austenconstable.com

An easy way to recursively delete files matching a particular pattern is to use this one liner:

find | grep "search" | perl -nle unlink

UPDATE – Another handy one liner to recursively delete directories is:

rm -rf `find . -type d -name .svn`

Obviously replacing “.svn” with whatever your directories are called.

The ‘traditional’ way to search and replace on the command line was to use some combination of grep/find/perl/sed etc. Which offers great flexibility but at the end of the day can turn into a right pain in order to complete a simple task. Turns out only to be a pain in the ass if you don’t know or can’t remember the correct syntax!

Recently I stumbled across rpl. (http://freshmeat.net/projects/rpl/) It’s a nice little text replacement utility which is as simple as:

rpl -R search replace *

Although rpl is easy, the other alternatives are hardly difficult. (At least once you know them)

For non-recursive search and replace try: Perl or sed. (At some point I’m sure I’ll get around to finding recursive Perl and sed alternatives.)

Intoduction

FFmpeg is a superb video processing tool used to encode and transcode video files. In this particular project I needed to build “youtube” style video upload which would transcode into FLV, specifically catering for video files from the Nokia N95.

I spent quite a long time messing about with the stock version of ffmpeg on CentOS 4/Ubuntu trying to make it work, but it turned out not to be new enough/have all the right support compiled in.

This howto was written because I couldn’t find anything that fitted the bill for CentOS/RHEL (And being a Ubuntu man, found it a pain to get it compiled and working under CentOS). It’s based on the excellent tutorial by FakeOutdoorsman over on the Ubuntu forums. So big thanks to them.

These instructions have been tested on a fresh minimal install of CentOS 4.6 running in a VirtualBox VM.

Preparation

1. Ensure that you have the rpmforge repo’s added to yum. See here for instructions.
2. Update the install

   yum update

3. (If you are not installing onto a fresh minimal install) Remove ffmpeg, x264 and faad2 to avoid confusion.

   yum remove ffmpeg x264 faad2 faad2-devel

4. Install the necessary build tools

   yum install gcc gcc-c++ automake autoconf libtool yasm git subversion

5. Install the necessary libraries

   yum install zlib-devel libmad-devel libvorbis-devel libtheora-devel lame-devel faac-devel a52dec-devel xvidcore-devel freetype-devel

Compile supporting libraries

1. Compile & Install faad2 (for some reason I couldn’t get it to compile against the standard rpm version)

   cd ~
   wget http://downloads.sourceforge.net/faac/faad2-2.6.1.tar.gz
   tar xzvf faad2-2.6.1.tar.gz
   cd faad2
   autoreconf -vif
   ./configure
   make
   make install

2. Compile & Install GPAC

   cd ~
   wget http://downloads.sourceforge.net/gpac/gpac-0.4.4.tar.gz
   tar -xzvf gpac-0.4.4.tar.gz
   cd gpac
   ./configure
   make
   make install
   make install-lib

   Note: if the compile fails with a osmozilla related error, please see here. I had to remove mozilla support to get it to compile.

3. Update the links to the shared libs

   echo '/usr/local/lib/' > /etc/ld.so.conf.d/gapc-1386.conf
   ldconfig

4. Compile & Install x264

   cd ~
   git clone git://git.videolan.org/x264.git
   cd x264
   ./configure  --enable-pthread --enable-mp4-output --enable-shared
   make
   make install

5. Update the links to the shared libs…again

   ldconfig

Install ffmpeg

1. cd ~
   svn export svn://svn.mplayerhq.hu/ffmpeg/trunk ffmpeg
   cd ffmpeg
   ./configure --prefix=/usr/local --disable-debug --enable-shared --enable-gpl --enable-nonfree --enable-postproc --enable-swscale --enable-pthreads --enable-x11grab --enable-liba52 --enable-libx264 --enable-libxvid --enable-libvorbis --enable-libfaac --enable-libfaad --enable-libmp3lame
   make
   make install

2. If ffmpeg has problems finding shared libraries, set the LD_LIBRARY_PATH

   echo 'LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib; export LD_LIBRARY_PATH' >> /etc/ld.so.conf
   ldconfig

   I’m not convinced that this is the correct thing to do, or the correct way to do it…but it seems to work…

3. All done.

Additional resources:

http://www.nazly.net/index.php?page=showevents&selTopic=230

http://www.tuxmachines.org/node/17063