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modulate alpha-compression effort according to config.method

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we vary linearly lossless-method between 0 and 6,
and lossless-quality between 50 and 100, so that encoding
speed can go from 'quite fast' to 'rather slow'.
Impact on size is moderate, but visible.

Change-Id: I0b7917e7170eb50258afb1a4e248028cd9e9207d
This commit is contained in:
Pascal Massimino 2012-05-24 01:54:12 -07:00
parent f5f2fff657
commit 18da1f53fc
1 changed files with 17 additions and 8 deletions
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25
src/enc/alpha.c
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@ -28,7 +28,7 @@ extern "C" {
// -----------------------------------------------------------------------------
// int EncodeAlpha(const uint8_t* data, int width, int height, int stride,
// int quality, int method, int filter,
// int quality, int method, int filter, int effort_level,
// uint8_t** output, size_t* output_size)
//
// Encodes the given alpha data 'data' of size 'stride'x'height' via specified
@ -40,7 +40,9 @@ extern "C" {
// 'filter' values [0, 4] correspond to prediction modes none, horizontal,
// vertical & gradient filters. The prediction mode 4 will try all the
// prediction modes (0 to 3) and pick the best prediction mode.
// 'effort_level': specifies how much effort must be spent to try and reduce
// the compressed output size. In range 0 (quick) to 6 (slow).
//
// 'output' corresponds to the buffer containing compressed alpha data.
// This buffer is allocated by this method and caller should call
// free(*output) when done.
@ -56,6 +58,7 @@ extern "C" {
#include "../enc/vp8li.h"
static int EncodeLossless(const uint8_t* data, int width, int height,
int effort_level, // in [0..6] range
VP8BitWriter* const bw) {
int ok = 0;
@ -85,8 +88,10 @@ static int EncodeLossless(const uint8_t* data, int width, int height,
WebPConfigInit(&config);
config.lossless = 1;
config.method = 2;
config.quality = 100; // TODO(skal): make it adjustable.
config.method = effort_level; // impact is very small
// quality below 50 doesn't change things much (in speed and size).
// quality above 80 can be very very slow.
config.quality = 40 + 10 * effort_level;
VP8LBitWriterInit(&tmp_bw, (width * height) >> 3);
ok = (VP8LEncodeStream(&config, &picture, &tmp_bw) == VP8_ENC_OK);
@ -106,6 +111,7 @@ static int EncodeLossless(const uint8_t* data, int width, int height,
static int EncodeAlphaInternal(const uint8_t* data, int width, int height,
int method, int filter, int reduce_levels,
int effort_level, // in [0..6] range
uint8_t* tmp_alpha, VP8BitWriter* const bw) {
int ok = 0;
const uint8_t* alpha_src;
@ -145,9 +151,10 @@ static int EncodeAlphaInternal(const uint8_t* data, int width, int height,
ok = ok && !bw->error_;
} else {
#ifdef USE_LOSSLESS_ENCODER
ok = EncodeLossless(alpha_src, width, height, bw);
ok = EncodeLossless(alpha_src, width, height, effort_level, bw);
VP8BitWriterFinish(bw);
#else
(void)effort_level;
assert(0); // not reached.
#endif
}
@ -168,6 +175,7 @@ static void CopyPlane(const uint8_t* src, int src_stride,
static int EncodeAlpha(const uint8_t* data, int width, int height, int stride,
int quality, int method, int filter,
int effort_level,
uint8_t** output, size_t* output_size) {
uint8_t* quant_alpha = NULL;
const size_t data_size = width * height;
@ -214,7 +222,7 @@ static int EncodeAlpha(const uint8_t* data, int width, int height, int stride,
// We always test WEBP_FILTER_NONE first.
ok = EncodeAlphaInternal(quant_alpha, width, height,
method, WEBP_FILTER_NONE, reduce_levels,
NULL, &bw);
effort_level, NULL, &bw);
if (!ok) {
VP8BitWriterWipeOut(&bw);
goto End;
@ -246,7 +254,7 @@ static int EncodeAlpha(const uint8_t* data, int width, int height, int stride,
ok = EncodeAlphaInternal(quant_alpha, width, height,
method, test_filter, reduce_levels,
filtered_alpha, &tmp_bw);
effort_level, filtered_alpha, &tmp_bw);
if (ok) {
const size_t score = VP8BitWriterSize(&tmp_bw);
if (score < best_score) {
@ -289,6 +297,7 @@ int VP8EncFinishAlpha(VP8Encoder* enc) {
const WebPPicture* pic = enc->pic_;
uint8_t* tmp_data = NULL;
size_t tmp_size = 0;
const int effort_level = config->method; // maps to [0..6]
const WEBP_FILTER_TYPE filter =
(config->alpha_filtering == 0) ? WEBP_FILTER_NONE :
(config->alpha_filtering == 1) ? WEBP_FILTER_FAST :
@ -297,7 +306,7 @@ int VP8EncFinishAlpha(VP8Encoder* enc) {
assert(pic->a);
if (!EncodeAlpha(pic->a, pic->width, pic->height, pic->a_stride,
config->alpha_quality, config->alpha_compression,
filter, &tmp_data, &tmp_size)) {
filter, effort_level, &tmp_data, &tmp_size)) {
return 0;
}
if (tmp_size != (uint32_t)tmp_size) { // Sanity check.