From fb887f7fe6214d547cd3b8f1fb260b178bace968 Mon Sep 17 00:00:00 2001
From: Urvang Joshi <urvang@google.com>
Date: Mon, 30 Sep 2013 14:25:58 -0700
Subject: [PATCH] gif2webp: Different kmin/kmax defaults for lossy and lossless

These were the best values found considering the compression gain and
decoding speed.

Change-Id: Iddae4c5b78c6aa42b1f8a034d1c1b93843071a81
---
 examples/gif2webp.c | 16 ++++++++++++++--
 man/gif2webp.1      |  6 +++---
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/examples/gif2webp.c b/examples/gif2webp.c
index 2f9b1e65..24e2d35c 100644
--- a/examples/gif2webp.c
+++ b/examples/gif2webp.c
@@ -307,8 +307,11 @@ int main(int argc, const char *argv[]) {
   WebPData webp_data = { NULL, 0 };
   int stored_icc = 0;  // Whether we have already stored an ICC profile.
   int stored_xmp = 0;
-  size_t kmin = 9;
-  size_t kmax = 17;
+
+  int default_kmin = 1;  // Whether to use default kmin value.
+  int default_kmax = 1;
+  size_t kmin = 0;
+  size_t kmax = 0;
 
   memset(&frame, 0, sizeof(frame));
   frame.id = WEBP_CHUNK_ANMF;
@@ -341,8 +344,10 @@ int main(int argc, const char *argv[]) {
       config.method = strtol(argv[++c], NULL, 0);
     } else if (!strcmp(argv[c], "-kmax") && c < argc - 1) {
       kmax = strtoul(argv[++c], NULL, 0);
+      default_kmax = 0;
     } else if (!strcmp(argv[c], "-kmin") && c < argc - 1) {
       kmin = strtoul(argv[++c], NULL, 0);
+      default_kmin = 0;
     } else if (!strcmp(argv[c], "-f") && c < argc - 1) {
       config.filter_strength = strtol(argv[++c], NULL, 0);
     } else if (!strcmp(argv[c], "-version")) {
@@ -366,6 +371,13 @@ int main(int argc, const char *argv[]) {
     }
   }
 
+  // Appropriate default kmin, kmax values for lossy and lossless.
+  if (default_kmin) {
+    kmin = config.lossless ? 9 : 3;
+  }
+  if (default_kmax) {
+    kmax = config.lossless ? 17 : 5;
+  }
   SanitizeKeyFrameIntervals(&kmin, &kmax);
 
   cache = WebPFrameCacheNew(kmin, kmax);
diff --git a/man/gif2webp.1 b/man/gif2webp.1
index f2fcfcb8..ed5feb83 100644
--- a/man/gif2webp.1
+++ b/man/gif2webp.1
@@ -1,5 +1,5 @@
 .\"                                      Hey, EMACS: -*- nroff -*-
-.TH GIF2WEBP 1 "February 01, 2013"
+.TH GIF2WEBP 1 "September 30, 2013"
 .SH NAME
 gif2webp \- Convert a GIF image to WebP
 .SH SYNOPSIS
@@ -58,8 +58,8 @@ some key frames into the output animation as needed so that this criteria is
 satisfied.
 .br
 A 'kmin' value of 0 will turn off insertion of key frames.
-Typical values are in the range 5 to 30. Default values are kmin = 9 and
-kmax = 17.
+Typical values are in the range 3 to 30. Default values are kmin = 9,
+kmax = 17 for lossless compression and kmin = 3, kmax = 5 for lossy compression.
 .br
 These two options are relevant only for animated images with large number of
 frames (>50).