[x265] [PATCH] modify the minimum keyint value

[Tom Vaughan]

We concluded that it doesn’t make sense to prevent the ability to encode
with a fixed GOP size, regardless of whether or not a user wants scenecut
enabled.  This patch enables users to specify a min-keyint that is equal to
keyint (a fixed keyint) that x265 does not override.  Separately, we’ve
also fixed our scenecut option to enable the benefits of scenecut detection
with fixed GOP structures.



*From:* x265-devel [mailto:x265-devel-bounces at videolan.org] *On Behalf
Of *Deepthi
Nandakumar
*Sent:* Monday, September 26, 2016 12:01 PM
*To:* Development for x265
*Subject:* Re: [x265] [PATCH] modify the minimum keyint value



Earlier, keyframeMin was fixed to the range (1, keyframeMax/2 + 1). This
patch removes the upper bound, but does not change behaviour wrt scenecut
threshold in any way.



On Thu, Sep 22, 2016 at 3:14 AM, <gopi.satykrishna at multicorewareinc.com>
wrote:

# HG changeset patch
# User Gopi Satykrishna Akisetty <gopi.satykrishna at multicorewareinc.com>
# Date 1474539223 -19800
#      Thu Sep 22 15:43:43 2016 +0530
# Node ID 24ecccf7b435e849545e161a0992f452875f6bbc
# Parent  bdf098eefd35b70b68419f5a204e60f1df4aeae1
modify the minimum keyint value

This patch enables fixed gop size even when scenecut option is enabled

diff -r bdf098eefd35 -r 24ecccf7b435 doc/reST/cli.rst
--- a/doc/reST/cli.rst  Thu Sep 22 13:26:57 2016 +0530
+++ b/doc/reST/cli.rst  Thu Sep 22 15:43:43 2016 +0530
@@ -1141,10 +1141,10 @@
 .. option:: --min-keyint, -i <integer>

        Minimum GOP size. Scenecuts closer together than this are coded as I
-       or P, not IDR. Minimum keyint is clamped to be at least half of
-       :option:`--keyint`. If you wish to force regular keyframe intervals
+       or P, not IDR. If you wish to force regular keyframe intervals
        and disable adaptive I frame placement, you must use
-       :option:`--no-scenecut`.
+       :option:`--no-scenecut` or give minimum keyint equal to keyint
+       with scenecut enabled.

        **Range of values:** >=0 (0: auto)

diff -r bdf098eefd35 -r 24ecccf7b435 source/encoder/encoder.cpp
--- a/source/encoder/encoder.cpp        Thu Sep 22 13:26:57 2016 +0530
+++ b/source/encoder/encoder.cpp        Thu Sep 22 15:43:43 2016 +0530
@@ -1660,7 +1660,7 @@
         double fps = (double)p->fpsNum / p->fpsDenom;
         p->keyframeMin = X265_MIN((int)fps, p->keyframeMax / 10);
     }
-    p->keyframeMin = X265_MAX(1, X265_MIN(p->keyframeMin, p->keyframeMax /
2 + 1));
+    p->keyframeMin = X265_MAX(1, p->keyframeMin);

     if (!p->bframes)
         p->bBPyramid = 0;
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-- 

Deepthi
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