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Speed up ApplyPalette for ARGB pixels.

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Added 1 pixel cache for palette colors for faster lookup.
This will speedup images that require ApplyPalette by 6.5% for lossless
compression.

Change-Id: Id0c5174d797ffabdb09905c2ba76e60601b686f8
This commit is contained in:
Vikas Arora 2013-05-16 15:43:12 -07:00
parent 2451e47dca
commit 742110ccce
1 changed files with 57 additions and 41 deletions
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98
src/enc/vp8l.c
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@ -86,7 +86,7 @@ static int AnalyzeAndCreatePalette(const WebPPicture* const pic,
argb += pic->argb_stride;
}
// TODO(skal): could we reuse in_use[] to speed up ApplyPalette()?
// TODO(skal): could we reuse in_use[] to speed up EncodePalette()?
num_colors = 0;
for (i = 0; i < (int)(sizeof(in_use) / sizeof(in_use[0])); ++i) {
if (in_use[i]) {
@ -811,39 +811,12 @@ static WebPEncodingError AllocateTransformBuffer(VP8LEncoder* const enc,
return err;
}
// Note: Expects "enc->palette_" to be set properly.
// Also, "enc->palette_" will be modified after this call and should not be used
// later.
static WebPEncodingError ApplyPalette(VP8LBitWriter* const bw,
VP8LEncoder* const enc, int quality) {
WebPEncodingError err = VP8_ENC_OK;
static void ApplyPalette(uint32_t* src, uint32_t* dst,
uint32_t src_stride, uint32_t dst_stride,
const uint32_t* palette, int palette_size,
int width, int height, int xbits, uint8_t* row) {
int i, x, y;
const WebPPicture* const pic = enc->pic_;
uint32_t* src = pic->argb;
uint32_t* dst;
const int width = pic->width;
const int height = pic->height;
uint32_t* const palette = enc->palette_;
const int palette_size = enc->palette_size_;
uint8_t* row = NULL;
int xbits;
int is_alpha = 1;
// Replace each input pixel by corresponding palette index.
// This is done line by line.
if (palette_size <= 4) {
xbits = (palette_size <= 2) ? 3 : 2;
} else {
xbits = (palette_size <= 16) ? 1 : 0;
}
err = AllocateTransformBuffer(enc, VP8LSubSampleSize(width, xbits), height);
if (err != VP8_ENC_OK) goto Error;
dst = enc->argb_;
row = WebPSafeMalloc((uint64_t)width, sizeof(*row));
if (row == NULL) return VP8_ENC_ERROR_OUT_OF_MEMORY;
for (i = 0; i < palette_size; ++i) {
if ((palette[i] & 0x00ff00ffu) != 0) {
is_alpha = 0;
@ -863,25 +836,68 @@ static WebPEncodingError ApplyPalette(VP8LBitWriter* const bw,
row[x] = inv_palette[color];
}
VP8LBundleColorMap(row, width, xbits, dst);
src += pic->argb_stride;
dst += enc->current_width_;
src += src_stride;
dst += dst_stride;
}
} else {
// Use 1 pixel cache for ARGB pixels.
uint32_t last_pix = palette[0];
int last_idx = 0;
for (y = 0; y < height; ++y) {
for (x = 0; x < width; ++x) {
const uint32_t pix = src[x];
for (i = 0; i < palette_size; ++i) {
if (pix == palette[i]) {
row[x] = i;
break;
if (pix != last_pix) {
for (i = 0; i < palette_size; ++i) {
if (pix == palette[i]) {
last_idx = i;
last_pix = pix;
break;
}
}
}
row[x] = last_idx;
}
VP8LBundleColorMap(row, width, xbits, dst);
src += pic->argb_stride;
dst += enc->current_width_;
src += src_stride;
dst += dst_stride;
}
}
}
// Note: Expects "enc->palette_" to be set properly.
// Also, "enc->palette_" will be modified after this call and should not be used
// later.
static WebPEncodingError EncodePalette(VP8LBitWriter* const bw,
VP8LEncoder* const enc, int quality) {
WebPEncodingError err = VP8_ENC_OK;
int i;
const WebPPicture* const pic = enc->pic_;
uint32_t* src = pic->argb;
uint32_t* dst;
const int width = pic->width;
const int height = pic->height;
uint32_t* const palette = enc->palette_;
const int palette_size = enc->palette_size_;
uint8_t* row = NULL;
int xbits;
// Replace each input pixel by corresponding palette index.
// This is done line by line.
if (palette_size <= 4) {
xbits = (palette_size <= 2) ? 3 : 2;
} else {
xbits = (palette_size <= 16) ? 1 : 0;
}
err = AllocateTransformBuffer(enc, VP8LSubSampleSize(width, xbits), height);
if (err != VP8_ENC_OK) goto Error;
dst = enc->argb_;
row = WebPSafeMalloc((uint64_t)width, sizeof(*row));
if (row == NULL) return VP8_ENC_ERROR_OUT_OF_MEMORY;
ApplyPalette(src, dst, pic->argb_stride, enc->current_width_,
palette, palette_size, width, height, xbits, row);
// Save palette to bitstream.
VP8LWriteBits(bw, 1, TRANSFORM_PRESENT);
@ -978,7 +994,7 @@ WebPEncodingError VP8LEncodeStream(const WebPConfig* const config,
FinishEncParams(enc);
if (enc->use_palette_) {
err = ApplyPalette(bw, enc, quality);
err = EncodePalette(bw, enc, quality);
if (err != VP8_ENC_OK) goto Error;
// Color cache is disabled for palette.
enc->cache_bits_ = 0;