Difference between `make clean` and `make distclean`

ffmpegmake

I installed ffmpeg from sources with help this page.
https://trac.ffmpeg.org/wiki/CentosCompilationGuide

I noticed that most of this tutorial calls make distclean after make install.
But only libvpx calls make clean after installing.

According this document,
http://www.gnu.org/software/automake/manual/automake.html#Clean
make clean deletes all files that make created, and make distclean deltes all files that ./configure created.

make clean

Erase from the build tree the files built by make all.

make distclean

Additionally erase anything ./configure created.

I understand that make distclean is called for for next installation,
but I could not understand why make clean is called after installation.

The installed ffmpeg works without problem.
So I asked this question because I only want to improve my knowledge about linux.
It would be very helpful that someone give me a explanation for it.

Best Answer

The parameter used after make is just dependent on the developer(s) who wrote the Makefile. The documentation you later reference, Autotools, is just one of many ways to create a Makefile.

The typical standard is make clean will remove all intermediate files, and make distclean makes the tree just the way it was when it was un-tarred (or something pretty close) including removing any configure script output. This is the way the Linux kernel works for instance.

In other words, it's totally dependent on the developers for each of those libraries, and this is why sometimes its clean and other times it's distclean. By the way, you don't need to run clean/distclean - I guess they have you run it just to save disk space. make install usually copies the files to the destination directory (again dependent on the developers) - typically places like /usr/lib or /usr/bin (also determined by the configure script, if it's an Autotools build system)

These nuances are the main reason people use package management systems like RPM or Debian packages.

Related Solutions

Using Make from Windows PowerShell – Guide

Take a look at "Make for Windows". After installing you simply call "make" from CMD or PowerShell.

FFMPEG multiple outputs performance (Single instance vs Multiple instances)

A less obvious problem is that depending on your input/output or filters ffmpeg might need to do pixel format conversion internally and in certain cases this becomes a bottleneck when using parallel outputs if done on each stream separately.

The idea is to do the pixel format conversion once if possible, like:

-filter_complex '[0:v]format=yuv420p, split=3[s1][s2][s3]' \
-map '[s1]' ... \
-map '[s2]' ... \
-map '[s3]' ... \

Same filters applied to all outputs should also be used only once. Some filters might need a specific pixel format.

For other causes see the small note at the bottom of the wiki:

Parallel encoding

Outputting and re encoding multiple times in the same FFmpeg process will typically slow down to the "slowest encoder" in your list. Some encoders (like libx264) perform their encoding "threaded and in the background" so they will effectively allow for parallel encodings, however audio encoding may be serial and become the bottleneck, etc. It seems that if you do have any encodings that are serial, it will be treated as "real serial" by FFmpeg and thus your FFmpeg may not use all available cores.

Best Answer

Related Solutions

Using Make from Windows PowerShell – Guide

FFMPEG multiple outputs performance (Single instance vs Multiple instances)

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