[FFmpeg-devel] [PATCH] Fix warnings about int64 toint32conversion

Gavin Kinsey gkinsey at ad-holdings.co.uk
Mon May 21 14:29:32 CEST 2012

On Wednesday 16 May 2012 12:18:57 Don Moir wrote:
> I think the pragma in ffmpeg would be more clutter then the cast but I
> have a ffmpeg.h file that does whatever for my needs. For the include
> part it does this:
> extern "C"
> {
>     #pragma warning(disable:4244)
>     #include <libavcodec/avcodec.h>
>     #include <libavformat/avformat.h>
>     #include <libswscale/swscale.h>
>     #include <libswresample/swresample.h>
>     #include <libavutil/opt.h>
>     #pragma warning(default:4244)
> }
> The #pragma warning number is going to be compiler specific but this does
> the trick for MS compiler. I would prefer not to use the pragma so I will
> know if I get a warning but it can be so annoying that I do it for
> ffmpeg.

I do the same but in what is a slightly more cross-platform way.  The 
following disables the warnings for Visual Studio and clang, these are the 
only two compilers I've found so far that emit warnings for this code.

// Switch off the conversion warning we get from libavutil/common.h
#if defined(_MSC_VER) 
#pragma warning( push )
#pragma warning( disable : 4244 )
#elif defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wconversion"

extern "C" {
#    include "libavcodec/avcodec.h"
#    include "libavfilter/avfilter.h"
#    include "libswscale/swscale.h"

// Re-enable conversion warning
#if defined(_MSC_VER) 
#pragma warning( pop )
#elif defined(__clang__)
#pragma clang diagnostic pop

Gavin Kinsey
AD Holdings Plc

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