Hello Tanguy:
This probably isn't the place for the battle of ffmpeg. I have
already had lengthy discussions on the ffmpeg chat list about it and
variable initialization and they wouldn't accept my patches for it.
Honestly I have not read up on the C standard and only took what they
said as being true. They said they adhere to the C99 standard and
they sent me a cut and past from the C99 standard that said variables
are to be initialized to 0 but honestly can't remember if that is for
static or non static or both. It is true that non gcc style compilers
will probably not be able to build ffmpeg so for windows your only
option I think will be a dll using mingw. I had no problems with this
compiler and integrating into existing Microsoft builds but I turn off
mmx and mmx2 which is mostly assembly and forces your builds to be GPL
instead of LGPL when enabled. This is true also for the libswscale
tha they now have you use. If it has assembly enabled then you are
GPL else you can use it in an LGPL fashion.
It is a tough library to build but if you can do it it is a very good
library at supporting all the codecs. We are getting mpeg feeds with
embedded geometries that have a codec that only ffmpeg has been able
to read and non of the commercial vendors like Quicktime, Windows
media player can read.
Take care
Garrett
On Jul 13, 2009, at 7:24 AM, Tanguy Fautre wrote:
Hi Garrett,
A bit OT, but which part of the C standard says that all
uninitialized variables shall default to 0? The only zero
initialization guarantee of the C standard I know of is related to
static variables (which MSVC supports).
If what you say about FFmpeg expected C behaviour is true, it sounds
to me that FFmpeg is relying on a non-standard extensions of GCC.
If you don’t mind, I’ll take your email as an opportunity to express
my biggest complain about the FFmpeg project: its portability.
On the current situation of FFmpeg on Windows, IMHO the FFmpeg dev
team has abslolutely no valid reasons for not making FFmpeg
portable. In fact, it looks like they took several decisions with
the sole purpose of making FFmpeg a GCC-only / MSVC-incompatible
product. Reading their rant about MSVC on the official website tends
to confirm that some of their choices are mainly motivated by anti-
microsoft political reasons rather than technical.
- They’ve chosen to rely on the C99 standard, which is not as widely
as supported as C89 and C++98. GCC is the only widely-used compiler
that comes close to having a full C99 support (followed by the Intel
compiler), but even GCC is still missing several features (http://gcc.gnu.org/c99status.html
). MSVC and Borland have little C99 support.
- They use the AT&T assembly syntax for x86/x86-64 assembly code
instead of using the Intel assembly syntax or Intel intrinsics.
These two decisions alone mean that one would have to rewrite most
of FFmpeg to get it compiling on any compiler that is not a GCC-
clone. While there is nothing close to FFmpeg on the market (open or
closed source), while I’m a huge supported of FFmpeg and related
projects, such poor decisions are ridicule from a software
engineering point of view and ultimately hurts FFmpeg.
Tanguy
From: [email protected] [mailto:[email protected]
] On Behalf Of Garrett Potts
Sent: 11 July 2009 03:24
To: OpenSceneGraph Users
Subject: Re: [osg-users] ffmpeg stdint on Windows?
Hello All:
The link below is the one I used before to add stdint.h and
inttypes.h. I use it for the builds on windws. I have sucessfully
used mingw then use Microsofts implib tool to create a import lib
for the dll.
Like they said below. ffmpeg will not build on MSVC and even if
you can the ffmpeg dev team rely heavily on c standard that defines
all uninitialized variables shall default to 0. MSVC does not put
anything in an uninitialized variables and most of the variable
definitions in ffmpeg core library are unnitialized. The only
option is to use mingw to build a dll file and I use the implib to
generate a import library for the dll.
Take care all
Garrett
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