<div dir="ltr"><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Nov 8, 2017 at 8:44 AM, <span dir="ltr"><<a href="mailto:mont3z.claro5@gmail.com" target="_blank">mont3z.claro5@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"># HG changeset patch<br>
# User hribeiro<br>
# Date 1510110049 28800<br>
# Tue Nov 07 19:00:49 2017 -0800<br>
# Node ID e7e951834b57633ae474f50e7878b2<wbr>4271afabd2<br>
# Parent b6c692f5f5b145eb8d874cfb44db8c<wbr>85fc2978cc<br>
Disable QP limitations for lowpass subband dct<br></blockquote><div><br></div><div>Thanks. Temporarily, I agree that removing the requirement to do support lowpass-dct only with CQP>23 is good.</div><div>I've slightly adjusted the docs below and pushed this to default branch.</div><div><br></div><div>We need to figure out if we can do this dynamically based on the content.<br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
diff -r b6c692f5f5b1 -r e7e951834b57 doc/reST/cli.rst<br>
--- a/doc/reST/cli.rst Tue Nov 07 19:15:31 2017 +0530<br>
+++ b/doc/reST/cli.rst Tue Nov 07 19:00:49 2017 -0800<br>
@@ -2165,10 +2165,10 @@<br>
<br>
.. option:: --lowpass-dct<br>
<br>
- If enabled, x265 will use low-pass truncated dct approximation instead of the<br>
- standard dct. This approximation is less computational intesive but it generates<br>
- truncated coefficient matrixes for the transformed block. Empirical analysis shows<br>
- this approximation gives good PSNR results for QP>=23.<br>
+ If enabled, x265 will use low-pass subband dct approximation instead of the<br>
+ standard dct for 16x16 and 32x32 blocks. This approximation is less computational<br>
+ intesive but it generates truncated coefficient matrixes for the transformed block.<br>
+ Empirical analysis shows marginal loss in compression and performance gains up to 10%.<br>
<br>
This approximation should be considered for platforms with performance and time<br>
constrains.<br>
diff -r b6c692f5f5b1 -r e7e951834b57 source/common/primitives.cpp<br>
--- a/source/common/primitives.cpp Tue Nov 07 19:15:31 2017 +0530<br>
+++ b/source/common/primitives.cpp Tue Nov 07 19:00:49 2017 -0800<br>
@@ -272,7 +272,7 @@<br>
<br>
setupAliasPrimitives(<wbr>primitives);<br>
<br>
- if (param->bLowPassDct && param->rc.qp > 20)<br>
+ if (param->bLowPassDct)<br>
{<br>
enableLowpassDCTPrimitives(<wbr>primitives);<br>
}<br>
diff -r b6c692f5f5b1 -r e7e951834b57 source/x265.h<br>
--- a/source/x265.h Tue Nov 07 19:15:31 2017 +0530<br>
+++ b/source/x265.h Tue Nov 07 19:00:49 2017 -0800<br>
@@ -1510,9 +1510,8 @@<br>
/* Disable lookahead */<br>
int bDisableLookahead;<br>
<br>
- /* Use low-pass truncated dct approximation<br>
- * This DCT approximation is less computational intensive and gives results close to<br>
- * standard DCT for QP >= 23 */<br>
+ /* Use low-pass subband dct approximation<br>
+ * This DCT approximation is less computational intensive and gives results close to standard DCT */<br>
int bLowPassDct;<br>
<br>
/* Sets the portion of the decode buffer that must be available after all the<br>
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<br></blockquote></div><br></div></div>