---
libavcodec/ac3enc.c | 118 +++++++++++++++++++++++++-------------------------
1 files changed, 59 insertions(+), 59 deletions(-)
diff --git libavcodec/ac3enc.c libavcodec/ac3enc.c
index f574246..f973f9a 100644
--- libavcodec/ac3enc.c
+++ libavcodec/ac3enc.c
@@ -76,6 +76,12 @@ typedef struct AC3EncodeContext {
int16_t last_samples[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< last 256 samples from previous frame
} AC3EncodeContext;
+/**
+ * LUT for number of exponent groups.
+ * exponent_group_tab[exponent strategy][number of coefficients]
+ */
+int exponent_group_tab[3][256];
+
static int16_t costab[64];
static int16_t sintab[64];
static int16_t xcos1[128];
@@ -308,58 +314,56 @@ static void exponent_min(uint8_t exp[AC3_MAX_COEFS], uint8_t exp1[AC3_MAX_COEFS]
/* update the exponents so that they are the ones the decoder will
decode. Return the number of bits used to code the exponents */
-static int encode_exp(uint8_t encoded_exp[AC3_MAX_COEFS],
- uint8_t exp[AC3_MAX_COEFS], int nb_exps, int exp_strategy)
+static int encode_exp(uint8_t *exp, int nb_exps, int exp_strategy)
{
- int group_size, nb_groups, i, j, k, exp_min;
- uint8_t exp1[AC3_MAX_COEFS];
+ int nb_groups, i, k;
+ int exp_min1, exp_min2;
- switch(exp_strategy) {
- case EXP_D15:
- group_size = 1;
- break;
+ nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
+
+ /* constraint for DC exponent */
+ exp[0] = FFMIN(exp[0], 15);
+
+ /* for each group, compute the minimum exponent */
+ switch (exp_strategy) {
case EXP_D25:
- group_size = 2;
+ for (i = 1, k = 1; i <= nb_groups; i++) {
+ exp[i] = FFMIN(exp[k], exp[k+1]);
+ k += 2;
+ }
break;
- default:
case EXP_D45:
- group_size = 4;
- break;
- }
- nb_groups = ((nb_exps + (group_size * 3) - 4) / (3 * group_size)) * 3;
-
- /* for each group, compute the minimum exponent */
- exp1[0] = exp[0]; /* DC exponent is handled separately */
- k = 1;
- for (i = 1; i <= nb_groups; i++) {
- exp_min = exp[k];
- assert(exp_min >= 0 && exp_min <= 24);
- for (j = 1; j < group_size; j++) {
- if (exp[k+j] < exp_min)
- exp_min = exp[k+j];
+ for (i = 1, k = 1; i <= nb_groups; i++) {
+ exp_min1 = FFMIN(exp[k ], exp[k+1]);
+ exp_min2 = FFMIN(exp[k+2], exp[k+3]);
+ exp[i] = FFMIN(exp_min1, exp_min2);
+ k += 4;
}
- exp1[i] = exp_min;
- k += group_size;
+ break;
}
- /* constraint for DC exponent */
- if (exp1[0] > 15)
- exp1[0] = 15;
-
/* Decrease the delta between each groups to within 2
* so that they can be differentially encoded */
for (i = 1; i <= nb_groups; i++)
- exp1[i] = FFMIN(exp1[i], exp1[i-1] + 2);
- for (i = nb_groups-1; i >= 0; i--)
- exp1[i] = FFMIN(exp1[i], exp1[i+1] + 2);
+ exp[i] = FFMIN(exp[i], exp[i-1] + 2);
+ i--;
+ while(--i >= 0)
+ exp[i] = FFMIN(exp[i], exp[i+1] + 2);
/* now we have the exponent values the decoder will see */
- encoded_exp[0] = exp1[0];
- k = 1;
- for (i = 1; i <= nb_groups; i++) {
- for (j = 0; j < group_size; j++)
- encoded_exp[k+j] = exp1[i];
- k += group_size;
+ switch (exp_strategy) {
+ case EXP_D25:
+ for (i = nb_groups, k = nb_groups*2; i > 0; i--) {
+ exp[k] = exp[k-1] = exp[i];
+ k -= 2;
+ }
+ break;
+ case EXP_D45:
+ for (i = nb_groups, k = nb_groups*4; i > 0; i--) {
+ exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
+ k -= 4;
+ }
+ break;
}
#ifdef DEBUG
@@ -734,6 +738,15 @@ static av_cold int AC3_encode_init(AVCodecContext *avctx)
mdct_init();
+ for (j = 0; j < 256; j++) {
+ exponent_group_tab[0][j] = (j - 1) / 3;
+ exponent_group_tab[1][j] = (j + 2) / 6;
+ exponent_group_tab[2][j] = (j + 8) / 12;
+ }
+ exponent_group_tab[0][7] =
+ exponent_group_tab[1][7] =
+ exponent_group_tab[2][7] = 2;
+
avctx->coded_frame = avcodec_alloc_frame();
avctx->coded_frame->key_frame= 1;
@@ -867,21 +880,10 @@ static void output_audio_block(AC3EncodeContext *s,
/* exponents */
for (ch = 0; ch < s->channels; ch++) {
- switch(exp_strategy[ch]) {
- case EXP_REUSE:
+ if (exp_strategy[ch] == EXP_REUSE)
continue;
- case EXP_D15:
- group_size = 1;
- break;
- case EXP_D25:
- group_size = 2;
- break;
- default:
- case EXP_D45:
- group_size = 4;
- break;
- }
- nb_groups = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size);
+ group_size = exp_strategy[ch] + (exp_strategy[ch] == EXP_D45);
+ nb_groups = exponent_group_tab[exp_strategy[ch]-1][s->nb_coefs[ch]];
p = encoded_exp[ch];
/* first exponent */
@@ -1154,7 +1156,6 @@ static int AC3_encode_frame(AVCodecContext *avctx,
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];
- uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
uint8_t bap[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
int8_t exp_samples[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS];
int frame_bits;
@@ -1223,12 +1224,11 @@ static int AC3_encode_frame(AVCodecContext *avctx,
exponent_min(exp[i][ch], exp[j][ch], s->nb_coefs[ch]);
j++;
}
- frame_bits += encode_exp(encoded_exp[i][ch],
- exp[i][ch], s->nb_coefs[ch],
+ frame_bits += encode_exp(exp[i][ch], s->nb_coefs[ch],
exp_strategy[i][ch]);
/* copy encoded exponents for reuse case */
for (k = i+1; k < j; k++) {
- memcpy(encoded_exp[k][ch], encoded_exp[i][ch],
+ memcpy(exp[k][ch], exp[i][ch],
s->nb_coefs[ch] * sizeof(uint8_t));
}
i = j;
@@ -1244,12 +1244,12 @@ static int AC3_encode_frame(AVCodecContext *avctx,
s->bits_written += s->frame_size * 16;
s->samples_written += AC3_FRAME_SIZE;
- compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits);
+ compute_bit_allocation(s, bap, exp, exp_strategy, frame_bits);
/* everything is known... let's output the frame */
output_frame_header(s, frame);
for (i = 0; i < AC3_MAX_BLOCKS; i++) {
- output_audio_block(s, exp_strategy[i], encoded_exp[i], bap[i],
+ output_audio_block(s, exp_strategy[i], exp[i], bap[i],
mdct_coef[i], exp_samples[i], i);
}
return output_frame_end(s);
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