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-------- Original Message --------
Subject: [FFmpeg-devel] [PATCH] ac3enc: replace nb_coefs with
start_freq and end_freq in AC3EncodeContext.
Date: Fri, 4 Mar 2011 19:12:51 -0500
From: Justin Ruggles <[email protected]>
Reply-To: FFmpeg development discussions and patches
<[email protected]>
To: [email protected]
Currently start_freq is always 0, but it will be non-zero for the coupling
channel after channel coupling is implemented.
---
libavcodec/ac3enc.c | 74
+++++++++++++++++++++++++++++---------------------
1 files changed, 43 insertions(+), 31 deletions(-)
diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c
index 676bb5e..3602c04 100644
--- a/libavcodec/ac3enc.c
+++ b/libavcodec/ac3enc.c
@@ -114,7 +114,8 @@ typedef struct AC3EncodeContext {
int cutoff; ///< user-specified cutoff frequency, in Hz
int bandwidth_code[AC3_MAX_CHANNELS]; ///< bandwidth code (0 to 60) (chbwcod)
- int nb_coefs[AC3_MAX_CHANNELS];
+ int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin for each channel (strtmant)
+ int end_freq[AC3_MAX_CHANNELS]; ///< end frequency bin for each channel (endmant)
int rematrixing; ///< determines how rematrixing strategy is calculated
int num_rematrixing_bands; ///< number of rematrixing bands
@@ -302,7 +303,7 @@ static void rematrixing_init(AC3EncodeContext *s)
*/
static void compute_rematrixing_strategy(AC3EncodeContext *s)
{
- int nb_coefs;
+ int end_freq;
int blk, bnd, i;
AC3Block *block, *block0;
@@ -311,7 +312,7 @@ static void compute_rematrixing_strategy(AC3EncodeContext *s)
if (s->rematrixing & AC3_REMATRIXING_IS_STATIC)
return;
- nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
+ end_freq = FFMIN(s->end_freq[0], s->end_freq[1]);
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
block = &s->blocks[blk];
@@ -319,7 +320,7 @@ static void compute_rematrixing_strategy(AC3EncodeContext *s)
for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
/* calculate calculate sum of squared coeffs for one band in one block */
int start = ff_ac3_rematrix_band_tab[bnd];
- int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
+ int end = FFMIN(end_freq, ff_ac3_rematrix_band_tab[bnd+1]);
CoefSumType sum[4] = {0,};
for (i = start; i < end; i++) {
CoefType lt = block->mdct_coef[0][i];
@@ -354,7 +355,7 @@ static void compute_rematrixing_strategy(AC3EncodeContext *s)
*/
static void apply_rematrixing(AC3EncodeContext *s)
{
- int nb_coefs;
+ int end_freq;
int blk, bnd, i;
int start, end;
uint8_t *flags;
@@ -362,7 +363,7 @@ static void apply_rematrixing(AC3EncodeContext *s)
if (s->rematrixing == AC3_REMATRIXING_NONE)
return;
- nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
+ end_freq = FFMIN(s->end_freq[0], s->end_freq[1]);
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
AC3Block *block = &s->blocks[blk];
@@ -371,7 +372,7 @@ static void apply_rematrixing(AC3EncodeContext *s)
for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
if (flags[bnd]) {
start = ff_ac3_rematrix_band_tab[bnd];
- end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
+ end = FFMIN(end_freq, ff_ac3_rematrix_band_tab[bnd+1]);
for (i = start; i < end; i++) {
int32_t lt = block->fixed_coef[0][i];
int32_t rt = block->fixed_coef[1][i];
@@ -577,12 +578,13 @@ static void encode_exponents(AC3EncodeContext *s)
{
int blk, blk1, ch;
uint8_t *exp, *exp1, *exp_strategy;
- int nb_coefs, num_reuse_blocks;
+ int start, nb_coefs, num_reuse_blocks;
for (ch = 0; ch < s->channels; ch++) {
- exp = s->blocks[0].exp[ch];
+ start = s->start_freq[ch];
+ exp = &s->blocks[0].exp[ch][start];
exp_strategy = s->exp_strategy[ch];
- nb_coefs = s->nb_coefs[ch];
+ nb_coefs = s->end_freq[ch] - start;
blk = 0;
while (blk < AC3_MAX_BLOCKS) {
@@ -594,7 +596,7 @@ static void encode_exponents(AC3EncodeContext *s)
num_reuse_blocks = blk1 - blk - 1;
/* for the EXP_REUSE case we select the min of the exponents */
- s->ac3dsp.ac3_exponent_min(exp, num_reuse_blocks, nb_coefs);
+ s->ac3dsp.ac3_exponent_min(exp-start, num_reuse_blocks, s->end_freq[ch]);
encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk]);
@@ -630,10 +632,11 @@ static void group_exponents(AC3EncodeContext *s)
AC3Block *block = &s->blocks[blk];
for (ch = 0; ch < s->channels; ch++) {
int exp_strategy = s->exp_strategy[ch][blk];
+ int nb_coefs = s->end_freq[ch] - s->start_freq[ch];
if (exp_strategy == EXP_REUSE)
continue;
group_size = exp_strategy + (exp_strategy == EXP_D45);
- nb_groups = exponent_group_tab[exp_strategy-1][s->nb_coefs[ch]];
+ nb_groups = exponent_group_tab[exp_strategy-1][nb_coefs];
bit_count += 4 + (nb_groups * 7);
p = block->exp[ch];
@@ -803,12 +806,13 @@ static void count_frame_bits(AC3EncodeContext *s)
/**
* Calculate the number of bits needed to encode a set of mantissas.
*/
-static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
+static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int start,
+ int end)
{
int bits, b, i;
bits = 0;
- for (i = 0; i < nb_coefs; i++) {
+ for (i = start; i < end; i++) {
b = bap[i];
if (b <= 4) {
// bap=1 to bap=4 will be counted in compute_mantissa_size_final
@@ -856,11 +860,11 @@ static void bit_alloc_masking(AC3EncodeContext *s)
Since we currently do not calculate bap when exponent
strategy is EXP_REUSE we do not need to calculate psd or mask. */
if (s->exp_strategy[ch][blk] != EXP_REUSE) {
- ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
- s->nb_coefs[ch],
+ ff_ac3_bit_alloc_calc_psd(block->exp[ch], s->start_freq[ch],
+ s->end_freq[ch],
block->psd[ch], block->band_psd[ch]);
ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
- 0, s->nb_coefs[ch],
+ s->start_freq[ch], s->end_freq[ch],
ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
ch == s->lfe_channel,
DBA_NONE, 0, NULL, NULL, NULL,
@@ -921,12 +925,14 @@ static int bit_alloc(AC3EncodeContext *s, int snr_offset)
if (s->exp_strategy[ch][blk] == EXP_REUSE) {
memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
} else {
- ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
- s->nb_coefs[ch], snr_offset,
- s->bit_alloc.floor, ff_ac3_bap_tab,
- block->bap[ch]);
+ ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch],
+ s->start_freq[ch], s->end_freq[ch],
+ snr_offset, s->bit_alloc.floor,
+ ff_ac3_bap_tab, block->bap[ch]);
}
- mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
+ mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch],
+ s->start_freq[ch],
+ s->end_freq[ch]);
}
mantissa_bits += compute_mantissa_size_final(mant_cnt);
}
@@ -1035,7 +1041,7 @@ static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
if (s->bandwidth_code[0] > min_bw_code) {
for (ch = 0; ch < s->fbw_channels; ch++) {
s->bandwidth_code[ch]--;
- s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
+ s->end_freq[ch] = s->bandwidth_code[ch] * 3 + 73;
}
return 0;
}
@@ -1133,11 +1139,12 @@ static inline int asym_quant(int c, int e, int qbits)
*/
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, int32_t *fixed_coef,
int8_t exp_shift, uint8_t *exp,
- uint8_t *bap, uint16_t *qmant, int n)
+ uint8_t *bap, uint16_t *qmant, int start,
+ int end)
{
int i;
- for (i = 0; i < n; i++) {
+ for (i = start; i < end; i++) {
int v;
int c = fixed_coef[i];
int e = exp[i] - exp_shift;
@@ -1238,7 +1245,8 @@ static void quantize_mantissas(AC3EncodeContext *s)
for (ch = 0; ch < s->channels; ch++) {
quantize_mantissas_blk_ch(s, block->fixed_coef[ch], block->exp_shift[ch],
block->exp[ch], block->bap[ch],
- block->qmant[ch], s->nb_coefs[ch]);
+ block->qmant[ch], s->start_freq[ch],
+ s->end_freq[ch]);
}
}
}
@@ -1327,6 +1335,7 @@ static void output_audio_block(AC3EncodeContext *s, int blk)
/* exponents */
for (ch = 0; ch < s->channels; ch++) {
int nb_groups;
+ int nb_coefs = s->end_freq[ch] - s->start_freq[ch];
if (s->exp_strategy[ch][blk] == EXP_REUSE)
continue;
@@ -1335,7 +1344,7 @@ static void output_audio_block(AC3EncodeContext *s, int blk)
put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
/* exponent groups */
- nb_groups = exponent_group_tab[s->exp_strategy[ch][blk]-1][s->nb_coefs[ch]];
+ nb_groups = exponent_group_tab[s->exp_strategy[ch][blk]-1][nb_coefs];
for (i = 1; i <= nb_groups; i++)
put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
@@ -1371,7 +1380,7 @@ static void output_audio_block(AC3EncodeContext *s, int blk)
/* mantissas */
for (ch = 0; ch < s->channels; ch++) {
int b, q;
- for (i = 0; i < s->nb_coefs[ch]; i++) {
+ for (i = s->start_freq[ch]; i < s->end_freq[ch]; i++) {
q = block->qmant[ch][i];
b = block->bap[ch][i];
switch (b) {
@@ -1688,10 +1697,13 @@ static av_cold void set_bandwidth(AC3EncodeContext *s)
/* set number of coefficients for each channel */
for (ch = 0; ch < s->fbw_channels; ch++) {
s->bandwidth_code[ch] = bw_code;
- s->nb_coefs[ch] = bw_code * 3 + 73;
+ s->start_freq[ch] = 0;
+ s->end_freq[ch] = bw_code * 3 + 73;
+ }
+ if (s->lfe_on) {
+ s->start_freq[s->lfe_channel] = 0;
+ s->end_freq[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
}
- if (s->lfe_on)
- s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
}
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