news

比较早的MPEG－2的解码源程序

mpeg2dec-0.4.0 Tue Dec 23 03:04:35 PST 2003 

Jeez, it's been way too long since the last release.

The big functionality that warrants a 0.4.x version number is that we
added support for 4:2:2 for 4:4:4 chroma formats. Thanks to Peter
Gubanov for starting the effort there.

A large part of the development effort has been to fix corner cases
that happen with bad or corrupted streams, concatenated streams,
etc... Regis Duchesne created test cases for this, which was a huge
help. Right now the situation is that we don't know how to make
libmpeg2 crash even when we try hard.

There is a new helper library for color conversion to common format
(currently rgb and uyvy). The ABI between libmpeg2 and libmpeg2convert
might change in the future, but source code compatibility will be
preserved. In the past people were supposed to write their own color
conversion routines which was a pain since the API was messy.

David S. Miller contributed some very nice sparc VIS optimizations for
the motion compensation. There are no VIS optimizations for the IDCT
yet but the plan is to get these in for a future 0.4.1 release.

New functions have been added to set the buffer stride and to reset
the decoder (typically after seeking thru a file).

There is some very basic documentation in doc/* - it's still quite
limited though. My good resolution for 2004 is to write better
documentation :) In the mean time feel free to ask on mpeg2dec-devel
or on irc.freenode.net channel #livid

The speed has not changed much since last release - we tend to be
about 1% faster. That's not too bad considering we have new features.


mpeg2dec-0.3.1 Fri Dec 13 22:15:36 PST 2002

This is mainly a maintainance release. On the API side, libmpeg2 now
includes some CPU detection code - so it will by default automatically
use whatever features are available on the CPU it runs on. There is a
function to override this, mainly for testing purposes.

There has been a few speed improvements too - there is now some alpha
specific code that makes the library more than twice faster on these
machines, and the C IDCT has also been improved which translates to
about 6% speed improvement for people who use this code.

Finally, a few bugs have been fixed, most notably some memory leaks
and sparc/HPPA/IA64 build issues.


mpeg2dec-0.3.0 Wed Nov 27 23:23:23 PST 2002

The main goal of this release is to preview the new libmpeg2 API. The
old API was not flexible enough for most users, as a result various
projects (xine, mplayer etc...) ended up rewriting their own versions
of decode.c. The goal with this new API is that it will be flexible
enough for people to actually use it instead of rolling their own :)

In many respects, this code is less mature than the 0.2.x codebase
was. There will probably be a few changes in future versions regarding
color conversion and CPU detection, to cite a few. The goal is to get
a release out and then add the missing features in future 0.3.x
releases.

In addition to the new API, there are a few new features already too.
For example, we now have improved the error handling, which should
help applications who do seeking for example. Also a few minor speed
improvements (about 7%) and SIMD optimizations now enabled in the VC++
port too.


mpeg2dec-0.2.1 Sun Mar 17 23:24:04 PST 2002

Two major new features: First, a much higher tolerance to corrupted
streams. Instead of just segfaulting, we should now be able to keep
going after errors. There is no test suite for this feature yet though.

Second, the altivec optimizations provide a huge speedup (more than
2.5x) on ppc g4 machines.

High definition video streams are now supported.

There is also native support for compiling using VC++.

And, the libvo interface has been slightly extended so people can more
easily make use of the various mpeg flags.


mpeg2dec-0.2.0 Thu Feb 15 20:12:34 PST 2001

The most important new feature is the support for field
pictures. mpeg2dec is now able to display any conformant
"main profile @ main level" mpeg-2 stream. This means any
stream you should actually encounter in practice :)

We also added some more accelerations for motion compensation and
color conversion - 3Dnow and SSE. Non-x86 accelerations would be
welcome - patches anyone ?

libmpeg2 and libvo are now fully reentrant. This will enable other
projects to reuse the mpeg2dec codebase without patches. For the same
reason we added support for "make install"

Libvo has been switched to a new API. The immediate advantage is that
it allowed us to get rid of the "HACK_MODE" setting - you really dont
want to know. In the future this will also help a lot with the
implementation of synchro.

Portability enhancements - including support for win32 DLLs. This was
done to get into the hearts of a few more developpers :)


mpeg2dec-0.1.7 Thu Nov  2 21:38:33 PST 2000

First release since march ! Lots of new features : improved
performance, mpeg-1 and mpeg-2 support, integrated demuxer, standards
compliance.

The major missing feature is mpeg-2 field pictures, this is planned
for mpeg2dec-0.2.0