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New previous coef context experiment

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Adds an experiment to derive the previous context of a coefficient
not just from the previous coefficient in the scan order but from a
combination of several neighboring coefficients previously encountered
in scan order.  A precomputed table of neighbors for each location
for each scan type and block size is used. Currently 5 neighbors are
used.

Results are about 0.2% positive using a strategy where the max coef
magnitude from the 5 neigbors is used to derive the context.

Change-Id: Ie708b54d8e1898af742846ce2d1e2b0d89fd4ad5
This commit is contained in:
Deb Mukherjee
2012-11-27 15:51:06 -08:00
parent de52948665
commit 08f0c7cc9c
8 changed files with 325 additions and 32 deletions
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34
vp9/decoder/vp9_detokenize.c
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@@ -63,11 +63,24 @@ static int get_signed(BOOL_DECODER *br, int value_to_sign) {
return decode_bool(br, 128) ? -value_to_sign : value_to_sign;
}
#define INCREMENT_COUNT(token) \
do { \
#if CONFIG_NEWCOEFCONTEXT
#define PT pn
#define INCREMENT_COUNT(token) \
do { \
coef_counts[type][coef_bands[c]][pn][token]++; \
pn = pt = vp9_prev_token_class[token]; \
if (c < seg_eob - 1 && NEWCOEFCONTEXT_BAND_COND(coef_bands[c + 1])) \
pn = vp9_get_coef_neighbor_context( \
qcoeff_ptr, nodc, neighbors, scan[c + 1]); \
} while (0)
#else
#define PT pt
#define INCREMENT_COUNT(token) \
do { \
coef_counts[type][coef_bands[c]][pt][token]++; \
pt = vp9_prev_token_class[token]; \
} while (0)
#endif /* CONFIG_NEWCOEFCONTEXT */
#define WRITE_COEF_CONTINUE(val, token) \
{ \
@@ -92,7 +105,12 @@ static int decode_coefs(VP9D_COMP *dx, const MACROBLOCKD *xd,
const int *const scan, TX_SIZE txfm_size,
const int *coef_bands) {
FRAME_CONTEXT *const fc = &dx->common.fc;
int pt, c = (type == PLANE_TYPE_Y_NO_DC);
#if CONFIG_NEWCOEFCONTEXT
const int *neighbors;
int pn;
#endif
int nodc = (type == PLANE_TYPE_Y_NO_DC);
int pt, c = nodc;
vp9_coeff_probs *coef_probs;
vp9_prob *prob;
vp9_coeff_count *coef_counts;
@@ -135,11 +153,15 @@ static int decode_coefs(VP9D_COMP *dx, const MACROBLOCKD *xd,
}
VP9_COMBINEENTROPYCONTEXTS(pt, *a, *l);
#if CONFIG_NEWCOEFCONTEXT
pn = pt;
neighbors = vp9_get_coef_neighbors_handle(scan);
#endif
while (1) {
int val;
const uint8_t *cat6 = cat6_prob;
if (c >= seg_eob) break;
prob = coef_probs[type][coef_bands[c]][pt];
prob = coef_probs[type][coef_bands[c]][PT];
if (!vp9_read(br, prob[EOB_CONTEXT_NODE]))
break;
SKIP_START:
@@ -147,7 +169,7 @@ SKIP_START:
if (!vp9_read(br, prob[ZERO_CONTEXT_NODE])) {
INCREMENT_COUNT(ZERO_TOKEN);
++c;
prob = coef_probs[type][coef_bands[c]][pt];
prob = coef_probs[type][coef_bands[c]][PT];
goto SKIP_START;
}
// ONE_CONTEXT_NODE_0_
@@ -211,7 +233,7 @@ SKIP_START:
}
if (c < seg_eob)
coef_counts[type][coef_bands[c]][pt][DCT_EOB_TOKEN]++;
coef_counts[type][coef_bands[c]][PT][DCT_EOB_TOKEN]++;
a[0] = l[0] = (c > !type);