// Copyright 2014 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. // ----------------------------------------------------------------------------- // // AnimEncoder implementation. // #include <assert.h> #include <limits.h> #include <stdio.h> #include "../utils/utils.h" #include "webp/decode.h" #include "webp/encode.h" #include "webp/format_constants.h" #include "webp/mux.h" #if defined(_MSC_VER) && _MSC_VER < 1900 #define snprintf _snprintf #endif #define ERROR_STR_MAX_LENGTH 100 //------------------------------------------------------------------------------ // Internal structs. // Stores frame rectangle dimensions. typedef struct { int x_offset_, y_offset_, width_, height_; } FrameRect; // Used to store two candidates of encoded data for an animation frame. One of // the two will be chosen later. typedef struct { WebPMuxFrameInfo sub_frame_; // Encoded frame rectangle. WebPMuxFrameInfo key_frame_; // Encoded frame if it is a key-frame. int is_key_frame_; // True if 'key_frame' has been chosen. } EncodedFrame; struct WebPAnimEncoder { const int canvas_width_; // Canvas width. const int canvas_height_; // Canvas height. const WebPAnimEncoderOptions options_; // Global encoding options. FrameRect prev_rect_; // Previous WebP frame rectangle. WebPConfig last_config_; // Cached in case a re-encode is needed. WebPConfig last_config2_; // 2nd cached config; only valid if // 'options_.allow_mixed' is true. WebPPicture* curr_canvas_; // Only pointer; we don't own memory. // Canvas buffers. WebPPicture curr_canvas_copy_; // Possibly modified current canvas. int curr_canvas_copy_modified_; // True if pixels in 'curr_canvas_copy_' // differ from those in 'curr_canvas_'. WebPPicture prev_canvas_; // Previous canvas. WebPPicture prev_canvas_disposed_; // Previous canvas disposed to background. // Encoded data. EncodedFrame* encoded_frames_; // Array of encoded frames. size_t size_; // Number of allocated frames. size_t start_; // Frame start index. size_t count_; // Number of valid frames. size_t flush_count_; // If >0, 'flush_count' frames starting from // 'start' are ready to be added to mux. // key-frame related. int64_t best_delta_; // min(canvas size - frame size) over the frames. // Can be negative in certain cases due to // transparent pixels in a frame. int keyframe_; // Index of selected key-frame relative to 'start_'. int count_since_key_frame_; // Frames seen since the last key-frame. int first_timestamp_; // Timestamp of the first frame. int prev_timestamp_; // Timestamp of the last added frame. int prev_candidate_undecided_; // True if it's not yet decided if previous // frame would be a sub-frame or a key-frame. // Misc. int is_first_frame_; // True if first frame is yet to be added/being added. int got_null_frame_; // True if WebPAnimEncoderAdd() has already been called // with a NULL frame. size_t in_frame_count_; // Number of input frames processed so far. size_t out_frame_count_; // Number of frames added to mux so far. This may be // different from 'in_frame_count_' due to merging. WebPMux* mux_; // Muxer to assemble the WebP bitstream. char error_str_[ERROR_STR_MAX_LENGTH]; // Error string. Empty if no error. }; // ----------------------------------------------------------------------------- // Life of WebPAnimEncoder object. #define DELTA_INFINITY (1ULL << 32) #define KEYFRAME_NONE (-1) // Reset the counters in the WebPAnimEncoder. static void ResetCounters(WebPAnimEncoder* const enc) { enc->start_ = 0; enc->count_ = 0; enc->flush_count_ = 0; enc->best_delta_ = DELTA_INFINITY; enc->keyframe_ = KEYFRAME_NONE; } static void DisableKeyframes(WebPAnimEncoderOptions* const enc_options) { enc_options->kmax = INT_MAX; enc_options->kmin = enc_options->kmax - 1; } #define MAX_CACHED_FRAMES 30 static void SanitizeEncoderOptions(WebPAnimEncoderOptions* const enc_options) { int print_warning = enc_options->verbose; if (enc_options->minimize_size) { DisableKeyframes(enc_options); } if (enc_options->kmin <= 0) { DisableKeyframes(enc_options); print_warning = 0; } if (enc_options->kmax <= 0) { // All frames will be key-frames. enc_options->kmin = 0; enc_options->kmax = 0; return; } if (enc_options->kmin >= enc_options->kmax) { enc_options->kmin = enc_options->kmax - 1; if (print_warning) { fprintf(stderr, "WARNING: Setting kmin = %d, so that kmin < kmax.\n", enc_options->kmin); } } else { const int kmin_limit = enc_options->kmax / 2 + 1; if (enc_options->kmin < kmin_limit && kmin_limit < enc_options->kmax) { // This ensures that enc.keyframe + kmin >= kmax is always true. So, we // can flush all the frames in the 'count_since_key_frame == kmax' case. enc_options->kmin = kmin_limit; if (print_warning) { fprintf(stderr, "WARNING: Setting kmin = %d, so that kmin >= kmax / 2 + 1.\n", enc_options->kmin); } } } // Limit the max number of frames that are allocated. if (enc_options->kmax - enc_options->kmin > MAX_CACHED_FRAMES) { enc_options->kmin = enc_options->kmax - MAX_CACHED_FRAMES; if (print_warning) { fprintf(stderr, "WARNING: Setting kmin = %d, so that kmax - kmin <= %d.\n", enc_options->kmin, MAX_CACHED_FRAMES); } } assert(enc_options->kmin < enc_options->kmax); } #undef MAX_CACHED_FRAMES static void DefaultEncoderOptions(WebPAnimEncoderOptions* const enc_options) { enc_options->anim_params.loop_count = 0; enc_options->anim_params.bgcolor = 0xffffffff; // White. enc_options->minimize_size = 0; DisableKeyframes(enc_options); enc_options->allow_mixed = 0; } int WebPAnimEncoderOptionsInitInternal(WebPAnimEncoderOptions* enc_options, int abi_version) { if (enc_options == NULL || WEBP_ABI_IS_INCOMPATIBLE(abi_version, WEBP_MUX_ABI_VERSION)) { return 0; } DefaultEncoderOptions(enc_options); return 1; } #define TRANSPARENT_COLOR 0x00ffffff static void ClearRectangle(WebPPicture* const picture, int left, int top, int width, int height) { int j; for (j = top; j < top + height; ++j) { uint32_t* const dst = picture->argb + j * picture->argb_stride; int i; for (i = left; i < left + width; ++i) { dst[i] = TRANSPARENT_COLOR; } } } static void WebPUtilClearPic(WebPPicture* const picture, const FrameRect* const rect) { if (rect != NULL) { ClearRectangle(picture, rect->x_offset_, rect->y_offset_, rect->width_, rect->height_); } else { ClearRectangle(picture, 0, 0, picture->width, picture->height); } } static void MarkNoError(WebPAnimEncoder* const enc) { enc->error_str_[0] = '\0'; // Empty string. } static void MarkError(WebPAnimEncoder* const enc, const char* str) { if (snprintf(enc->error_str_, ERROR_STR_MAX_LENGTH, "%s.", str) < 0) { assert(0); // FIX ME! } } static void MarkError2(WebPAnimEncoder* const enc, const char* str, int error_code) { if (snprintf(enc->error_str_, ERROR_STR_MAX_LENGTH, "%s: %d.", str, error_code) < 0) { assert(0); // FIX ME! } } WebPAnimEncoder* WebPAnimEncoderNewInternal( int width, int height, const WebPAnimEncoderOptions* enc_options, int abi_version) { WebPAnimEncoder* enc; if (WEBP_ABI_IS_INCOMPATIBLE(abi_version, WEBP_MUX_ABI_VERSION)) { return NULL; } if (width <= 0 || height <= 0 || (width * (uint64_t)height) >= MAX_IMAGE_AREA) { return NULL; } enc = (WebPAnimEncoder*)WebPSafeCalloc(1, sizeof(*enc)); if (enc == NULL) return NULL; // sanity inits, so we can call WebPAnimEncoderDelete(): enc->encoded_frames_ = NULL; enc->mux_ = NULL; MarkNoError(enc); // Dimensions and options. *(int*)&enc->canvas_width_ = width; *(int*)&enc->canvas_height_ = height; if (enc_options != NULL) { *(WebPAnimEncoderOptions*)&enc->options_ = *enc_options; SanitizeEncoderOptions((WebPAnimEncoderOptions*)&enc->options_); } else { DefaultEncoderOptions((WebPAnimEncoderOptions*)&enc->options_); } // Canvas buffers. if (!WebPPictureInit(&enc->curr_canvas_copy_) || !WebPPictureInit(&enc->prev_canvas_) || !WebPPictureInit(&enc->prev_canvas_disposed_)) { goto Err; } enc->curr_canvas_copy_.width = width; enc->curr_canvas_copy_.height = height; enc->curr_canvas_copy_.use_argb = 1; if (!WebPPictureAlloc(&enc->curr_canvas_copy_) || !WebPPictureCopy(&enc->curr_canvas_copy_, &enc->prev_canvas_) || !WebPPictureCopy(&enc->curr_canvas_copy_, &enc->prev_canvas_disposed_)) { goto Err; } WebPUtilClearPic(&enc->prev_canvas_, NULL); enc->curr_canvas_copy_modified_ = 1; // Encoded frames. 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; enc->mux_ = WebPMuxNew(); if (enc->mux_ == NULL) goto Err; enc->count_since_key_frame_ = 0; enc->first_timestamp_ = 0; enc->prev_timestamp_ = 0; enc->prev_candidate_undecided_ = 0; enc->is_first_frame_ = 1; enc->got_null_frame_ = 0; return enc; // All OK. Err: WebPAnimEncoderDelete(enc); return NULL; } // Release the data contained by 'encoded_frame'. static void FrameRelease(EncodedFrame* const encoded_frame) { if (encoded_frame != NULL) { WebPDataClear(&encoded_frame->sub_frame_.bitstream); WebPDataClear(&encoded_frame->key_frame_.bitstream); memset(encoded_frame, 0, sizeof(*encoded_frame)); } } void WebPAnimEncoderDelete(WebPAnimEncoder* enc) { if (enc != NULL) { WebPPictureFree(&enc->curr_canvas_copy_); WebPPictureFree(&enc->prev_canvas_); WebPPictureFree(&enc->prev_canvas_disposed_); if (enc->encoded_frames_ != NULL) { size_t i; for (i = 0; i < enc->size_; ++i) { FrameRelease(&enc->encoded_frames_[i]); } WebPSafeFree(enc->encoded_frames_); } WebPMuxDelete(enc->mux_); WebPSafeFree(enc); } } // ----------------------------------------------------------------------------- // Frame addition. // Returns cached frame at the given 'position'. static EncodedFrame* GetFrame(const WebPAnimEncoder* const enc, size_t position) { assert(enc->start_ + position < enc->size_); return &enc->encoded_frames_[enc->start_ + position]; } // Returns true if 'length' number of pixels in 'src' and 'dst' are identical, // assuming the given step sizes between pixels. static WEBP_INLINE int ComparePixels(const uint32_t* src, int src_step, const uint32_t* dst, int dst_step, int length) { assert(length > 0); while (length-- > 0) { if (*src != *dst) { return 0; } src += src_step; dst += dst_step; } return 1; } static int IsEmptyRect(const FrameRect* const rect) { return (rect->width_ == 0) || (rect->height_ == 0); } // Assumes that an initial valid guess of change rectangle 'rect' is passed. static void MinimizeChangeRectangle(const WebPPicture* const src, const WebPPicture* const dst, FrameRect* const rect) { int i, j; // Sanity checks. assert(src->width == dst->width && src->height == dst->height); assert(rect->x_offset_ + rect->width_ <= dst->width); assert(rect->y_offset_ + rect->height_ <= dst->height); // Left boundary. for (i = rect->x_offset_; i < rect->x_offset_ + rect->width_; ++i) { const uint32_t* const src_argb = &src->argb[rect->y_offset_ * src->argb_stride + i]; const uint32_t* const dst_argb = &dst->argb[rect->y_offset_ * dst->argb_stride + i]; if (ComparePixels(src_argb, src->argb_stride, dst_argb, dst->argb_stride, rect->height_)) { --rect->width_; // Redundant column. ++rect->x_offset_; } else { break; } } if (rect->width_ == 0) goto NoChange; // Right boundary. for (i = rect->x_offset_ + rect->width_ - 1; i >= rect->x_offset_; --i) { const uint32_t* const src_argb = &src->argb[rect->y_offset_ * src->argb_stride + i]; const uint32_t* const dst_argb = &dst->argb[rect->y_offset_ * dst->argb_stride + i]; if (ComparePixels(src_argb, src->argb_stride, dst_argb, dst->argb_stride, rect->height_)) { --rect->width_; // Redundant column. } else { break; } } if (rect->width_ == 0) goto NoChange; // Top boundary. for (j = rect->y_offset_; j < rect->y_offset_ + rect->height_; ++j) { const uint32_t* const src_argb = &src->argb[j * src->argb_stride + rect->x_offset_]; const uint32_t* const dst_argb = &dst->argb[j * dst->argb_stride + rect->x_offset_]; if (ComparePixels(src_argb, 1, dst_argb, 1, rect->width_)) { --rect->height_; // Redundant row. ++rect->y_offset_; } else { break; } } if (rect->height_ == 0) goto NoChange; // Bottom boundary. for (j = rect->y_offset_ + rect->height_ - 1; j >= rect->y_offset_; --j) { const uint32_t* const src_argb = &src->argb[j * src->argb_stride + rect->x_offset_]; const uint32_t* const dst_argb = &dst->argb[j * dst->argb_stride + rect->x_offset_]; if (ComparePixels(src_argb, 1, dst_argb, 1, rect->width_)) { --rect->height_; // Redundant row. } else { break; } } if (rect->height_ == 0) goto NoChange; if (IsEmptyRect(rect)) { NoChange: rect->x_offset_ = 0; rect->y_offset_ = 0; rect->width_ = 0; rect->height_ = 0; } } // Snap rectangle to even offsets (and adjust dimensions if needed). static WEBP_INLINE void SnapToEvenOffsets(FrameRect* const rect) { rect->width_ += (rect->x_offset_ & 1); rect->height_ += (rect->y_offset_ & 1); rect->x_offset_ &= ~1; rect->y_offset_ &= ~1; } // Given previous and current canvas, picks the optimal rectangle for the // current frame. The initial guess for 'rect' will be the full canvas. static int GetSubRect(const WebPPicture* const prev_canvas, const WebPPicture* const curr_canvas, int is_key_frame, int is_first_frame, int empty_rect_allowed, FrameRect* const rect, WebPPicture* const sub_frame) { rect->x_offset_ = 0; rect->y_offset_ = 0; rect->width_ = curr_canvas->width; rect->height_ = curr_canvas->height; if (!is_key_frame || is_first_frame) { // Optimize frame rectangle. // Note: This behaves as expected for first frame, as 'prev_canvas' is // initialized to a fully transparent canvas in the beginning. MinimizeChangeRectangle(prev_canvas, curr_canvas, rect); } if (IsEmptyRect(rect)) { if (empty_rect_allowed) { // No need to get 'sub_frame'. return 1; } else { // Force a 1x1 rectangle. rect->width_ = 1; rect->height_ = 1; assert(rect->x_offset_ == 0); assert(rect->y_offset_ == 0); } } SnapToEvenOffsets(rect); return WebPPictureView(curr_canvas, rect->x_offset_, rect->y_offset_, rect->width_, rect->height_, sub_frame); } static void DisposeFrameRectangle(int dispose_method, const FrameRect* const rect, WebPPicture* const curr_canvas) { assert(rect != NULL); if (dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) { WebPUtilClearPic(curr_canvas, rect); } } static uint32_t RectArea(const FrameRect* const rect) { return (uint32_t)rect->width_ * rect->height_; } static int IsBlendingPossible(const WebPPicture* const src, const WebPPicture* const dst, const FrameRect* const rect) { int i, j; assert(src->width == dst->width && src->height == dst->height); assert(rect->x_offset_ + rect->width_ <= dst->width); assert(rect->y_offset_ + rect->height_ <= dst->height); for (j = rect->y_offset_; j < rect->y_offset_ + rect->height_; ++j) { for (i = rect->x_offset_; i < rect->x_offset_ + rect->width_; ++i) { const uint32_t src_pixel = src->argb[j * src->argb_stride + i]; const uint32_t dst_pixel = dst->argb[j * dst->argb_stride + i]; const uint32_t dst_alpha = dst_pixel >> 24; if (dst_alpha != 0xff && src_pixel != dst_pixel) { // In this case, if we use blending, we can't attain the desired // 'dst_pixel' value for this pixel. So, blending is not possible. return 0; } } } return 1; } #define MIN_COLORS_LOSSY 31 // Don't try lossy below this threshold. #define MAX_COLORS_LOSSLESS 194 // Don't try lossless above this threshold. #define MAX_COLOR_COUNT 256 // Power of 2 greater than MAX_COLORS_LOSSLESS. #define HASH_SIZE (MAX_COLOR_COUNT * 4) #define HASH_RIGHT_SHIFT 22 // 32 - log2(HASH_SIZE). // TODO(urvang): Also used in enc/vp8l.c. Move to utils. // If the number of colors in the 'pic' is at least MAX_COLOR_COUNT, return // MAX_COLOR_COUNT. Otherwise, return the exact number of colors in the 'pic'. static int GetColorCount(const WebPPicture* const pic) { int x, y; int num_colors = 0; uint8_t in_use[HASH_SIZE] = { 0 }; uint32_t colors[HASH_SIZE]; static const uint32_t kHashMul = 0x1e35a7bd; const uint32_t* argb = pic->argb; const int width = pic->width; const int height = pic->height; uint32_t last_pix = ~argb[0]; // so we're sure that last_pix != argb[0] for (y = 0; y < height; ++y) { for (x = 0; x < width; ++x) { int key; if (argb[x] == last_pix) { continue; } last_pix = argb[x]; key = (kHashMul * last_pix) >> HASH_RIGHT_SHIFT; while (1) { if (!in_use[key]) { colors[key] = last_pix; in_use[key] = 1; ++num_colors; if (num_colors >= MAX_COLOR_COUNT) { return MAX_COLOR_COUNT; // Exact count not needed. } break; } else if (colors[key] == last_pix) { break; // The color is already there. } else { // Some other color sits here, so do linear conflict resolution. ++key; key &= (HASH_SIZE - 1); // Key mask. } } } argb += pic->argb_stride; } return num_colors; } #undef MAX_COLOR_COUNT #undef HASH_SIZE #undef HASH_RIGHT_SHIFT // For pixels in 'rect', replace those pixels in 'dst' that are same as 'src' by // transparent pixels. static void IncreaseTransparency(const WebPPicture* const src, const FrameRect* const rect, WebPPicture* const dst) { int i, j; assert(src != NULL && dst != NULL && rect != NULL); assert(src->width == dst->width && src->height == dst->height); for (j = rect->y_offset_; j < rect->y_offset_ + rect->height_; ++j) { const uint32_t* const psrc = src->argb + j * src->argb_stride; uint32_t* const pdst = dst->argb + j * dst->argb_stride; for (i = rect->x_offset_; i < rect->x_offset_ + rect->width_; ++i) { if (psrc[i] == pdst[i]) { pdst[i] = TRANSPARENT_COLOR; } } } } #undef TRANSPARENT_COLOR // Replace similar blocks of pixels by a 'see-through' transparent block // with uniform average color. static void FlattenSimilarBlocks(const WebPPicture* const src, const FrameRect* const rect, WebPPicture* const dst) { int i, j; const int block_size = 8; const int y_start = (rect->y_offset_ + block_size) & ~(block_size - 1); const int y_end = (rect->y_offset_ + rect->height_) & ~(block_size - 1); const int x_start = (rect->x_offset_ + block_size) & ~(block_size - 1); const int x_end = (rect->x_offset_ + rect->width_) & ~(block_size - 1); assert(src != NULL && dst != NULL && rect != NULL); assert(src->width == dst->width && src->height == dst->height); assert((block_size & (block_size - 1)) == 0); // must be a power of 2 // Iterate over each block and count similar pixels. for (j = y_start; j < y_end; j += block_size) { for (i = x_start; i < x_end; i += block_size) { int cnt = 0; int avg_r = 0, avg_g = 0, avg_b = 0; int x, y; const uint32_t* const psrc = src->argb + j * src->argb_stride + i; uint32_t* const pdst = dst->argb + j * dst->argb_stride + i; for (y = 0; y < block_size; ++y) { for (x = 0; x < block_size; ++x) { const uint32_t src_pixel = psrc[x + y * src->argb_stride]; const int alpha = src_pixel >> 24; if (alpha == 0xff && src_pixel == pdst[x + y * dst->argb_stride]) { ++cnt; avg_r += (src_pixel >> 16) & 0xff; avg_g += (src_pixel >> 8) & 0xff; avg_b += (src_pixel >> 0) & 0xff; } } } // If we have a fully similar block, we replace it with an // average transparent block. This compresses better in lossy mode. if (cnt == block_size * block_size) { const uint32_t color = (0x00 << 24) | ((avg_r / cnt) << 16) | ((avg_g / cnt) << 8) | ((avg_b / cnt) << 0); for (y = 0; y < block_size; ++y) { for (x = 0; x < block_size; ++x) { pdst[x + y * dst->argb_stride] = color; } } } } } } static int EncodeFrame(const WebPConfig* const config, WebPPicture* const pic, WebPMemoryWriter* const memory) { pic->use_argb = 1; pic->writer = WebPMemoryWrite; pic->custom_ptr = memory; if (!WebPEncode(config, pic)) { return 0; } return 1; } // Struct representing a candidate encoded frame including its metadata. typedef struct { WebPMemoryWriter mem_; WebPMuxFrameInfo info_; FrameRect rect_; int evaluate_; // True if this candidate should be evaluated. } Candidate; // Generates a candidate encoded frame given a picture and metadata. static WebPEncodingError EncodeCandidate(WebPPicture* const sub_frame, const FrameRect* const rect, const WebPConfig* const config, int use_blending, Candidate* const candidate) { WebPEncodingError error_code = VP8_ENC_OK; assert(candidate != NULL); memset(candidate, 0, sizeof(*candidate)); // Set frame rect and info. candidate->rect_ = *rect; candidate->info_.id = WEBP_CHUNK_ANMF; candidate->info_.x_offset = rect->x_offset_; candidate->info_.y_offset = rect->y_offset_; candidate->info_.dispose_method = WEBP_MUX_DISPOSE_NONE; // Set later. candidate->info_.blend_method = use_blending ? WEBP_MUX_BLEND : WEBP_MUX_NO_BLEND; candidate->info_.duration = 0; // Set in next call to WebPAnimEncoderAdd(). // Encode picture. WebPMemoryWriterInit(&candidate->mem_); if (!EncodeFrame(config, sub_frame, &candidate->mem_)) { error_code = sub_frame->error_code; goto Err; } candidate->evaluate_ = 1; return error_code; Err: WebPMemoryWriterClear(&candidate->mem_); return error_code; } static void CopyCurrentCanvas(WebPAnimEncoder* const enc) { if (enc->curr_canvas_copy_modified_) { WebPCopyPixels(enc->curr_canvas_, &enc->curr_canvas_copy_); enc->curr_canvas_copy_modified_ = 0; } } enum { LL_DISP_NONE = 0, LL_DISP_BG, LOSSY_DISP_NONE, LOSSY_DISP_BG, CANDIDATE_COUNT }; // Generates candidates for a given dispose method given pre-filled 'rect' // and 'sub_frame'. static WebPEncodingError GenerateCandidates( WebPAnimEncoder* const enc, Candidate candidates[CANDIDATE_COUNT], WebPMuxAnimDispose dispose_method, int is_lossless, int is_key_frame, const FrameRect* const rect, WebPPicture* sub_frame, const WebPConfig* const config_ll, const WebPConfig* const config_lossy) { WebPEncodingError error_code = VP8_ENC_OK; const int is_dispose_none = (dispose_method == WEBP_MUX_DISPOSE_NONE); Candidate* const candidate_ll = is_dispose_none ? &candidates[LL_DISP_NONE] : &candidates[LL_DISP_BG]; Candidate* const candidate_lossy = is_dispose_none ? &candidates[LOSSY_DISP_NONE] : &candidates[LOSSY_DISP_BG]; WebPPicture* const curr_canvas = &enc->curr_canvas_copy_; const WebPPicture* const prev_canvas = is_dispose_none ? &enc->prev_canvas_ : &enc->prev_canvas_disposed_; const int use_blending = !is_key_frame && IsBlendingPossible(prev_canvas, curr_canvas, rect); // Pick candidates to be tried. if (!enc->options_.allow_mixed) { candidate_ll->evaluate_ = is_lossless; candidate_lossy->evaluate_ = !is_lossless; } else { // Use a heuristic for trying lossless and/or lossy compression. const int num_colors = GetColorCount(sub_frame); candidate_ll->evaluate_ = (num_colors < MAX_COLORS_LOSSLESS); candidate_lossy->evaluate_ = (num_colors >= MIN_COLORS_LOSSY); } // Generate candidates. if (candidate_ll->evaluate_) { CopyCurrentCanvas(enc); if (use_blending) { IncreaseTransparency(prev_canvas, rect, curr_canvas); enc->curr_canvas_copy_modified_ = 1; } error_code = EncodeCandidate(sub_frame, rect, config_ll, use_blending, candidate_ll); if (error_code != VP8_ENC_OK) return error_code; } if (candidate_lossy->evaluate_) { CopyCurrentCanvas(enc); if (use_blending) { FlattenSimilarBlocks(prev_canvas, rect, curr_canvas); enc->curr_canvas_copy_modified_ = 1; } error_code = EncodeCandidate(sub_frame, rect, config_lossy, use_blending, candidate_lossy); if (error_code != VP8_ENC_OK) return error_code; } return error_code; } #undef MIN_COLORS_LOSSY #undef MAX_COLORS_LOSSLESS static void GetEncodedData(const WebPMemoryWriter* const memory, WebPData* const encoded_data) { encoded_data->bytes = memory->mem; encoded_data->size = memory->size; } // Sets dispose method of the previous frame to be 'dispose_method'. static void SetPreviousDisposeMethod(WebPAnimEncoder* const enc, WebPMuxAnimDispose dispose_method) { const size_t position = enc->count_ - 2; EncodedFrame* const prev_enc_frame = GetFrame(enc, position); assert(enc->count_ >= 2); // As current and previous frames are in enc. if (enc->prev_candidate_undecided_) { assert(dispose_method == WEBP_MUX_DISPOSE_NONE); prev_enc_frame->sub_frame_.dispose_method = dispose_method; prev_enc_frame->key_frame_.dispose_method = dispose_method; } else { WebPMuxFrameInfo* const prev_info = prev_enc_frame->is_key_frame_ ? &prev_enc_frame->key_frame_ : &prev_enc_frame->sub_frame_; prev_info->dispose_method = dispose_method; } } static int IncreasePreviousDuration(WebPAnimEncoder* const enc, int duration) { const size_t position = enc->count_ - 1; EncodedFrame* const prev_enc_frame = GetFrame(enc, position); int new_duration; assert(enc->count_ >= 1); assert(prev_enc_frame->sub_frame_.duration == prev_enc_frame->key_frame_.duration); assert(prev_enc_frame->sub_frame_.duration == (prev_enc_frame->sub_frame_.duration & (MAX_DURATION - 1))); assert(duration == (duration & (MAX_DURATION - 1))); new_duration = prev_enc_frame->sub_frame_.duration + duration; if (new_duration >= MAX_DURATION) { // Special case. // Separate out previous frame from earlier merged frames to avoid overflow. // We add a 1x1 transparent frame for the previous frame, with blending on. const FrameRect rect = { 0, 0, 1, 1 }; const uint8_t lossless_1x1_bytes[] = { 0x52, 0x49, 0x46, 0x46, 0x14, 0x00, 0x00, 0x00, 0x57, 0x45, 0x42, 0x50, 0x56, 0x50, 0x38, 0x4c, 0x08, 0x00, 0x00, 0x00, 0x2f, 0x00, 0x00, 0x00, 0x10, 0x88, 0x88, 0x08 }; const WebPData lossless_1x1 = { lossless_1x1_bytes, sizeof(lossless_1x1_bytes) }; const uint8_t lossy_1x1_bytes[] = { 0x52, 0x49, 0x46, 0x46, 0x40, 0x00, 0x00, 0x00, 0x57, 0x45, 0x42, 0x50, 0x56, 0x50, 0x38, 0x58, 0x0a, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x41, 0x4c, 0x50, 0x48, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x56, 0x50, 0x38, 0x20, 0x18, 0x00, 0x00, 0x00, 0x30, 0x01, 0x00, 0x9d, 0x01, 0x2a, 0x01, 0x00, 0x01, 0x00, 0x02, 0x00, 0x34, 0x25, 0xa4, 0x00, 0x03, 0x70, 0x00, 0xfe, 0xfb, 0xfd, 0x50, 0x00 }; const WebPData lossy_1x1 = { lossy_1x1_bytes, sizeof(lossy_1x1_bytes) }; const int can_use_lossless = (enc->last_config_.lossless || enc->options_.allow_mixed); EncodedFrame* const curr_enc_frame = GetFrame(enc, enc->count_); curr_enc_frame->is_key_frame_ = 0; curr_enc_frame->sub_frame_.id = WEBP_CHUNK_ANMF; curr_enc_frame->sub_frame_.x_offset = 0; curr_enc_frame->sub_frame_.y_offset = 0; curr_enc_frame->sub_frame_.dispose_method = WEBP_MUX_DISPOSE_NONE; curr_enc_frame->sub_frame_.blend_method = WEBP_MUX_BLEND; curr_enc_frame->sub_frame_.duration = duration; if (!WebPDataCopy(can_use_lossless ? &lossless_1x1 : &lossy_1x1, &curr_enc_frame->sub_frame_.bitstream)) { return 0; } ++enc->count_; ++enc->count_since_key_frame_; enc->flush_count_ = enc->count_ - 1; enc->prev_candidate_undecided_ = 0; enc->prev_rect_ = rect; } else { // Regular case. // Increase duration of the previous frame by 'duration'. prev_enc_frame->sub_frame_.duration = new_duration; prev_enc_frame->key_frame_.duration = new_duration; } return 1; } // Pick the candidate encoded frame with smallest size and release other // candidates. // TODO(later): Perhaps a rough SSIM/PSNR produced by the encoder should // also be a criteria, in addition to sizes. static void PickBestCandidate(WebPAnimEncoder* const enc, Candidate* const candidates, int is_key_frame, EncodedFrame* const encoded_frame) { int i; int best_idx = -1; size_t best_size = ~0; for (i = 0; i < CANDIDATE_COUNT; ++i) { if (candidates[i].evaluate_) { const size_t candidate_size = candidates[i].mem_.size; if (candidate_size < best_size) { best_idx = i; best_size = candidate_size; } } } assert(best_idx != -1); for (i = 0; i < CANDIDATE_COUNT; ++i) { if (candidates[i].evaluate_) { if (i == best_idx) { WebPMuxFrameInfo* const dst = is_key_frame ? &encoded_frame->key_frame_ : &encoded_frame->sub_frame_; *dst = candidates[i].info_; GetEncodedData(&candidates[i].mem_, &dst->bitstream); if (!is_key_frame) { // Note: Previous dispose method only matters for non-keyframes. // Also, we don't want to modify previous dispose method that was // selected when a non key-frame was assumed. const WebPMuxAnimDispose prev_dispose_method = (best_idx == LL_DISP_NONE || best_idx == LOSSY_DISP_NONE) ? WEBP_MUX_DISPOSE_NONE : WEBP_MUX_DISPOSE_BACKGROUND; SetPreviousDisposeMethod(enc, prev_dispose_method); } enc->prev_rect_ = candidates[i].rect_; // save for next frame. } else { WebPMemoryWriterClear(&candidates[i].mem_); candidates[i].evaluate_ = 0; } } } } // Depending on the configuration, tries different compressions // (lossy/lossless), dispose methods, blending methods etc to encode the current // frame and outputs the best one in 'encoded_frame'. // 'frame_skipped' will be set to true if this frame should actually be skipped. static WebPEncodingError SetFrame(WebPAnimEncoder* const enc, const WebPConfig* const config, int is_key_frame, EncodedFrame* const encoded_frame, int* const frame_skipped) { int i; WebPEncodingError error_code = VP8_ENC_OK; const WebPPicture* const curr_canvas = &enc->curr_canvas_copy_; const WebPPicture* const prev_canvas = &enc->prev_canvas_; Candidate candidates[CANDIDATE_COUNT]; const int is_lossless = config->lossless; const int is_first_frame = enc->is_first_frame_; int try_dispose_none = 1; // Default. FrameRect rect_none; WebPPicture sub_frame_none; // First frame cannot be skipped as there is no 'previous frame' to merge it // to. So, empty rectangle is not allowed for the first frame. const int empty_rect_allowed_none = !is_first_frame; // If current frame is a key-frame, dispose method of previous frame doesn't // matter, so we don't try dispose to background. // Also, if key-frame insertion is on, and previous frame could be picked as // either a sub-frame or a key-frame, then we can't be sure about what frame // rectangle would be disposed. In that case too, we don't try dispose to // background. const int dispose_bg_possible = !is_key_frame && !enc->prev_candidate_undecided_; int try_dispose_bg = 0; // Default. FrameRect rect_bg; WebPPicture sub_frame_bg; WebPConfig config_ll = *config; WebPConfig config_lossy = *config; config_ll.lossless = 1; config_lossy.lossless = 0; enc->last_config_ = *config; enc->last_config2_ = config->lossless ? config_lossy : config_ll; *frame_skipped = 0; if (!WebPPictureInit(&sub_frame_none) || !WebPPictureInit(&sub_frame_bg)) { return VP8_ENC_ERROR_INVALID_CONFIGURATION; } for (i = 0; i < CANDIDATE_COUNT; ++i) { candidates[i].evaluate_ = 0; } // Change-rectangle assuming previous frame was DISPOSE_NONE. GetSubRect(prev_canvas, curr_canvas, is_key_frame, is_first_frame, empty_rect_allowed_none, &rect_none, &sub_frame_none); if (IsEmptyRect(&rect_none)) { // Don't encode the frame at all. Instead, the duration of the previous // frame will be increased later. assert(empty_rect_allowed_none); *frame_skipped = 1; goto End; } if (dispose_bg_possible) { // Change-rectangle assuming previous frame was DISPOSE_BACKGROUND. WebPPicture* const prev_canvas_disposed = &enc->prev_canvas_disposed_; WebPCopyPixels(prev_canvas, prev_canvas_disposed); DisposeFrameRectangle(WEBP_MUX_DISPOSE_BACKGROUND, &enc->prev_rect_, prev_canvas_disposed); // Even if there is exact pixel match between 'disposed previous canvas' and // 'current canvas', we can't skip current frame, as there may not be exact // pixel match between 'previous canvas' and 'current canvas'. So, we don't // allow empty rectangle in this case. GetSubRect(prev_canvas_disposed, curr_canvas, is_key_frame, is_first_frame, 0 /* empty_rect_allowed */, &rect_bg, &sub_frame_bg); assert(!IsEmptyRect(&rect_bg)); if (enc->options_.minimize_size) { // Try both dispose methods. try_dispose_bg = 1; try_dispose_none = 1; } else if (RectArea(&rect_bg) < RectArea(&rect_none)) { try_dispose_bg = 1; // Pick DISPOSE_BACKGROUND. try_dispose_none = 0; } } if (try_dispose_none) { error_code = GenerateCandidates( enc, candidates, WEBP_MUX_DISPOSE_NONE, is_lossless, is_key_frame, &rect_none, &sub_frame_none, &config_ll, &config_lossy); if (error_code != VP8_ENC_OK) goto Err; } if (try_dispose_bg) { assert(!enc->is_first_frame_); assert(dispose_bg_possible); error_code = GenerateCandidates( enc, candidates, WEBP_MUX_DISPOSE_BACKGROUND, is_lossless, is_key_frame, &rect_bg, &sub_frame_bg, &config_ll, &config_lossy); if (error_code != VP8_ENC_OK) goto Err; } PickBestCandidate(enc, candidates, is_key_frame, encoded_frame); goto End; Err: for (i = 0; i < CANDIDATE_COUNT; ++i) { if (candidates[i].evaluate_) { WebPMemoryWriterClear(&candidates[i].mem_); } } End: WebPPictureFree(&sub_frame_none); WebPPictureFree(&sub_frame_bg); return error_code; } // Calculate the penalty incurred if we encode given frame as a key frame // instead of a sub-frame. static int64_t KeyFramePenalty(const EncodedFrame* const encoded_frame) { return ((int64_t)encoded_frame->key_frame_.bitstream.size - encoded_frame->sub_frame_.bitstream.size); } static int CacheFrame(WebPAnimEncoder* const enc, const WebPConfig* const config) { int ok = 0; int frame_skipped = 0; WebPEncodingError error_code = VP8_ENC_OK; const size_t position = enc->count_; EncodedFrame* const encoded_frame = GetFrame(enc, position); ++enc->count_; if (enc->is_first_frame_) { // Add this as a key-frame. error_code = SetFrame(enc, config, 1, encoded_frame, &frame_skipped); if (error_code != VP8_ENC_OK) goto End; assert(frame_skipped == 0); // First frame can't be skipped, even if empty. assert(position == 0 && enc->count_ == 1); encoded_frame->is_key_frame_ = 1; enc->flush_count_ = 0; enc->count_since_key_frame_ = 0; enc->prev_candidate_undecided_ = 0; } else { ++enc->count_since_key_frame_; if (enc->count_since_key_frame_ <= enc->options_.kmin) { // Add this as a frame rectangle. error_code = SetFrame(enc, config, 0, encoded_frame, &frame_skipped); if (error_code != VP8_ENC_OK) goto End; if (frame_skipped) goto Skip; encoded_frame->is_key_frame_ = 0; enc->flush_count_ = enc->count_ - 1; enc->prev_candidate_undecided_ = 0; } else { int64_t curr_delta; // Add this as a frame rectangle to enc. error_code = SetFrame(enc, config, 0, encoded_frame, &frame_skipped); if (error_code != VP8_ENC_OK) goto End; if (frame_skipped) goto Skip; // Add this as a key-frame to enc, too. error_code = SetFrame(enc, config, 1, encoded_frame, &frame_skipped); if (error_code != VP8_ENC_OK) goto End; assert(frame_skipped == 0); // Key-frame cannot be an empty rectangle. // Analyze size difference of the two variants. curr_delta = KeyFramePenalty(encoded_frame); if (curr_delta <= enc->best_delta_) { // Pick this as the key-frame. if (enc->keyframe_ != KEYFRAME_NONE) { EncodedFrame* const old_keyframe = GetFrame(enc, enc->keyframe_); assert(old_keyframe->is_key_frame_); old_keyframe->is_key_frame_ = 0; } encoded_frame->is_key_frame_ = 1; enc->keyframe_ = (int)position; enc->best_delta_ = curr_delta; enc->flush_count_ = enc->count_ - 1; // We can flush previous frames. } else { encoded_frame->is_key_frame_ = 0; } // 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; enc->best_delta_ = DELTA_INFINITY; } enc->prev_candidate_undecided_ = 1; } } // Update previous to previous and previous canvases for next call. WebPCopyPixels(enc->curr_canvas_, &enc->prev_canvas_); enc->is_first_frame_ = 0; Skip: ok = 1; ++enc->in_frame_count_; End: if (!ok || frame_skipped) { FrameRelease(encoded_frame); // We reset some counters, as the frame addition failed/was skipped. --enc->count_; if (!enc->is_first_frame_) --enc->count_since_key_frame_; if (!ok) { MarkError2(enc, "ERROR adding frame. WebPEncodingError", error_code); } } enc->curr_canvas_->error_code = error_code; // report error_code assert(ok || error_code != VP8_ENC_OK); return ok; } static int FlushFrames(WebPAnimEncoder* const enc) { while (enc->flush_count_ > 0) { WebPMuxError err; EncodedFrame* const curr = GetFrame(enc, 0); const WebPMuxFrameInfo* const info = curr->is_key_frame_ ? &curr->key_frame_ : &curr->sub_frame_; assert(enc->mux_ != NULL); err = WebPMuxPushFrame(enc->mux_, info, 1); if (err != WEBP_MUX_OK) { MarkError2(enc, "ERROR adding frame. WebPMuxError", err); return 0; } if (enc->options_.verbose) { fprintf(stderr, "INFO: Added frame. offset:%d,%d dispose:%d blend:%d\n", info->x_offset, info->y_offset, info->dispose_method, info->blend_method); } ++enc->out_frame_count_; FrameRelease(curr); ++enc->start_; --enc->flush_count_; --enc->count_; if (enc->keyframe_ != KEYFRAME_NONE) --enc->keyframe_; } if (enc->count_ == 1 && enc->start_ != 0) { // Move enc->start to index 0. const int enc_start_tmp = (int)enc->start_; EncodedFrame temp = enc->encoded_frames_[0]; enc->encoded_frames_[0] = enc->encoded_frames_[enc_start_tmp]; enc->encoded_frames_[enc_start_tmp] = temp; FrameRelease(&enc->encoded_frames_[enc_start_tmp]); enc->start_ = 0; } return 1; } #undef DELTA_INFINITY #undef KEYFRAME_NONE int WebPAnimEncoderAdd(WebPAnimEncoder* enc, WebPPicture* frame, int timestamp, const WebPConfig* encoder_config) { WebPConfig config; if (enc == NULL) { return 0; } MarkNoError(enc); if (!enc->is_first_frame_) { // Make sure timestamps are non-decreasing (integer wrap-around is OK). const uint32_t prev_frame_duration = (uint32_t)timestamp - enc->prev_timestamp_; if (prev_frame_duration >= MAX_DURATION) { if (frame != NULL) { frame->error_code = VP8_ENC_ERROR_INVALID_CONFIGURATION; } MarkError(enc, "ERROR adding frame: timestamps must be non-decreasing"); return 0; } if (!IncreasePreviousDuration(enc, (int)prev_frame_duration)) { return 0; } } else { enc->first_timestamp_ = timestamp; } if (frame == NULL) { // Special: last call. enc->got_null_frame_ = 1; enc->prev_timestamp_ = timestamp; return 1; } if (frame->width != enc->canvas_width_ || frame->height != enc->canvas_height_) { frame->error_code = VP8_ENC_ERROR_INVALID_CONFIGURATION; MarkError(enc, "ERROR adding frame: Invalid frame dimensions"); return 0; } if (!frame->use_argb) { // Convert frame from YUV(A) to ARGB. if (enc->options_.verbose) { fprintf(stderr, "WARNING: Converting frame from YUV(A) to ARGB format; " "this incurs a small loss.\n"); } if (!WebPPictureYUVAToARGB(frame)) { MarkError(enc, "ERROR converting frame from YUV(A) to ARGB"); return 0; } } if (encoder_config != NULL) { config = *encoder_config; } else { WebPConfigInit(&config); config.lossless = 1; } assert(enc->curr_canvas_ == NULL); enc->curr_canvas_ = frame; // Store reference. assert(enc->curr_canvas_copy_modified_ == 1); CopyCurrentCanvas(enc); if (!CacheFrame(enc, &config)) { return 0; } if (!FlushFrames(enc)) { return 0; } enc->curr_canvas_ = NULL; enc->curr_canvas_copy_modified_ = 1; enc->prev_timestamp_ = timestamp; return 1; } // ----------------------------------------------------------------------------- // Bitstream assembly. static int DecodeFrameOntoCanvas(const WebPMuxFrameInfo* const frame, WebPPicture* const canvas) { const WebPData* const image = &frame->bitstream; WebPPicture sub_image; WebPDecoderConfig config; WebPInitDecoderConfig(&config); WebPUtilClearPic(canvas, NULL); if (WebPGetFeatures(image->bytes, image->size, &config.input) != VP8_STATUS_OK) { return 0; } if (!WebPPictureView(canvas, frame->x_offset, frame->y_offset, config.input.width, config.input.height, &sub_image)) { return 0; } config.output.is_external_memory = 1; config.output.colorspace = MODE_BGRA; config.output.u.RGBA.rgba = (uint8_t*)sub_image.argb; config.output.u.RGBA.stride = sub_image.argb_stride * 4; config.output.u.RGBA.size = config.output.u.RGBA.stride * sub_image.height; if (WebPDecode(image->bytes, image->size, &config) != VP8_STATUS_OK) { return 0; } return 1; } static int FrameToFullCanvas(WebPAnimEncoder* const enc, const WebPMuxFrameInfo* const frame, WebPData* const full_image) { WebPPicture* const canvas_buf = &enc->curr_canvas_copy_; WebPMemoryWriter mem1, mem2; WebPMemoryWriterInit(&mem1); WebPMemoryWriterInit(&mem2); if (!DecodeFrameOntoCanvas(frame, canvas_buf)) goto Err; if (!EncodeFrame(&enc->last_config_, canvas_buf, &mem1)) goto Err; GetEncodedData(&mem1, full_image); if (enc->options_.allow_mixed) { if (!EncodeFrame(&enc->last_config_, canvas_buf, &mem2)) goto Err; if (mem2.size < mem1.size) { GetEncodedData(&mem2, full_image); WebPMemoryWriterClear(&mem1); } else { WebPMemoryWriterClear(&mem2); } } return 1; Err: WebPMemoryWriterClear(&mem1); WebPMemoryWriterClear(&mem2); return 0; } // Convert a single-frame animation to a non-animated image if appropriate. // TODO(urvang): Can we pick one of the two heuristically (based on frame // rectangle and/or presence of alpha)? static WebPMuxError OptimizeSingleFrame(WebPAnimEncoder* const enc, WebPData* const webp_data) { WebPMuxError err = WEBP_MUX_OK; int canvas_width, canvas_height; WebPMuxFrameInfo frame; WebPData full_image; WebPData webp_data2; WebPMux* const mux = WebPMuxCreate(webp_data, 0); if (mux == NULL) return WEBP_MUX_BAD_DATA; assert(enc->out_frame_count_ == 1); WebPDataInit(&frame.bitstream); WebPDataInit(&full_image); WebPDataInit(&webp_data2); err = WebPMuxGetFrame(mux, 1, &frame); if (err != WEBP_MUX_OK) goto End; if (frame.id != WEBP_CHUNK_ANMF) goto End; // Non-animation: nothing to do. err = WebPMuxGetCanvasSize(mux, &canvas_width, &canvas_height); if (err != WEBP_MUX_OK) goto End; if (!FrameToFullCanvas(enc, &frame, &full_image)) { err = WEBP_MUX_BAD_DATA; goto End; } err = WebPMuxSetImage(mux, &full_image, 1); if (err != WEBP_MUX_OK) goto End; err = WebPMuxAssemble(mux, &webp_data2); if (err != WEBP_MUX_OK) goto End; if (webp_data2.size < webp_data->size) { // Pick 'webp_data2' if smaller. WebPDataClear(webp_data); *webp_data = webp_data2; WebPDataInit(&webp_data2); } End: WebPDataClear(&frame.bitstream); WebPDataClear(&full_image); WebPMuxDelete(mux); WebPDataClear(&webp_data2); return err; } int WebPAnimEncoderAssemble(WebPAnimEncoder* enc, WebPData* webp_data) { WebPMux* mux; WebPMuxError err; if (enc == NULL) { return 0; } MarkNoError(enc); if (webp_data == NULL) { MarkError(enc, "ERROR assembling: NULL input"); return 0; } if (enc->in_frame_count_ == 0) { MarkError(enc, "ERROR: No frames to assemble"); return 0; } if (!enc->got_null_frame_ && enc->in_frame_count_ > 1 && enc->count_ > 0) { // set duration of the last frame to be avg of durations of previous frames. const double delta_time = enc->prev_timestamp_ - enc->first_timestamp_; const int average_duration = (int)(delta_time / (enc->in_frame_count_ - 1)); if (!IncreasePreviousDuration(enc, average_duration)) { return 0; } } // Flush any remaining frames. enc->flush_count_ = enc->count_; if (!FlushFrames(enc)) { return 0; } // Set definitive canvas size. mux = enc->mux_; err = WebPMuxSetCanvasSize(mux, enc->canvas_width_, enc->canvas_height_); if (err != WEBP_MUX_OK) goto Err; err = WebPMuxSetAnimationParams(mux, &enc->options_.anim_params); if (err != WEBP_MUX_OK) goto Err; // Assemble into a WebP bitstream. err = WebPMuxAssemble(mux, webp_data); if (err != WEBP_MUX_OK) goto Err; if (enc->out_frame_count_ == 1) { err = OptimizeSingleFrame(enc, webp_data); if (err != WEBP_MUX_OK) goto Err; } return 1; Err: MarkError2(enc, "ERROR assembling WebP", err); return 0; } const char* WebPAnimEncoderGetError(WebPAnimEncoder* enc) { if (enc == NULL) return NULL; return enc->error_str_; } // -----------------------------------------------------------------------------