static int MBAnalyzeBestIntra4Mode(VP8EncIterator* const it,
int best_alpha) {
uint8_t modes[16];
const int max_mode = (it->enc_->method_ >= 3) ? MAX_INTRA4_MODE : NUM_BMODES;
int i4_alpha = 0;
VP8IteratorStartI4(it);
do {
int mode;
int best_mode_alpha = -1;
const uint8_t* const src = it->yuv_in_ + Y_OFF + VP8Scan[it->i4_];
VP8MakeIntra4Preds(it);
for (mode = 0; mode < max_mode; ++mode) {
const int alpha = VP8CollectHistogram(src,
it->yuv_p_ + VP8I4ModeOffsets[mode],
0, 1);
if (alpha > best_mode_alpha) {
best_mode_alpha = alpha;
modes[it->i4_] = mode;
}
}
i4_alpha += best_mode_alpha;
// Note: we reuse the original samples for predictors
} while (VP8IteratorRotateI4(it, it->yuv_in_ + Y_OFF));
if (i4_alpha > best_alpha) {
VP8SetIntra4Mode(it, modes);
best_alpha = ClipAlpha(i4_alpha);
}
return best_alpha;
}
static int MBAnalyzeBestIntra4Mode(VP8EncIterator* const it,
int best_alpha) {
uint8_t modes[16];
const int max_mode =
(it->enc_->method_ >= FAST_ANALYSIS_METHOD) ? MAX_INTRA4_MODE
: NUM_BMODES;
int i4_alpha;
VP8Histogram total_histo = { { 0 } };
int cur_histo = 0;
VP8IteratorStartI4(it);
do {
int mode;
int best_mode_alpha = DEFAULT_ALPHA;
VP8Histogram histos[2];
const uint8_t* const src = it->yuv_in_ + Y_OFF + VP8Scan[it->i4_];
VP8MakeIntra4Preds(it);
for (mode = 0; mode < max_mode; ++mode) {
int alpha;
memset(&histos[cur_histo], 0, sizeof(histos[cur_histo]));
VP8CollectHistogram(src, it->yuv_p_ + VP8I4ModeOffsets[mode],
0, 1, &histos[cur_histo]);
alpha = GetAlpha(&histos[cur_histo]);
if (IS_BETTER_ALPHA(alpha, best_mode_alpha)) {
best_mode_alpha = alpha;
modes[it->i4_] = mode;
cur_histo ^= 1; // keep track of best histo so far.
}
}
// accumulate best histogram
MergeHistograms(&histos[cur_histo ^ 1], &total_histo);
// Note: we reuse the original samples for predictors
} while (VP8IteratorRotateI4(it, it->yuv_in_ + Y_OFF));
i4_alpha = GetAlpha(&total_histo);
if (IS_BETTER_ALPHA(i4_alpha, best_alpha)) {
VP8SetIntra4Mode(it, modes);
best_alpha = i4_alpha;
}
return best_alpha;
}
