[Libav-user] Probing a file

[Gonzalo Garramuno]

I am wondering, in code, what's the most reliable way to probe a file to 
see if ffmpeg will open it.  I can open a context and see the return 
value.  However, this returns true for image formats like jpeg, png, and 
others and I find those handled better with other libraries.  Is there a 
way to have ffmpeg test to open only video codecs with no image codecs.
Currently the hack I have is:

bool aviImage::test_filename( const char* buf )
{
    AVFormatContext* ctx = NULL;
    int error = avformat_open_input( &ctx, buf, NULL, NULL );
    if ( ctx )
       avformat_close_input( &ctx );

    if ( error <= 0 ) return false;

    return true;
}

The error <= 0 line is intentional instead of just error < 0.  This hack 
seems to avoid jpeg and others detection.