
+    ```
+
+2.  Modify Makefile and/or patches if you wish to make a custom build.
+
+3.  Build everything:
+    ```bash
+    docker run --rm -it -v /path/to/ffmpeg.js:/mnt kagamihi/ffmpeg.js
+    # cp -a /mnt/{.git,build,Makefile} /opt && cd /opt && . /root/emsdk/emsdk_env.sh && make && cp ffmpeg*js /mnt
+    ```
+
+That's it. ffmpeg.js modules should appear in your repository clone.
+
+## Build without Docker
+
+Ubuntu example:
 
 ```bash
-apt-get update
-apt-get -y install python python3-distutils git automake libtool build-essential
+apt-get update && apt-get install -y git python build-essential automake libtool pkg-config
 
-cd /root # or /home/whatever
-git clone https://github.com/emscripten-core/emsdk.git
-cd emsdk
+cd /root
+git clone https://github.com/emscripten-core/emsdk.git && cd emsdk
 ./emsdk install latest
 ./emsdk activate latest
-source ./emsdk_env.sh
+source emsdk_env.sh
 
-cd /root # or /home/whatever
-git clone https://github.com/Kagami/ffmpeg.js.git --recurse-submodules
-cd ffmpeg.js
+cd /root
+git clone https://github.com/Kagami/ffmpeg.js.git --recurse-submodules && cd ffmpeg.js
 make
 ```