Bug fix for second reference stats.
Immediately following a key frame the trailing second reference error in the first pass stats will be based on a reference frame from the prior key frame group and will thus usually be much larger. This fix eliminates that effect (which typically triggers a short arf group immediately after a key frame). It also changes the accounting for the first frame in each new arf group. This change gives large gains on a couple of clips that contain mid sequence key frames (e.g. 6% on 1080P tennis). Overall there was a net gain in PSNR and PSNR-HVS ~(0.05- 0.4%) and mixed results for SSIM (+/- 0.2%). Change-Id: I8e00538ac2c0b5c2e7e637903cac329ce5c2a375
Showing with 5 additions and 2 deletions