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Use histogram_bits to initalize transform_bits.

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This change gains back 1% in compression density for method=3 and 0.5% for
method=4, at the expense of 10% slower compression speed.

Change-Id: I491aa1c726def934161d4a4377e009737fbeff82
This commit is contained in:
Vikas Arora 2014-04-02 11:46:04 -07:00
parent 2132992d47
commit bc374ff39e
1 changed files with 11 additions and 2 deletions
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13
src/enc/vp8l.c
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@ -929,15 +929,24 @@ static int GetHistoBits(int method, int use_palette, int width, int height) {
(histo_bits > MAX_HUFFMAN_BITS) ? MAX_HUFFMAN_BITS : histo_bits;
}
static int GetTransformBits(int method, int histo_bits) {
const int max_transform_bits = (method < 4) ? 6 : (method > 4) ? 4 : 5;
return (histo_bits > max_transform_bits) ? max_transform_bits : histo_bits;
}
static int GetCacheBits(float quality) {
return (quality <= 25.f) ? 0 : 7;
}
static void FinishEncParams(VP8LEncoder* const enc) {
const WebPConfig* const config = enc->config_;
const WebPPicture* const pic = enc->pic_;
const int method = config->method;
const float quality = config->quality;
const int use_palette = enc->use_palette_;
enc->transform_bits_ = (method < 4) ? 5 : (method > 4) ? 3 : 4;
enc->histo_bits_ = GetHistoBits(method, use_palette, pic->width, pic->height);
enc->cache_bits_ = (quality <= 25.f) ? 0 : 7;
enc->transform_bits_ = GetTransformBits(method, enc->histo_bits_);
enc->cache_bits_ = GetCacheBits(quality);
}
// -----------------------------------------------------------------------------