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Use the plane code and not the distance when computing statistics.

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As backward references use the plane code when checking the cost
of a distance, statistics used to compute the cost should use it too.
This provides a small compression improvement at no speed cost.

Change-Id: Icade150929ee39ef6dc0d8b1fc85973086ecf41d
This commit is contained in:
Vincent Rabaud
2017-06-01 17:08:43 +02:00
parent b903b80c30
commit f209a5481e
3 changed files with 26 additions and 8 deletions
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14
src/enc/backward_references_cost_enc.c
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@ -58,13 +58,21 @@ static void ConvertPopulationCountTableToBitEstimates(
}
}
static int CostModelBuild(CostModel* const m, int cache_bits,
static int CostModelBuild(CostModel* const m, int xsize, int cache_bits,
const VP8LBackwardRefs* const refs) {
int ok = 0;
VP8LRefsCursor c = VP8LRefsCursorInit(refs);
VP8LHistogram* const histo = VP8LAllocateHistogram(cache_bits);
if (histo == NULL) goto Error;
VP8LHistogramCreate(histo, refs, cache_bits);
// The following code is similar to VP8LHistogramCreate but converts the
// distance to plane code.
VP8LHistogramInit(histo, cache_bits);
while (VP8LRefsCursorOk(&c)) {
VP8LHistogramAddSinglePixOrCopy(histo, c.cur_pos, VP8LDistanceToPlaneCode,
xsize);
VP8LRefsCursorNext(&c);
}
ConvertPopulationCountTableToBitEstimates(
VP8LHistogramNumCodes(histo->palette_code_bits_),
@ -583,7 +591,7 @@ static int BackwardReferencesHashChainDistanceOnly(
if (!cc_init) goto Error;
}
if (!CostModelBuild(cost_model, cache_bits, refs)) {
if (!CostModelBuild(cost_model, xsize, cache_bits, refs)) {
goto Error;
}