Used 3 * standard_deviation in internal threshold calculation
instead of fit curve. This actually approached the algorithm
better.
For comparison, similar tests were done:
The overall psnr loss is less than before.
1. derf set:
when static-thresh = 1, psnr loss is 0.329%;
when static-thresh = 500, psnr loss is 0.970%;
2. stdhd set:
when static-thresh = 1, psnr loss is 0.922%;
when static-thresh = 500, psnr loss is 1.307%;
Similar speedup is achieved. For example,
clip bitrate static-thresh psnr time
akiyo(cif) 500 0 48.952 5.077s(50f)
akiyo 500 500 48.866 4.169s(50f)
parkjoy(1080p) 4000 0 30.388 78.20s(30f)
parkjoy 4000 500 30.367 70.85s(30f)
sunflower(1080p) 4000 0 44.402 74.55s(30f)
sunflower 4000 500 44.414 68.69s(30f)
Change-Id: Ic78833642ce1911dbbd1cb6c899a2d7e2dfcc1f3
52256cdbca