>An alternative technique that may be better in that regard, then, >would be to measure distortion with both phases, and pick the phase >that yields the lowest distortion? That's a very good suggestion. Since the main problem with M/S and IS was phasing this might be a way to solve that too. I'll give it a try.
On 21 July 2015 at 02:02, Claudio Freire <klaussfre...@gmail.com> wrote: > On Fri, Jul 17, 2015 at 11:19 PM, Rostislav Pehlivanov > <atomnu...@gmail.com> wrote: > >>But even if not used for avoding I/S, it can be used to pick whether > >>to invert the phases, where it was clearly more stable. > > In case the phase is very clearly wrong then there will be an increase in > > the distortion which should cause the dist2 <= dist1 check to fail and > thus > > not use IS. So the phase isn't even very important. The whole point of > the > > phase check is to pick out the obviously wrong phases and save time by > not > > having to calculate the error of the spectral coefficients. And this > works > > better when you individually pick out a majority rather than just summing > > them up and then doing the decisions. > > All the more reason to use energy then. > > If you use this sign-difference count, low-energy noise may change the > count while being inaudible, yielding an incorrect phase value. After > that, distortion will be huge and the band won't be I/S encoded, but > it might if the phase value was otherwise. > > In general, this algorithm seems fragile (ie: not robust in the > presence of noise). > > Why not forego the optimization and optimize efficiency instead? (it's > the priority now, running time optimization should be done after > exploiting the technique to increase quality as much as posibble). > > An alternative technique that may be better in that regard, then, > would be to measure distortion with both phases, and pick the phase > that yields the lowest distortion? > > Give it a try. > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel