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Only call WebPDequantizeLevels() on cropped area

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this might change some crc slightly, since WebPDequantizeLevels()
performs an analysis pass, counting levels, which impacts the smoothing.
Now, the cropping area is not the same, so minor diffs are expected here
and there.

Change-Id: I3cce1e40c6f11c25b7c841044d637685c5740352
This commit is contained in:
Pascal Massimino 2016-04-05 11:21:21 +02:00
parent cf6c713a0b
commit 238cdcdbe1
1 changed files with 11 additions and 7 deletions
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18
src/dec/alpha.c
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@ -129,7 +129,7 @@ static int ALPHDecode(VP8Decoder* const dec, int row, int num_rows) {
unfilter_func(width, height, width, row, num_rows, output); unfilter_func(width, height, width, row, num_rows, output);
} }
if (row + num_rows == dec->pic_hdr_.height_) { if (row + num_rows >= alph_dec->io_.crop_bottom) {
dec->is_alpha_decoded_ = 1; dec->is_alpha_decoded_ = 1;
} }
return 1; return 1;
@ -167,7 +167,7 @@ const uint8_t* VP8DecompressAlphaRows(VP8Decoder* const dec,
assert(dec != NULL && io != NULL); assert(dec != NULL && io != NULL);
if (row < 0 || num_rows <= 0 || row + num_rows > io->height) { if (row < 0 || num_rows <= 0 || row + num_rows > height) {
return NULL; // sanity check. return NULL; // sanity check.
} }
@ -182,22 +182,26 @@ const uint8_t* VP8DecompressAlphaRows(VP8Decoder* const dec,
} }
// if we allowed use of alpha dithering, check whether it's needed at all // if we allowed use of alpha dithering, check whether it's needed at all
if (dec->alph_dec_->pre_processing_ != ALPHA_PREPROCESSED_LEVELS) { if (dec->alph_dec_->pre_processing_ != ALPHA_PREPROCESSED_LEVELS) {
dec->alpha_dithering_ = 0; // disable dithering dec->alpha_dithering_ = 0; // disable dithering
} else { } else {
num_rows = io->height - row; // decode everything in one pass num_rows = height - row; // decode everything in one pass
} }
} }
assert(dec->alph_dec_ != NULL); assert(dec->alph_dec_ != NULL);
assert(row + num_rows <= io->height); assert(row + num_rows <= height);
if (!ALPHDecode(dec, row, num_rows)) goto Error; if (!ALPHDecode(dec, row, num_rows)) goto Error;
if (dec->is_alpha_decoded_) { // finished? if (dec->is_alpha_decoded_) { // finished?
ALPHDelete(dec->alph_dec_); ALPHDelete(dec->alph_dec_);
dec->alph_dec_ = NULL; dec->alph_dec_ = NULL;
if (dec->alpha_dithering_ > 0) { if (dec->alpha_dithering_ > 0) {
if (!WebPDequantizeLevels(dec->alpha_plane_, width, height, width, uint8_t* const alpha = dec->alpha_plane_ + io->crop_top * width
dec->alpha_dithering_)) { + io->crop_left;
if (!WebPDequantizeLevels(alpha,
io->crop_right - io->crop_left,
io->crop_bottom - io->crop_top,
width, dec->alpha_dithering_)) {
goto Error; goto Error;
} }
} }