update ChangeLog

Change-Id: Ica00314a3dfacad89ec62a3dc2df0d476e6397af

ChangeLog

@@ -1,3 +1,6 @@
+8d510751 webp-container-spec: correct frame duration=0 note
+e6b2164e vwebp: Copy Chrome's behavior w/frame duration == 0
+d20b7707 update ChangeLog (tag: v1.0.0-rc3)
 0d5fad46 add WEBP_DSP_INIT / WEBP_DSP_INIT_FUNC
 c1cb86af fix 16b overflow in SSE2
 e577feb7 makefile.unix: add DEBUG flag for compiling w/ debug-symbol

doc/webp-container-spec.txt

@@ -446,8 +446,9 @@ Frame Height Minus One: 24 bits (_uint24_)
 Frame Duration: 24 bits (_uint24_)
 
 : The time to wait before displaying the next frame, in 1 millisecond units.
-  In particular, frame duration of 0 is useful when one wants to update
-  multiple areas of the canvas at once during the animation.
+  Note the interpretation of frame duration of 0 (and often <= 10) is
+  implementation defined. Many tools and browsers assign a minimum duration
+  similar to GIF.
 
 Reserved: 6 bits
 

examples/vwebp.c

@@ -205,6 +205,11 @@ static void decode_callback(int what) {
         }
       }
       duration = curr->duration;
+      // Behavior copied from Chrome, cf:
+      // https://cs.chromium.org/chromium/src/third_party/WebKit/Source/
+      // platform/graphics/DeferredImageDecoder.cpp?
+      // rcl=b4c33049f096cd283f32be9a58b9a9e768227c26&l=246
+      if (duration <= 10) duration = 100;
     }
     if (!Decode()) {
       kParams.decoding_error = 1;