This will allow for changing the exponent strategies later and
recalculating the final exponents.
---
libavcodec/ac3enc.c | 90 +++++++++++++++++++++++++++++++++-----------------
1 files changed, 59 insertions(+), 31 deletions(-)
diff --git libavcodec/ac3enc.c libavcodec/ac3enc.c
index 425b842..0f876e8 100644
--- libavcodec/ac3enc.c
+++ libavcodec/ac3enc.c
@@ -304,6 +304,38 @@ static void apply_mdct(AC3EncodeContext *s,
}
}
+/**
+ * Calculate MDCT coefficient exponents.
+ */
+static void calculate_exponents(AC3EncodeContext *s,
+ int32_t mdct_coef[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
+ uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
+ int8_t exp_shift[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS])
+{
+ int ch, blk, i, v;
+
+ for (ch = 0; ch < s->channels; ch++) {
+ /* fixed mdct to the six sub blocks & exponent computation */
+ for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+ /* compute "exponents". We take into account the normalization there */
+ for (i = 0; i < AC3_MAX_COEFS; i++) {
+ int e;
+ v = abs(mdct_coef[blk][ch][i]);
+ if (v == 0)
+ e = 24;
+ else {
+ e = 23 - av_log2(v) + exp_shift[blk][ch];
+ if (e >= 24) {
+ e = 24;
+ mdct_coef[blk][ch][i] = 0;
+ }
+ }
+ exp[blk][ch][i] = e;
+ }
+ }
+ }
+}
+
/* XXX: use another norm ? */
static int calc_exp_diff(uint8_t *exp1, uint8_t *exp2, int n)
{
@@ -434,41 +466,19 @@ static int encode_exp_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
return 4 + (nb_groups / 3) * 7;
}
-static void process_exponents(AC3EncodeContext *s,
- int32_t mdct_coef[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
- uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
- uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
- int8_t exp_shift[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
- int *frame_bits)
+/**
+ * Compute the exponents as the decoder will see them.
+ * The EXP_REUSE case must be handled carefully : we select the min of the exponents.
+ */
+static void encode_exponents(AC3EncodeContext *s,
+ uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
+ uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
+ int *frame_bits)
{
- int ch, blk, i, v;
+ int ch, blk;
*frame_bits = 0;
for (ch = 0; ch < s->channels; ch++) {
- /* fixed mdct to the six sub blocks & exponent computation */
- for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
- /* compute "exponents". We take into account the normalization there */
- for (i = 0; i < AC3_MAX_COEFS; i++) {
- int e;
- v = abs(mdct_coef[blk][ch][i]);
- if (v == 0)
- e = 24;
- else {
- e = 23 - av_log2(v) + exp_shift[blk][ch];
- if (e >= 24) {
- e = 24;
- mdct_coef[blk][ch][i] = 0;
- }
- }
- exp[blk][ch][i] = e;
- }
- }
-
- compute_exp_strategy(exp_strategy, exp, ch, ch == s->lfe_ch);
-
- /* compute the exponents as the decoder will see them. The
- EXP_REUSE case must be handled carefully : we select the
- min of the exponents */
blk = 0;
while (blk < AC3_MAX_BLOCKS) {
int blk2;
@@ -489,6 +499,24 @@ static void process_exponents(AC3EncodeContext *s,
}
}
+static void process_exponents(AC3EncodeContext *s,
+ int32_t mdct_coef[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
+ uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
+ uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
+ int8_t exp_shift[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
+ int *frame_bits)
+{
+ int ch;
+
+ calculate_exponents(s, mdct_coef, exp, exp_shift);
+
+ for (ch = 0; ch < s->channels; ch++) {
+ compute_exp_strategy(exp_strategy, exp, ch, ch == s->lfe_ch);
+ }
+
+ encode_exponents(s, exp, exp_strategy, frame_bits);
+}
+
/* return the size in bits taken by the mantissa */
static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *m, int nb_coefs)
{
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