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FlattenSimilarBlocks should only be tried when blending is possible.

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This is because, FlattenSimilarBlocks() replaces some opaque pixels by
transparent ones. This results in an equivalent output only if blending
is turned on for the current frame.

Change-Id: I05612c952fdbd4b3a6e0ac9f3a7d49822f0cfb9b
This commit is contained in:
Urvang Joshi 2014-11-05 10:44:07 -08:00
parent 4171b6724e
commit 5cccdadf2e
1 changed files with 4 additions and 6 deletions
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10
examples/gif2webp_util.c
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@ -674,11 +674,9 @@ static WebPEncodingError GenerateCandidates(
}
}
if (candidate_lossy->evaluate) {
if (!is_key_frame) {
// For lossy compression of a frame, it's better to:
// * Replace transparent pixels of 'curr' with actual RGB values,
// whenever possible, and
// * Replace similar blocks of pixels by a transparent block.
if (use_blending) {
// For lossy compression of a frame, it's better to replace similar blocks
// of pixels by a transparent block.
if (!curr_canvas_saved) { // save if not already done so.
CopyPixels(curr_canvas, curr_canvas_tmp);
}
@ -687,7 +685,7 @@ static WebPEncodingError GenerateCandidates(
error_code = EncodeCandidate(sub_frame, rect, config_lossy, use_blending,
duration, candidate_lossy);
if (error_code != VP8_ENC_OK) return error_code;
if (!is_key_frame) {
if (use_blending) {
CopyPixels(curr_canvas_tmp, curr_canvas); // restore
}
}