mirror of
https://github.com/webmproject/libwebp.git
synced 2024-11-20 04:18:26 +01:00
simplify the alpha-filter testing loop
Change-Id: Iacebae749c37edc87a3c94c76cd589a2565ee642
This commit is contained in:
skal
parent
0d25876bad
commit
2053c2cff2
187
src/enc/alpha.c
187
src/enc/alpha.c
@ -97,6 +97,7 @@ static int EncodeLossless(const uint8_t* const data, int width, int height,
|
||||
|
||||
// -----------------------------------------------------------------------------
|
||||
|
||||
// This function always returns an initialized 'bw' object, even upon error.
|
||||
static int EncodeAlphaInternal(const uint8_t* const data, int width, int height,
|
||||
int method, int filter, int reduce_levels,
|
||||
int effort_level, // in [0..6] range
|
||||
@ -175,6 +176,92 @@ static int GetNumColors(const uint8_t* data, int width, int height,
|
||||
return colors;
|
||||
}
|
||||
|
||||
// Given the input 'filter' option, return an OR'd bit-set of filters to try.
|
||||
static uint32_t GetFilterMap(const uint8_t* alpha, int width, int height,
|
||||
int filter, int effort_level) {
|
||||
uint32_t bit_map = 0U;
|
||||
if (filter == WEBP_FILTER_FAST) {
|
||||
// Quick estimate of the best candidate.
|
||||
int try_filter_none = (effort_level > 3);
|
||||
const int kMinColorsForFilterNone = 16;
|
||||
const int kMaxColorsForFilterNone = 192;
|
||||
const int num_colors = GetNumColors(alpha, width, height, width);
|
||||
// For low number of colors, NONE yeilds better compression.
|
||||
filter = (num_colors <= kMinColorsForFilterNone) ? WEBP_FILTER_NONE :
|
||||
EstimateBestFilter(alpha, width, height, width);
|
||||
bit_map |= 1 << filter;
|
||||
// For large number of colors, try FILTER_NONE in addition to the best
|
||||
// filter as well.
|
||||
if (try_filter_none || num_colors > kMaxColorsForFilterNone) {
|
||||
bit_map |= 1 << WEBP_FILTER_NONE;
|
||||
}
|
||||
} else if (filter == WEBP_FILTER_NONE) {
|
||||
bit_map = 1 << WEBP_FILTER_NONE;
|
||||
} else { // WEBP_FILTER_BEST
|
||||
bit_map = (1 << WEBP_FILTER_LAST) - 1; // try all.
|
||||
}
|
||||
return bit_map;
|
||||
}
|
||||
|
||||
// Small struct to hold the result of a filter mode compression attempt.
|
||||
typedef struct {
|
||||
size_t score;
|
||||
VP8BitWriter bw;
|
||||
WebPAuxStats stats;
|
||||
} FilterTrial;
|
||||
|
||||
static void InitFilterTrial(FilterTrial* const score) {
|
||||
score->score = (size_t)~0U;
|
||||
VP8BitWriterInit(&score->bw, 0);
|
||||
}
|
||||
|
||||
static int ApplyFilters(const uint8_t* alpha, int width, int height,
|
||||
uint64_t data_size, int method, int filter,
|
||||
int reduce_levels, int effort_level,
|
||||
uint8_t** const output, size_t* const output_size,
|
||||
WebPAuxStats* const stats) {
|
||||
int ok = 1;
|
||||
uint8_t* filtered_alpha = NULL;
|
||||
uint32_t try_map = GetFilterMap(alpha, width, height, filter, effort_level);
|
||||
|
||||
filtered_alpha = (uint8_t*)malloc(data_size);
|
||||
ok = (filtered_alpha != NULL);
|
||||
|
||||
if (ok) {
|
||||
FilterTrial best;
|
||||
InitFilterTrial(&best);
|
||||
|
||||
for (filter = WEBP_FILTER_NONE; try_map; ++filter, try_map >>= 1) {
|
||||
if (try_map & 1) {
|
||||
FilterTrial trial;
|
||||
ok = EncodeAlphaInternal(alpha, width, height, method, filter,
|
||||
reduce_levels, effort_level, filtered_alpha,
|
||||
&trial.bw, stats);
|
||||
if (ok) {
|
||||
trial.score = VP8BitWriterSize(&trial.bw);
|
||||
if (trial.score < best.score) {
|
||||
VP8BitWriterWipeOut(&best.bw);
|
||||
best = trial;
|
||||
if (stats != NULL) best.stats = *stats;
|
||||
}
|
||||
} else {
|
||||
VP8BitWriterWipeOut(&trial.bw);
|
||||
VP8BitWriterWipeOut(&best.bw);
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
if (ok) {
|
||||
if (stats != NULL) *stats = best.stats;
|
||||
*output_size = VP8BitWriterSize(&best.bw);
|
||||
*output = VP8BitWriterBuf(&best.bw);
|
||||
}
|
||||
free(filtered_alpha);
|
||||
}
|
||||
return ok;
|
||||
}
|
||||
|
||||
static int EncodeAlpha(VP8Encoder* const enc,
|
||||
int quality, int method, int filter,
|
||||
int effort_level,
|
||||
@ -223,105 +310,19 @@ static int EncodeAlpha(VP8Encoder* const enc,
|
||||
}
|
||||
|
||||
if (ok) {
|
||||
VP8BitWriter bw;
|
||||
int test_filter;
|
||||
uint8_t* filtered_alpha = NULL;
|
||||
int try_filter_none = (effort_level > 3);
|
||||
|
||||
if (filter == WEBP_FILTER_FAST) { // Quick estimate of the best candidate.
|
||||
const int kMinColorsForFilterNone = 16;
|
||||
const int kMaxColorsForFilterNone = 192;
|
||||
const int num_colors = GetNumColors(quant_alpha, width, height, width);
|
||||
// For low number of colors, NONE yeilds better compression.
|
||||
filter = (num_colors <= kMinColorsForFilterNone) ? WEBP_FILTER_NONE :
|
||||
EstimateBestFilter(quant_alpha, width, height, width);
|
||||
// For large number of colors, try FILTER_NONE in addition to the best
|
||||
// filter as well.
|
||||
if (num_colors > kMaxColorsForFilterNone) {
|
||||
try_filter_none = 1;
|
||||
}
|
||||
ok = ApplyFilters(quant_alpha, width, height, data_size, method, filter,
|
||||
reduce_levels, effort_level, output, output_size,
|
||||
pic->stats);
|
||||
if (pic->stats != NULL) { // need stats?
|
||||
pic->stats->coded_size += (int)(*output_size);
|
||||
enc->sse_[3] = sse;
|
||||
}
|
||||
|
||||
// Test for WEBP_FILTER_NONE for higher effort levels.
|
||||
if (try_filter_none || filter == WEBP_FILTER_NONE) {
|
||||
ok = EncodeAlphaInternal(quant_alpha, width, height,
|
||||
method, WEBP_FILTER_NONE, reduce_levels,
|
||||
effort_level, NULL, &bw, pic->stats);
|
||||
|
||||
if (!ok) {
|
||||
VP8BitWriterWipeOut(&bw);
|
||||
goto End;
|
||||
}
|
||||
}
|
||||
// Stop?
|
||||
if (filter == WEBP_FILTER_NONE) {
|
||||
goto Ok;
|
||||
}
|
||||
|
||||
filtered_alpha = (uint8_t*)malloc(data_size);
|
||||
ok = (filtered_alpha != NULL);
|
||||
if (!ok) {
|
||||
goto End;
|
||||
}
|
||||
|
||||
// Try the other mode(s).
|
||||
{
|
||||
WebPAuxStats best_stats;
|
||||
size_t best_score = try_filter_none ?
|
||||
VP8BitWriterSize(&bw) : (size_t)~0U;
|
||||
int wipe_tmp_bw = try_filter_none;
|
||||
|
||||
memset(&best_stats, 0, sizeof(best_stats)); // prevent spurious warning
|
||||
if (pic->stats != NULL) best_stats = *pic->stats;
|
||||
for (test_filter =
|
||||
try_filter_none ? WEBP_FILTER_HORIZONTAL : WEBP_FILTER_NONE;
|
||||
ok && (test_filter <= WEBP_FILTER_GRADIENT);
|
||||
++test_filter) {
|
||||
VP8BitWriter tmp_bw;
|
||||
if (filter != WEBP_FILTER_BEST && test_filter != filter) {
|
||||
continue;
|
||||
}
|
||||
ok = EncodeAlphaInternal(quant_alpha, width, height,
|
||||
method, test_filter, reduce_levels,
|
||||
effort_level, filtered_alpha, &tmp_bw,
|
||||
pic->stats);
|
||||
if (ok) {
|
||||
const size_t score = VP8BitWriterSize(&tmp_bw);
|
||||
if (score < best_score) {
|
||||
// swap bitwriter objects.
|
||||
VP8BitWriter tmp = tmp_bw;
|
||||
tmp_bw = bw;
|
||||
bw = tmp;
|
||||
best_score = score;
|
||||
if (pic->stats != NULL) best_stats = *pic->stats;
|
||||
}
|
||||
} else {
|
||||
VP8BitWriterWipeOut(&bw);
|
||||
}
|
||||
if (wipe_tmp_bw) {
|
||||
VP8BitWriterWipeOut(&tmp_bw);
|
||||
}
|
||||
wipe_tmp_bw = 1; // For next filter trial for WEBP_FILTER_BEST.
|
||||
}
|
||||
if (pic->stats != NULL) *pic->stats = best_stats;
|
||||
}
|
||||
Ok:
|
||||
if (ok) {
|
||||
*output_size = VP8BitWriterSize(&bw);
|
||||
*output = VP8BitWriterBuf(&bw);
|
||||
if (pic->stats != NULL) { // need stats?
|
||||
pic->stats->coded_size += (int)(*output_size);
|
||||
enc->sse_[3] = sse;
|
||||
}
|
||||
}
|
||||
free(filtered_alpha);
|
||||
}
|
||||
End:
|
||||
|
||||
free(quant_alpha);
|
||||
return ok;
|
||||
}
|
||||
|
||||
|
||||
//------------------------------------------------------------------------------
|
||||
// Main calls
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user