anchor.diff:  
   
   # copy ffmpeg static with libfdk from mwader docker image
  -COPY --from=mwader/static-ffmpeg:4.2.2 /ffmpeg /usr/local/bin/
  +COPY --from=mwader/static-ffmpeg:4.4.0 /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/
  
positive.code: #   m4b-tool development image
  #
  ##############################
  FROM alpine:3.9.2
  ENV WORKDIR /mnt/
  ENV M4BTOOL_TMP_DIR /tmp/m4b-tool/
  
  
negative.code: #   alias m4b-tool='docker run -it --rm -u $(id -u):$(id -g) -v "$(pwd)":/mnt m4b-tool'
  #   alias m4b-tool='docker run -it --entrypoint=m4b-tool-pre --rm -u $(id -u):$(id -g) -v "$(pwd)":/mnt m4b-tool'
  ##############################
  FROM alpine:3.14 as builder
  
  ARG FDK_AAC_VERSION=2.0.1
  ARG FDK_AAC_URL="https://github.com/mstorsjo/fdk-aac/archive/v$FDK_AAC_VERSION.tar.gz"
  