| // Copyright 2011 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. |
| // ----------------------------------------------------------------------------- |
| // |
| // Alpha-plane compression. |
| // |
| // Author: Skal (pascal.massimino@gmail.com) |
| |
| #if defined(STARBOARD) |
| #include "third_party/libwebp/starboard_private.h" |
| #else |
| #include <assert.h> |
| #include <stdlib.h> |
| #endif |
| |
| #include "./vp8enci.h" |
| #include "../utils/filters.h" |
| #include "../utils/quant_levels.h" |
| #include "../webp/format_constants.h" |
| |
| #if defined(__cplusplus) || defined(c_plusplus) |
| extern "C" { |
| #endif |
| |
| // ----------------------------------------------------------------------------- |
| // Encodes the given alpha data via specified compression method 'method'. |
| // The pre-processing (quantization) is performed if 'quality' is less than 100. |
| // For such cases, the encoding is lossy. The valid range is [0, 100] for |
| // 'quality' and [0, 1] for 'method': |
| // 'method = 0' - No compression; |
| // 'method = 1' - Use lossless coder on the alpha plane only |
| // 'filter' values [0, 4] correspond to prediction modes none, horizontal, |
| // vertical & gradient filters. The prediction mode 4 will try all the |
| // prediction modes 0 to 3 and pick the best one. |
| // 'effort_level': specifies how much effort must be spent to try and reduce |
| // the compressed output size. In range 0 (quick) to 6 (slow). |
| // |
| // 'output' corresponds to the buffer containing compressed alpha data. |
| // This buffer is allocated by this method and caller should call |
| // free(*output) when done. |
| // 'output_size' corresponds to size of this compressed alpha buffer. |
| // |
| // Returns 1 on successfully encoding the alpha and |
| // 0 if either: |
| // invalid quality or method, or |
| // memory allocation for the compressed data fails. |
| |
| #include "../enc/vp8li.h" |
| |
| static int EncodeLossless(const uint8_t* const data, int width, int height, |
| int effort_level, // in [0..6] range |
| VP8BitWriter* const bw, |
| WebPAuxStats* const stats) { |
| int ok = 0; |
| WebPConfig config; |
| WebPPicture picture; |
| VP8LBitWriter tmp_bw; |
| |
| WebPPictureInit(&picture); |
| picture.width = width; |
| picture.height = height; |
| picture.use_argb = 1; |
| picture.stats = stats; |
| if (!WebPPictureAlloc(&picture)) return 0; |
| |
| // Transfer the alpha values to the green channel. |
| { |
| int i, j; |
| uint32_t* dst = picture.argb; |
| const uint8_t* src = data; |
| for (j = 0; j < picture.height; ++j) { |
| for (i = 0; i < picture.width; ++i) { |
| dst[i] = (src[i] << 8) | 0xff000000u; |
| } |
| src += width; |
| dst += picture.argb_stride; |
| } |
| } |
| |
| WebPConfigInit(&config); |
| config.lossless = 1; |
| config.method = effort_level; // impact is very small |
| // Set a moderate default quality setting for alpha. |
| config.quality = 10.f * effort_level; |
| assert(config.quality >= 0 && config.quality <= 100.f); |
| |
| ok = VP8LBitWriterInit(&tmp_bw, (width * height) >> 3); |
| ok = ok && (VP8LEncodeStream(&config, &picture, &tmp_bw) == VP8_ENC_OK); |
| WebPPictureFree(&picture); |
| if (ok) { |
| const uint8_t* const buffer = VP8LBitWriterFinish(&tmp_bw); |
| const size_t buffer_size = VP8LBitWriterNumBytes(&tmp_bw); |
| VP8BitWriterAppend(bw, buffer, buffer_size); |
| } |
| VP8LBitWriterDestroy(&tmp_bw); |
| return ok && !bw->error_; |
| } |
| |
| // ----------------------------------------------------------------------------- |
| |
| static int EncodeAlphaInternal(const uint8_t* const data, int width, int height, |
| int method, int filter, int reduce_levels, |
| int effort_level, // in [0..6] range |
| uint8_t* const tmp_alpha, |
| VP8BitWriter* const bw, |
| WebPAuxStats* const stats) { |
| int ok = 0; |
| const uint8_t* alpha_src; |
| WebPFilterFunc filter_func; |
| uint8_t header; |
| size_t expected_size; |
| const size_t data_size = width * height; |
| |
| assert((uint64_t)data_size == (uint64_t)width * height); // as per spec |
| assert(filter >= 0 && filter < WEBP_FILTER_LAST); |
| assert(method >= ALPHA_NO_COMPRESSION); |
| assert(method <= ALPHA_LOSSLESS_COMPRESSION); |
| assert(sizeof(header) == ALPHA_HEADER_LEN); |
| // TODO(skal): have a common function and #define's to validate alpha params. |
| |
| expected_size = |
| (method == ALPHA_NO_COMPRESSION) ? (ALPHA_HEADER_LEN + data_size) |
| : (data_size >> 5); |
| header = method | (filter << 2); |
| if (reduce_levels) header |= ALPHA_PREPROCESSED_LEVELS << 4; |
| |
| VP8BitWriterInit(bw, expected_size); |
| VP8BitWriterAppend(bw, &header, ALPHA_HEADER_LEN); |
| |
| filter_func = WebPFilters[filter]; |
| if (filter_func != NULL) { |
| filter_func(data, width, height, width, tmp_alpha); |
| alpha_src = tmp_alpha; |
| } else { |
| alpha_src = data; |
| } |
| |
| if (method == ALPHA_NO_COMPRESSION) { |
| ok = VP8BitWriterAppend(bw, alpha_src, width * height); |
| ok = ok && !bw->error_; |
| } else { |
| ok = EncodeLossless(alpha_src, width, height, effort_level, bw, stats); |
| VP8BitWriterFinish(bw); |
| } |
| return ok; |
| } |
| |
| // ----------------------------------------------------------------------------- |
| |
| // TODO(skal): move to dsp/ ? |
| 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; |
| } |
| } |
| |
| static int GetNumColors(const uint8_t* data, int width, int height, |
| int stride) { |
| int j; |
| int colors = 0; |
| uint8_t color[256] = { 0 }; |
| |
| for (j = 0; j < height; ++j) { |
| int i; |
| const uint8_t* const p = data + j * stride; |
| for (i = 0; i < width; ++i) { |
| color[p[i]] = 1; |
| } |
| } |
| for (j = 0; j < 256; ++j) { |
| if (color[j] > 0) ++colors; |
| } |
| return colors; |
| } |
| |
| static int EncodeAlpha(VP8Encoder* const enc, |
| int quality, int method, int filter, |
| int effort_level, |
| uint8_t** const output, size_t* const output_size) { |
| const WebPPicture* const pic = enc->pic_; |
| const int width = pic->width; |
| const int height = pic->height; |
| |
| uint8_t* quant_alpha = NULL; |
| const size_t data_size = width * height; |
| uint64_t sse = 0; |
| int ok = 1; |
| const int reduce_levels = (quality < 100); |
| |
| // quick sanity checks |
| assert((uint64_t)data_size == (uint64_t)width * height); // as per spec |
| assert(enc != NULL && pic != NULL && pic->a != NULL); |
| assert(output != NULL && output_size != NULL); |
| assert(width > 0 && height > 0); |
| assert(pic->a_stride >= width); |
| assert(filter >= WEBP_FILTER_NONE && filter <= WEBP_FILTER_FAST); |
| |
| if (quality < 0 || quality > 100) { |
| return 0; |
| } |
| |
| if (method < ALPHA_NO_COMPRESSION || method > ALPHA_LOSSLESS_COMPRESSION) { |
| return 0; |
| } |
| |
| quant_alpha = (uint8_t*)malloc(data_size); |
| if (quant_alpha == NULL) { |
| return 0; |
| } |
| |
| // Extract alpha data (width x height) from raw_data (stride x height). |
| CopyPlane(pic->a, pic->a_stride, quant_alpha, width, width, height); |
| |
| if (reduce_levels) { // No Quantization required for 'quality = 100'. |
| // 16 alpha levels gives quite a low MSE w.r.t original alpha plane hence |
| // mapped to moderate quality 70. Hence Quality:[0, 70] -> Levels:[2, 16] |
| // and Quality:]70, 100] -> Levels:]16, 256]. |
| const int alpha_levels = (quality <= 70) ? (2 + quality / 5) |
| : (16 + (quality - 70) * 8); |
| ok = QuantizeLevels(quant_alpha, width, height, alpha_levels, &sse); |
| } |
| |
| if (ok) { |
| VP8BitWriter bw; |
| int test_filter; |
| uint8_t* filtered_alpha = NULL; |
| int try_filter_none = (effort_level > 3); |
| |
| if (filter == WEBP_FILTER_FAST) { // Quick estimate of the best candidate. |
| const int kMinColorsForFilterNone = 16; |
| const int kMaxColorsForFilterNone = 192; |
| const int num_colors = GetNumColors(quant_alpha, width, height, width); |
| // For low number of colors, NONE yeilds better compression. |
| filter = (num_colors <= kMinColorsForFilterNone) ? WEBP_FILTER_NONE : |
| EstimateBestFilter(quant_alpha, width, height, width); |
| // For large number of colors, try FILTER_NONE in addition to the best |
| // filter as well. |
| if (num_colors > kMaxColorsForFilterNone) { |
| try_filter_none = 1; |
| } |
| } |
| |
| // Test for WEBP_FILTER_NONE for higher effort levels. |
| if (try_filter_none || filter == WEBP_FILTER_NONE) { |
| ok = EncodeAlphaInternal(quant_alpha, width, height, |
| method, WEBP_FILTER_NONE, reduce_levels, |
| effort_level, NULL, &bw, pic->stats); |
| |
| if (!ok) { |
| VP8BitWriterWipeOut(&bw); |
| goto End; |
| } |
| } |
| // Stop? |
| if (filter == WEBP_FILTER_NONE) { |
| goto Ok; |
| } |
| |
| filtered_alpha = (uint8_t*)malloc(data_size); |
| ok = (filtered_alpha != NULL); |
| if (!ok) { |
| goto End; |
| } |
| |
| // Try the other mode(s). |
| { |
| WebPAuxStats best_stats; |
| size_t best_score = try_filter_none ? |
| VP8BitWriterSize(&bw) : (size_t)~0U; |
| int wipe_tmp_bw = try_filter_none; |
| |
| memset(&best_stats, 0, sizeof(best_stats)); // prevent spurious warning |
| if (pic->stats != NULL) best_stats = *pic->stats; |
| for (test_filter = |
| try_filter_none ? WEBP_FILTER_HORIZONTAL : WEBP_FILTER_NONE; |
| ok && (test_filter <= WEBP_FILTER_GRADIENT); |
| ++test_filter) { |
| VP8BitWriter tmp_bw; |
| if (filter != WEBP_FILTER_BEST && test_filter != filter) { |
| continue; |
| } |
| ok = EncodeAlphaInternal(quant_alpha, width, height, |
| method, test_filter, reduce_levels, |
| effort_level, filtered_alpha, &tmp_bw, |
| pic->stats); |
| if (ok) { |
| const size_t score = VP8BitWriterSize(&tmp_bw); |
| if (score < best_score) { |
| // swap bitwriter objects. |
| VP8BitWriter tmp = tmp_bw; |
| tmp_bw = bw; |
| bw = tmp; |
| best_score = score; |
| if (pic->stats != NULL) best_stats = *pic->stats; |
| } |
| } else { |
| VP8BitWriterWipeOut(&bw); |
| } |
| if (wipe_tmp_bw) { |
| VP8BitWriterWipeOut(&tmp_bw); |
| } |
| wipe_tmp_bw = 1; // For next filter trial for WEBP_FILTER_BEST. |
| } |
| if (pic->stats != NULL) *pic->stats = best_stats; |
| } |
| Ok: |
| if (ok) { |
| *output_size = VP8BitWriterSize(&bw); |
| *output = VP8BitWriterBuf(&bw); |
| if (pic->stats != NULL) { // need stats? |
| pic->stats->coded_size += (int)(*output_size); |
| enc->sse_[3] = sse; |
| } |
| } |
| free(filtered_alpha); |
| } |
| End: |
| free(quant_alpha); |
| return ok; |
| } |
| |
| |
| //------------------------------------------------------------------------------ |
| // Main calls |
| |
| static int CompressAlphaJob(VP8Encoder* const enc, void* dummy) { |
| const WebPConfig* config = enc->config_; |
| uint8_t* alpha_data = NULL; |
| size_t alpha_size = 0; |
| const int effort_level = config->method; // maps to [0..6] |
| const WEBP_FILTER_TYPE filter = |
| (config->alpha_filtering == 0) ? WEBP_FILTER_NONE : |
| (config->alpha_filtering == 1) ? WEBP_FILTER_FAST : |
| WEBP_FILTER_BEST; |
| if (!EncodeAlpha(enc, config->alpha_quality, config->alpha_compression, |
| filter, effort_level, &alpha_data, &alpha_size)) { |
| return 0; |
| } |
| if (alpha_size != (uint32_t)alpha_size) { // Sanity check. |
| free(alpha_data); |
| return 0; |
| } |
| enc->alpha_data_size_ = (uint32_t)alpha_size; |
| enc->alpha_data_ = alpha_data; |
| (void)dummy; |
| return 1; |
| } |
| |
| void VP8EncInitAlpha(VP8Encoder* const enc) { |
| enc->has_alpha_ = WebPPictureHasTransparency(enc->pic_); |
| enc->alpha_data_ = NULL; |
| enc->alpha_data_size_ = 0; |
| if (enc->thread_level_ > 0) { |
| WebPWorker* const worker = &enc->alpha_worker_; |
| WebPWorkerInit(worker); |
| worker->data1 = enc; |
| worker->data2 = NULL; |
| worker->hook = (WebPWorkerHook)CompressAlphaJob; |
| } |
| } |
| |
| int VP8EncStartAlpha(VP8Encoder* const enc) { |
| if (enc->has_alpha_) { |
| if (enc->thread_level_ > 0) { |
| WebPWorker* const worker = &enc->alpha_worker_; |
| if (!WebPWorkerReset(worker)) { // Makes sure worker is good to go. |
| return 0; |
| } |
| WebPWorkerLaunch(worker); |
| return 1; |
| } else { |
| return CompressAlphaJob(enc, NULL); // just do the job right away |
| } |
| } |
| return 1; |
| } |
| |
| int VP8EncFinishAlpha(VP8Encoder* const enc) { |
| if (enc->has_alpha_) { |
| if (enc->thread_level_ > 0) { |
| WebPWorker* const worker = &enc->alpha_worker_; |
| if (!WebPWorkerSync(worker)) return 0; // error |
| } |
| } |
| return WebPReportProgress(enc->pic_, enc->percent_ + 20, &enc->percent_); |
| } |
| |
| int VP8EncDeleteAlpha(VP8Encoder* const enc) { |
| int ok = 1; |
| if (enc->thread_level_ > 0) { |
| WebPWorker* const worker = &enc->alpha_worker_; |
| ok = WebPWorkerSync(worker); // finish anything left in flight |
| WebPWorkerEnd(worker); // still need to end the worker, even if !ok |
| } |
| free(enc->alpha_data_); |
| enc->alpha_data_ = NULL; |
| enc->alpha_data_size_ = 0; |
| enc->has_alpha_ = 0; |
| return ok; |
| } |
| |
| #if defined(__cplusplus) || defined(c_plusplus) |
| } // extern "C" |
| #endif |
