# HG changeset patch # User Deepthi Nandakumar <[email protected]> # Date 1460210548 -19800 # Node ID 40afead3177d7c128066334bfe075042388e86b0 # Parent 31a417fa69ce37a76e41c203a017686fe7f73877 doc: update tune grain documentation
diff -r 31a417fa69ce -r 40afead3177d doc/reST/presets.rst --- a/doc/reST/presets.rst Sat Apr 09 19:06:56 2016 +0530 +++ b/doc/reST/presets.rst Sat Apr 09 19:32:28 2016 +0530 @@ -121,29 +121,22 @@ ~~~~~~~~~~~~~~~~~~~~ :option:`--tune` *grain* tries to improve the retention of film grain in -the reconstructed output. It disables rate distortion optimizations in -quantization, and increases the default psy-rd. +the reconstructed output. Varying the quantization parameter within and +across frames causes grain strobing (uneven distribution of grain), which +is visually distracting. :option: `--tune` *grain* severely dials down +algorithms that vary the quantization parameter. - * :option:`--psy-rd` 0.5 - * :option:`--rdoq-level` 0 - * :option:`--psy-rdoq` 0 + * :option:`--aq-mode` 0 + * :option:`--cu-tree` 0 + * :option:`--ip-factor` 1.1 + * :option:`--pb-factor` 1.0 + * :option:`--qp-step` 1 -It lowers the strength of adaptive quantization, so residual energy can -be more evenly distributed across the (noisy) picture: - - * :option:`--aq-strength` 0.3 - -And it similarly tunes rate control to prevent the slice QP from -swinging too wildly from frame to frame: - - * :option:`--ipratio` 1.1 - * :option:`--pbratio` 1.1 - * :option:`--qcomp` 0.8 - -And lastly it reduces the strength of deblocking to prevent grain being -blurred on block boundaries: - - * :option:`--deblock` -2 +It also enables a specialised ratecontrol algorithm :option:`--rc-grain` +that strictly minimises QP fluctuations across frames, while still allowing +the encoder to hit bitrate targets and VBV buffer limits (with a slightly +higher margin of error than normal). It is highly recommended that this +algorithm is used only through the :option:`--tune` *grain* feature. Fast Decode ~~~~~~~~~~~ _______________________________________________ x265-devel mailing list [email protected] https://mailman.videolan.org/listinfo/x265-devel
