204 lines
7.4 KiB
Text
204 lines
7.4 KiB
Text
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ABOUT LIBMPEG2
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libmpeg2 is a free library for decoding mpeg-2 and mpeg-1 video
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streams. It is released under the terms of the GPL license.
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The main goals in libmpeg2 development are:
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* Conformance - libmpeg2 is able to decode all mpeg streams that
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conform to certain restrictions: "constrained parameters" for
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mpeg-1, and "main profile" for mpeg-2. In practice, this is
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what most people are using. For streams that follow these
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restrictions, we believe libmpeg2 is 100% conformant to the
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mpeg standards - and we have a pretty extensive test suite to
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check this.
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* Speed - there has been huge efforts there, and we believe
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libmpeg2 is the fastest library around for what it
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does. Please tell us if you find a faster one ! With typical
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video streams as found on DVD's, and doing only decoding with
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no display, you should be able to get about 110 fps on a
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PIII/666, or 150 fps on an Athlon/950. This is less than 20
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cycles per output pixel. In a real player program, the display
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routines will probably take as much time as the actual
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decoding !
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* Portability - most of the code is written in C, and when we
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use platform-specific optimizations (typically assembly
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routines, currently used for the motion compensation and the
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inverse cosine transform stages) we always have a generic C
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routine to fall back on. This should be portable to all
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architectures - at least we have heard reports from people
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running this code on x86, ppc, sparc, arm and
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sh4. Assembly-optimized implementations are available on x86
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(MMX) and ppc (altivec) architectures. Ultrasparc (VIS) is
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probably the next on the list - we'll see.
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* Reuseability - we do not want libmpeg2 to include any
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project-specific code, but it should still include enough
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features to be used by very diverse projects. We are only
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starting to get there - the best way to help here is to give
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us some feedback !
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The project homepage is at http://libmpeg2.sourceforge.net/
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MPEG2DEC
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mpeg2dec is a test program for libmpeg2. It decodes mpeg-1 and mpeg-2
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video streams, and also includes a demultiplexer for mpeg-1 and mpeg-2
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program streams. It is purposely kept simple : it does not include
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features like reading files from a DVD, CSS, fullscreen output,
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navigation, etc... The main purpose of mpeg2dec is to have a simple
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test bed for libmpeg2.
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The libmpeg2 source code is always distributed in the mpeg2dec
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package, to make it easier for people to test it.
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The basic usage is to just type "mpeg2dec file" where file is a
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demultiplexed mpeg video file.
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The "-s" option must be used for multiplexed (audio and video) mpeg
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files using the "program stream" format. These files are usualy found
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on the internet or on unencrypted DVDs.
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The "-t" option must be used for multiplexed (audio and video) mpeg
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files using the "transport stream" format. These files are usualy
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found in digital TV applications.
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The "-o" option is used to select a given output module - for example
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to redirect the output to a file. This is also used for performance
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testing and conformance testing.
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The "-c" option is used to disable all optimizations.
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OTHER PROJECTS USING LIBMPEG2
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libmpeg2 is being used by various other projects, including:
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* xine (http://xine.sourceforge.net/) - started as a simple
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mpeg-2 audio and video decoder, but it since became a
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full-featured DVD and video media player.
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* VideoLAN (http://www.videolan.org/) - video streaming over an
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ethernet network, can also be used as a standalone player.
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* MPlayer (http://www.MPlayerHQ.hu) - another good player, it is
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also very robust against damaged streams.
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* movietime (http://movietime.sourceforge.net/) - still quite
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young, but it looks very promising !
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* mpeg2decX (http://homepage1.nifty.com/~toku/software_en.html) -
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a graphical interface for mpeg2dec for macintosh osX.
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* TCVP (http://tcvp.sf.net) - video and music player for unix.
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* drip (http://drip.sourceforge.net/) - a DVD to DIVX transcoder.
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* PoMP
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(http://www.dmclab.hanyang.ac.kr/research/project/PoDS/PoDS_sw.htm) -
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a research player optimized to minimize disk power consumption.
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* OMS (http://www.linuxvideo.org/oms/)
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* XMPS (http://xmps.sourceforge.net/)
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* GStreamer (http://www.gstreamer.net/) - a framework for
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streaming media; it has an mpeg2 decoding plugin based on
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libmpeg2.
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* mpeglib (http://mpeglib.sourceforge.net/) - a video decoding
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library that usess libmpeg2 when decoding mpeg streams.
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* daphne (http://daphne.rulecity.com/) - a laserdisc arcade game
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simulator.
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* GOPchop (http://outflux.net/unix/software/GOPchop/) - a
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GOP-accurate editor for MPEG2 streams.
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If you use libmpeg2 in another project, let us know !
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TASKS
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There are several places where we could easily use some help:
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* Documentation: libmpeg2 still has no documentation. Every
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project using it has had to figure things out by looking at
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the header files, at the mpeg2dec sample application, and by
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asking questions. Writing down a nice documentation would make
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the code more easily reuseable.
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* Testing: If you find any stream that does not decode right
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with libmpeg2, let us know ! The best thing would be to mail
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to the libmpeg2-devel mailing list. Also, it would be nice to
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build a stress test so we can make sure libmpeg2 never crashes
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on bad streams.
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* Coding: There is a small TODO list in the mpeg2dec package,
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you can have a look there ! Most items are pretty terse
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though.
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* Porting: If you're porting to a new architecture, you might
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want to experiment with the compile flags defined in
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configure.in . When you figure out whats fastest on your
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platform, send us a patch !
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* Assembly optimizations: We only have x86 and altivec
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optimizations yet, it would be worthwhile writing routines for
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other architectures, especially those that have SIMD
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instruction set extensions ! Also the yuv2rgb x86 routines
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could probably be optimized a lot.
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CVS SNAPSHOTS
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A daily snapshot is created using "make distcheck" every night and
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uploaded to http://libmpeg2.sourceforge.net/files/mpeg2dec-snapshot.tar.gz .
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It is easier to use than the CVS repository, because you do not need
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to have the right versions of automake, autoconf and libtool
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installed. It might be convenient when working on a libmpeg2 port for
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example.
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CVS REPOSITORY
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The latest libmpeg2 and mpeg2dec source code can always be found by
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anonymous CVS:
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# export CVSROOT=:pserver:anonymous@cvs.libmpeg2.sourceforge.net:/cvsroot/libmpeg2
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# cvs login (Just press Return when prompted for a password)
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# cvs checkout mpeg2dec
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You can also browse the latest changes online at
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http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/libmpeg2/mpeg2dec/
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The other CVS modules are mpeg2dec-streams for the test suite, and
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mpeg2dec-livid for the CVS history of the project while it was still
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hosted on the linuxvideo.org servers.
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MAILING LISTS
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See the subscription information at http://libmpeg2.sourceforge.net/lists.html
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libmpeg2-devel
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This is the main mailing list for technical discussion about
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libmpeg2. Anyone wanting to work on libmpeg2, or maybe just stay
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informed about the development process, should probably subscribe to
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this list.
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libmpeg2-checkins
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All libmpeg2 checkins are announced there. This is a good way to keep
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track of what goes into CVS.
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libmpeg2-announce
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This is a very low traffic mailing list, only for announcements of new
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versions of libmpeg2. Only project administrators can post there.
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