gif2webp: Support a 'min' and 'max' key frame interval

Change-Id: If910c8849d7210e7227db0f45affa26fce7da102
2025-07-13 14:34:33 +02:00 · 2013-09-12 13:41:09 -07:00
parent 80b54e1c69
commit d538cea8c2
6 changed files with 633 additions and 256 deletions
--- a/examples/gif2webp_util.h
+++ b/examples/gif2webp_util.h
@ -0,0 +1,110 @@
+// Copyright 2013 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+//  Helper structs and methods for gif2webp tool.
+//
+// Author: Urvang (urvang@google.com)
+
+#ifndef WEBP_EXAMPLES_GIF2WEBP_UTIL_H_
+#define WEBP_EXAMPLES_GIF2WEBP_UTIL_H_
+
+#include <stdlib.h>
+
+#include "webp/mux.h"
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+//------------------------------------------------------------------------------
+// Frame cache.
+
+typedef struct WebPFrameCache WebPFrameCache;
+
+// Given the minimum distance between key frames 'kmin' and maximum distance
+// between key frames 'kmax', returns an appropriately allocated cache object.
+// Use WebPFrameCacheDelete() to deallocate the 'cache'.
+WebPFrameCache* WebPFrameCacheNew(size_t kmin, size_t kmax);
+
+// Release all the frame data from 'cache' and free 'cache'.
+void WebPFrameCacheDelete(WebPFrameCache* const cache);
+
+// Add encoded frame in the cache. 'sub_frame_info' and 'sub_frame_pic' are used
+// to encode the frame rectangle, while 'key_frame_info' and 'key_frame_pic' are
+// used to encode the key frame. Either 'sub_frame_pic' (and 'sub_frame_info')
+// or 'key_frame_pic' (and 'key_frame_info') can be NULL; in which case the
+// corresponding variant will be omitted.
+// Returns true on success.
+int WebPFrameCacheAddFrame(WebPFrameCache* const cache,
+                           const WebPConfig* const config,
+                           const WebPMuxFrameInfo* const sub_frame_info,
+                           WebPPicture* const sub_frame_pic,
+                           const WebPMuxFrameInfo* const key_frame_info,
+                           WebPPicture* const key_frame_pic);
+
+// Flush the *ready* frames from cache and add them to 'mux'. If 'verbose' is
+// true, prints the information about these frames.
+WebPMuxError WebPFrameCacheFlush(WebPFrameCache* const cache, int verbose,
+                                 WebPMux* const mux);
+
+// Similar to 'WebPFrameCacheFlushFrames()', but flushes *all* the frames.
+WebPMuxError WebPFrameCacheFlushAll(WebPFrameCache* const cache, int verbose,
+                                    WebPMux* const mux);
+
+// Returns true if subsequent call to WebPFrameCacheAddFrame() should
+// incorporate a potential keyframe.
+int WebPFrameCacheShouldTryKeyFrame(const WebPFrameCache* const cache);
+
+//------------------------------------------------------------------------------
+// Frame rectangle and related utilities.
+
+#define TRANSPARENT_COLOR    0x00ffffff
+
+typedef struct {
+  int x_offset, y_offset, width, height;
+} WebPFrameRect;
+
+struct WebPPicture;
+
+// Clear pixels in 'picture' within given 'rect' to transparent color.
+void WebPUtilClearPic(struct WebPPicture* const picture,
+                      const WebPFrameRect* const rect);
+
+// Copy pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are assumed
+// to be already allocated.
+void WebPUtilCopyPixels(const struct WebPPicture* const src,
+                        WebPPicture* const dst);
+
+// Given 'src' picture and its frame rectangle 'rect', blend it into 'dst'.
+void WebPUtilBlendPixels(const struct WebPPicture* const src,
+                         const WebPFrameRect* const src_rect,
+                         struct WebPPicture* const dst);
+
+//------------------------------------------------------------------------------
+// Key frame related.
+
+// Returns true if 'curr' frame with frame rectangle 'curr_rect' is a key frame,
+// that is, it can be decoded independently of 'prev' canvas.
+int WebPUtilIsKeyFrame(const WebPPicture* const curr,
+                       const WebPFrameRect* const curr_rect,
+                       const WebPPicture* const prev);
+
+// Given 'prev' frame and current frame rectangle 'rect', convert 'curr' frame
+// to a key frame.
+void WebPUtilConvertToKeyFrame(const WebPPicture* const prev,
+                               WebPFrameRect* const rect,
+                               WebPPicture* const curr);
+
+//------------------------------------------------------------------------------
+
+#if defined(__cplusplus) || defined(c_plusplus)
+}    // extern "C"
+#endif
+
+#endif  // WEBP_EXAMPLES_GIF2WEBP_UTIL_H_