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FastMBAnalyze() for quick i16/i4 decision

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The decision is based on the variance between DC values of each
sub-4x4 block. This heuristic is rather ok for predicting whether
the 2nd transform (intra-16) is going to help or not.
The decision threshold varies with quality (=quantization).

It's only used for -m 0 and -m 1, where no full RD-opt is performed.
It actually makes these modes quite faster, with RD curve much
closer to the -m 2 mode.

Change-Id: I15f972db97ba4082cbd1dfd16bee3eb2eca701a8
This commit is contained in:
skal
2016-07-15 11:21:08 -07:00
parent 567e697776
commit 5b60db5c9d
5 changed files with 89 additions and 9 deletions
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16
src/dsp/enc.c
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@ -551,6 +551,20 @@ static int SSE4x4(const uint8_t* a, const uint8_t* b) {
return GetSSE(a, b, 4, 4);
}
static void Mean16x4(const uint8_t* ref, uint32_t dc[4]) {
int k, x, y;
for (k = 0; k < 4; ++k) {
uint32_t avg = 0;
for (y = 0; y < 4; ++y) {
for (x = 0; x < 4; ++x) {
avg += ref[x + y * BPS];
}
}
dc[k] = avg;
ref += 4; // go to next 4x4 block.
}
}
//------------------------------------------------------------------------------
// Texture distortion
//
@ -757,6 +771,7 @@ VP8Metric VP8SSE16x8;
VP8Metric VP8SSE4x4;
VP8WMetric VP8TDisto4x4;
VP8WMetric VP8TDisto16x16;
VP8MeanMetric VP8Mean16x4;
VP8QuantizeBlock VP8EncQuantizeBlock;
VP8Quantize2Blocks VP8EncQuantize2Blocks;
VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
@ -795,6 +810,7 @@ WEBP_TSAN_IGNORE_FUNCTION void VP8EncDspInit(void) {
VP8SSE4x4 = SSE4x4;
VP8TDisto4x4 = Disto4x4;
VP8TDisto16x16 = Disto16x16;
VP8Mean16x4 = Mean16x4;
VP8EncQuantizeBlock = QuantizeBlock;
VP8EncQuantize2Blocks = Quantize2Blocks;
VP8EncQuantizeBlockWHT = QuantizeBlock;