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Analyze the transform entropy on the whole image.

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The first column was skipped before.

Change-Id: I11521a6a48288d771e8fb83869fda08753f0fbcb
This commit is contained in:
Vincent Rabaud 2017-02-28 15:48:59 +01:00
parent a5e4e3aff1
commit 6f75a51b58
1 changed files with 9 additions and 17 deletions
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26
src/enc/vp8l_enc.c
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@ -196,7 +196,7 @@ static int AnalyzeEntropy(const uint32_t* argb,
if (use_palette && palette_size <= 16) { if (use_palette && palette_size <= 16) {
// In the case of small palettes, we pack 2, 4 or 8 pixels together. In // In the case of small palettes, we pack 2, 4 or 8 pixels together. In
// practice, small palette are better than any other transform. // practice, small palettes are better than any other transform.
*min_entropy_ix = kPalette; *min_entropy_ix = kPalette;
*red_and_blue_always_zero = 1; *red_and_blue_always_zero = 1;
return 1; return 1;
@ -206,10 +206,12 @@ static int AnalyzeEntropy(const uint32_t* argb,
int i, x, y; int i, x, y;
const uint32_t* prev_row = NULL; const uint32_t* prev_row = NULL;
const uint32_t* curr_row = argb; const uint32_t* curr_row = argb;
uint32_t pix_prev = argb[0]; // Skip the first pixel.
for (y = 0; y < height; ++y) { for (y = 0; y < height; ++y) {
for (x = 1; x < width; ++x) { for (x = 0; x < width; ++x) {
const uint32_t pix = curr_row[x]; const uint32_t pix = curr_row[x];
const uint32_t pix_diff = VP8LSubPixels(pix, curr_row[x - 1]); const uint32_t pix_diff = VP8LSubPixels(pix, pix_prev);
pix_prev = pix;
if ((pix_diff == 0) || (prev_row != NULL && pix == prev_row[x])) { if ((pix_diff == 0) || (prev_row != NULL && pix == prev_row[x])) {
continue; continue;
} }
@ -292,20 +294,10 @@ static int AnalyzeEntropy(const uint32_t* argb,
// lower cost than sizeof(uint32_t)*8. // lower cost than sizeof(uint32_t)*8.
entropy[kPalette] += palette_size * 8; entropy[kPalette] += palette_size * 8;
if (use_palette && entropy[kDirect] == 0) { *min_entropy_ix = kDirect;
// If the entropy is null, there should only be one color, for (k = kDirect + 1; k <= last_mode_to_analyze; ++k) {
// and that case is handled at the very beginning of that function. if (entropy[*min_entropy_ix] > entropy[k]) {
// Unfortunately, we can also have a null entropy because we skip the *min_entropy_ix = (EntropyIx)k;
// first column (an image with constant values on each line generates
// a null entropy but could have a different color per line).
// TODO(vrabaud) investigate and fix.
*min_entropy_ix = kPalette;
} else {
*min_entropy_ix = kDirect;
for (k = kDirect + 1; k <= last_mode_to_analyze; ++k) {
if (entropy[*min_entropy_ix] > entropy[k]) {
*min_entropy_ix = (EntropyIx)k;
}
} }
} }
assert((int)*min_entropy_ix <= last_mode_to_analyze); assert((int)*min_entropy_ix <= last_mode_to_analyze);