Re: rounding issue with RTCRtpEncodingParameters scales?

I think each layer is a ratio of the input.  So, if you want 30%, 20%, 10%,
you'd use 0.3, 0.2, 0.1 (not 0.3, .66666, .33333)


On Fri, Jul 18, 2014 at 2:37 PM, Robin Raymond <robin@hookflash.com> wrote:

>
> I still don’t think I fully understand exactly what those values need to
> be set to in order to setup the correct ratios. For the sake of clarity, if
> the base layer is scaled resolution of 30%, and you had 3 geometric spatial
> layers, what exactly would be the value of the encoding parameters for each
> layer?
>
>  --
> Robin Raymond
>
> On July 18, 2014 at 3:09:57 PM, Peter Thatcher (pthatcher@google.com)
> wrote:
>
>  I think we can until we run into real implementation issues.  I have a
> feeling it won't be a big deal.
>
>
> On Thu, Jul 17, 2014 at 12:37 PM, Robin Raymond <robin@hookflash.com>
> wrote:
>
>>
>> dictionary RTCRtpEncodingParameters {
>>     //...
>>      double              resolutionScale;
>>     double              framerateScale;
>>  }
>>
>> These are floats with relative values. The trouble is that there are
>> fixed geometric relations. It must be 1.0, 0.5, 0.25, 0.125, etc for
>> resolution scaling…
>>
>> Maybe this isn’t an issue but I’m a bit concerned that float rounding
>> issues might cause us problems.
>>
>> For example, if you start at a base scale of 0.3 (i.e. resolution is 0.3
>> of source), are the layerings relative to 0.3, i.e. (1/1 * 0.3), (1/2 *
>> 0.3), (1/4 * 0.3) ?
>>
>> or would the scale be like this:
>> 0.3, 1/1, 1/2, 1/4, 1/8, etc?
>>
>> Also if people use dividers vs fixed value like: 1/8 vs 0.125, could we
>> end up in situations where the values almost match but don’t quite due to
>> float rounding problems?
>>
>>
>> Just a concern…
>>
>> Robin
>>
>>
>