#include "audioconvert.h"
-#define MDCT_NBITS 9
-#define MDCT_SAMPLES (1 << MDCT_NBITS)
-
/** Maximum number of exponent groups. +1 for separate DC exponent. */
#define AC3_MAX_EXP_GROUPS 85
/** Scale a float value by 2^bits and convert to an integer. */
#define SCALE_FLOAT(a, bits) lrintf((a) * (float)(1 << (bits)))
-/** Scale a float value by 2^15, convert to an integer, and clip to int16_t range. */
-#define FIX15(a) av_clip_int16(SCALE_FLOAT(a, 15))
+typedef int16_t SampleType;
+typedef int32_t CoefType;
+
+#define SCALE_COEF(a) (a)
+
+/** Scale a float value by 2^15, convert to an integer, and clip to range -32767..32767. */
+#define FIX15(a) av_clip(SCALE_FLOAT(a, 15), -32767, 32767)
/**
} IComplex;
typedef struct AC3MDCTContext {
- AVCodecContext *avctx; ///< parent context for av_log()
+ const int16_t *window; ///< MDCT window function
+ int nbits; ///< log2(transform size)
+ int16_t *costab; ///< FFT cos table
+ int16_t *sintab; ///< FFT sin table
+ int16_t *xcos1; ///< MDCT cos table
+ int16_t *xsin1; ///< MDCT sin table
int16_t *rot_tmp; ///< temp buffer for pre-rotated samples
IComplex *cplx_tmp; ///< temp buffer for complex pre-rotated samples
} AC3MDCTContext;
*/
typedef struct AC3Block {
uint8_t **bap; ///< bit allocation pointers (bap)
- int32_t **mdct_coef; ///< MDCT coefficients
+ CoefType **mdct_coef; ///< MDCT coefficients
uint8_t **exp; ///< original exponents
uint8_t **grouped_exp; ///< grouped exponents
int16_t **psd; ///< psd per frequency bin
int frame_size_min; ///< minimum frame size in case rounding is necessary
int frame_size; ///< current frame size in bytes
int frame_size_code; ///< frame size code (frmsizecod)
+ uint16_t crc_inv[2];
int bits_written; ///< bit count (used to avg. bitrate)
int samples_written; ///< sample count (used to avg. bitrate)
int channel_mode; ///< channel mode (acmod)
const uint8_t *channel_map; ///< channel map used to reorder channels
+ 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];
int16_t **planar_samples;
uint8_t *bap_buffer;
uint8_t *bap1_buffer;
- int32_t *mdct_coef_buffer;
+ CoefType *mdct_coef_buffer;
uint8_t *exp_buffer;
uint8_t *grouped_exp_buffer;
int16_t *psd_buffer;
int16_t *mask_buffer;
uint16_t *qmant_buffer;
- DECLARE_ALIGNED(16, int16_t, windowed_samples)[AC3_WINDOW_SIZE];
+ DECLARE_ALIGNED(16, SampleType, windowed_samples)[AC3_WINDOW_SIZE];
} AC3EncodeContext;
-/** MDCT and FFT tables */
-static int16_t costab[64];
-static int16_t sintab[64];
-static int16_t xcos1[128];
-static int16_t xsin1[128];
-
/**
* LUT for number of exponent groups.
* exponent_group_tab[exponent strategy-1][number of coefficients]
*/
-uint8_t exponent_group_tab[3][256];
+static uint8_t exponent_group_tab[3][256];
+
+
+/**
+ * List of supported channel layouts.
+ */
+static const int64_t ac3_channel_layouts[] = {
+ AV_CH_LAYOUT_MONO,
+ AV_CH_LAYOUT_STEREO,
+ AV_CH_LAYOUT_2_1,
+ AV_CH_LAYOUT_SURROUND,
+ AV_CH_LAYOUT_2_2,
+ AV_CH_LAYOUT_QUAD,
+ AV_CH_LAYOUT_4POINT0,
+ AV_CH_LAYOUT_5POINT0,
+ AV_CH_LAYOUT_5POINT0_BACK,
+ (AV_CH_LAYOUT_MONO | AV_CH_LOW_FREQUENCY),
+ (AV_CH_LAYOUT_STEREO | AV_CH_LOW_FREQUENCY),
+ (AV_CH_LAYOUT_2_1 | AV_CH_LOW_FREQUENCY),
+ (AV_CH_LAYOUT_SURROUND | AV_CH_LOW_FREQUENCY),
+ (AV_CH_LAYOUT_2_2 | AV_CH_LOW_FREQUENCY),
+ (AV_CH_LAYOUT_QUAD | AV_CH_LOW_FREQUENCY),
+ (AV_CH_LAYOUT_4POINT0 | AV_CH_LOW_FREQUENCY),
+ AV_CH_LAYOUT_5POINT1,
+ AV_CH_LAYOUT_5POINT1_BACK,
+ 0
+};
/**
* Channels are reordered from FFmpeg's default order to AC-3 order.
*/
static void deinterleave_input_samples(AC3EncodeContext *s,
- const int16_t *samples)
+ const SampleType *samples)
{
int ch, i;
/* deinterleave and remap input samples */
for (ch = 0; ch < s->channels; ch++) {
- const int16_t *sptr;
+ const SampleType *sptr;
int sinc;
/* copy last 256 samples of previous frame to the start of the current frame */
*/
static av_cold void mdct_end(AC3MDCTContext *mdct)
{
+ mdct->nbits = 0;
+ av_freep(&mdct->costab);
+ av_freep(&mdct->sintab);
+ av_freep(&mdct->xcos1);
+ av_freep(&mdct->xsin1);
av_freep(&mdct->rot_tmp);
av_freep(&mdct->cplx_tmp);
}
-
/**
* Initialize FFT tables.
* @param ln log2(FFT size)
*/
-static av_cold void fft_init(int ln)
+static av_cold int fft_init(AVCodecContext *avctx, AC3MDCTContext *mdct, int ln)
{
int i, n, n2;
float alpha;
n = 1 << ln;
n2 = n >> 1;
+ FF_ALLOC_OR_GOTO(avctx, mdct->costab, n2 * sizeof(*mdct->costab), fft_alloc_fail);
+ FF_ALLOC_OR_GOTO(avctx, mdct->sintab, n2 * sizeof(*mdct->sintab), fft_alloc_fail);
+
for (i = 0; i < n2; i++) {
alpha = 2.0 * M_PI * i / n;
- costab[i] = FIX15(cos(alpha));
- sintab[i] = FIX15(sin(alpha));
+ mdct->costab[i] = FIX15(cos(alpha));
+ mdct->sintab[i] = FIX15(sin(alpha));
}
+
+ return 0;
+fft_alloc_fail:
+ mdct_end(mdct);
+ return AVERROR(ENOMEM);
}
* Initialize MDCT tables.
* @param nbits log2(MDCT size)
*/
-static av_cold int mdct_init(AC3MDCTContext *mdct, int nbits)
+static av_cold int mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct,
+ int nbits)
{
- int i, n, n4;
+ int i, n, n4, ret;
n = 1 << nbits;
n4 = n >> 2;
- fft_init(nbits - 2);
+ mdct->nbits = nbits;
- FF_ALLOC_OR_GOTO(mdct->avctx, mdct->rot_tmp, n * sizeof(*mdct->rot_tmp),
- mdct_alloc_fail);
- FF_ALLOC_OR_GOTO(mdct->avctx, mdct->cplx_tmp, n4 * sizeof(*mdct->cplx_tmp),
- mdct_alloc_fail);
+ ret = fft_init(avctx, mdct, nbits - 2);
+ if (ret)
+ return ret;
+
+ mdct->window = ff_ac3_window;
+
+ FF_ALLOC_OR_GOTO(avctx, mdct->xcos1, n4 * sizeof(*mdct->xcos1), mdct_alloc_fail);
+ FF_ALLOC_OR_GOTO(avctx, mdct->xsin1, n4 * sizeof(*mdct->xsin1), mdct_alloc_fail);
+ FF_ALLOC_OR_GOTO(avctx, mdct->rot_tmp, n * sizeof(*mdct->rot_tmp), mdct_alloc_fail);
+ FF_ALLOC_OR_GOTO(avctx, mdct->cplx_tmp, n4 * sizeof(*mdct->cplx_tmp), mdct_alloc_fail);
for (i = 0; i < n4; i++) {
float alpha = 2.0 * M_PI * (i + 1.0 / 8.0) / n;
- xcos1[i] = FIX15(-cos(alpha));
- xsin1[i] = FIX15(-sin(alpha));
+ mdct->xcos1[i] = FIX15(-cos(alpha));
+ mdct->xsin1[i] = FIX15(-sin(alpha));
}
return 0;
mdct_alloc_fail:
+ mdct_end(mdct);
return AVERROR(ENOMEM);
}
* @param z complex input/output samples
* @param ln log2(FFT size)
*/
-static void fft(IComplex *z, int ln)
+static void fft(AC3MDCTContext *mdct, IComplex *z, int ln)
{
int j, l, np, np2;
int nblocks, nloops;
p++;
q++;
for(l = nblocks; l < np2; l += nblocks) {
- CMUL(tmp_re, tmp_im, costab[l], -sintab[l], q->re, q->im);
+ CMUL(tmp_re, tmp_im, mdct->costab[l], -mdct->sintab[l], q->re, q->im);
BF(p->re, p->im, q->re, q->im,
p->re, p->im, tmp_re, tmp_im);
p++;
*/
static void mdct512(AC3MDCTContext *mdct, int32_t *out, int16_t *in)
{
- int i, re, im;
+ int i, re, im, n, n2, n4;
int16_t *rot = mdct->rot_tmp;
IComplex *x = mdct->cplx_tmp;
+ n = 1 << mdct->nbits;
+ n2 = n >> 1;
+ n4 = n >> 2;
+
/* shift to simplify computations */
- for (i = 0; i < MDCT_SAMPLES/4; i++)
- rot[i] = -in[i + 3*MDCT_SAMPLES/4];
- memcpy(&rot[MDCT_SAMPLES/4], &in[0], 3*MDCT_SAMPLES/4*sizeof(*in));
+ for (i = 0; i <n4; i++)
+ rot[i] = -in[i + 3*n4];
+ memcpy(&rot[n4], &in[0], 3*n4*sizeof(*in));
/* pre rotation */
- for (i = 0; i < MDCT_SAMPLES/4; i++) {
- re = ((int)rot[ 2*i] - (int)rot[MDCT_SAMPLES -1-2*i]) >> 1;
- im = -((int)rot[MDCT_SAMPLES/2+2*i] - (int)rot[MDCT_SAMPLES/2-1-2*i]) >> 1;
- CMUL(x[i].re, x[i].im, re, im, -xcos1[i], xsin1[i]);
+ for (i = 0; i < n4; i++) {
+ re = ((int)rot[ 2*i] - (int)rot[ n-1-2*i]) >> 1;
+ im = -((int)rot[n2+2*i] - (int)rot[n2-1-2*i]) >> 1;
+ CMUL(x[i].re, x[i].im, re, im, -mdct->xcos1[i], mdct->xsin1[i]);
}
- fft(x, MDCT_NBITS - 2);
+ fft(mdct, x, mdct->nbits - 2);
/* post rotation */
- for (i = 0; i < MDCT_SAMPLES/4; i++) {
+ for (i = 0; i < n4; i++) {
re = x[i].re;
im = x[i].im;
- CMUL(out[MDCT_SAMPLES/2-1-2*i], out[2*i], re, im, xsin1[i], xcos1[i]);
+ CMUL(out[n2-1-2*i], out[2*i], re, im, mdct->xsin1[i], mdct->xcos1[i]);
}
}
for (ch = 0; ch < s->channels; ch++) {
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
AC3Block *block = &s->blocks[blk];
- const int16_t *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
+ const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
- apply_window(s->windowed_samples, input_samples, ff_ac3_window, AC3_WINDOW_SIZE);
+ apply_window(s->windowed_samples, input_samples, s->mdct.window, AC3_WINDOW_SIZE);
block->exp_shift[ch] = normalize_samples(s);
exponent_group_tab[1][i] = (i + 2) / 6;
exponent_group_tab[2][i] = (i + 8) / 12;
}
+ /* LFE */
+ exponent_group_tab[0][7] = 2;
}
AC3Block *block = &s->blocks[blk];
for (i = 0; i < AC3_MAX_COEFS; i++) {
int e;
- int v = abs(block->mdct_coef[ch][i]);
+ int v = abs(SCALE_COEF(block->mdct_coef[ch][i]));
if (v == 0)
e = 24;
else {
/**
* Calculate exponent strategies for all blocks in a single channel.
*/
-static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy, uint8_t **exp)
+static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy,
+ uint8_t **exp)
{
int blk, blk1;
int exp_diff;
else
exp_strategy[blk] = EXP_REUSE;
}
+ emms_c();
/* now select the encoding strategy type : if exponents are often
recoded, we use a coarse encoding */
/**
* Update the exponents so that they are the ones the decoder will decode.
*/
-static void encode_exponents_blk_ch(uint8_t *exp,
- int nb_exps, int exp_strategy)
+static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
{
int nb_groups, i, k;
s->slow_decay_code = 2;
s->fast_decay_code = 1;
s->slow_gain_code = 1;
- s->db_per_bit_code = 2;
+ s->db_per_bit_code = 3;
s->floor_code = 4;
for (ch = 0; ch < s->channels; ch++)
s->fast_gain_code[ch] = 4;
/**
* Calculate the number of bits needed to encode a set of mantissas.
*/
-static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *bap, int nb_coefs)
+static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
{
int bits, b, i;
bits = 0;
for (i = 0; i < nb_coefs; i++) {
b = bap[i];
- switch (b) {
- case 0:
- /* bap=0 mantissas are not encoded */
- break;
- case 1:
- /* 3 mantissas in 5 bits */
- if (s->mant1_cnt == 0)
- bits += 5;
- if (++s->mant1_cnt == 3)
- s->mant1_cnt = 0;
- break;
- case 2:
- /* 3 mantissas in 7 bits */
- if (s->mant2_cnt == 0)
- bits += 7;
- if (++s->mant2_cnt == 3)
- s->mant2_cnt = 0;
- break;
- case 3:
- bits += 3;
- break;
- case 4:
- /* 2 mantissas in 7 bits */
- if (s->mant4_cnt == 0)
- bits += 7;
- if (++s->mant4_cnt == 2)
- s->mant4_cnt = 0;
- break;
- case 14:
- bits += 14;
- break;
- case 15:
- bits += 16;
- break;
- default:
+ if (b <= 4) {
+ // bap=1 to bap=4 will be counted in compute_mantissa_size_final
+ mant_cnt[b]++;
+ } else if (b <= 13) {
+ // bap=5 to bap=13 use (bap-1) bits
bits += b - 1;
- break;
+ } else {
+ // bap=14 uses 14 bits and bap=15 uses 16 bits
+ bits += (b == 14) ? 14 : 16;
}
}
return bits;
}
+/**
+ * Finalize the mantissa bit count by adding in the grouped mantissas.
+ */
+static int compute_mantissa_size_final(int mant_cnt[5])
+{
+ // bap=1 : 3 mantissas in 5 bits
+ int bits = (mant_cnt[1] / 3) * 5;
+ // bap=2 : 3 mantissas in 7 bits
+ // bap=4 : 2 mantissas in 7 bits
+ bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
+ // bap=3 : each mantissa is 3 bits
+ bits += mant_cnt[3] * 3;
+ return bits;
+}
+
+
/**
* Calculate masking curve based on the final exponents.
* Also calculate the power spectral densities to use in future calculations.
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
AC3Block *block = &s->blocks[blk];
for (ch = 0; ch < s->channels; ch++) {
- if (block->exp_strategy[ch] == EXP_REUSE) {
- AC3Block *block1 = &s->blocks[blk-1];
- memcpy(block->psd[ch], block1->psd[ch], AC3_MAX_COEFS*sizeof(block->psd[0][0]));
- memcpy(block->mask[ch], block1->mask[ch], AC3_CRITICAL_BANDS*sizeof(block->mask[0][0]));
- } else {
+ /* We only need psd and mask for calculating bap.
+ Since we currently do not calculate bap when exponent
+ strategy is EXP_REUSE we do not need to calculate psd or mask. */
+ if (block->exp_strategy[ch] != EXP_REUSE) {
ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
s->nb_coefs[ch],
block->psd[ch], block->band_psd[ch]);
* @return the number of bits needed for mantissas if the given SNR offset is
* is used.
*/
-static int bit_alloc(AC3EncodeContext *s,
- int snr_offset)
+static int bit_alloc(AC3EncodeContext *s, int snr_offset)
{
int blk, ch;
int mantissa_bits;
+ int mant_cnt[5];
snr_offset = (snr_offset - 240) << 2;
mantissa_bits = 0;
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
AC3Block *block = &s->blocks[blk];
- s->mant1_cnt = 0;
- s->mant2_cnt = 0;
- s->mant4_cnt = 0;
+ // initialize grouped mantissa counts. these are set so that they are
+ // padded to the next whole group size when bits are counted in
+ // compute_mantissa_size_final
+ mant_cnt[0] = mant_cnt[3] = 0;
+ mant_cnt[1] = mant_cnt[2] = 2;
+ mant_cnt[4] = 1;
for (ch = 0; ch < s->channels; ch++) {
- 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]);
- mantissa_bits += compute_mantissa_size(s, block->bap[ch], s->nb_coefs[ch]);
+ /* Currently the only bit allocation parameters which vary across
+ blocks within a frame are the exponent values. We can take
+ advantage of that by reusing the bit allocation pointers
+ whenever we reuse exponents. */
+ if (block->exp_strategy[ch] == 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]);
+ }
+ mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
}
+ mantissa_bits += compute_mantissa_size_final(mant_cnt);
}
return mantissa_bits;
}
{
int ch;
int bits_left;
- int snr_offset;
+ int snr_offset, snr_incr;
bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
return AVERROR(EINVAL);
FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
- while (snr_offset + 64 <= 1023 &&
- bit_alloc(s, snr_offset + 64) <= bits_left) {
- snr_offset += 64;
- FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
- }
- while (snr_offset + 16 <= 1023 &&
- bit_alloc(s, snr_offset + 16) <= bits_left) {
- snr_offset += 16;
- FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
- }
- while (snr_offset + 4 <= 1023 &&
- bit_alloc(s, snr_offset + 4) <= bits_left) {
- snr_offset += 4;
- FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
- }
- while (snr_offset + 1 <= 1023 &&
- bit_alloc(s, snr_offset + 1) <= bits_left) {
- snr_offset++;
- FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
+ for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
+ while (snr_offset + 64 <= 1023 &&
+ bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
+ snr_offset += snr_incr;
+ FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
+ }
}
FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
reset_block_bap(s);
}
+/**
+ * Downgrade exponent strategies to reduce the bits used by the exponents.
+ * This is a fallback for when bit allocation fails with the normal exponent
+ * strategies. Each time this function is run it only downgrades the
+ * strategy in 1 channel of 1 block.
+ * @return non-zero if downgrade was unsuccessful
+ */
+static int downgrade_exponents(AC3EncodeContext *s)
+{
+ int ch, blk;
+
+ for (ch = 0; ch < s->fbw_channels; ch++) {
+ for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
+ if (s->blocks[blk].exp_strategy[ch] == EXP_D15) {
+ s->blocks[blk].exp_strategy[ch] = EXP_D25;
+ return 0;
+ }
+ }
+ }
+ for (ch = 0; ch < s->fbw_channels; ch++) {
+ for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
+ if (s->blocks[blk].exp_strategy[ch] == EXP_D25) {
+ s->blocks[blk].exp_strategy[ch] = EXP_D45;
+ return 0;
+ }
+ }
+ }
+ for (ch = 0; ch < s->fbw_channels; ch++) {
+ /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
+ the block number > 0 */
+ for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
+ if (s->blocks[blk].exp_strategy[ch] > EXP_REUSE) {
+ s->blocks[blk].exp_strategy[ch] = EXP_REUSE;
+ return 0;
+ }
+ }
+ }
+ return -1;
+}
+
+
+/**
+ * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
+ * This is a second fallback for when bit allocation still fails after exponents
+ * have been downgraded.
+ * @return non-zero if bandwidth reduction was unsuccessful
+ */
+static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
+{
+ int ch;
+
+ 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;
+ }
+ return 0;
+ }
+ return -1;
+}
+
+
/**
* Perform bit allocation search.
* Finds the SNR offset value that maximizes quality and fits in the specified
*/
static int compute_bit_allocation(AC3EncodeContext *s)
{
+ int ret;
+
count_frame_bits(s);
bit_alloc_masking(s);
- return cbr_bit_allocation(s);
+ ret = cbr_bit_allocation(s);
+ while (ret) {
+ /* fallback 1: downgrade exponents */
+ if (!downgrade_exponents(s)) {
+ extract_exponents(s);
+ encode_exponents(s);
+ group_exponents(s);
+ ret = compute_bit_allocation(s);
+ continue;
+ }
+
+ /* fallback 2: reduce bandwidth */
+ /* only do this if the user has not specified a specific cutoff
+ frequency */
+ if (!s->cutoff && !reduce_bandwidth(s, 0)) {
+ process_exponents(s);
+ ret = compute_bit_allocation(s);
+ continue;
+ }
+
+ /* fallbacks were not enough... */
+ break;
+ }
+
+ return ret;
}
/**
* Quantize a set of mantissas for a single channel in a single block.
*/
-static void quantize_mantissas_blk_ch(AC3EncodeContext *s,
- int32_t *mdct_coef, int8_t exp_shift,
- uint8_t *exp, uint8_t *bap,
- uint16_t *qmant, int n)
+static void quantize_mantissas_blk_ch(AC3EncodeContext *s, CoefType *mdct_coef,
+ int8_t exp_shift, uint8_t *exp,
+ uint8_t *bap, uint16_t *qmant, int n)
{
int i;
for (i = 0; i < n; i++) {
int v;
- int c = mdct_coef[i];
+ int c = SCALE_COEF(mdct_coef[i]);
int e = exp[i] - exp_shift;
int b = bap[i];
switch (b) {
/**
* Write one audio block to the output bitstream.
*/
-static void output_audio_block(AC3EncodeContext *s,
- int block_num)
+static void output_audio_block(AC3EncodeContext *s, int block_num)
{
int ch, i, baie, rbnd;
AC3Block *block = &s->blocks[block_num];
*/
static void output_frame_end(AC3EncodeContext *s)
{
- int frame_size, frame_size_58, pad_bytes, crc1, crc2, crc_inv;
+ const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
+ int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
uint8_t *frame;
- frame_size = s->frame_size;
- frame_size_58 = ((frame_size >> 2) + (frame_size >> 4)) << 1;
+ frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
/* pad the remainder of the frame with zeros */
flush_put_bits(&s->pb);
/* compute crc1 */
/* this is not so easy because it is at the beginning of the data... */
- crc1 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
- frame + 4, frame_size_58 - 4));
- /* XXX: could precompute crc_inv */
- crc_inv = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
+ crc1 = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
+ crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
AV_WB16(frame + 2, crc1);
/* compute crc2 */
- crc2 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
- frame + frame_size_58,
- frame_size - frame_size_58 - 2));
- AV_WB16(frame + frame_size - 2, crc2);
+ crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
+ s->frame_size - frame_size_58 - 3);
+ crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
+ /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
+ if (crc2 == 0x770B) {
+ frame[s->frame_size - 3] ^= 0x1;
+ crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
+ }
+ crc2 = av_bswap16(crc2);
+ AV_WB16(frame + s->frame_size - 2, crc2);
}
/**
* Write the frame to the output bitstream.
*/
-static void output_frame(AC3EncodeContext *s,
- unsigned char *frame)
+static void output_frame(AC3EncodeContext *s, unsigned char *frame)
{
int blk;
/**
* Encode a single AC-3 frame.
*/
-static int ac3_encode_frame(AVCodecContext *avctx,
- unsigned char *frame, int buf_size, void *data)
+static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
+ int buf_size, void *data)
{
AC3EncodeContext *s = avctx->priv_data;
- const int16_t *samples = data;
+ const SampleType *samples = data;
int ret;
if (s->bit_alloc.sr_code == 1)
s->bit_rate = avctx->bit_rate;
s->frame_size_code = i << 1;
+ /* validate cutoff */
+ if (avctx->cutoff < 0) {
+ av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
+ return AVERROR(EINVAL);
+ }
+ s->cutoff = avctx->cutoff;
+ if (s->cutoff > (s->sample_rate >> 1))
+ s->cutoff = s->sample_rate >> 1;
+
return 0;
}
* The user can optionally supply a cutoff frequency. Otherwise an appropriate
* default value will be used.
*/
-static av_cold void set_bandwidth(AC3EncodeContext *s, int cutoff)
+static av_cold void set_bandwidth(AC3EncodeContext *s)
{
int ch, bw_code;
- if (cutoff) {
+ if (s->cutoff) {
/* calculate bandwidth based on user-specified cutoff frequency */
int fbw_coeffs;
- cutoff = av_clip(cutoff, 1, s->sample_rate >> 1);
- fbw_coeffs = cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
+ fbw_coeffs = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
} else {
/* use default bandwidth setting */
static av_cold int ac3_encode_init(AVCodecContext *avctx)
{
AC3EncodeContext *s = avctx->priv_data;
- int ret;
+ int ret, frame_size_58;
avctx->frame_size = AC3_FRAME_SIZE;
s->samples_written = 0;
s->frame_size = s->frame_size_min;
- set_bandwidth(s, avctx->cutoff);
+ /* calculate crc_inv for both possible frame sizes */
+ frame_size_58 = (( s->frame_size >> 2) + ( s->frame_size >> 4)) << 1;
+ s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
+ if (s->bit_alloc.sr_code == 1) {
+ frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
+ s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
+ }
+
+ set_bandwidth(s);
exponent_init(s);
bit_alloc_init(s);
- s->mdct.avctx = avctx;
- ret = mdct_init(&s->mdct, 9);
+ ret = mdct_init(avctx, &s->mdct, 9);
if (ret)
goto init_fail;
#include "libavutil/lfg.h"
+#define MDCT_NBITS 9
+#define MDCT_SAMPLES (1 << MDCT_NBITS)
#define FN (MDCT_SAMPLES/4)
-static void fft_test(AVLFG *lfg)
+static void fft_test(AC3MDCTContext *mdct, AVLFG *lfg)
{
IComplex in[FN], in1[FN];
int k, n, i;
in[i].im = av_lfg_get(lfg) % 65535 - 32767;
in1[i] = in[i];
}
- fft(in, 7);
+ fft(mdct, in, 7);
/* do it by hand */
for (k = 0; k < FN; k++) {
}
-static void mdct_test(AVLFG *lfg)
+static void mdct_test(AC3MDCTContext *mdct, AVLFG *lfg)
{
int16_t input[MDCT_SAMPLES];
int32_t output[AC3_MAX_COEFS];
input1[i] = input[i];
}
- mdct512(output, input);
+ mdct512(mdct, output, input);
/* do it by hand */
for (k = 0; k < AC3_MAX_COEFS; k++) {
int main(void)
{
AVLFG lfg;
+ AC3MDCTContext mdct;
+ mdct.avctx = NULL;
av_log_set_level(AV_LOG_DEBUG);
- mdct_init(9);
+ mdct_init(&mdct, 9);
- fft_test(&lfg);
- mdct_test(&lfg);
+ fft_test(&mdct, &lfg);
+ mdct_test(&mdct, &lfg);
return 0;
}
NULL,
.sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},
.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
- .channel_layouts = (const int64_t[]){
- AV_CH_LAYOUT_MONO,
- AV_CH_LAYOUT_STEREO,
- AV_CH_LAYOUT_2_1,
- AV_CH_LAYOUT_SURROUND,
- AV_CH_LAYOUT_2_2,
- AV_CH_LAYOUT_QUAD,
- AV_CH_LAYOUT_4POINT0,
- AV_CH_LAYOUT_5POINT0,
- AV_CH_LAYOUT_5POINT0_BACK,
- (AV_CH_LAYOUT_MONO | AV_CH_LOW_FREQUENCY),
- (AV_CH_LAYOUT_STEREO | AV_CH_LOW_FREQUENCY),
- (AV_CH_LAYOUT_2_1 | AV_CH_LOW_FREQUENCY),
- (AV_CH_LAYOUT_SURROUND | AV_CH_LOW_FREQUENCY),
- (AV_CH_LAYOUT_2_2 | AV_CH_LOW_FREQUENCY),
- (AV_CH_LAYOUT_QUAD | AV_CH_LOW_FREQUENCY),
- (AV_CH_LAYOUT_4POINT0 | AV_CH_LOW_FREQUENCY),
- AV_CH_LAYOUT_5POINT1,
- AV_CH_LAYOUT_5POINT1_BACK,
- 0 },
+ .channel_layouts = ac3_channel_layouts,
};
projects / ffmpeg / blobdiff