libmpeg2 0.4.1

libmpeg2 is a free library for decoding mpeg-2 and mpeg-1 video streams. libmpeg2 is released under the terms of the GPL license.
mpeg2dec
mpeg2dec is a test program for libmpeg2. It decodes mpeg-1 and mpeg-2 video streams, and also includes a demultiplexer for mpeg-1 and mpeg-2 program streams.
It is purposely kept simple : it does not include features like reading files from a DVD, CSS, fullscreen output, navigation, etc... The main purpose of mpeg2dec is to have a simple test bed for libmpeg2.
The libmpeg2 source code is always distributed in the mpeg2dec package, to make it easier for people to test it.
Main features:
- Conformance - libmpeg2 is able to decode all mpeg streams that conform to certain restrictions: "constrained parameters" for mpeg-1, and "main profile" for mpeg-2. In practice, this is what most people are using. For streams that follow these restrictions, we believe libmpeg2 is 100% conformant to the mpeg standards - and we have a pretty extensive test suite to check this.
- Speed - there has been huge efforts there, and we believe libmpeg2 is the fastest library around for what it does. Please tell us if you find a faster one ! With typical video streams as found on DVDs, and doing only decoding with no display, you should be able to get about 110 fps on a PIII/666, or 150 fps on an Athlon/950. This is less than 20 cycles per output pixel. In a real player program, the display routines will probably take as much time as the actual decoding !
- Portability - most of the code is written in C, and when we use platform-specific optimizations (typically assembly routines, currently used for the motion compensation and the inverse cosine transform stages) we always have a generic C routine to fall back on. This should be portable to all architectures - at least we have heard reports from people running this code on x86, ppc, sparc, arm and sh4. Assembly-optimized implementations are available on x86 (MMX) and ppc (altivec) architectures. Ultrasparc (VIS) is probably the next on the list - well see.
- Reuseability - we do not want libmpeg2 to include any project-specific code, but it should still include enough features to be used by very diverse projects. We are only starting to get there - the best way to help here is to give us some feedback !
Enhancements:
- Newer versions of the autotools and FreeBSD and OS X systems are better handled.
- x86 accelerations are now supported on the AMD-64 CPU, including on FreeBSD.
- The AltiVec features are also better detected.
- The 4:4:4 chroma handling, a memory leak in the Xshm code on remote displays, and alignment issues in the sample programs were fixed.
- The parser is more tolerant with invalid sequence display extension.