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smartYUV: fix and simplify the over-zealous stop criterion

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We usually need at least 2 iterations to converge
(and usually not much more after that). Only 1 was not enough.

Change-Id: Iaf802ea81afa2596f4ba045c92f5eaff61623b7b
This commit is contained in:
Pascal Massimino 2016-09-09 10:10:13 +02:00
parent 8de08483b6
commit 894232be56
1 changed files with 9 additions and 36 deletions
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45
src/enc/picture_csp.c
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@ -155,7 +155,7 @@ static int RGBToV(int r, int g, int b, VP8Random* const rg) {
//------------------------------------------------------------------------------
// Smart RGB->YUV conversion
static const int kNumIterations = 6;
static const int kNumIterations = 4;
static const int kMinDimensionIterativeConversion = 4;
// We could use SFIX=0 and only uint8_t for fixed_y_t, but it produces some
@ -262,18 +262,13 @@ static WEBP_INLINE void UpdateW(const fixed_y_t* src, fixed_y_t* dst, int len) {
}
}
static int UpdateChroma(const fixed_y_t* src1,
const fixed_y_t* src2,
fixed_t* dst, fixed_y_t* tmp, int len) {
int diff = 0;
static void UpdateChroma(const fixed_y_t* src1, const fixed_y_t* src2,
fixed_t* dst, fixed_y_t* tmp, int len) {
while (len--> 0) {
const int r = ScaleDown(src1[0], src1[3], src2[0], src2[3]);
const int g = ScaleDown(src1[1], src1[4], src2[1], src2[4]);
const int b = ScaleDown(src1[2], src1[5], src2[2], src2[5]);
const int W = RGBToGray(r, g, b);
const int r_avg = (src1[0] + src1[3] + src2[0] + src2[3] + 2) >> 2;
const int g_avg = (src1[1] + src1[4] + src2[1] + src2[4] + 2) >> 2;
const int b_avg = (src1[2] + src1[5] + src2[2] + src2[5] + 2) >> 2;
dst[0] = (fixed_t)(r - W);
dst[1] = (fixed_t)(g - W);
dst[2] = (fixed_t)(b - W);
@ -284,9 +279,7 @@ static int UpdateChroma(const fixed_y_t* src1,
tmp[0] = tmp[1] = clip_y(W);
tmp += 2;
}
diff += abs(RGBToGray(r_avg, g_avg, b_avg) - W);
}
return diff;
}
//------------------------------------------------------------------------------
@ -441,11 +434,8 @@ static int PreprocessARGB(const uint8_t* const r_ptr,
fixed_t* const best_uv = SAFE_ALLOC(uv_w * 3, uv_h, fixed_t);
fixed_t* const target_uv = SAFE_ALLOC(uv_w * 3, uv_h, fixed_t);
fixed_t* const best_rgb_uv = SAFE_ALLOC(uv_w * 3, 1, fixed_t);
const uint64_t diff_y_threshold = (uint64_t)(3.5 * w * h);
int ok;
int diff_sum = 0;
const int first_diff_threshold = (int)(2.5 * w * h);
const int min_improvement = 5; // stop if improvement is below this %
const int min_first_improvement = 80;
if (best_y == NULL || best_uv == NULL ||
target_y == NULL || target_uv == NULL ||
@ -478,18 +468,16 @@ static int PreprocessARGB(const uint8_t* const r_ptr,
}
UpdateW(src1, target_y + (j + 0) * w, w);
UpdateW(src2, target_y + (j + 1) * w, w);
diff_sum += UpdateChroma(src1, src2, target_uv + uv_off, dst_y, uv_w);
UpdateChroma(src1, src2, target_uv + uv_off, dst_y, uv_w);
memcpy(best_uv + uv_off, target_uv + uv_off, 3 * uv_w * sizeof(*best_uv));
memcpy(dst_y + w, dst_y, w * sizeof(*dst_y));
}
// Iterate and resolve clipping conflicts.
for (iter = 0; iter < kNumIterations; ++iter) {
int k;
const fixed_t* cur_uv = best_uv;
const fixed_t* prev_uv = best_uv;
const int old_diff_sum = diff_sum;
diff_sum = 0;
uint64_t diff_y_sum = 0;
for (j = 0; j < h; j += 2) {
fixed_y_t* const src1 = tmp_buffer;
fixed_y_t* const src2 = tmp_buffer + 3 * w;
@ -503,7 +491,7 @@ static int PreprocessARGB(const uint8_t* const r_ptr,
UpdateW(src1, best_rgb_y + 0 * w, w);
UpdateW(src2, best_rgb_y + 1 * w, w);
diff_sum += UpdateChroma(src1, src2, best_rgb_uv, NULL, uv_w);
UpdateChroma(src1, src2, best_rgb_uv, NULL, uv_w);
// update two rows of Y and one row of RGB
for (i = 0; i < 2 * w; ++i) {
@ -511,6 +499,7 @@ static int PreprocessARGB(const uint8_t* const r_ptr,
const int diff_y = target_y[off] - best_rgb_y[i];
const int new_y = (int)best_y[off] + diff_y;
best_y[off] = clip_y(new_y);
diff_y_sum += (uint64_t)abs(diff_y);
}
for (i = 0; i < uv_w; ++i) {
const int off = 3 * (i + (j >> 1) * uv_w);
@ -526,24 +515,8 @@ static int PreprocessARGB(const uint8_t* const r_ptr,
}
}
// test exit condition
if (diff_sum > 0) {
const int improvement = 100 * abs(diff_sum - old_diff_sum) / diff_sum;
// Check if first iteration gave good result already, without a large
// jump of improvement (otherwise it means we need to try few extra
// iterations, just to be sure).
if (iter == 0 && diff_sum < first_diff_threshold &&
improvement < min_first_improvement) {
break;
}
// then, check if improvement is stalling.
if (improvement < min_improvement) {
break;
}
} else {
break;
}
if (iter > 0 && diff_y_sum < diff_y_threshold) break;
}
// final reconstruction
ok = ConvertWRGBToYUV(best_y, best_uv, picture);