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// 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 <math.h> // for pow()
#include <stdio.h>
#include <stdlib.h> // for abs()
#include "../mux/animi.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_config_reversed_; // If 'last_config_' uses lossless, then
// this config uses lossy and vice versa;
// 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;
enc_options->verbose = 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;
}
// This starting value is more fit to WebPCleanupTransparentAreaLossless().
#define TRANSPARENT_COLOR 0x00000000
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];
}
typedef int (*ComparePixelsFunc)(const uint32_t*, int, const uint32_t*, int,
int, int);
// Returns true if 'length' number of pixels in 'src' and 'dst' are equal,
// assuming the given step sizes between pixels.
// 'max_allowed_diff' is unused and only there to allow function pointer use.
static WEBP_INLINE int ComparePixelsLossless(const uint32_t* src, int src_step,
const uint32_t* dst, int dst_step,
int length, int max_allowed_diff) {
(void)max_allowed_diff;
assert(length > 0);
while (length-- > 0) {
if (*src != *dst) {
return 0;
}
src += src_step;
dst += dst_step;
}
return 1;
}
// Helper to check if each channel in 'src' and 'dst' is at most off by
// 'max_allowed_diff'.
static WEBP_INLINE int PixelsAreSimilar(uint32_t src, uint32_t dst,
int max_allowed_diff) {
const int src_a = (src >> 24) & 0xff;
const int src_r = (src >> 16) & 0xff;
const int src_g = (src >> 8) & 0xff;
const int src_b = (src >> 0) & 0xff;
const int dst_a = (dst >> 24) & 0xff;
const int dst_r = (dst >> 16) & 0xff;
const int dst_g = (dst >> 8) & 0xff;
const int dst_b = (dst >> 0) & 0xff;
return (src_a == dst_a) &&
(abs(src_r - dst_r) * dst_a <= (max_allowed_diff * 255)) &&
(abs(src_g - dst_g) * dst_a <= (max_allowed_diff * 255)) &&
(abs(src_b - dst_b) * dst_a <= (max_allowed_diff * 255));
}
// Returns true if 'length' number of pixels in 'src' and 'dst' are within an
// error bound, assuming the given step sizes between pixels.
static WEBP_INLINE int ComparePixelsLossy(const uint32_t* src, int src_step,
const uint32_t* dst, int dst_step,
int length, int max_allowed_diff) {
assert(length > 0);
while (length-- > 0) {
if (!PixelsAreSimilar(*src, *dst, max_allowed_diff)) {
return 0;
}
src += src_step;
dst += dst_step;
}
return 1;
}
static int IsEmptyRect(const FrameRect* const rect) {
return (rect->width_ == 0) || (rect->height_ == 0);
}
static int QualityToMaxDiff(float quality) {
const double val = pow(quality / 100., 0.5);
const double max_diff = 31 * (1 - val) + 1 * val;
return (int)(max_diff + 0.5);
}
// 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 is_lossless, float quality) {
int i, j;
const ComparePixelsFunc compare_pixels =
is_lossless ? ComparePixelsLossless : ComparePixelsLossy;
const int max_allowed_diff_lossy = QualityToMaxDiff(quality);
const int max_allowed_diff = is_lossless ? 0 : max_allowed_diff_lossy;
// 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 (compare_pixels(src_argb, src->argb_stride, dst_argb, dst->argb_stride,
rect->height_, max_allowed_diff)) {
--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 (compare_pixels(src_argb, src->argb_stride, dst_argb, dst->argb_stride,
rect->height_, max_allowed_diff)) {
--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 (compare_pixels(src_argb, 1, dst_argb, 1, rect->width_,
max_allowed_diff)) {
--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 (compare_pixels(src_argb, 1, dst_argb, 1, rect->width_,
max_allowed_diff)) {
--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;
}
typedef struct {
int should_try_; // Should try this set of parameters.
int empty_rect_allowed_; // Frame with empty rectangle can be skipped.
FrameRect rect_ll_; // Frame rectangle for lossless compression.
WebPPicture sub_frame_ll_; // Sub-frame pic for lossless compression.
FrameRect rect_lossy_; // Frame rectangle for lossy compression.
// Could be smaller than rect_ll_ as pixels
// with small diffs can be ignored.
WebPPicture sub_frame_lossy_; // Sub-frame pic for lossless compression.
} SubFrameParams;
static int SubFrameParamsInit(SubFrameParams* const params,
int should_try, int empty_rect_allowed) {
params->should_try_ = should_try;
params->empty_rect_allowed_ = empty_rect_allowed;
if (!WebPPictureInit(&params->sub_frame_ll_) ||
!WebPPictureInit(&params->sub_frame_lossy_)) {
return 0;
}
return 1;
}
static void SubFrameParamsFree(SubFrameParams* const params) {
WebPPictureFree(&params->sub_frame_ll_);
WebPPictureFree(&params->sub_frame_lossy_);
}
// Given previous and current canvas, picks the optimal rectangle for the
// current frame based on 'is_lossless' and other parameters. Assumes that the
// initial guess 'rect' is valid.
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,
int is_lossless, float quality, FrameRect* const rect,
WebPPicture* const sub_frame) {
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,
is_lossless, quality);
}
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);
}
// Picks optimal frame rectangle for both lossless and lossy compression. The
// initial guess for frame rectangles will be the full canvas.
static int GetSubRects(const WebPPicture* const prev_canvas,
const WebPPicture* const curr_canvas, int is_key_frame,
int is_first_frame, float quality,
SubFrameParams* const params) {
// Lossless frame rectangle.
params->rect_ll_.x_offset_ = 0;
params->rect_ll_.y_offset_ = 0;
params->rect_ll_.width_ = curr_canvas->width;
params->rect_ll_.height_ = curr_canvas->height;
if (!GetSubRect(prev_canvas, curr_canvas, is_key_frame, is_first_frame,
params->empty_rect_allowed_, 1, quality,
&params->rect_ll_, &params->sub_frame_ll_)) {
return 0;
}
// Lossy frame rectangle.
params->rect_lossy_ = params->rect_ll_; // seed with lossless rect.
return GetSubRect(prev_canvas, curr_canvas, is_key_frame, is_first_frame,
params->empty_rect_allowed_, 0, quality,
&params->rect_lossy_, &params->sub_frame_lossy_);
}
static WEBP_INLINE int clip(int v, int min_v, int max_v) {
return (v < min_v) ? min_v : (v > max_v) ? max_v : v;
}
int WebPAnimEncoderRefineRect(
const WebPPicture* const prev_canvas, const WebPPicture* const curr_canvas,
int is_lossless, float quality, int* const x_offset, int* const y_offset,
int* const width, int* const height) {
FrameRect rect;
const int right = clip(*x_offset + *width, 0, curr_canvas->width);
const int left = clip(*x_offset, 0, curr_canvas->width - 1);
const int bottom = clip(*y_offset + *height, 0, curr_canvas->height);
const int top = clip(*y_offset, 0, curr_canvas->height - 1);
if (prev_canvas == NULL || curr_canvas == NULL ||
prev_canvas->width != curr_canvas->width ||
prev_canvas->height != curr_canvas->height ||
!prev_canvas->use_argb || !curr_canvas->use_argb) {
return 0;
}
rect.x_offset_ = left;
rect.y_offset_ = top;
rect.width_ = clip(right - left, 0, curr_canvas->width - rect.x_offset_);
rect.height_ = clip(bottom - top, 0, curr_canvas->height - rect.y_offset_);
MinimizeChangeRectangle(prev_canvas, curr_canvas, &rect, is_lossless,
quality);
SnapToEvenOffsets(&rect);
*x_offset = rect.x_offset_;
*y_offset = rect.y_offset_;
*width = rect.width_;
*height = rect.height_;
return 1;
}
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 IsLosslessBlendingPossible(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;
}
static int IsLossyBlendingPossible(const WebPPicture* const src,
const WebPPicture* const dst,
const FrameRect* const rect,
float quality) {
const int max_allowed_diff_lossy = QualityToMaxDiff(quality);
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 &&
!PixelsAreSimilar(src_pixel, dst_pixel, max_allowed_diff_lossy)) {
// 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;
}
// For pixels in 'rect', replace those pixels in 'dst' that are same as 'src' by
// transparent pixels.
// Returns true if at least one pixel gets modified.
static int IncreaseTransparency(const WebPPicture* const src,
const FrameRect* const rect,
WebPPicture* const dst) {
int i, j;
int modified = 0;
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) {
pdst[i] = TRANSPARENT_COLOR;
modified = 1;
}
}
}
return modified;
}
#undef TRANSPARENT_COLOR
// Replace similar blocks of pixels by a 'see-through' transparent block
// with uniform average color.
// Assumes lossy compression is being used.
// Returns true if at least one pixel gets modified.
static int FlattenSimilarBlocks(const WebPPicture* const src,
const FrameRect* const rect,
WebPPicture* const dst, float quality) {
const int max_allowed_diff_lossy = QualityToMaxDiff(quality);
int i, j;
int modified = 0;
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 &&
PixelsAreSimilar(src_pixel, pdst[x + y * dst->argb_stride],
max_allowed_diff_lossy)) {
++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;
}
}
modified = 1;
}
}
}
return modified;
}
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 encoder_config,
int use_blending,
Candidate* const candidate) {
WebPConfig config = *encoder_config;
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 (!config.lossless && use_blending) {
// Disable filtering to avoid blockiness in reconstructed frames at the
// time of decoding.
config.autofilter = 0;
config.filter_strength = 0;
}
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_.progress_hook = enc->curr_canvas_->progress_hook;
enc->curr_canvas_copy_.user_data = enc->curr_canvas_->user_data;
enc->curr_canvas_copy_modified_ = 0;
}
}
enum {
LL_DISP_NONE = 0,
LL_DISP_BG,
LOSSY_DISP_NONE,
LOSSY_DISP_BG,
CANDIDATE_COUNT
};
#define MIN_COLORS_LOSSY 31 // Don't try lossy below this threshold.
#define MAX_COLORS_LOSSLESS 194 // Don't try lossless above this threshold.
// Generates candidates for a given dispose method given pre-filled sub-frame
// 'params'.
static WebPEncodingError GenerateCandidates(
WebPAnimEncoder* const enc, Candidate candidates[CANDIDATE_COUNT],
WebPMuxAnimDispose dispose_method, int is_lossless, int is_key_frame,
SubFrameParams* const params,
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_;
int use_blending_ll;
int use_blending_lossy;
CopyCurrentCanvas(enc);
use_blending_ll =
!is_key_frame &&
IsLosslessBlendingPossible(prev_canvas, curr_canvas, &params->rect_ll_);
use_blending_lossy =
!is_key_frame &&
IsLossyBlendingPossible(prev_canvas, curr_canvas, &params->rect_lossy_,
config_lossy->quality);
// Pick candidates to be tried.
if (!enc->options_.allow_mixed) {
candidate_ll->evaluate_ = is_lossless;
candidate_lossy->evaluate_ = !is_lossless;
} else if (enc->options_.minimize_size) {
candidate_ll->evaluate_ = 1;
candidate_lossy->evaluate_ = 1;
} else { // Use a heuristic for trying lossless and/or lossy compression.
const int num_colors = WebPGetColorPalette(&params->sub_frame_ll_, NULL);
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_ll) {
enc->curr_canvas_copy_modified_ =
IncreaseTransparency(prev_canvas, &params->rect_ll_, curr_canvas);
}
error_code = EncodeCandidate(&params->sub_frame_ll_, &params->rect_ll_,
config_ll, use_blending_ll, candidate_ll);
if (error_code != VP8_ENC_OK) return error_code;
}
if (candidate_lossy->evaluate_) {
CopyCurrentCanvas(enc);
if (use_blending_lossy) {
enc->curr_canvas_copy_modified_ =
FlattenSimilarBlocks(prev_canvas, &params->rect_lossy_, curr_canvas,
config_lossy->quality);
}
error_code =
EncodeCandidate(&params->sub_frame_lossy_, &params->rect_lossy_,
config_lossy, use_blending_lossy, candidate_lossy);
if (error_code != VP8_ENC_OK) return error_code;
enc->curr_canvas_copy_modified_ = 1;
}
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_;
// 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;
// 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.
const int empty_rect_allowed_bg = 0;
// 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_;
SubFrameParams dispose_none_params;
SubFrameParams dispose_bg_params;
WebPConfig config_ll = *config;
WebPConfig config_lossy = *config;
config_ll.lossless = 1;
config_lossy.lossless = 0;
enc->last_config_ = *config;
enc->last_config_reversed_ = config->lossless ? config_lossy : config_ll;
*frame_skipped = 0;
if (!SubFrameParamsInit(&dispose_none_params, 1, empty_rect_allowed_none) ||
!SubFrameParamsInit(&dispose_bg_params, 0, empty_rect_allowed_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.
if (!GetSubRects(prev_canvas, curr_canvas, is_key_frame, is_first_frame,
config_lossy.quality, &dispose_none_params)) {
error_code = VP8_ENC_ERROR_INVALID_CONFIGURATION;
goto Err;
}
if ((is_lossless && IsEmptyRect(&dispose_none_params.rect_ll_)) ||
(!is_lossless && IsEmptyRect(&dispose_none_params.rect_lossy_))) {
// 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);
if (!GetSubRects(prev_canvas_disposed, curr_canvas, is_key_frame,
is_first_frame, config_lossy.quality,
&dispose_bg_params)) {
error_code = VP8_ENC_ERROR_INVALID_CONFIGURATION;
goto Err;
}
assert(!IsEmptyRect(&dispose_bg_params.rect_ll_));
assert(!IsEmptyRect(&dispose_bg_params.rect_lossy_));
if (enc->options_.minimize_size) { // Try both dispose methods.
dispose_bg_params.should_try_ = 1;
dispose_none_params.should_try_ = 1;
} else if ((is_lossless &&
RectArea(&dispose_bg_params.rect_ll_) <
RectArea(&dispose_none_params.rect_ll_)) ||
(!is_lossless &&
RectArea(&dispose_bg_params.rect_lossy_) <
RectArea(&dispose_none_params.rect_lossy_))) {
dispose_bg_params.should_try_ = 1; // Pick DISPOSE_BACKGROUND.
dispose_none_params.should_try_ = 0;
}
}
if (dispose_none_params.should_try_) {
error_code = GenerateCandidates(
enc, candidates, WEBP_MUX_DISPOSE_NONE, is_lossless, is_key_frame,
&dispose_none_params, &config_ll, &config_lossy);
if (error_code != VP8_ENC_OK) goto Err;
}
if (dispose_bg_params.should_try_) {
assert(!enc->is_first_frame_);
assert(dispose_bg_possible);
error_code = GenerateCandidates(
enc, candidates, WEBP_MUX_DISPOSE_BACKGROUND, is_lossless, is_key_frame,
&dispose_bg_params, &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:
SubFrameParamsFree(&dispose_none_params);
SubFrameParamsFree(&dispose_bg_params);
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;
FrameRect prev_rect_key, prev_rect_sub;
// 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;
prev_rect_sub = enc->prev_rect_;
// 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.
prev_rect_key = enc->prev_rect_;
// 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->prev_candidate_undecided_ = 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;
enc->prev_candidate_undecided_ = 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;
}
if (!enc->prev_candidate_undecided_) {
enc->prev_rect_ =
encoded_frame->is_key_frame_ ? prev_rect_key : prev_rect_sub;
}
}
}
// 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;
int ok;
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) {
if (!WebPValidateConfig(encoder_config)) {
MarkError(enc, "ERROR adding frame: Invalid WebPConfig");
return 0;
}
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);
ok = CacheFrame(enc, &config) && FlushFrames(enc);
enc->curr_canvas_ = NULL;
enc->curr_canvas_copy_modified_ = 1;
if (ok) {
enc->prev_timestamp_ = timestamp;
}
return ok;
}
// -----------------------------------------------------------------------------
// 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_reversed_, 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_;
}
// -----------------------------------------------------------------------------