Cannot build docker image

[radres]

I clone the repository and do docker build . -t ffmpeg-tutorial

here is the error it gives me:

Setting up libssl-dev:amd64 (1.0.2g-1ubuntu4.16) ... Setting up libtool (2.4.6-0.1) ... Setting up nasm (2.11.08-1ubuntu0.1) ... Setting up pkg-config (0.29.1-0ubuntu1) ... Setting up yasm (1.3.0-2) ... Processing triggers for libc-bin (2.23-0ubuntu10) ... Removing intermediate container 1903411f7f23 ---> fd08780e9d53 Step 20/43 : RUN DIR=/tmp/opencore-amr && mkdir -p ${DIR} && cd ${DIR} && curl -sL https://sourceforge.net/projects/opencore-amr/files/opencore-amr/opencore-amr-${OPENCOREAMR_VERSION}.tar.gz | tar -zx --strip-components=1 && ./configure --prefix="${PREFIX}" --enable-shared && make && make install && rm -rf ${DIR} ---> Running in bd057e87ca3d

gzip: stdin: unexpected end of file tar: Child returned status 1 tar: Error is not recoverable: exiting now The command '/bin/sh -c DIR=/tmp/opencore-amr && mkdir -p ${DIR} && cd ${DIR} && curl -sL https://sourceforge.net/projects/opencore-amr/files/opencore-amr/opencore-amr-${OPENCOREAMR_VERSION}.tar.gz | tar -zx --strip-components=1 && ./configure --prefix="${PREFIX}" --enable-shared && make && make install && rm -rf ${DIR}' returned a non-zero code: 2

edit: doesn't look like this meant to be used this way. now I see that make command uses it to build the source