Re: [Bug 26526] Fix aspect ratio constraint

Out of curiosity, what's the advantage is being inexact when we can easily
be exact?

Best Regards,
Silvia.
On 15 Aug 2014 02:22, "Harald Alvestrand" <harald@alvestrand.no> wrote:

>  On 08/14/2014 05:45 PM, Gili T. wrote:
>
> Hi Harald,
>
> Can you please explain how an epsilon of 1/1000 equates to one pixel in HD?
>
>
> The aspect ratio of a 1024x768 image is 1.3333333333
> The aspect ratio of a 1025x768 image is 1.3346354166
> The difference is 0.0013020833, which is quite close to 1/1000.
>
>  What able future proofing? What happens when we want 4k resolution in
> the future?
>
>
> On 4K resolution, the difference will be ~4 pixels. Most coding schemes
> have 16-pixel macroblocks.
>
> The point is - 1/1000 is *precise enough for all practical purposes*.
>
> Nobody NEEDS to specify an aspect ratio of 1.3334 and not have it match
> 1.3333.
>
>  Thanks,
> Gili
> On Aug 13, 2014 1:11 PM, "Harald Alvestrand" <harald@alvestrand.no> wrote:
>
>>  On 08/13/2014 12:11 PM, Gili T. wrote:
>>
>> And I'll repeat that different ratios will need different epsilons.
>> Epsilons imply inaccuracy and there is no one number that will work for
>> every use case. Why not just go with "numerator/denominator", parse it to
>> two integers and compare with 100% accuracy?
>>
>>
>> Did you intend for this to go to me only?
>>
>> 1/1000 is one pixel in HD. We don't need more precision.
>>
>>
>>  Gili
>> On Aug 13, 2014 8:50 AM, "Harald Alvestrand" <harald@alvestrand.no>
>> wrote:
>>
>>> On 08/12/2014 06:17 PM, Jan-Ivar Bruaroey wrote:
>>>
>>>> On 8/11/14 6:17 PM, Martin Thomson wrote:
>>>>
>>>>> On 11 August 2014 14:34, Jan-Ivar Bruaroey <jib@mozilla.com> wrote:
>>>>>
>>>>>> Actually, the spec already says: "The exact aspect ratio (width in
>>>>>> pixels
>>>>>> divided by height in pixels), represented as a double rounded to the
>>>>>> tenth
>>>>>> decimal place" [1]
>>>>>>
>>>>>> So we effectively have our epsilon already: .0000000001
>>>>>>
>>>>>> So no action required it seems.
>>>>>>
>>>>> Oh, that's good, there's an epsilon; but it's bad.  1.777777778 isn't
>>>>> the same as 16/9 based on that.  Nor is 1.7777777777.  Add a single
>>>>> digit to either and it would match.  I may have counted wrong. I'm
>>>>> sure that others will too.
>>>>>
>>>>
>>>> Feel free to propose a different epsilon I suppose.
>>>>
>>>> I presume this would have nothing to do with inaccuracies inherent in
>>>> floating-point math then (or we could have picked an epsilon much closer to
>>>> everyone's worst machine epsilon), but instead from a desire to accommodate
>>>> people handwriting rounded decimal numbers for aspect. Just so we're clear
>>>> on the properties we seek.
>>>>
>>>
>>> I'll repeat my suggestion of an epsilon of 1/1000.
>>>
>>>
>>>> .: Jan-Ivar :.
>>>>
>>>>
>>>>
>>>
>>>
>>
>