- From: Peter Thatcher <pthatcher@google.com>
- Date: Fri, 18 Jul 2014 15:26:02 -0700
- To: Bernard Aboba <Bernard.Aboba@microsoft.com>
- Cc: Robin Raymond <robin@hookflash.com>, "public-ortc@w3.org" <public-ortc@w3.org>
- Message-ID: <CAJrXDUEEJa3Q-MOqiWTS0ntMewZPBNvGU-MDVnOC2d0VJw2fGA@mail.gmail.com>
I think that's the same thing I'm saying, but with a different way of thinking about it (and in reverse order from small to large). So I think we're in agreement. On Fri, Jul 18, 2014 at 3:22 PM, Bernard Aboba <Bernard.Aboba@microsoft.com> wrote: > Right now the resolutionScale is defined as cumulative, so if you had > three layers and you wanted to encode full resolution with all three, it > would be: > > .25, .5 and 1.0 > > S0 = one quarter resolution > S1 = one half resolution (add a pixel of width and height for each S0 > pixel) > S2 = full resolution (add a pixel of width and height for each S1 pixel) > > On Jul 18, 2014, at 2:45 PM, "Peter Thatcher" <pthatcher@google.com> > wrote: > > 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 >>> >>> >> >
Received on Friday, 18 July 2014 22:27:10 UTC