anchor.diff:  
   
   # copy ffmpeg static with libfdk from mwader docker image
  -COPY --from=mwader/static-ffmpeg:4.1.3-1 /ffmpeg /usr/local/bin/
  +COPY --from=mwader/static-ffmpeg:4.2.2 /ffmpeg /usr/local/bin/
   
   # copy compiled mp4v2 binaries, libs and fdkaac encoder to runtime image
   COPY --from=builder /usr/local/bin/mp4* /usr/local/bin/fdkaac /usr/local/bin/
   COPY --from=builder /usr/local/lib/libmp4v2* /usr/local/lib/
   
   
  +ARG M4B_TOOL_DOWNLOAD_LINK="https://github.com/sandreas/m4b-tool/releases/latest/download/m4b-tool.tar.gz"
  +
  +# workaround to copy a local m4b-tool.phar IF it exists
  +ADD ./Dockerfile ./dist/m4b-tool.phar* /tmp/
  +RUN echo "---- INSTALL M4B-TOOL ----" \
  +    && if [ ! -f /tmp/m4b-tool.phar ]; then \
  +            cd /tmp/ && \
  +            wget "${M4B_TOOL_DOWNLOAD_LINK}" && \
  +            if [ ! -f /tmp/m4b-tool.phar ]; then \
  +                tar xzf m4b-tool*.tar.gz && rm m4b-tool*.tar.gz ;\
  +            fi && \
  +            cd - ; \
  +       fi \
  +    && mv /tmp/m4b-tool.phar /usr/local/bin/m4b-tool \
  +    && chmod +x /usr/local/bin/m4b-tool
   
   WORKDIR ${WORKDIR}
  -# CMD ["list"]
  -ENTRYPOINT ["/bin/ash"]
  +CMD ["list"]
  +ENTRYPOINT ["m4b-tool"]
  +
  
positive.code: #
  ##############################
  FROM alpine:3.9.2
  
  ENV WORKDIR /m4b-tool
  ARG M4B_TOOL_DOWNLOAD_LINK="https://github.com/sandreas/m4b-tool/releases/latest/download/m4b-tool.phar"
  
  RUN echo "---- INSTALL RUNTIME PACKAGES ----" && \
    apk add --no-cache --update --upgrade \
  
negative.code:     && wget https://github.com/nu774/fdkaac/archive/1.0.0.tar.gz \
      && tar xzf 1.0.0.tar.gz \
      && cd fdkaac-1.0.0 \
      && autoreconf -i && ./configure --enable-static --disable-shared && make -j4 && make install && rm -rf /tmp/* \
  && echo "---- REMOVE BUILD DEPENDENCIES (to keep image small) ----" \
      && apk del --purge build-dependencies && rm -rf /tmp/*
  
  