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/*
* Copyright (c) 2022, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
#include "aom_dsp/pyramid.h"
#include "aom_mem/aom_mem.h"
#include "aom_ports/bitops.h"
#include "aom_util/aom_thread.h"
// TODO(rachelbarker): Move needed code from av1/ to aom_dsp/
#include "av1/common/resize.h"
#include <assert.h>
#include <string.h>
// Lifecycle:
// * Frame buffer alloc code calls aom_get_pyramid_alloc_size()
// to work out how much space is needed for a given number of pyramid
// levels. This is counted in the size checked against the max allocation
// limit
// * Then calls aom_alloc_pyramid() to actually create the pyramid
// * Pyramid is initially marked as invalid (no data)
// * Whenever pyramid is needed, we check the valid flag. If set, use existing
// data. If not set, compute full pyramid
// * Whenever frame buffer is reused, clear the valid flag
// * Whenever frame buffer is resized, reallocate pyramid
size_t aom_get_pyramid_alloc_size(int width, int height, int n_levels,
bool image_is_16bit) {
// Limit number of levels on small frames
const int msb = get_msb(AOMMIN(width, height));
const int max_levels = AOMMAX(msb - MIN_PYRAMID_SIZE_LOG2, 1);
n_levels = AOMMIN(n_levels, max_levels);
size_t alloc_size = 0;
alloc_size += sizeof(ImagePyramid);
alloc_size += n_levels * sizeof(PyramidLayer);
// Calculate how much memory is needed for downscaled frame buffers
size_t buffer_size = 0;
// Work out if we need to allocate a few extra bytes for alignment.
// aom_memalign() will ensure that the start of the allocation is aligned
// to a multiple of PYRAMID_ALIGNMENT. But we want the first image pixel
// to be aligned, not the first byte of the allocation.
//
// In the loop below, we ensure that the stride of every image is a multiple
// of PYRAMID_ALIGNMENT. Thus the allocated size of each pyramid level will
// also be a multiple of PYRAMID_ALIGNMENT. Thus, as long as we can get the
// first pixel in the first pyramid layer aligned properly, that will
// automatically mean that the first pixel of every row of every layer is
// properly aligned too.
//
// Thus all we need to consider is the first pixel in the first layer.
// This is located at offset
// extra_bytes + level_stride * PYRAMID_PADDING + PYRAMID_PADDING
// bytes into the buffer. Since level_stride is a multiple of
// PYRAMID_ALIGNMENT, we can ignore that. So we need
// extra_bytes + PYRAMID_PADDING = multiple of PYRAMID_ALIGNMENT
//
// To solve this, we can round PYRAMID_PADDING up to the next multiple
// of PYRAMID_ALIGNMENT, then subtract the orginal value to calculate
// how many extra bytes are needed.
size_t first_px_offset =
(PYRAMID_PADDING + PYRAMID_ALIGNMENT - 1) & ~(PYRAMID_ALIGNMENT - 1);
size_t extra_bytes = first_px_offset - PYRAMID_PADDING;
buffer_size += extra_bytes;
// If the original image is stored in an 8-bit buffer, then we can point the
// lowest pyramid level at that buffer rather than allocating a new one.
int first_allocated_level = image_is_16bit ? 0 : 1;
for (int level = first_allocated_level; level < n_levels; level++) {
int level_width = width >> level;
int level_height = height >> level;
// Allocate padding for each layer
int padded_width = level_width + 2 * PYRAMID_PADDING;
int padded_height = level_height + 2 * PYRAMID_PADDING;
// Align the layer stride to be a multiple of PYRAMID_ALIGNMENT
// This ensures that, as long as the top-left pixel in this pyramid level is
// properly aligned, then so will the leftmost pixel in every row of the
// pyramid level.
int level_stride =
(padded_width + PYRAMID_ALIGNMENT - 1) & ~(PYRAMID_ALIGNMENT - 1);
buffer_size += level_stride * padded_height;
}
alloc_size += buffer_size;
return alloc_size;
}
ImagePyramid *aom_alloc_pyramid(int width, int height, int n_levels,
bool image_is_16bit) {
// Limit number of levels on small frames
const int msb = get_msb(AOMMIN(width, height));
const int max_levels = AOMMAX(msb - MIN_PYRAMID_SIZE_LOG2, 1);
n_levels = AOMMIN(n_levels, max_levels);
ImagePyramid *pyr = aom_calloc(1, sizeof(*pyr));
if (!pyr) {
return NULL;
}
pyr->layers = aom_calloc(n_levels, sizeof(PyramidLayer));
if (!pyr->layers) {
aom_free(pyr);
return NULL;
}
pyr->valid = false;
pyr->n_levels = n_levels;
// Compute sizes and offsets for each pyramid level
// These are gathered up first, so that we can allocate all pyramid levels
// in a single buffer
size_t buffer_size = 0;
size_t *layer_offsets = aom_calloc(n_levels, sizeof(size_t));
if (!layer_offsets) {
aom_free(pyr);
aom_free(pyr->layers);
return NULL;
}
// Work out if we need to allocate a few extra bytes for alignment.
// aom_memalign() will ensure that the start of the allocation is aligned
// to a multiple of PYRAMID_ALIGNMENT. But we want the first image pixel
// to be aligned, not the first byte of the allocation.
//
// In the loop below, we ensure that the stride of every image is a multiple
// of PYRAMID_ALIGNMENT. Thus the allocated size of each pyramid level will
// also be a multiple of PYRAMID_ALIGNMENT. Thus, as long as we can get the
// first pixel in the first pyramid layer aligned properly, that will
// automatically mean that the first pixel of every row of every layer is
// properly aligned too.
//
// Thus all we need to consider is the first pixel in the first layer.
// This is located at offset
// extra_bytes + level_stride * PYRAMID_PADDING + PYRAMID_PADDING
// bytes into the buffer. Since level_stride is a multiple of
// PYRAMID_ALIGNMENT, we can ignore that. So we need
// extra_bytes + PYRAMID_PADDING = multiple of PYRAMID_ALIGNMENT
//
// To solve this, we can round PYRAMID_PADDING up to the next multiple
// of PYRAMID_ALIGNMENT, then subtract the orginal value to calculate
// how many extra bytes are needed.
size_t first_px_offset =
(PYRAMID_PADDING + PYRAMID_ALIGNMENT - 1) & ~(PYRAMID_ALIGNMENT - 1);
size_t extra_bytes = first_px_offset - PYRAMID_PADDING;
buffer_size += extra_bytes;
// If the original image is stored in an 8-bit buffer, then we can point the
// lowest pyramid level at that buffer rather than allocating a new one.
int first_allocated_level = image_is_16bit ? 0 : 1;
for (int level = first_allocated_level; level < n_levels; level++) {
PyramidLayer *layer = &pyr->layers[level];
int level_width = width >> level;
int level_height = height >> level;
// Allocate padding for each layer
int padded_width = level_width + 2 * PYRAMID_PADDING;
int padded_height = level_height + 2 * PYRAMID_PADDING;
// Align the layer stride to be a multiple of PYRAMID_ALIGNMENT
// This ensures that, as long as the top-left pixel in this pyramid level is
// properly aligned, then so will the leftmost pixel in every row of the
// pyramid level.
int level_stride =
(padded_width + PYRAMID_ALIGNMENT - 1) & ~(PYRAMID_ALIGNMENT - 1);
size_t level_alloc_start = buffer_size;
size_t level_start =
level_alloc_start + PYRAMID_PADDING * level_stride + PYRAMID_PADDING;
buffer_size += level_stride * padded_height;
layer_offsets[level] = level_start;
layer->width = level_width;
layer->height = level_height;
layer->stride = level_stride;
}
pyr->buffer_alloc =
aom_memalign(PYRAMID_ALIGNMENT, buffer_size * sizeof(*pyr->buffer_alloc));
if (!pyr->buffer_alloc) {
aom_free(pyr);
aom_free(pyr->layers);
aom_free(layer_offsets);
return NULL;
}
// Fill in pointers for each level
// If image is 8-bit, then the lowest level is left unconfigured for now,
// and will be set up properly when the pyramid is filled in
for (int level = first_allocated_level; level < n_levels; level++) {
PyramidLayer *layer = &pyr->layers[level];
layer->buffer = pyr->buffer_alloc + layer_offsets[level];
}
#if CONFIG_MULTITHREAD
pthread_mutex_init(&pyr->mutex, NULL);
#endif // CONFIG_MULTITHREAD
aom_free(layer_offsets);
return pyr;
}
// Fill the border region of a pyramid frame.
// This must be called after the main image area is filled out.
// `img_buf` should point to the first pixel in the image area,
// ie. it should be pyr->level_buffer + pyr->level_loc[level].
static INLINE void fill_border(uint8_t *img_buf, const int width,
const int height, const int stride) {
// Fill left and right areas
for (int row = 0; row < height; row++) {
uint8_t *row_start = &img_buf[row * stride];
uint8_t left_pixel = row_start[0];
memset(row_start - PYRAMID_PADDING, left_pixel, PYRAMID_PADDING);
uint8_t right_pixel = row_start[width - 1];
memset(row_start + width, right_pixel, PYRAMID_PADDING);
}
// Fill top area
for (int row = -PYRAMID_PADDING; row < 0; row++) {
uint8_t *row_start = &img_buf[row * stride];
memcpy(row_start - PYRAMID_PADDING, img_buf - PYRAMID_PADDING,
width + 2 * PYRAMID_PADDING);
}
// Fill bottom area
uint8_t *last_row_start = &img_buf[(height - 1) * stride];
for (int row = height; row < height + PYRAMID_PADDING; row++) {
uint8_t *row_start = &img_buf[row * stride];
memcpy(row_start - PYRAMID_PADDING, last_row_start - PYRAMID_PADDING,
width + 2 * PYRAMID_PADDING);
}
}
// Compute coarse to fine pyramids for a frame
// This must only be called while holding frame_pyr->mutex
static INLINE bool fill_pyramid(const YV12_BUFFER_CONFIG *frame, int bit_depth,
ImagePyramid *frame_pyr) {
int n_levels = frame_pyr->n_levels;
const int frame_width = frame->y_crop_width;
const int frame_height = frame->y_crop_height;
const int frame_stride = frame->y_stride;
assert((frame_width >> n_levels) >= 0);
assert((frame_height >> n_levels) >= 0);
PyramidLayer *first_layer = &frame_pyr->layers[0];
if (frame->flags & YV12_FLAG_HIGHBITDEPTH) {
// For frames stored in a 16-bit buffer, we need to downconvert to 8 bits
assert(first_layer->width == frame_width);
assert(first_layer->height == frame_height);
uint16_t *frame_buffer = CONVERT_TO_SHORTPTR(frame->y_buffer);
uint8_t *pyr_buffer = first_layer->buffer;
int pyr_stride = first_layer->stride;
for (int y = 0; y < frame_height; y++) {
uint16_t *frame_row = frame_buffer + y * frame_stride;
uint8_t *pyr_row = pyr_buffer + y * pyr_stride;
for (int x = 0; x < frame_width; x++) {
pyr_row[x] = frame_row[x] >> (bit_depth - 8);
}
}
fill_border(pyr_buffer, frame_width, frame_height, pyr_stride);
} else {
// For frames stored in an 8-bit buffer, we need to configure the first
// pyramid layer to point at the original image buffer
first_layer->buffer = frame->y_buffer;
first_layer->width = frame_width;
first_layer->height = frame_height;
first_layer->stride = frame_stride;
}
// Fill in the remaining levels through progressive downsampling
for (int level = 1; level < n_levels; ++level) {
PyramidLayer *prev_layer = &frame_pyr->layers[level - 1];
uint8_t *prev_buffer = prev_layer->buffer;
int prev_stride = prev_layer->stride;
PyramidLayer *this_layer = &frame_pyr->layers[level];
uint8_t *this_buffer = this_layer->buffer;
int this_width = this_layer->width;
int this_height = this_layer->height;
int this_stride = this_layer->stride;
// Compute the this pyramid level by downsampling the current level.
//
// We downsample by a factor of exactly 2, clipping the rightmost and
// bottommost pixel off of the current level if needed. We do this for
// two main reasons:
//
// 1) In the disflow code, when stepping from a higher pyramid level to a
// lower pyramid level, we need to not just interpolate the flow field
// but also to scale each flow vector by the upsampling ratio.
// So it is much more convenient if this ratio is simply 2.
//
// 2) Up/downsampling by a factor of 2 can be implemented much more
// efficiently than up/downsampling by a generic ratio.
// TODO(rachelbarker): Use optimized downsample-by-2 function
if (!av1_resize_plane(prev_buffer, this_height << 1, this_width << 1,
prev_stride, this_buffer, this_height, this_width,
this_stride))
return false;
fill_border(this_buffer, this_width, this_height, this_stride);
}
return true;
}
// Fill out a downsampling pyramid for a given frame.
//
// The top level (index 0) will always be an 8-bit copy of the input frame,
// regardless of the input bit depth. Additional levels are then downscaled
// by powers of 2.
//
// For small input frames, the number of levels actually constructed
// will be limited so that the smallest image is at least MIN_PYRAMID_SIZE
// pixels along each side.
//
// However, if the input frame has a side of length < MIN_PYRAMID_SIZE,
// we will still construct the top level.
bool aom_compute_pyramid(const YV12_BUFFER_CONFIG *frame, int bit_depth,
ImagePyramid *pyr) {
assert(pyr);
// Per the comments in the ImagePyramid struct, we must take this mutex
// before reading or writing the "valid" flag, and hold it while computing
// the pyramid, to ensure proper behaviour if multiple threads call this
// function simultaneously
#if CONFIG_MULTITHREAD
pthread_mutex_lock(&pyr->mutex);
#endif // CONFIG_MULTITHREAD
if (!pyr->valid) {
pyr->valid = fill_pyramid(frame, bit_depth, pyr);
}
bool valid = pyr->valid;
// At this point, the pyramid is guaranteed to be valid, and can be safely
// read from without holding the mutex any more
#if CONFIG_MULTITHREAD
pthread_mutex_unlock(&pyr->mutex);
#endif // CONFIG_MULTITHREAD
return valid;
}
#ifndef NDEBUG
// Check if a pyramid has already been computed.
// This is mostly a debug helper - as it is necessary to hold pyr->mutex
// while reading the valid flag, we cannot just write:
// assert(pyr->valid);
// This function allows the check to be correctly written as:
// assert(aom_is_pyramid_valid(pyr));
bool aom_is_pyramid_valid(ImagePyramid *pyr) {
assert(pyr);
// Per the comments in the ImagePyramid struct, we must take this mutex
// before reading or writing the "valid" flag, and hold it while computing
// the pyramid, to ensure proper behaviour if multiple threads call this
// function simultaneously
#if CONFIG_MULTITHREAD
pthread_mutex_lock(&pyr->mutex);
#endif // CONFIG_MULTITHREAD
bool valid = pyr->valid;
#if CONFIG_MULTITHREAD
pthread_mutex_unlock(&pyr->mutex);
#endif // CONFIG_MULTITHREAD
return valid;
}
#endif
// Mark a pyramid as no longer containing valid data.
// This must be done whenever the corresponding frame buffer is reused
void aom_invalidate_pyramid(ImagePyramid *pyr) {
if (pyr) {
#if CONFIG_MULTITHREAD
pthread_mutex_lock(&pyr->mutex);
#endif // CONFIG_MULTITHREAD
pyr->valid = false;
#if CONFIG_MULTITHREAD
pthread_mutex_unlock(&pyr->mutex);
#endif // CONFIG_MULTITHREAD
}
}
// Release the memory associated with a pyramid
void aom_free_pyramid(ImagePyramid *pyr) {
if (pyr) {
#if CONFIG_MULTITHREAD
pthread_mutex_destroy(&pyr->mutex);
#endif // CONFIG_MULTITHREAD
aom_free(pyr->buffer_alloc);
aom_free(pyr->layers);
aom_free(pyr);
}
}