// 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. // #include #include #include "utils/utils.h" #include "webp/encode.h" #include "./gif2webp_util.h" #define DELTA_INFINITY 1ULL << 32 #define KEYFRAME_NONE -1 //------------------------------------------------------------------------------ // Helper utilities. 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] = WEBP_UTIL_TRANSPARENT_COLOR; } } } void WebPUtilClearPic(WebPPicture* const picture, const WebPFrameRect* 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); } } // TODO: Also used in picture.c. Move to a common location? // Copy width x height pixels from 'src' to 'dst' honoring the strides. static void CopyPlane(const uint8_t* src, int src_stride, uint8_t* dst, int dst_stride, int width, int height) { while (height-- > 0) { memcpy(dst, src, width); src += src_stride; dst += dst_stride; } } // Copy pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are assumed // to be already allocated. static void CopyPixels(const WebPPicture* const src, WebPPicture* const dst) { assert(src->width == dst->width && src->height == dst->height); CopyPlane((uint8_t*)src->argb, 4 * src->argb_stride, (uint8_t*)dst->argb, 4 * dst->argb_stride, 4 * src->width, src->height); } // Given 'src' picture and its frame rectangle 'rect', blend it into 'dst'. static void BlendPixels(const WebPPicture* const src, const WebPFrameRect* const rect, WebPPicture* const dst) { int j; assert(src->width == dst->width && src->height == dst->height); for (j = rect->y_offset; j < rect->y_offset + rect->height; ++j) { int i; 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 int src_alpha = src_pixel >> 24; if (src_alpha != 0) { dst->argb[j * dst->argb_stride + i] = src_pixel; } } } } // 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; } // Assumes that an initial valid guess of change rectangle 'rect' is passed. static void MinimizeChangeRectangle(const WebPPicture* const src, const WebPPicture* const dst, WebPFrameRect* 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 End; // 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 End; // 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 End; // 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 End; if (rect->width == 0 || rect->height == 0) { End: // TODO(later): This rare case can happen for a bad GIF. In such a case, the // frame should not be encoded at all and the duration of prev frame should // be increased instead. For now, we just create a 1x1 frame at zero offset. rect->x_offset = 0; rect->y_offset = 0; rect->width = 1; rect->height = 1; } } // 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 WebPFrameRect* 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] = WEBP_UTIL_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 WebPFrameRect* 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; } } } } } } //------------------------------------------------------------------------------ // Encoded frame. // 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 was converted to keyframe. int is_key_frame; // True if 'key_frame' has been chosen. } EncodedFrame; // 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)); } } //------------------------------------------------------------------------------ // Frame cache. // Used to store encoded frames that haven't been output yet. struct WebPFrameCache { EncodedFrame* encoded_frames; // Array of encoded frames. size_t size; // Number of allocated data elements. size_t start; // Start index. size_t count; // Number of valid data elements. int flush_count; // If >0, ‘flush_count’ frames starting from // 'start' are ready to be added to mux. 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 keyframe relative to 'start'. // TODO(urvang): Create a struct WebPAnimationEncodingConfig for these // encoding parameters. int min_size; // If true, produce the smallest output. size_t kmin; // Min distance between key frames. size_t kmax; // Max distance between key frames. size_t count_since_key_frame; // Frames seen since the last key frame. int allow_mixed; // If true, each frame can be lossy or lossless. WebPFrameRect prev_orig_rect; // Previous input (e.g. GIF) frame rectangle. WebPFrameRect prev_webp_rect; // Previous WebP frame rectangle. FrameDisposeMethod prev_orig_dispose; // Previous input dispose method. int prev_candidate_undecided; // True if sub-frame vs keyframe decision // hasn't been made for the previous frame yet. WebPPicture curr_canvas; // Current canvas (NOT disposed). WebPPicture curr_canvas_tmp; // Temporary storage for current canvas. WebPPicture prev_canvas; // Previous canvas (NOT disposed). WebPPicture prev_canvas_disposed; // Previous canvas disposed to background. WebPPicture prev_to_prev_canvas_disposed; // Previous to previous canvas // (disposed as per its original // dispose method). int is_first_frame; // True if no frames have been added to the cache // since WebPFrameCacheNew(). }; // Reset the counters in the cache struct. Doesn't touch 'cache->encoded_frames' // and 'cache->size'. static void CacheReset(WebPFrameCache* const cache) { cache->start = 0; cache->count = 0; cache->flush_count = 0; cache->best_delta = DELTA_INFINITY; cache->keyframe = KEYFRAME_NONE; } WebPFrameCache* WebPFrameCacheNew(int width, int height, int minimize_size, size_t kmin, size_t kmax, int allow_mixed) { WebPFrameCache* cache = (WebPFrameCache*)WebPSafeCalloc(1, sizeof(*cache)); if (cache == NULL) return NULL; CacheReset(cache); // sanity init, so we can call WebPFrameCacheDelete(): cache->encoded_frames = NULL; cache->prev_candidate_undecided = 0; cache->is_first_frame = 1; // Picture buffers. if (!WebPPictureInit(&cache->curr_canvas) || !WebPPictureInit(&cache->curr_canvas_tmp) || !WebPPictureInit(&cache->prev_canvas) || !WebPPictureInit(&cache->prev_canvas_disposed) || !WebPPictureInit(&cache->prev_to_prev_canvas_disposed)) { return NULL; } cache->curr_canvas.width = width; cache->curr_canvas.height = height; cache->curr_canvas.use_argb = 1; if (!WebPPictureAlloc(&cache->curr_canvas) || !WebPPictureCopy(&cache->curr_canvas, &cache->curr_canvas_tmp) || !WebPPictureCopy(&cache->curr_canvas, &cache->prev_canvas) || !WebPPictureCopy(&cache->curr_canvas, &cache->prev_canvas_disposed) || !WebPPictureCopy(&cache->curr_canvas, &cache->prev_to_prev_canvas_disposed)) { goto Err; } WebPUtilClearPic(&cache->prev_canvas, NULL); WebPUtilClearPic(&cache->prev_canvas_disposed, NULL); WebPUtilClearPic(&cache->prev_to_prev_canvas_disposed, NULL); // Cache data. cache->min_size = minimize_size; cache->allow_mixed = allow_mixed; if (cache->min_size) { // Disable keyframe insertion. kmax = ~0; kmin = kmax - 1; } cache->kmin = kmin; cache->kmax = kmax; cache->count_since_key_frame = 0; assert(kmax > kmin); cache->size = kmax - kmin + 1; // One extra storage for previous frame. cache->encoded_frames = (EncodedFrame*)WebPSafeCalloc( cache->size, sizeof(*cache->encoded_frames)); if (cache->encoded_frames == NULL) goto Err; return cache; // All OK. Err: WebPFrameCacheDelete(cache); return NULL; } void WebPFrameCacheDelete(WebPFrameCache* const cache) { if (cache != NULL) { if (cache->encoded_frames != NULL) { size_t i; for (i = 0; i < cache->size; ++i) { FrameRelease(&cache->encoded_frames[i]); } WebPSafeFree(cache->encoded_frames); } WebPPictureFree(&cache->curr_canvas); WebPPictureFree(&cache->curr_canvas_tmp); WebPPictureFree(&cache->prev_canvas); WebPPictureFree(&cache->prev_canvas_disposed); WebPPictureFree(&cache->prev_to_prev_canvas_disposed); WebPSafeFree(cache); } } 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; } static void GetEncodedData(const WebPMemoryWriter* const memory, WebPData* const encoded_data) { encoded_data->bytes = memory->mem; encoded_data->size = memory->size; } #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 static void DisposeFrameRectangle(int dispose_method, const WebPFrameRect* const rect, const WebPPicture* const prev_canvas, WebPPicture* const curr_canvas) { assert(rect != NULL); if (dispose_method == FRAME_DISPOSE_BACKGROUND) { WebPUtilClearPic(curr_canvas, rect); } else if (dispose_method == FRAME_DISPOSE_RESTORE_PREVIOUS) { const int src_stride = prev_canvas->argb_stride; const uint32_t* const src = prev_canvas->argb + rect->x_offset + rect->y_offset * src_stride; const int dst_stride = curr_canvas->argb_stride; uint32_t* const dst = curr_canvas->argb + rect->x_offset + rect->y_offset * dst_stride; assert(prev_canvas != NULL); CopyPlane((uint8_t*)src, 4 * src_stride, (uint8_t*)dst, 4 * dst_stride, 4 * rect->width, rect->height); } } // Snap rectangle to even offsets (and adjust dimensions if needed). static WEBP_INLINE void SnapToEvenOffsets(WebPFrameRect* 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 'orig_rect' if is non-NULL, otherwise // the initial guess will be the full canvas. static int GetSubRect(const WebPPicture* const prev_canvas, const WebPPicture* const curr_canvas, const WebPFrameRect* const orig_rect, int is_key_frame, WebPFrameRect* const rect, WebPPicture* const sub_frame) { if (orig_rect != NULL) { *rect = *orig_rect; } else { rect->x_offset = 0; rect->y_offset = 0; rect->width = curr_canvas->width; rect->height = curr_canvas->height; } if (!is_key_frame) { // Optimize frame rectangle. MinimizeChangeRectangle(prev_canvas, curr_canvas, rect); } SnapToEvenOffsets(rect); return WebPPictureView(curr_canvas, rect->x_offset, rect->y_offset, rect->width, rect->height, sub_frame); } static int IsBlendingPossible(const WebPPicture* const src, const WebPPicture* const dst, const WebPFrameRect* 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; } static int RectArea(const WebPFrameRect* const rect) { return rect->width * rect->height; } // Struct representing a candidate encoded frame including its metadata. typedef struct { WebPMemoryWriter mem; WebPMuxFrameInfo info; WebPFrameRect 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 WebPFrameRect* const rect, const WebPConfig* const config, int use_blending, int duration, 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 = duration; // 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; } // Returns cached frame at given 'position' index. static EncodedFrame* CacheGetFrame(const WebPFrameCache* const cache, size_t position) { assert(cache->start + position < cache->size); return &cache->encoded_frames[cache->start + position]; } // Sets dispose method of the previous frame to be 'dispose_method'. static void SetPreviousDisposeMethod(WebPFrameCache* const cache, WebPMuxAnimDispose dispose_method) { const size_t position = cache->count - 2; EncodedFrame* const prev_enc_frame = CacheGetFrame(cache, position); assert(cache->count >= 2); // As current and previous frames are in cache. if (cache->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; } } 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( WebPFrameCache* const cache, Candidate candidates[CANDIDATE_COUNT], WebPMuxAnimDispose dispose_method, int is_lossless, int is_key_frame, const WebPFrameRect* const rect, WebPPicture* sub_frame, int duration, 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 = &cache->curr_canvas; WebPPicture* const curr_canvas_tmp = &cache->curr_canvas_tmp; const WebPPicture* const prev_canvas = is_dispose_none ? &cache->prev_canvas : &cache->prev_canvas_disposed; const int use_blending = !is_key_frame && IsBlendingPossible(prev_canvas, curr_canvas, rect); int curr_canvas_saved = 0; // If 'curr_canvas' is saved in 'curr_canvas_tmp'. // Pick candidates to be tried. if (!cache->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) { if (use_blending) { CopyPixels(curr_canvas, curr_canvas_tmp); // save curr_canvas_saved = 1; IncreaseTransparency(prev_canvas, rect, curr_canvas); } error_code = EncodeCandidate(sub_frame, rect, config_ll, use_blending, duration, candidate_ll); if (error_code != VP8_ENC_OK) return error_code; if (use_blending) { CopyPixels(curr_canvas_tmp, curr_canvas); // restore } } if (candidate_lossy->evaluate) { if (use_blending) { // For lossy compression of a frame, it's better to replace similar blocks // of pixels by a transparent block. if (!curr_canvas_saved) { // save if not already done so. CopyPixels(curr_canvas, curr_canvas_tmp); } FlattenSimilarBlocks(prev_canvas, rect, curr_canvas); } error_code = EncodeCandidate(sub_frame, rect, config_lossy, use_blending, duration, candidate_lossy); if (error_code != VP8_ENC_OK) return error_code; if (use_blending) { CopyPixels(curr_canvas_tmp, curr_canvas); // restore } } return error_code; } // 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(WebPFrameCache* const cache, 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(cache, prev_dispose_method); } cache->prev_webp_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'. static WebPEncodingError SetFrame(WebPFrameCache* const cache, const WebPConfig* const config, int duration, const WebPFrameRect* const orig_rect, int is_key_frame, EncodedFrame* const encoded_frame) { int i; WebPEncodingError error_code = VP8_ENC_OK; WebPPicture* const curr_canvas = &cache->curr_canvas; const WebPPicture* const prev_canvas = &cache->prev_canvas; WebPPicture* const prev_canvas_disposed = &cache->prev_canvas_disposed; Candidate candidates[CANDIDATE_COUNT]; const int is_lossless = config->lossless; int try_dispose_none = 1; // Default. WebPFrameRect rect_none; WebPPicture sub_frame_none; // 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 keyframe insertion is on, and previous frame could be picked as // either a sub-frame or a keyframe, 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 && !cache->prev_candidate_undecided; int try_dispose_bg = 0; // Default. WebPFrameRect rect_bg; WebPPicture sub_frame_bg; WebPConfig config_ll = *config; WebPConfig config_lossy = *config; config_ll.lossless = 1; config_lossy.lossless = 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, orig_rect, is_key_frame, &rect_none, &sub_frame_none); if (dispose_bg_possible) { // Change-rectangle assuming previous frame was DISPOSE_BACKGROUND. CopyPixels(prev_canvas, prev_canvas_disposed); DisposeFrameRectangle(WEBP_MUX_DISPOSE_BACKGROUND, &cache->prev_webp_rect, NULL, prev_canvas_disposed); GetSubRect(prev_canvas_disposed, curr_canvas, orig_rect, is_key_frame, &rect_bg, &sub_frame_bg); if (cache->min_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( cache, candidates, WEBP_MUX_DISPOSE_NONE, is_lossless, is_key_frame, &rect_none, &sub_frame_none, duration, &config_ll, &config_lossy); if (error_code != VP8_ENC_OK) goto Err; } if (try_dispose_bg) { assert(!cache->is_first_frame); assert(dispose_bg_possible); error_code = GenerateCandidates(cache, candidates, WEBP_MUX_DISPOSE_BACKGROUND, is_lossless, is_key_frame, &rect_bg, &sub_frame_bg, duration, &config_ll, &config_lossy); if (error_code != VP8_ENC_OK) goto Err; } PickBestCandidate(cache, 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; } #undef MIN_COLORS_LOSSY #undef MAX_COLORS_LOSSLESS // 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); } int WebPFrameCacheAddFrame(WebPFrameCache* const cache, const WebPConfig* const config, const WebPFrameRect* const orig_rect_ptr, FrameDisposeMethod orig_dispose_method, int duration, WebPPicture* const frame) { // Initialize. int ok = 0; WebPEncodingError error_code = VP8_ENC_OK; WebPPicture* const curr_canvas = &cache->curr_canvas; WebPPicture* const prev_canvas = &cache->prev_canvas; WebPPicture* const prev_to_prev_canvas_disposed = &cache->prev_to_prev_canvas_disposed; WebPPicture* const prev_canvas_disposed = &cache->prev_canvas_disposed; const size_t position = cache->count; EncodedFrame* const encoded_frame = CacheGetFrame(cache, position); WebPFrameRect orig_rect; assert(position < cache->size); if (frame == NULL) { return 0; } // As we are encoding (part of) 'curr_canvas', and not 'frame' directly, make // sure the progress is still reported back. curr_canvas->progress_hook = frame->progress_hook; curr_canvas->user_data = frame->user_data; curr_canvas->stats = frame->stats; if (orig_rect_ptr == NULL) { orig_rect.width = frame->width; orig_rect.height = frame->height; orig_rect.x_offset = 0; orig_rect.y_offset = 0; } else { orig_rect = *orig_rect_ptr; } // Main frame addition. ++cache->count; if (cache->is_first_frame) { // 'curr_canvas' is same as 'frame'. CopyPixels(frame, curr_canvas); // Add this as a key frame. // Note: we use original rectangle as-is for the first frame. error_code = SetFrame(cache, config, duration, &orig_rect, 1, encoded_frame); if (error_code != VP8_ENC_OK) { goto End; } assert(position == 0 && cache->count == 1); encoded_frame->is_key_frame = 1; cache->flush_count = 0; cache->count_since_key_frame = 0; cache->prev_candidate_undecided = 0; } else { // Store previous to previous and previous canvases. CopyPixels(prev_canvas_disposed, prev_to_prev_canvas_disposed); CopyPixels(curr_canvas, prev_canvas); // Create curr_canvas: // * Start with disposed previous canvas. // * Then blend 'frame' onto it. DisposeFrameRectangle(cache->prev_orig_dispose, &cache->prev_orig_rect, prev_to_prev_canvas_disposed, curr_canvas); CopyPixels(curr_canvas, prev_canvas_disposed); BlendPixels(frame, &orig_rect, curr_canvas); ++cache->count_since_key_frame; if (cache->count_since_key_frame <= cache->kmin) { // Add this as a frame rectangle. error_code = SetFrame(cache, config, duration, NULL, 0, encoded_frame); if (error_code != VP8_ENC_OK) { goto End; } encoded_frame->is_key_frame = 0; cache->flush_count = cache->count - 1; cache->prev_candidate_undecided = 0; } else { int64_t curr_delta; // Add frame rectangle to cache. error_code = SetFrame(cache, config, duration, NULL, 0, encoded_frame); if (error_code != VP8_ENC_OK) { goto End; } // Add key frame to cache, too. error_code = SetFrame(cache, config, duration, NULL, 1, encoded_frame); if (error_code != VP8_ENC_OK) goto End; // Analyze size difference of the two variants. curr_delta = KeyFramePenalty(encoded_frame); if (curr_delta <= cache->best_delta) { // Pick this as keyframe. if (cache->keyframe != KEYFRAME_NONE) { EncodedFrame* const old_keyframe = CacheGetFrame(cache, cache->keyframe); assert(old_keyframe->is_key_frame); old_keyframe->is_key_frame = 0; } encoded_frame->is_key_frame = 1; cache->keyframe = position; cache->best_delta = curr_delta; cache->flush_count = cache->count - 1; // We can flush previous frames. } else { encoded_frame->is_key_frame = 0; } if (cache->count_since_key_frame == cache->kmax) { cache->flush_count = cache->count - 1; cache->count_since_key_frame = 0; } cache->prev_candidate_undecided = 1; } // Recalculate prev_canvas_disposed (as it might have been modified). CopyPixels(prev_canvas, prev_canvas_disposed); DisposeFrameRectangle(cache->prev_orig_dispose, &cache->prev_orig_rect, prev_to_prev_canvas_disposed, prev_canvas_disposed); } // Dispose the 'frame'. DisposeFrameRectangle(orig_dispose_method, &orig_rect, prev_canvas_disposed, frame); cache->is_first_frame = 0; cache->prev_orig_dispose = orig_dispose_method; cache->prev_orig_rect = orig_rect; ok = 1; End: if (!ok) { FrameRelease(encoded_frame); --cache->count; // We reset the count, as the frame addition failed. } frame->error_code = error_code; // report error_code assert(ok || error_code != VP8_ENC_OK); return ok; } WebPMuxError WebPFrameCacheFlush(WebPFrameCache* const cache, int verbose, WebPMux* const mux) { while (cache->flush_count > 0) { WebPMuxFrameInfo* info; WebPMuxError err; EncodedFrame* const curr = CacheGetFrame(cache, 0); // Pick frame or full canvas. if (curr->is_key_frame) { info = &curr->key_frame; if (cache->keyframe == 0) { cache->keyframe = KEYFRAME_NONE; cache->best_delta = DELTA_INFINITY; } } else { info = &curr->sub_frame; } // Add to mux. err = WebPMuxPushFrame(mux, info, 1); if (err != WEBP_MUX_OK) return err; if (verbose) { printf("Added frame. offset:%d,%d duration:%d dispose:%d blend:%d\n", info->x_offset, info->y_offset, info->duration, info->dispose_method, info->blend_method); } FrameRelease(curr); ++cache->start; --cache->flush_count; --cache->count; if (cache->keyframe != KEYFRAME_NONE) --cache->keyframe; } if (cache->count == 1 && cache->start != 0) { // Move cache->start to index 0. const int cache_start_tmp = (int)cache->start; EncodedFrame temp = cache->encoded_frames[0]; cache->encoded_frames[0] = cache->encoded_frames[cache_start_tmp]; cache->encoded_frames[cache_start_tmp] = temp; FrameRelease(&cache->encoded_frames[cache_start_tmp]); cache->start = 0; } return WEBP_MUX_OK; } WebPMuxError WebPFrameCacheFlushAll(WebPFrameCache* const cache, int verbose, WebPMux* const mux) { cache->flush_count = cache->count; // Force flushing of all frames. return WebPFrameCacheFlush(cache, verbose, mux); } //------------------------------------------------------------------------------