JL yuvutils

About

This is JL yuvutils version 1.1. It includes four small utility programs for processing YUV4MPEG video streams as produced and consumed by the tools included in the MJPEG tools package.

I implemented these utilities to enhance some poor quality home videos and to convert them into PAL frame rate. I do not have any real experience on video processing so be warned that I am probably doing lot of things wrong with these utilities. However, these utilities made it possible for me to easily improve the quality of my home videos (as part of automated scripted preprocessing before authoring them into a DVD) so I was thinking someone else might find them useful too.

Let me shortly introduce the included programs.

yuvinfo
displays information about YUV4MPEG streams. Optionally also produces YUV histograms and inserts them into the video stream as overlays.
yuvcut
cuts selected ranges of frames from a YUV4MPEG stream. The ranges can be specified as absolute frame numbers or by using time code format.
yuvadjust
automatically adjusts luminance level, contrast and white balance of YUV4MPEG streams. Luminance and colors are adjusted based on the gray world assumption (i.e. assuming the content is 50% gray on average). This can be used to enhance poor quality video material such as too dark or reddish/blueish video. It probably does more harm than good on high quality material, though.
yuvresample
resamples a video stream for a different frame rate, optionally changing the interlacing mode as well. Yuvresample does not simply drop or duplicate input frames like yuvfps from the MJPEG tools package does. It produces output frames or fields using the weighted average of the two temporally closest input frames or fields. This eliminates much of the visible stepping that occurs when frames are dropped or duplicated. The drawback is that fast moving objects get blurred. However, I personally prefer the output of yuvresample when downsampling videos from 30 FPS (my digital camera) to 25 FPS (PAL). Your mileage may vary. This utility can also be used to create slow motion or speed up effects.

Obsolete: The same weighted average resampling code has also been included in the CVS version of yuvfps since 8 January 2006 (see the -w option).

The latest version of this software can be obtained from JL yuvutils web page at http://www.jlehtinen.net/yuvutils/.

License

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

See the license text for details.

Download

The source code distribution is available here:

jl-yuvutils-1.1.tar.gz (2006-01-25, 28.2 KiB)

Subversion repository is available at:

http://svn.jlehtinen.net/svn/jlyuvutils

Building

On a standard Linux system (and hopefully also on other Unix-like systems if you have GNU tools installed) you should be able to build the software using the supplied Makefile assuming you have MJPEG tools installed. This software was developed against MJPEG tools version 1.8.0.

Build the software using:

make

Optionally, you can also specify the path to MJPEG tools headers and the mjpegutils library by giving make the following arguments:

MJPEGTOOLS_INCLUDE_PATH=-I/somewhere/include/mjpegtools
MJPEGTOOLS_LIBMJPEGUTILS=/somewhere/lib/libmjpegutils.so

The default is to search for headers in /usr/local/include/mjpegtools (in addition to the default include path) and to use -lmjpegutils for the library.

The software can be installed either by manually copying the binaries "yuvinfo", "yuvcut", "yuvadjust" and "yuvresample" and the corresponding man pages from the "man" subdirectory or by doing:

make install

This will install the software under /usr/local/bin and /usr/local/man. You can change the installation location using the standard variables:

prefix=<top-level prefix>
exec_prefix=<top-level prefix for binaries>
bindir=<directory for binaries>
mandir=<directory for man pages>
DESTDIR=<use this directory as the root directory>

Author

Author of this software is Johannes Lehtinen. Feel free to contact me if you have any feedback, bug fixes or suggestions regarding this software.

These utilities use MJPEG tools library to read and write YUV4MPEG video streams.

25 January 2006
Halikko, Finland

Johannes Lehtinen <johannes.lehtinen@iki.fi>