From b9df35f7143c6e08f64819a5271c5c4972bccb2c Mon Sep 17 00:00:00 2001
From: Urvang Joshi <urvang@google.com>
Date: Tue, 3 Feb 2015 11:42:13 -0800
Subject: [PATCH] AnimEncode API: kmax=0 should imply all keyframes.

Earlier, it wasn't adding any keyframes at all.

Change-Id: If3824fc8e57548b8610a52e875fb9279f862fa57
---
 man/gif2webp.1        |  3 ++-
 src/mux/anim_encode.c | 15 ++++++++++-----
 src/webp/mux.h        |  3 ++-
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/man/gif2webp.1 b/man/gif2webp.1
index ccc61726..1acff850 100644
--- a/man/gif2webp.1
+++ b/man/gif2webp.1
@@ -68,7 +68,8 @@ Specify the minimum and maximum distance between consecutive key frames
 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.
+A 'kmin' value of 0 will turn off insertion of key frames. A 'kmax' value of 0
+will result in all frames being key frames.
 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
diff --git a/src/mux/anim_encode.c b/src/mux/anim_encode.c
index d2898f74..3b42510d 100644
--- a/src/mux/anim_encode.c
+++ b/src/mux/anim_encode.c
@@ -111,9 +111,9 @@ static void SanitizeEncoderOptions(WebPAnimEncoderOptions* const enc_options) {
     DisableKeyframes(enc_options);
     print_warning = 0;
   }
-  if (enc_options->kmax == 0) {
-    enc_options->kmax = ~0;
-    print_warning = 0;
+  if (enc_options->kmax == 0) {  // All frames will be key-frames.
+    enc_options->kmin = 0;
+    return;
   }
 
   if (enc_options->kmin >= enc_options->kmax) {
@@ -144,7 +144,7 @@ static void SanitizeEncoderOptions(WebPAnimEncoderOptions* const enc_options) {
               (int)enc_options->kmin, MAX_CACHED_FRAMES);
     }
   }
-  assert(enc_options->kmin <= enc_options->kmax);
+  assert(enc_options->kmin < enc_options->kmax);
 }
 
 #undef MAX_CACHED_FRAMES
@@ -242,6 +242,9 @@ WebPAnimEncoder* WebPAnimEncoderNewInternal(
   ResetCounters(enc);
   // Note: one extra storage is for the previous frame.
   enc->size_ = enc->options_.kmax - enc->options_.kmin + 1;
+  // We need space for at least 2 frames. But when kmin, kmax are both zero,
+  // enc->size_ will be 1. So we handle that special case below.
+  if (enc->size_ < 2) enc->size_ = 2;
   enc->encoded_frames_ =
       (EncodedFrame*)WebPSafeCalloc(enc->size_, sizeof(*enc->encoded_frames_));
   if (enc->encoded_frames_ == NULL) goto Err;
@@ -972,7 +975,9 @@ static int CacheFrame(WebPAnimEncoder* const enc, int duration,
       } else {
         encoded_frame->is_key_frame_ = 0;
       }
-      if (enc->count_since_key_frame_ == enc->options_.kmax) {
+      // Note: We need '>=' below because when kmin and kmax are both zero,
+      // count_since_key_frame will always be > kmax.
+      if (enc->count_since_key_frame_ >= enc->options_.kmax) {
         enc->flush_count_ = enc->count_ - 1;
         enc->count_since_key_frame_ = 0;
         enc->keyframe_ = KEYFRAME_NONE;
diff --git a/src/webp/mux.h b/src/webp/mux.h
index 5126ad5d..28492956 100644
--- a/src/webp/mux.h
+++ b/src/webp/mux.h
@@ -427,7 +427,8 @@ typedef struct {
                         // frames as needed to satisfy this criteria.
                         // Note that these conditions should hold: kmax > kmin
                         // and kmin >= kmax / 2 + 1. Also, if kmin == 0, then
-                        // key-frame insertion is disabled.
+                        // key-frame insertion is disabled; and if kmax == 0,
+                        // then all frames will be key-frames.
   int allow_mixed;      // If true, use mixed compression mode; may choose
                         // either lossy and lossless for each frame.