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WebP-Lossless encoding improvements.

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Lossy (with Alpha) image compression gets 2.3X speedup.
Compressing lossless images is 20%-40% faster now.

Change-Id: I41f0225838b48ae5c60b1effd1b0de72fecb3ae6
This commit is contained in:
Vikas Arora
2013-05-08 17:19:04 -07:00
parent 4cb234d5b5
commit 8eae188a62
6 changed files with 159 additions and 94 deletions
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84
src/enc/vp8l.c
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@ -811,27 +811,6 @@ static WebPEncodingError AllocateTransformBuffer(VP8LEncoder* const enc,
return err;
}
// Bundles multiple (1, 2, 4 or 8) pixels into a single pixel.
static void BundleColorMap(const uint8_t* const row, int width,
int xbits, uint32_t* const dst) {
int x;
if (xbits > 0) {
const int bit_depth = 1 << (3 - xbits);
const int mask = (1 << xbits) - 1;
uint32_t code = 0xff000000;
for (x = 0; x < width; ++x) {
const int xsub = x & mask;
if (xsub == 0) {
code = 0xff000000;
}
code |= row[x] << (8 + bit_depth * xsub);
dst[x >> xbits] = code;
}
} else {
for (x = 0; x < width; ++x) dst[x] = 0xff000000 | (row[x] << 8);
}
}
// Note: Expects "enc->palette_" to be set properly.
// Also, "enc->palette_" will be modified after this call and should not be used
// later.
@ -848,6 +827,7 @@ static WebPEncodingError ApplyPalette(VP8LBitWriter* const bw,
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.
@ -864,19 +844,43 @@ static WebPEncodingError ApplyPalette(VP8LBitWriter* const bw,
row = WebPSafeMalloc((uint64_t)width, sizeof(*row));
if (row == NULL) return VP8_ENC_ERROR_OUT_OF_MEMORY;
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;
for (i = 0; i < palette_size; ++i) {
if ((palette[i] & 0x00ff00ffu) != 0) {
is_alpha = 0;
break;
}
}
if (is_alpha) {
int inv_palette[MAX_PALETTE_SIZE] = { 0 };
for (i = 0; i < palette_size; ++i) {
const int color = (palette[i] >> 8) & 0xff;
inv_palette[color] = i;
}
for (y = 0; y < height; ++y) {
for (x = 0; x < width; ++x) {
const int color = (src[x] >> 8) & 0xff;
row[x] = inv_palette[color];
}
VP8LBundleColorMap(row, width, xbits, dst);
src += pic->argb_stride;
dst += enc->current_width_;
}
} else {
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;
}
}
}
VP8LBundleColorMap(row, width, xbits, dst);
src += pic->argb_stride;
dst += enc->current_width_;
}
BundleColorMap(row, width, xbits, dst);
src += pic->argb_stride;
dst += enc->current_width_;
}
// Save palette to bitstream.
@ -899,13 +903,10 @@ static WebPEncodingError ApplyPalette(VP8LBitWriter* const bw,
// -----------------------------------------------------------------------------
static int GetHistoBits(const WebPConfig* const config,
const WebPPicture* const pic) {
const int width = pic->width;
const int height = pic->height;
static int GetHistoBits(int method, int use_palette, int width, int height) {
const uint64_t hist_size = sizeof(VP8LHistogram);
// Make tile size a function of encoding method (Range: 0 to 6).
int histo_bits = 7 - config->method;
int histo_bits = (use_palette ? 9 : 7) - method;
while (1) {
const uint64_t huff_image_size = VP8LSubSampleSize(width, histo_bits) *
VP8LSubSampleSize(height, histo_bits) *
@ -917,13 +918,14 @@ static int GetHistoBits(const WebPConfig* const config,
(histo_bits > MAX_HUFFMAN_BITS) ? MAX_HUFFMAN_BITS : histo_bits;
}
static void InitEncParams(VP8LEncoder* const enc) {
static void FinishEncParams(VP8LEncoder* const enc) {
const WebPConfig* const config = enc->config_;
const WebPPicture* const picture = enc->pic_;
const WebPPicture* const pic = enc->pic_;
const int method = config->method;
const float quality = config->quality;
const int use_palette = enc->use_palette_;
enc->transform_bits_ = (method < 4) ? 5 : (method > 4) ? 3 : 4;
enc->histo_bits_ = GetHistoBits(config, picture);
enc->histo_bits_ = GetHistoBits(method, use_palette, pic->width, pic->height);
enc->cache_bits_ = (quality <= 25.f) ? 0 : 7;
}
@ -965,8 +967,6 @@ WebPEncodingError VP8LEncodeStream(const WebPConfig* const config,
goto Error;
}
InitEncParams(enc);
// ---------------------------------------------------------------------------
// Analyze image (entropy, num_palettes etc)
@ -975,6 +975,8 @@ WebPEncodingError VP8LEncodeStream(const WebPConfig* const config,
goto Error;
}
FinishEncParams(enc);
if (enc->use_palette_) {
err = ApplyPalette(bw, enc, quality);
if (err != VP8_ENC_OK) goto Error;