Shutter speed conversion...

[foucquet]

When pulling exif data from an image I have pretty much everythiung nailed down except for the Shutter Speed value. When pulled from the image this is returned as:-

 

'Shutter' => string '0.0015625'

 

Now I know that the actual shutter speed at the time of shooting was 1/640 sec; does anyone have any ideas about how one would convert... 'Shutter' => string '0.0015625' to 1/640 sec... I have been scratching my head over this problem for a few days now and am stiull no wiser     

[Adam]

Since the decimal is basically 'point x of one', you just need to find out how many times it goes into 1:

 

1 / 0.0015625 = 640

[ManiacDan]

Note that this won't be 100% accurate in some cases because of the problem of fractions and binary math.  You might want to do a "close enough" disclaimer, or make use of the round() function.

[ignace]

To get "around" the binary math problem of close-enough. You can use the BC Math extension. Be sure though that the number is always a string both when storing (or use DECIMAL if your precision is smaller than 65) and manipulating or your result may be off:

 

$var = bcdiv(1, '0.0015625'); // note the quotes 

[foucquet]

Thanks for all of the suggestions, in the end I used the PHP exif_read_data() function (don't know why I didn't think of it in the first place  ) rather than the inbuilt Wordpress function, the PHP function actually returns the exif data as wanted except that one then has to split the DateTime into two variables rather than the one returned, but that's simple