[Libav-user] Building with MSVC toolchain resulting in seeking problem?

"René J.V. Bertin" rjvbertin at gmail.com
Tue Mar 12 16:23:59 CET 2013

On Mar 12, 2013, at 16:04, Carl Eugen Hoyos wrote:

> I don't think there is any glue code.

But there is a conversion so that MSVC can compile the C 'dialect' ffmpeg uses, right?

> (Remember the gcc bugs you recently found, a but 
                                               ^^^ bug?
It's not me who claimed it was a gcc bug, not before I know exactly what goes wrong where (this is about compiling with auto-vectorisation; a few test cases fail because of it).

>>> and that might include seek-related code that is 
>>> particularly non-optimal.
> It could of course be related to the glue code mingw 
> uses...

Yes, but in that case one would expect it in all mingw builds.

> Apart from the fact that I still cannot understand why 
> building with a cross-compiler in a VM can be easier than 

For me, it's the build environment rather than the compiler. The build utilities evolved in and for unix/linux environments so IMHO everything just works smoother there (and MSYS doesn't help). Of course the balance may tip the other way if you start having to maintain a whole slew of libraries ffmpeg depends on (in case it's impossible to use prebuilt 'native mswin' builds of said libraries).

BTW, last time I looked (a while ago), it wasn't that evident to find mingw binaries based on current/recent gcc versions (and capable to compile for 64 bits). With the build script available on zeranoe, it just takes a few hours to build an up to date cross compiler; it will even download and build the required dependencies.

> doing a native mingw build: For years, this was one of the 
> most often requested "features", probably to allow 
> debugging within msvc.

msvc debugging code generated with mingw? If indeed it can do that, it ought to work just as well if the code was generated by a mingw cross-compiler.

> the gcc compiler you installed should work fine, no reason 
> to setup Ubuntu to compile for win32.

I kind of expect this to be available in a pre-configured image. 


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