Transition from using popen() to using fork()/dup2()/execl() to provide
a way to read stderr from ffmpeg.
Co-Authored by: PatTheMav <PatTheMav@users.noreply.github.com>
Previously, any short write would be treated elsewhere as a failure. The
easiest solution is to have pipe_write() automatically retry until either
it's written everything, or it couldn't write anything at all.
Code submissions have continually suffered from formatting
inconsistencies that constantly have to be addressed. Using
clang-format simplifies this by making code formatting more consistent,
and allows automation of the code formatting so that maintainers can
focus more on the code itself instead of code formatting.
The size parameter is the size of the elements, not the size of the
data. The size parameter should be 1, and the elements should be the
number of bytes.
The reason why I'm making this change is because the fread/fwrite would
fail when the parameters were swapped.
This adds functions for piping a command line program's stdin or stdout.
Note however that this is unidirectional only.
This will be especially useful later on when implementing MP4 output,
because MP4 output has to be piped to prevent unexpected program
termination from corrupting the file.
