diff options
Diffstat (limited to 'media/libwebp/src/dec/frame_dec.c')
| -rw-r--r-- | media/libwebp/src/dec/frame_dec.c | 803 |
1 files changed, 803 insertions, 0 deletions
diff --git a/media/libwebp/src/dec/frame_dec.c b/media/libwebp/src/dec/frame_dec.c new file mode 100644 index 0000000000..04609a8e56 --- /dev/null +++ b/media/libwebp/src/dec/frame_dec.c @@ -0,0 +1,803 @@ +// Copyright 2010 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. +// ----------------------------------------------------------------------------- +// +// Frame-reconstruction function. Memory allocation. +// +// Author: Skal (pascal.massimino@gmail.com) + +#include <stdlib.h> +#include "src/dec/vp8i_dec.h" +#include "src/utils/utils.h" + +//------------------------------------------------------------------------------ +// Main reconstruction function. + +static const uint16_t kScan[16] = { + 0 + 0 * BPS, 4 + 0 * BPS, 8 + 0 * BPS, 12 + 0 * BPS, + 0 + 4 * BPS, 4 + 4 * BPS, 8 + 4 * BPS, 12 + 4 * BPS, + 0 + 8 * BPS, 4 + 8 * BPS, 8 + 8 * BPS, 12 + 8 * BPS, + 0 + 12 * BPS, 4 + 12 * BPS, 8 + 12 * BPS, 12 + 12 * BPS +}; + +static int CheckMode(int mb_x, int mb_y, int mode) { + if (mode == B_DC_PRED) { + if (mb_x == 0) { + return (mb_y == 0) ? B_DC_PRED_NOTOPLEFT : B_DC_PRED_NOLEFT; + } else { + return (mb_y == 0) ? B_DC_PRED_NOTOP : B_DC_PRED; + } + } + return mode; +} + +static void Copy32b(uint8_t* const dst, const uint8_t* const src) { + memcpy(dst, src, 4); +} + +static WEBP_INLINE void DoTransform(uint32_t bits, const int16_t* const src, + uint8_t* const dst) { + switch (bits >> 30) { + case 3: + VP8Transform(src, dst, 0); + break; + case 2: + VP8TransformAC3(src, dst); + break; + case 1: + VP8TransformDC(src, dst); + break; + default: + break; + } +} + +static void DoUVTransform(uint32_t bits, const int16_t* const src, + uint8_t* const dst) { + if (bits & 0xff) { // any non-zero coeff at all? + if (bits & 0xaa) { // any non-zero AC coefficient? + VP8TransformUV(src, dst); // note we don't use the AC3 variant for U/V + } else { + VP8TransformDCUV(src, dst); + } + } +} + +static void ReconstructRow(const VP8Decoder* const dec, + const VP8ThreadContext* ctx) { + int j; + int mb_x; + const int mb_y = ctx->mb_y_; + const int cache_id = ctx->id_; + uint8_t* const y_dst = dec->yuv_b_ + Y_OFF; + uint8_t* const u_dst = dec->yuv_b_ + U_OFF; + uint8_t* const v_dst = dec->yuv_b_ + V_OFF; + + // Initialize left-most block. + for (j = 0; j < 16; ++j) { + y_dst[j * BPS - 1] = 129; + } + for (j = 0; j < 8; ++j) { + u_dst[j * BPS - 1] = 129; + v_dst[j * BPS - 1] = 129; + } + + // Init top-left sample on left column too. + if (mb_y > 0) { + y_dst[-1 - BPS] = u_dst[-1 - BPS] = v_dst[-1 - BPS] = 129; + } else { + // we only need to do this init once at block (0,0). + // Afterward, it remains valid for the whole topmost row. + memset(y_dst - BPS - 1, 127, 16 + 4 + 1); + memset(u_dst - BPS - 1, 127, 8 + 1); + memset(v_dst - BPS - 1, 127, 8 + 1); + } + + // Reconstruct one row. + for (mb_x = 0; mb_x < dec->mb_w_; ++mb_x) { + const VP8MBData* const block = ctx->mb_data_ + mb_x; + + // Rotate in the left samples from previously decoded block. We move four + // pixels at a time for alignment reason, and because of in-loop filter. + if (mb_x > 0) { + for (j = -1; j < 16; ++j) { + Copy32b(&y_dst[j * BPS - 4], &y_dst[j * BPS + 12]); + } + for (j = -1; j < 8; ++j) { + Copy32b(&u_dst[j * BPS - 4], &u_dst[j * BPS + 4]); + Copy32b(&v_dst[j * BPS - 4], &v_dst[j * BPS + 4]); + } + } + { + // bring top samples into the cache + VP8TopSamples* const top_yuv = dec->yuv_t_ + mb_x; + const int16_t* const coeffs = block->coeffs_; + uint32_t bits = block->non_zero_y_; + int n; + + if (mb_y > 0) { + memcpy(y_dst - BPS, top_yuv[0].y, 16); + memcpy(u_dst - BPS, top_yuv[0].u, 8); + memcpy(v_dst - BPS, top_yuv[0].v, 8); + } + + // predict and add residuals + if (block->is_i4x4_) { // 4x4 + uint32_t* const top_right = (uint32_t*)(y_dst - BPS + 16); + + if (mb_y > 0) { + if (mb_x >= dec->mb_w_ - 1) { // on rightmost border + memset(top_right, top_yuv[0].y[15], sizeof(*top_right)); + } else { + memcpy(top_right, top_yuv[1].y, sizeof(*top_right)); + } + } + // replicate the top-right pixels below + top_right[BPS] = top_right[2 * BPS] = top_right[3 * BPS] = top_right[0]; + + // predict and add residuals for all 4x4 blocks in turn. + for (n = 0; n < 16; ++n, bits <<= 2) { + uint8_t* const dst = y_dst + kScan[n]; + VP8PredLuma4[block->imodes_[n]](dst); + DoTransform(bits, coeffs + n * 16, dst); + } + } else { // 16x16 + const int pred_func = CheckMode(mb_x, mb_y, block->imodes_[0]); + VP8PredLuma16[pred_func](y_dst); + if (bits != 0) { + for (n = 0; n < 16; ++n, bits <<= 2) { + DoTransform(bits, coeffs + n * 16, y_dst + kScan[n]); + } + } + } + { + // Chroma + const uint32_t bits_uv = block->non_zero_uv_; + const int pred_func = CheckMode(mb_x, mb_y, block->uvmode_); + VP8PredChroma8[pred_func](u_dst); + VP8PredChroma8[pred_func](v_dst); + DoUVTransform(bits_uv >> 0, coeffs + 16 * 16, u_dst); + DoUVTransform(bits_uv >> 8, coeffs + 20 * 16, v_dst); + } + + // stash away top samples for next block + if (mb_y < dec->mb_h_ - 1) { + memcpy(top_yuv[0].y, y_dst + 15 * BPS, 16); + memcpy(top_yuv[0].u, u_dst + 7 * BPS, 8); + memcpy(top_yuv[0].v, v_dst + 7 * BPS, 8); + } + } + // Transfer reconstructed samples from yuv_b_ cache to final destination. + { + const int y_offset = cache_id * 16 * dec->cache_y_stride_; + const int uv_offset = cache_id * 8 * dec->cache_uv_stride_; + uint8_t* const y_out = dec->cache_y_ + mb_x * 16 + y_offset; + uint8_t* const u_out = dec->cache_u_ + mb_x * 8 + uv_offset; + uint8_t* const v_out = dec->cache_v_ + mb_x * 8 + uv_offset; + for (j = 0; j < 16; ++j) { + memcpy(y_out + j * dec->cache_y_stride_, y_dst + j * BPS, 16); + } + for (j = 0; j < 8; ++j) { + memcpy(u_out + j * dec->cache_uv_stride_, u_dst + j * BPS, 8); + memcpy(v_out + j * dec->cache_uv_stride_, v_dst + j * BPS, 8); + } + } + } +} + +//------------------------------------------------------------------------------ +// Filtering + +// kFilterExtraRows[] = How many extra lines are needed on the MB boundary +// for caching, given a filtering level. +// Simple filter: up to 2 luma samples are read and 1 is written. +// Complex filter: up to 4 luma samples are read and 3 are written. Same for +// U/V, so it's 8 samples total (because of the 2x upsampling). +static const uint8_t kFilterExtraRows[3] = { 0, 2, 8 }; + +static void DoFilter(const VP8Decoder* const dec, int mb_x, int mb_y) { + const VP8ThreadContext* const ctx = &dec->thread_ctx_; + const int cache_id = ctx->id_; + const int y_bps = dec->cache_y_stride_; + const VP8FInfo* const f_info = ctx->f_info_ + mb_x; + uint8_t* const y_dst = dec->cache_y_ + cache_id * 16 * y_bps + mb_x * 16; + const int ilevel = f_info->f_ilevel_; + const int limit = f_info->f_limit_; + if (limit == 0) { + return; + } + assert(limit >= 3); + if (dec->filter_type_ == 1) { // simple + if (mb_x > 0) { + VP8SimpleHFilter16(y_dst, y_bps, limit + 4); + } + if (f_info->f_inner_) { + VP8SimpleHFilter16i(y_dst, y_bps, limit); + } + if (mb_y > 0) { + VP8SimpleVFilter16(y_dst, y_bps, limit + 4); + } + if (f_info->f_inner_) { + VP8SimpleVFilter16i(y_dst, y_bps, limit); + } + } else { // complex + const int uv_bps = dec->cache_uv_stride_; + uint8_t* const u_dst = dec->cache_u_ + cache_id * 8 * uv_bps + mb_x * 8; + uint8_t* const v_dst = dec->cache_v_ + cache_id * 8 * uv_bps + mb_x * 8; + const int hev_thresh = f_info->hev_thresh_; + if (mb_x > 0) { + VP8HFilter16(y_dst, y_bps, limit + 4, ilevel, hev_thresh); + VP8HFilter8(u_dst, v_dst, uv_bps, limit + 4, ilevel, hev_thresh); + } + if (f_info->f_inner_) { + VP8HFilter16i(y_dst, y_bps, limit, ilevel, hev_thresh); + VP8HFilter8i(u_dst, v_dst, uv_bps, limit, ilevel, hev_thresh); + } + if (mb_y > 0) { + VP8VFilter16(y_dst, y_bps, limit + 4, ilevel, hev_thresh); + VP8VFilter8(u_dst, v_dst, uv_bps, limit + 4, ilevel, hev_thresh); + } + if (f_info->f_inner_) { + VP8VFilter16i(y_dst, y_bps, limit, ilevel, hev_thresh); + VP8VFilter8i(u_dst, v_dst, uv_bps, limit, ilevel, hev_thresh); + } + } +} + +// Filter the decoded macroblock row (if needed) +static void FilterRow(const VP8Decoder* const dec) { + int mb_x; + const int mb_y = dec->thread_ctx_.mb_y_; + assert(dec->thread_ctx_.filter_row_); + for (mb_x = dec->tl_mb_x_; mb_x < dec->br_mb_x_; ++mb_x) { + DoFilter(dec, mb_x, mb_y); + } +} + +//------------------------------------------------------------------------------ +// Precompute the filtering strength for each segment and each i4x4/i16x16 mode. + +static void PrecomputeFilterStrengths(VP8Decoder* const dec) { + if (dec->filter_type_ > 0) { + int s; + const VP8FilterHeader* const hdr = &dec->filter_hdr_; + for (s = 0; s < NUM_MB_SEGMENTS; ++s) { + int i4x4; + // First, compute the initial level + int base_level; + if (dec->segment_hdr_.use_segment_) { + base_level = dec->segment_hdr_.filter_strength_[s]; + if (!dec->segment_hdr_.absolute_delta_) { + base_level += hdr->level_; + } + } else { + base_level = hdr->level_; + } + for (i4x4 = 0; i4x4 <= 1; ++i4x4) { + VP8FInfo* const info = &dec->fstrengths_[s][i4x4]; + int level = base_level; + if (hdr->use_lf_delta_) { + level += hdr->ref_lf_delta_[0]; + if (i4x4) { + level += hdr->mode_lf_delta_[0]; + } + } + level = (level < 0) ? 0 : (level > 63) ? 63 : level; + if (level > 0) { + int ilevel = level; + if (hdr->sharpness_ > 0) { + if (hdr->sharpness_ > 4) { + ilevel >>= 2; + } else { + ilevel >>= 1; + } + if (ilevel > 9 - hdr->sharpness_) { + ilevel = 9 - hdr->sharpness_; + } + } + if (ilevel < 1) ilevel = 1; + info->f_ilevel_ = ilevel; + info->f_limit_ = 2 * level + ilevel; + info->hev_thresh_ = (level >= 40) ? 2 : (level >= 15) ? 1 : 0; + } else { + info->f_limit_ = 0; // no filtering + } + info->f_inner_ = i4x4; + } + } + } +} + +//------------------------------------------------------------------------------ +// Dithering + +// minimal amp that will provide a non-zero dithering effect +#define MIN_DITHER_AMP 4 + +#define DITHER_AMP_TAB_SIZE 12 +static const uint8_t kQuantToDitherAmp[DITHER_AMP_TAB_SIZE] = { + // roughly, it's dqm->uv_mat_[1] + 8, 7, 6, 4, 4, 2, 2, 2, 1, 1, 1, 1 +}; + +void VP8InitDithering(const WebPDecoderOptions* const options, + VP8Decoder* const dec) { + assert(dec != NULL); + if (options != NULL) { + const int d = options->dithering_strength; + const int max_amp = (1 << VP8_RANDOM_DITHER_FIX) - 1; + const int f = (d < 0) ? 0 : (d > 100) ? max_amp : (d * max_amp / 100); + if (f > 0) { + int s; + int all_amp = 0; + for (s = 0; s < NUM_MB_SEGMENTS; ++s) { + VP8QuantMatrix* const dqm = &dec->dqm_[s]; + if (dqm->uv_quant_ < DITHER_AMP_TAB_SIZE) { + const int idx = (dqm->uv_quant_ < 0) ? 0 : dqm->uv_quant_; + dqm->dither_ = (f * kQuantToDitherAmp[idx]) >> 3; + } + all_amp |= dqm->dither_; + } + if (all_amp != 0) { + VP8InitRandom(&dec->dithering_rg_, 1.0f); + dec->dither_ = 1; + } + } + // potentially allow alpha dithering + dec->alpha_dithering_ = options->alpha_dithering_strength; + if (dec->alpha_dithering_ > 100) { + dec->alpha_dithering_ = 100; + } else if (dec->alpha_dithering_ < 0) { + dec->alpha_dithering_ = 0; + } + } +} + +// Convert to range: [-2,2] for dither=50, [-4,4] for dither=100 +static void Dither8x8(VP8Random* const rg, uint8_t* dst, int bps, int amp) { + uint8_t dither[64]; + int i; + for (i = 0; i < 8 * 8; ++i) { + dither[i] = VP8RandomBits2(rg, VP8_DITHER_AMP_BITS + 1, amp); + } + VP8DitherCombine8x8(dither, dst, bps); +} + +static void DitherRow(VP8Decoder* const dec) { + int mb_x; + assert(dec->dither_); + for (mb_x = dec->tl_mb_x_; mb_x < dec->br_mb_x_; ++mb_x) { + const VP8ThreadContext* const ctx = &dec->thread_ctx_; + const VP8MBData* const data = ctx->mb_data_ + mb_x; + const int cache_id = ctx->id_; + const int uv_bps = dec->cache_uv_stride_; + if (data->dither_ >= MIN_DITHER_AMP) { + uint8_t* const u_dst = dec->cache_u_ + cache_id * 8 * uv_bps + mb_x * 8; + uint8_t* const v_dst = dec->cache_v_ + cache_id * 8 * uv_bps + mb_x * 8; + Dither8x8(&dec->dithering_rg_, u_dst, uv_bps, data->dither_); + Dither8x8(&dec->dithering_rg_, v_dst, uv_bps, data->dither_); + } + } +} + +//------------------------------------------------------------------------------ +// This function is called after a row of macroblocks is finished decoding. +// It also takes into account the following restrictions: +// * In case of in-loop filtering, we must hold off sending some of the bottom +// pixels as they are yet unfiltered. They will be when the next macroblock +// row is decoded. Meanwhile, we must preserve them by rotating them in the +// cache area. This doesn't hold for the very bottom row of the uncropped +// picture of course. +// * we must clip the remaining pixels against the cropping area. The VP8Io +// struct must have the following fields set correctly before calling put(): + +#define MACROBLOCK_VPOS(mb_y) ((mb_y) * 16) // vertical position of a MB + +// Finalize and transmit a complete row. Return false in case of user-abort. +static int FinishRow(void* arg1, void* arg2) { + VP8Decoder* const dec = (VP8Decoder*)arg1; + VP8Io* const io = (VP8Io*)arg2; + int ok = 1; + const VP8ThreadContext* const ctx = &dec->thread_ctx_; + const int cache_id = ctx->id_; + const int extra_y_rows = kFilterExtraRows[dec->filter_type_]; + const int ysize = extra_y_rows * dec->cache_y_stride_; + const int uvsize = (extra_y_rows / 2) * dec->cache_uv_stride_; + const int y_offset = cache_id * 16 * dec->cache_y_stride_; + const int uv_offset = cache_id * 8 * dec->cache_uv_stride_; + uint8_t* const ydst = dec->cache_y_ - ysize + y_offset; + uint8_t* const udst = dec->cache_u_ - uvsize + uv_offset; + uint8_t* const vdst = dec->cache_v_ - uvsize + uv_offset; + const int mb_y = ctx->mb_y_; + const int is_first_row = (mb_y == 0); + const int is_last_row = (mb_y >= dec->br_mb_y_ - 1); + + if (dec->mt_method_ == 2) { + ReconstructRow(dec, ctx); + } + + if (ctx->filter_row_) { + FilterRow(dec); + } + + if (dec->dither_) { + DitherRow(dec); + } + + if (io->put != NULL) { + int y_start = MACROBLOCK_VPOS(mb_y); + int y_end = MACROBLOCK_VPOS(mb_y + 1); + if (!is_first_row) { + y_start -= extra_y_rows; + io->y = ydst; + io->u = udst; + io->v = vdst; + } else { + io->y = dec->cache_y_ + y_offset; + io->u = dec->cache_u_ + uv_offset; + io->v = dec->cache_v_ + uv_offset; + } + + if (!is_last_row) { + y_end -= extra_y_rows; + } + if (y_end > io->crop_bottom) { + y_end = io->crop_bottom; // make sure we don't overflow on last row. + } + // If dec->alpha_data_ is not NULL, we have some alpha plane present. + io->a = NULL; + if (dec->alpha_data_ != NULL && y_start < y_end) { + io->a = VP8DecompressAlphaRows(dec, io, y_start, y_end - y_start); + if (io->a == NULL) { + return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR, + "Could not decode alpha data."); + } + } + if (y_start < io->crop_top) { + const int delta_y = io->crop_top - y_start; + y_start = io->crop_top; + assert(!(delta_y & 1)); + io->y += dec->cache_y_stride_ * delta_y; + io->u += dec->cache_uv_stride_ * (delta_y >> 1); + io->v += dec->cache_uv_stride_ * (delta_y >> 1); + if (io->a != NULL) { + io->a += io->width * delta_y; + } + } + if (y_start < y_end) { + io->y += io->crop_left; + io->u += io->crop_left >> 1; + io->v += io->crop_left >> 1; + if (io->a != NULL) { + io->a += io->crop_left; + } + io->mb_y = y_start - io->crop_top; + io->mb_w = io->crop_right - io->crop_left; + io->mb_h = y_end - y_start; + ok = io->put(io); + } + } + // rotate top samples if needed + if (cache_id + 1 == dec->num_caches_) { + if (!is_last_row) { + memcpy(dec->cache_y_ - ysize, ydst + 16 * dec->cache_y_stride_, ysize); + memcpy(dec->cache_u_ - uvsize, udst + 8 * dec->cache_uv_stride_, uvsize); + memcpy(dec->cache_v_ - uvsize, vdst + 8 * dec->cache_uv_stride_, uvsize); + } + } + + return ok; +} + +#undef MACROBLOCK_VPOS + +//------------------------------------------------------------------------------ + +int VP8ProcessRow(VP8Decoder* const dec, VP8Io* const io) { + int ok = 1; + VP8ThreadContext* const ctx = &dec->thread_ctx_; + const int filter_row = + (dec->filter_type_ > 0) && + (dec->mb_y_ >= dec->tl_mb_y_) && (dec->mb_y_ <= dec->br_mb_y_); + if (dec->mt_method_ == 0) { + // ctx->id_ and ctx->f_info_ are already set + ctx->mb_y_ = dec->mb_y_; + ctx->filter_row_ = filter_row; + ReconstructRow(dec, ctx); + ok = FinishRow(dec, io); + } else { + WebPWorker* const worker = &dec->worker_; + // Finish previous job *before* updating context + ok &= WebPGetWorkerInterface()->Sync(worker); + assert(worker->status_ == OK); + if (ok) { // spawn a new deblocking/output job + ctx->io_ = *io; + ctx->id_ = dec->cache_id_; + ctx->mb_y_ = dec->mb_y_; + ctx->filter_row_ = filter_row; + if (dec->mt_method_ == 2) { // swap macroblock data + VP8MBData* const tmp = ctx->mb_data_; + ctx->mb_data_ = dec->mb_data_; + dec->mb_data_ = tmp; + } else { + // perform reconstruction directly in main thread + ReconstructRow(dec, ctx); + } + if (filter_row) { // swap filter info + VP8FInfo* const tmp = ctx->f_info_; + ctx->f_info_ = dec->f_info_; + dec->f_info_ = tmp; + } + // (reconstruct)+filter in parallel + WebPGetWorkerInterface()->Launch(worker); + if (++dec->cache_id_ == dec->num_caches_) { + dec->cache_id_ = 0; + } + } + } + return ok; +} + +//------------------------------------------------------------------------------ +// Finish setting up the decoding parameter once user's setup() is called. + +VP8StatusCode VP8EnterCritical(VP8Decoder* const dec, VP8Io* const io) { + // Call setup() first. This may trigger additional decoding features on 'io'. + // Note: Afterward, we must call teardown() no matter what. + if (io->setup != NULL && !io->setup(io)) { + VP8SetError(dec, VP8_STATUS_USER_ABORT, "Frame setup failed"); + return dec->status_; + } + + // Disable filtering per user request + if (io->bypass_filtering) { + dec->filter_type_ = 0; + } + + // Define the area where we can skip in-loop filtering, in case of cropping. + // + // 'Simple' filter reads two luma samples outside of the macroblock + // and filters one. It doesn't filter the chroma samples. Hence, we can + // avoid doing the in-loop filtering before crop_top/crop_left position. + // For the 'Complex' filter, 3 samples are read and up to 3 are filtered. + // Means: there's a dependency chain that goes all the way up to the + // top-left corner of the picture (MB #0). We must filter all the previous + // macroblocks. + { + const int extra_pixels = kFilterExtraRows[dec->filter_type_]; + if (dec->filter_type_ == 2) { + // For complex filter, we need to preserve the dependency chain. + dec->tl_mb_x_ = 0; + dec->tl_mb_y_ = 0; + } else { + // For simple filter, we can filter only the cropped region. + // We include 'extra_pixels' on the other side of the boundary, since + // vertical or horizontal filtering of the previous macroblock can + // modify some abutting pixels. + dec->tl_mb_x_ = (io->crop_left - extra_pixels) >> 4; + dec->tl_mb_y_ = (io->crop_top - extra_pixels) >> 4; + if (dec->tl_mb_x_ < 0) dec->tl_mb_x_ = 0; + if (dec->tl_mb_y_ < 0) dec->tl_mb_y_ = 0; + } + // We need some 'extra' pixels on the right/bottom. + dec->br_mb_y_ = (io->crop_bottom + 15 + extra_pixels) >> 4; + dec->br_mb_x_ = (io->crop_right + 15 + extra_pixels) >> 4; + if (dec->br_mb_x_ > dec->mb_w_) { + dec->br_mb_x_ = dec->mb_w_; + } + if (dec->br_mb_y_ > dec->mb_h_) { + dec->br_mb_y_ = dec->mb_h_; + } + } + PrecomputeFilterStrengths(dec); + return VP8_STATUS_OK; +} + +int VP8ExitCritical(VP8Decoder* const dec, VP8Io* const io) { + int ok = 1; + if (dec->mt_method_ > 0) { + ok = WebPGetWorkerInterface()->Sync(&dec->worker_); + } + + if (io->teardown != NULL) { + io->teardown(io); + } + return ok; +} + +//------------------------------------------------------------------------------ +// For multi-threaded decoding we need to use 3 rows of 16 pixels as delay line. +// +// Reason is: the deblocking filter cannot deblock the bottom horizontal edges +// immediately, and needs to wait for first few rows of the next macroblock to +// be decoded. Hence, deblocking is lagging behind by 4 or 8 pixels (depending +// on strength). +// With two threads, the vertical positions of the rows being decoded are: +// Decode: [ 0..15][16..31][32..47][48..63][64..79][... +// Deblock: [ 0..11][12..27][28..43][44..59][... +// If we use two threads and two caches of 16 pixels, the sequence would be: +// Decode: [ 0..15][16..31][ 0..15!!][16..31][ 0..15][... +// Deblock: [ 0..11][12..27!!][-4..11][12..27][... +// The problem occurs during row [12..15!!] that both the decoding and +// deblocking threads are writing simultaneously. +// With 3 cache lines, one get a safe write pattern: +// Decode: [ 0..15][16..31][32..47][ 0..15][16..31][32..47][0.. +// Deblock: [ 0..11][12..27][28..43][-4..11][12..27][28... +// Note that multi-threaded output _without_ deblocking can make use of two +// cache lines of 16 pixels only, since there's no lagging behind. The decoding +// and output process have non-concurrent writing: +// Decode: [ 0..15][16..31][ 0..15][16..31][... +// io->put: [ 0..15][16..31][ 0..15][... + +#define MT_CACHE_LINES 3 +#define ST_CACHE_LINES 1 // 1 cache row only for single-threaded case + +// Initialize multi/single-thread worker +static int InitThreadContext(VP8Decoder* const dec) { + dec->cache_id_ = 0; + if (dec->mt_method_ > 0) { + WebPWorker* const worker = &dec->worker_; + if (!WebPGetWorkerInterface()->Reset(worker)) { + return VP8SetError(dec, VP8_STATUS_OUT_OF_MEMORY, + "thread initialization failed."); + } + worker->data1 = dec; + worker->data2 = (void*)&dec->thread_ctx_.io_; + worker->hook = FinishRow; + dec->num_caches_ = + (dec->filter_type_ > 0) ? MT_CACHE_LINES : MT_CACHE_LINES - 1; + } else { + dec->num_caches_ = ST_CACHE_LINES; + } + return 1; +} + +int VP8GetThreadMethod(const WebPDecoderOptions* const options, + const WebPHeaderStructure* const headers, + int width, int height) { + if (options == NULL || options->use_threads == 0) { + return 0; + } + (void)headers; + (void)width; + (void)height; + assert(headers == NULL || !headers->is_lossless); +#if defined(WEBP_USE_THREAD) + if (width >= MIN_WIDTH_FOR_THREADS) return 2; +#endif + return 0; +} + +#undef MT_CACHE_LINES +#undef ST_CACHE_LINES + +//------------------------------------------------------------------------------ +// Memory setup + +static int AllocateMemory(VP8Decoder* const dec) { + const int num_caches = dec->num_caches_; + const int mb_w = dec->mb_w_; + // Note: we use 'size_t' when there's no overflow risk, uint64_t otherwise. + const size_t intra_pred_mode_size = 4 * mb_w * sizeof(uint8_t); + const size_t top_size = sizeof(VP8TopSamples) * mb_w; + const size_t mb_info_size = (mb_w + 1) * sizeof(VP8MB); + const size_t f_info_size = + (dec->filter_type_ > 0) ? + mb_w * (dec->mt_method_ > 0 ? 2 : 1) * sizeof(VP8FInfo) + : 0; + const size_t yuv_size = YUV_SIZE * sizeof(*dec->yuv_b_); + const size_t mb_data_size = + (dec->mt_method_ == 2 ? 2 : 1) * mb_w * sizeof(*dec->mb_data_); + const size_t cache_height = (16 * num_caches + + kFilterExtraRows[dec->filter_type_]) * 3 / 2; + const size_t cache_size = top_size * cache_height; + // alpha_size is the only one that scales as width x height. + const uint64_t alpha_size = (dec->alpha_data_ != NULL) ? + (uint64_t)dec->pic_hdr_.width_ * dec->pic_hdr_.height_ : 0ULL; + const uint64_t needed = (uint64_t)intra_pred_mode_size + + top_size + mb_info_size + f_info_size + + yuv_size + mb_data_size + + cache_size + alpha_size + WEBP_ALIGN_CST; + uint8_t* mem; + + if (needed != (size_t)needed) return 0; // check for overflow + if (needed > dec->mem_size_) { + WebPSafeFree(dec->mem_); + dec->mem_size_ = 0; + dec->mem_ = WebPSafeMalloc(needed, sizeof(uint8_t)); + if (dec->mem_ == NULL) { + return VP8SetError(dec, VP8_STATUS_OUT_OF_MEMORY, + "no memory during frame initialization."); + } + // down-cast is ok, thanks to WebPSafeMalloc() above. + dec->mem_size_ = (size_t)needed; + } + + mem = (uint8_t*)dec->mem_; + dec->intra_t_ = mem; + mem += intra_pred_mode_size; + + dec->yuv_t_ = (VP8TopSamples*)mem; + mem += top_size; + + dec->mb_info_ = ((VP8MB*)mem) + 1; + mem += mb_info_size; + + dec->f_info_ = f_info_size ? (VP8FInfo*)mem : NULL; + mem += f_info_size; + dec->thread_ctx_.id_ = 0; + dec->thread_ctx_.f_info_ = dec->f_info_; + if (dec->filter_type_ > 0 && dec->mt_method_ > 0) { + // secondary cache line. The deblocking process need to make use of the + // filtering strength from previous macroblock row, while the new ones + // are being decoded in parallel. We'll just swap the pointers. + dec->thread_ctx_.f_info_ += mb_w; + } + + mem = (uint8_t*)WEBP_ALIGN(mem); + assert((yuv_size & WEBP_ALIGN_CST) == 0); + dec->yuv_b_ = mem; + mem += yuv_size; + + dec->mb_data_ = (VP8MBData*)mem; + dec->thread_ctx_.mb_data_ = (VP8MBData*)mem; + if (dec->mt_method_ == 2) { + dec->thread_ctx_.mb_data_ += mb_w; + } + mem += mb_data_size; + + dec->cache_y_stride_ = 16 * mb_w; + dec->cache_uv_stride_ = 8 * mb_w; + { + const int extra_rows = kFilterExtraRows[dec->filter_type_]; + const int extra_y = extra_rows * dec->cache_y_stride_; + const int extra_uv = (extra_rows / 2) * dec->cache_uv_stride_; + dec->cache_y_ = mem + extra_y; + dec->cache_u_ = dec->cache_y_ + + 16 * num_caches * dec->cache_y_stride_ + extra_uv; + dec->cache_v_ = dec->cache_u_ + + 8 * num_caches * dec->cache_uv_stride_ + extra_uv; + dec->cache_id_ = 0; + } + mem += cache_size; + + // alpha plane + dec->alpha_plane_ = alpha_size ? mem : NULL; + mem += alpha_size; + assert(mem <= (uint8_t*)dec->mem_ + dec->mem_size_); + + // note: left/top-info is initialized once for all. + memset(dec->mb_info_ - 1, 0, mb_info_size); + VP8InitScanline(dec); // initialize left too. + + // initialize top + memset(dec->intra_t_, B_DC_PRED, intra_pred_mode_size); + + return 1; +} + +static void InitIo(VP8Decoder* const dec, VP8Io* io) { + // prepare 'io' + io->mb_y = 0; + io->y = dec->cache_y_; + io->u = dec->cache_u_; + io->v = dec->cache_v_; + io->y_stride = dec->cache_y_stride_; + io->uv_stride = dec->cache_uv_stride_; + io->a = NULL; +} + +int VP8InitFrame(VP8Decoder* const dec, VP8Io* const io) { + if (!InitThreadContext(dec)) return 0; // call first. Sets dec->num_caches_. + if (!AllocateMemory(dec)) return 0; + InitIo(dec, io); + VP8DspInit(); // Init critical function pointers and look-up tables. + return 1; +} + +//------------------------------------------------------------------------------ |