[Ffmpeg-cvslog] r8305 - trunk/libavcodec/ac3.c
jbr
subversion
Fri Mar 9 14:54:44 CET 2007
Author: jbr
Date: Fri Mar 9 14:54:44 2007
New Revision: 8305
Added:
trunk/libavcodec/ac3.c
- copied, changed from r8304, /trunk/libavcodec/ac3enc.c
Log:
Create ac3.c which will be used for AC-3 common code.
Copied: trunk/libavcodec/ac3.c (from r8304, /trunk/libavcodec/ac3enc.c)
==============================================================================
--- /trunk/libavcodec/ac3enc.c (original)
+++ trunk/libavcodec/ac3.c Fri Mar 9 14:54:44 2007
@@ -1,5 +1,5 @@
/*
- * The simplest AC3 encoder
+ * Common code between AC3 encoder and decoder
* Copyright (c) 2000 Fabrice Bellard.
*
* This file is part of FFmpeg.
@@ -20,69 +20,14 @@
*/
/**
- * @file ac3enc.c
- * The simplest AC3 encoder.
+ * @file ac3.c
+ * Common code between AC3 encoder and decoder.
*/
-//#define DEBUG
-//#define DEBUG_BITALLOC
+
#include "avcodec.h"
-#include "bitstream.h"
-#include "crc.h"
#include "ac3.h"
-
-typedef struct AC3EncodeContext {
- PutBitContext pb;
- int nb_channels;
- int nb_all_channels;
- int lfe_channel;
- int bit_rate;
- unsigned int sample_rate;
- unsigned int bsid;
- unsigned int frame_size_min; /* minimum frame size in case rounding is necessary */
- unsigned int frame_size; /* current frame size in words */
- unsigned int bits_written;
- unsigned int samples_written;
- int halfratecod;
- unsigned int frmsizecod;
- unsigned int fscod; /* frequency */
- unsigned int acmod;
- int lfe;
- unsigned int bsmod;
- short last_samples[AC3_MAX_CHANNELS][256];
- unsigned int chbwcod[AC3_MAX_CHANNELS];
- int nb_coefs[AC3_MAX_CHANNELS];
-
- /* bitrate allocation control */
- int sgaincod, sdecaycod, fdecaycod, dbkneecod, floorcod;
- AC3BitAllocParameters bit_alloc;
- int csnroffst;
- int fgaincod[AC3_MAX_CHANNELS];
- int fsnroffst[AC3_MAX_CHANNELS];
- /* mantissa encoding */
- int mant1_cnt, mant2_cnt, mant4_cnt;
-} AC3EncodeContext;
-
#include "ac3tab.h"
-#define MDCT_NBITS 9
-#define N (1 << MDCT_NBITS)
-
-/* new exponents are sent if their Norm 1 exceed this number */
-#define EXP_DIFF_THRESHOLD 1000
-
-static void fft_init(int ln);
-
-static inline int16_t fix15(float a)
-{
- int v;
- v = (int)(a * (float)(1 << 15));
- if (v < -32767)
- v = -32767;
- else if (v > 32767)
- v = 32767;
- return v;
-}
-
static inline int calc_lowcomp1(int a, int b0, int b1, int c)
{
if ((b0 + 256) == b1) {
@@ -236,511 +181,6 @@ void ac3_parametric_bit_allocation(AC3Bi
} while (end > bndtab[j++]);
}
-typedef struct IComplex {
- short re,im;
-} IComplex;
-
-static void fft_init(int ln)
-{
- int i, j, m, n;
- float alpha;
-
- n = 1 << ln;
-
- for(i=0;i<(n/2);i++) {
- alpha = 2 * M_PI * (float)i / (float)n;
- costab[i] = fix15(cos(alpha));
- sintab[i] = fix15(sin(alpha));
- }
-
- for(i=0;i<n;i++) {
- m=0;
- for(j=0;j<ln;j++) {
- m |= ((i >> j) & 1) << (ln-j-1);
- }
- fft_rev[i]=m;
- }
-}
-
-/* butter fly op */
-#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
-{\
- int ax, ay, bx, by;\
- bx=pre1;\
- by=pim1;\
- ax=qre1;\
- ay=qim1;\
- pre = (bx + ax) >> 1;\
- pim = (by + ay) >> 1;\
- qre = (bx - ax) >> 1;\
- qim = (by - ay) >> 1;\
-}
-
-#define MUL16(a,b) ((a) * (b))
-
-#define CMUL(pre, pim, are, aim, bre, bim) \
-{\
- pre = (MUL16(are, bre) - MUL16(aim, bim)) >> 15;\
- pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15;\
-}
-
-
-/* do a 2^n point complex fft on 2^ln points. */
-static void fft(IComplex *z, int ln)
-{
- int j, l, np, np2;
- int nblocks, nloops;
- register IComplex *p,*q;
- int tmp_re, tmp_im;
-
- np = 1 << ln;
-
- /* reverse */
- for(j=0;j<np;j++) {
- int k;
- IComplex tmp;
- k = fft_rev[j];
- if (k < j) {
- tmp = z[k];
- z[k] = z[j];
- z[j] = tmp;
- }
- }
-
- /* pass 0 */
-
- p=&z[0];
- j=(np >> 1);
- do {
- BF(p[0].re, p[0].im, p[1].re, p[1].im,
- p[0].re, p[0].im, p[1].re, p[1].im);
- p+=2;
- } while (--j != 0);
-
- /* pass 1 */
-
- p=&z[0];
- j=np >> 2;
- do {
- BF(p[0].re, p[0].im, p[2].re, p[2].im,
- p[0].re, p[0].im, p[2].re, p[2].im);
- BF(p[1].re, p[1].im, p[3].re, p[3].im,
- p[1].re, p[1].im, p[3].im, -p[3].re);
- p+=4;
- } while (--j != 0);
-
- /* pass 2 .. ln-1 */
-
- nblocks = np >> 3;
- nloops = 1 << 2;
- np2 = np >> 1;
- do {
- p = z;
- q = z + nloops;
- for (j = 0; j < nblocks; ++j) {
-
- BF(p->re, p->im, q->re, q->im,
- p->re, p->im, q->re, q->im);
-
- p++;
- q++;
- for(l = nblocks; l < np2; l += nblocks) {
- CMUL(tmp_re, tmp_im, costab[l], -sintab[l], q->re, q->im);
- BF(p->re, p->im, q->re, q->im,
- p->re, p->im, tmp_re, tmp_im);
- p++;
- q++;
- }
- p += nloops;
- q += nloops;
- }
- nblocks = nblocks >> 1;
- nloops = nloops << 1;
- } while (nblocks != 0);
-}
-
-/* do a 512 point mdct */
-static void mdct512(int32_t *out, int16_t *in)
-{
- int i, re, im, re1, im1;
- int16_t rot[N];
- IComplex x[N/4];
-
- /* shift to simplify computations */
- for(i=0;i<N/4;i++)
- rot[i] = -in[i + 3*N/4];
- for(i=N/4;i<N;i++)
- rot[i] = in[i - N/4];
-
- /* pre rotation */
- for(i=0;i<N/4;i++) {
- re = ((int)rot[2*i] - (int)rot[N-1-2*i]) >> 1;
- im = -((int)rot[N/2+2*i] - (int)rot[N/2-1-2*i]) >> 1;
- CMUL(x[i].re, x[i].im, re, im, -xcos1[i], xsin1[i]);
- }
-
- fft(x, MDCT_NBITS - 2);
-
- /* post rotation */
- for(i=0;i<N/4;i++) {
- re = x[i].re;
- im = x[i].im;
- CMUL(re1, im1, re, im, xsin1[i], xcos1[i]);
- out[2*i] = im1;
- out[N/2-1-2*i] = re1;
- }
-}
-
-/* XXX: use another norm ? */
-static int calc_exp_diff(uint8_t *exp1, uint8_t *exp2, int n)
-{
- int sum, i;
- sum = 0;
- for(i=0;i<n;i++) {
- sum += abs(exp1[i] - exp2[i]);
- }
- return sum;
-}
-
-static void compute_exp_strategy(uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
- uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
- int ch, int is_lfe)
-{
- int i, j;
- int exp_diff;
-
- /* estimate if the exponent variation & decide if they should be
- reused in the next frame */
- exp_strategy[0][ch] = EXP_NEW;
- for(i=1;i<NB_BLOCKS;i++) {
- exp_diff = calc_exp_diff(exp[i][ch], exp[i-1][ch], N/2);
-#ifdef DEBUG
- av_log(NULL, AV_LOG_DEBUG, "exp_diff=%d\n", exp_diff);
-#endif
- if (exp_diff > EXP_DIFF_THRESHOLD)
- exp_strategy[i][ch] = EXP_NEW;
- else
- exp_strategy[i][ch] = EXP_REUSE;
- }
- if (is_lfe)
- return;
-
- /* now select the encoding strategy type : if exponents are often
- recoded, we use a coarse encoding */
- i = 0;
- while (i < NB_BLOCKS) {
- j = i + 1;
- while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE)
- j++;
- switch(j - i) {
- case 1:
- exp_strategy[i][ch] = EXP_D45;
- break;
- case 2:
- case 3:
- exp_strategy[i][ch] = EXP_D25;
- break;
- default:
- exp_strategy[i][ch] = EXP_D15;
- break;
- }
- i = j;
- }
-}
-
-/* set exp[i] to min(exp[i], exp1[i]) */
-static void exponent_min(uint8_t exp[N/2], uint8_t exp1[N/2], int n)
-{
- int i;
-
- for(i=0;i<n;i++) {
- if (exp1[i] < exp[i])
- exp[i] = exp1[i];
- }
-}
-
-/* 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[N/2],
- uint8_t exp[N/2],
- int nb_exps,
- int exp_strategy)
-{
- int group_size, nb_groups, i, j, k, exp_min;
- uint8_t exp1[N/2];
-
- switch(exp_strategy) {
- case EXP_D15:
- group_size = 1;
- break;
- case EXP_D25:
- group_size = 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];
- }
- exp1[i] = exp_min;
- k += group_size;
- }
-
- /* 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);
-
- /* 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;
- }
-
-#if defined(DEBUG)
- av_log(NULL, AV_LOG_DEBUG, "exponents: strategy=%d\n", exp_strategy);
- for(i=0;i<=nb_groups * group_size;i++) {
- av_log(NULL, AV_LOG_DEBUG, "%d ", encoded_exp[i]);
- }
- av_log(NULL, AV_LOG_DEBUG, "\n");
-#endif
-
- return 4 + (nb_groups / 3) * 7;
-}
-
-/* return the size in bits taken by the mantissa */
-static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *m, int nb_coefs)
-{
- int bits, mant, i;
-
- bits = 0;
- for(i=0;i<nb_coefs;i++) {
- mant = m[i];
- switch(mant) {
- case 0:
- /* nothing */
- break;
- case 1:
- /* 3 mantissa in 5 bits */
- if (s->mant1_cnt == 0)
- bits += 5;
- if (++s->mant1_cnt == 3)
- s->mant1_cnt = 0;
- break;
- case 2:
- /* 3 mantissa 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 mantissa 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:
- bits += mant - 1;
- break;
- }
- }
- return bits;
-}
-
-
-static int bit_alloc(AC3EncodeContext *s,
- uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
- uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
- uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
- int frame_bits, int csnroffst, int fsnroffst)
-{
- int i, ch;
-
- /* compute size */
- for(i=0;i<NB_BLOCKS;i++) {
- s->mant1_cnt = 0;
- s->mant2_cnt = 0;
- s->mant4_cnt = 0;
- for(ch=0;ch<s->nb_all_channels;ch++) {
- ac3_parametric_bit_allocation(&s->bit_alloc,
- bap[i][ch], (int8_t *)encoded_exp[i][ch],
- 0, s->nb_coefs[ch],
- (((csnroffst-15) << 4) +
- fsnroffst) << 2,
- fgaintab[s->fgaincod[ch]],
- ch == s->lfe_channel,
- 2, 0, NULL, NULL, NULL);
- frame_bits += compute_mantissa_size(s, bap[i][ch],
- s->nb_coefs[ch]);
- }
- }
-#if 0
- printf("csnr=%d fsnr=%d frame_bits=%d diff=%d\n",
- csnroffst, fsnroffst, frame_bits,
- 16 * s->frame_size - ((frame_bits + 7) & ~7));
-#endif
- return 16 * s->frame_size - frame_bits;
-}
-
-#define SNR_INC1 4
-
-static int compute_bit_allocation(AC3EncodeContext *s,
- uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
- uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
- uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
- int frame_bits)
-{
- int i, ch;
- int csnroffst, fsnroffst;
- uint8_t bap1[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
- static int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
-
- /* init default parameters */
- s->sdecaycod = 2;
- s->fdecaycod = 1;
- s->sgaincod = 1;
- s->dbkneecod = 2;
- s->floorcod = 4;
- for(ch=0;ch<s->nb_all_channels;ch++)
- s->fgaincod[ch] = 4;
-
- /* compute real values */
- s->bit_alloc.fscod = s->fscod;
- s->bit_alloc.halfratecod = s->halfratecod;
- s->bit_alloc.sdecay = sdecaytab[s->sdecaycod] >> s->halfratecod;
- s->bit_alloc.fdecay = fdecaytab[s->fdecaycod] >> s->halfratecod;
- s->bit_alloc.sgain = sgaintab[s->sgaincod];
- s->bit_alloc.dbknee = dbkneetab[s->dbkneecod];
- s->bit_alloc.floor = floortab[s->floorcod];
-
- /* header size */
- frame_bits += 65;
- // if (s->acmod == 2)
- // frame_bits += 2;
- frame_bits += frame_bits_inc[s->acmod];
-
- /* audio blocks */
- for(i=0;i<NB_BLOCKS;i++) {
- frame_bits += s->nb_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
- if (s->acmod == 2) {
- frame_bits++; /* rematstr */
- if(i==0) frame_bits += 4;
- }
- frame_bits += 2 * s->nb_channels; /* chexpstr[2] * c */
- if (s->lfe)
- frame_bits++; /* lfeexpstr */
- for(ch=0;ch<s->nb_channels;ch++) {
- if (exp_strategy[i][ch] != EXP_REUSE)
- frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
- }
- frame_bits++; /* baie */
- frame_bits++; /* snr */
- frame_bits += 2; /* delta / skip */
- }
- frame_bits++; /* cplinu for block 0 */
- /* bit alloc info */
- /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
- /* csnroffset[6] */
- /* (fsnoffset[4] + fgaincod[4]) * c */
- frame_bits += 2*4 + 3 + 6 + s->nb_all_channels * (4 + 3);
-
- /* auxdatae, crcrsv */
- frame_bits += 2;
-
- /* CRC */
- frame_bits += 16;
-
- /* now the big work begins : do the bit allocation. Modify the snr
- offset until we can pack everything in the requested frame size */
-
- csnroffst = s->csnroffst;
- while (csnroffst >= 0 &&
- bit_alloc(s, bap, encoded_exp, exp_strategy, frame_bits, csnroffst, 0) < 0)
- csnroffst -= SNR_INC1;
- if (csnroffst < 0) {
- av_log(NULL, AV_LOG_ERROR, "Bit allocation failed, try increasing the bitrate, -ab 384 for example!\n");
- return -1;
- }
- while ((csnroffst + SNR_INC1) <= 63 &&
- bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits,
- csnroffst + SNR_INC1, 0) >= 0) {
- csnroffst += SNR_INC1;
- memcpy(bap, bap1, sizeof(bap1));
- }
- while ((csnroffst + 1) <= 63 &&
- bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits, csnroffst + 1, 0) >= 0) {
- csnroffst++;
- memcpy(bap, bap1, sizeof(bap1));
- }
-
- fsnroffst = 0;
- while ((fsnroffst + SNR_INC1) <= 15 &&
- bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits,
- csnroffst, fsnroffst + SNR_INC1) >= 0) {
- fsnroffst += SNR_INC1;
- memcpy(bap, bap1, sizeof(bap1));
- }
- while ((fsnroffst + 1) <= 15 &&
- bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits,
- csnroffst, fsnroffst + 1) >= 0) {
- fsnroffst++;
- memcpy(bap, bap1, sizeof(bap1));
- }
-
- s->csnroffst = csnroffst;
- for(ch=0;ch<s->nb_all_channels;ch++)
- s->fsnroffst[ch] = fsnroffst;
-#if defined(DEBUG_BITALLOC)
- {
- int j;
-
- for(i=0;i<6;i++) {
- for(ch=0;ch<s->nb_all_channels;ch++) {
- printf("Block #%d Ch%d:\n", i, ch);
- printf("bap=");
- for(j=0;j<s->nb_coefs[ch];j++) {
- printf("%d ",bap[i][ch][j]);
- }
- printf("\n");
- }
- }
- }
-#endif
- return 0;
-}
-
void ac3_common_init(void)
{
int i, j, k, l, v;
@@ -755,750 +195,3 @@ void ac3_common_init(void)
}
bndtab[50] = l;
}
-
-
-static int AC3_encode_init(AVCodecContext *avctx)
-{
- int freq = avctx->sample_rate;
- int bitrate = avctx->bit_rate;
- int channels = avctx->channels;
- AC3EncodeContext *s = avctx->priv_data;
- int i, j, ch;
- float alpha;
- static const uint8_t acmod_defs[6] = {
- 0x01, /* C */
- 0x02, /* L R */
- 0x03, /* L C R */
- 0x06, /* L R SL SR */
- 0x07, /* L C R SL SR */
- 0x07, /* L C R SL SR (+LFE) */
- };
-
- avctx->frame_size = AC3_FRAME_SIZE;
-
- /* number of channels */
- if (channels < 1 || channels > 6)
- return -1;
- s->acmod = acmod_defs[channels - 1];
- s->lfe = (channels == 6) ? 1 : 0;
- s->nb_all_channels = channels;
- s->nb_channels = channels > 5 ? 5 : channels;
- s->lfe_channel = s->lfe ? 5 : -1;
-
- /* frequency */
- for(i=0;i<3;i++) {
- for(j=0;j<3;j++)
- if ((ac3_freqs[j] >> i) == freq)
- goto found;
- }
- return -1;
- found:
- s->sample_rate = freq;
- s->halfratecod = i;
- s->fscod = j;
- s->bsid = 8 + s->halfratecod;
- s->bsmod = 0; /* complete main audio service */
-
- /* bitrate & frame size */
- bitrate /= 1000;
- for(i=0;i<19;i++) {
- if ((ac3_bitratetab[i] >> s->halfratecod) == bitrate)
- break;
- }
- if (i == 19)
- return -1;
- s->bit_rate = bitrate;
- s->frmsizecod = i << 1;
- s->frame_size_min = (bitrate * 1000 * AC3_FRAME_SIZE) / (freq * 16);
- s->bits_written = 0;
- s->samples_written = 0;
- s->frame_size = s->frame_size_min;
-
- /* bit allocation init */
- for(ch=0;ch<s->nb_channels;ch++) {
- /* bandwidth for each channel */
- /* XXX: should compute the bandwidth according to the frame
- size, so that we avoid anoying high freq artefacts */
- s->chbwcod[ch] = 50; /* sample bandwidth as mpeg audio layer 2 table 0 */
- s->nb_coefs[ch] = ((s->chbwcod[ch] + 12) * 3) + 37;
- }
- if (s->lfe) {
- s->nb_coefs[s->lfe_channel] = 7; /* fixed */
- }
- /* initial snr offset */
- s->csnroffst = 40;
-
- ac3_common_init();
-
- /* mdct init */
- fft_init(MDCT_NBITS - 2);
- for(i=0;i<N/4;i++) {
- alpha = 2 * M_PI * (i + 1.0 / 8.0) / (float)N;
- xcos1[i] = fix15(-cos(alpha));
- xsin1[i] = fix15(-sin(alpha));
- }
-
- avctx->coded_frame= avcodec_alloc_frame();
- avctx->coded_frame->key_frame= 1;
-
- return 0;
-}
-
-/* output the AC3 frame header */
-static void output_frame_header(AC3EncodeContext *s, unsigned char *frame)
-{
- init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
-
- put_bits(&s->pb, 16, 0x0b77); /* frame header */
- put_bits(&s->pb, 16, 0); /* crc1: will be filled later */
- put_bits(&s->pb, 2, s->fscod);
- put_bits(&s->pb, 6, s->frmsizecod + (s->frame_size - s->frame_size_min));
- put_bits(&s->pb, 5, s->bsid);
- put_bits(&s->pb, 3, s->bsmod);
- put_bits(&s->pb, 3, s->acmod);
- if ((s->acmod & 0x01) && s->acmod != 0x01)
- put_bits(&s->pb, 2, 1); /* XXX -4.5 dB */
- if (s->acmod & 0x04)
- put_bits(&s->pb, 2, 1); /* XXX -6 dB */
- if (s->acmod == 0x02)
- put_bits(&s->pb, 2, 0); /* surround not indicated */
- put_bits(&s->pb, 1, s->lfe); /* LFE */
- put_bits(&s->pb, 5, 31); /* dialog norm: -31 db */
- put_bits(&s->pb, 1, 0); /* no compression control word */
- put_bits(&s->pb, 1, 0); /* no lang code */
- put_bits(&s->pb, 1, 0); /* no audio production info */
- put_bits(&s->pb, 1, 0); /* no copyright */
- put_bits(&s->pb, 1, 1); /* original bitstream */
- put_bits(&s->pb, 1, 0); /* no time code 1 */
- put_bits(&s->pb, 1, 0); /* no time code 2 */
- put_bits(&s->pb, 1, 0); /* no addtional bit stream info */
-}
-
-/* symetric quantization on 'levels' levels */
-static inline int sym_quant(int c, int e, int levels)
-{
- int v;
-
- if (c >= 0) {
- v = (levels * (c << e)) >> 24;
- v = (v + 1) >> 1;
- v = (levels >> 1) + v;
- } else {
- v = (levels * ((-c) << e)) >> 24;
- v = (v + 1) >> 1;
- v = (levels >> 1) - v;
- }
- assert (v >= 0 && v < levels);
- return v;
-}
-
-/* asymetric quantization on 2^qbits levels */
-static inline int asym_quant(int c, int e, int qbits)
-{
- int lshift, m, v;
-
- lshift = e + qbits - 24;
- if (lshift >= 0)
- v = c << lshift;
- else
- v = c >> (-lshift);
- /* rounding */
- v = (v + 1) >> 1;
- m = (1 << (qbits-1));
- if (v >= m)
- v = m - 1;
- assert(v >= -m);
- return v & ((1 << qbits)-1);
-}
-
-/* Output one audio block. There are NB_BLOCKS audio blocks in one AC3
- frame */
-static void output_audio_block(AC3EncodeContext *s,
- uint8_t exp_strategy[AC3_MAX_CHANNELS],
- uint8_t encoded_exp[AC3_MAX_CHANNELS][N/2],
- uint8_t bap[AC3_MAX_CHANNELS][N/2],
- int32_t mdct_coefs[AC3_MAX_CHANNELS][N/2],
- int8_t global_exp[AC3_MAX_CHANNELS],
- int block_num)
-{
- int ch, nb_groups, group_size, i, baie, rbnd;
- uint8_t *p;
- uint16_t qmant[AC3_MAX_CHANNELS][N/2];
- int exp0, exp1;
- int mant1_cnt, mant2_cnt, mant4_cnt;
- uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr;
- int delta0, delta1, delta2;
-
- for(ch=0;ch<s->nb_channels;ch++)
- put_bits(&s->pb, 1, 0); /* 512 point MDCT */
- for(ch=0;ch<s->nb_channels;ch++)
- put_bits(&s->pb, 1, 1); /* no dither */
- put_bits(&s->pb, 1, 0); /* no dynamic range */
- if (block_num == 0) {
- /* for block 0, even if no coupling, we must say it. This is a
- waste of bit :-) */
- put_bits(&s->pb, 1, 1); /* coupling strategy present */
- put_bits(&s->pb, 1, 0); /* no coupling strategy */
- } else {
- put_bits(&s->pb, 1, 0); /* no new coupling strategy */
- }
-
- if (s->acmod == 2)
- {
- if(block_num==0)
- {
- /* first block must define rematrixing (rematstr) */
- put_bits(&s->pb, 1, 1);
-
- /* dummy rematrixing rematflg(1:4)=0 */
- for (rbnd=0;rbnd<4;rbnd++)
- put_bits(&s->pb, 1, 0);
- }
- else
- {
- /* no matrixing (but should be used in the future) */
- put_bits(&s->pb, 1, 0);
- }
- }
-
-#if defined(DEBUG)
- {
- static int count = 0;
- av_log(NULL, AV_LOG_DEBUG, "Block #%d (%d)\n", block_num, count++);
- }
-#endif
- /* exponent strategy */
- for(ch=0;ch<s->nb_channels;ch++) {
- put_bits(&s->pb, 2, exp_strategy[ch]);
- }
-
- if (s->lfe) {
- put_bits(&s->pb, 1, exp_strategy[s->lfe_channel]);
- }
-
- for(ch=0;ch<s->nb_channels;ch++) {
- if (exp_strategy[ch] != EXP_REUSE)
- put_bits(&s->pb, 6, s->chbwcod[ch]);
- }
-
- /* exponents */
- for (ch = 0; ch < s->nb_all_channels; ch++) {
- switch(exp_strategy[ch]) {
- case 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);
- p = encoded_exp[ch];
-
- /* first exponent */
- exp1 = *p++;
- put_bits(&s->pb, 4, exp1);
-
- /* next ones are delta encoded */
- for(i=0;i<nb_groups;i++) {
- /* merge three delta in one code */
- exp0 = exp1;
- exp1 = p[0];
- p += group_size;
- delta0 = exp1 - exp0 + 2;
-
- exp0 = exp1;
- exp1 = p[0];
- p += group_size;
- delta1 = exp1 - exp0 + 2;
-
- exp0 = exp1;
- exp1 = p[0];
- p += group_size;
- delta2 = exp1 - exp0 + 2;
-
- put_bits(&s->pb, 7, ((delta0 * 5 + delta1) * 5) + delta2);
- }
-
- if (ch != s->lfe_channel)
- put_bits(&s->pb, 2, 0); /* no gain range info */
- }
-
- /* bit allocation info */
- baie = (block_num == 0);
- put_bits(&s->pb, 1, baie);
- if (baie) {
- put_bits(&s->pb, 2, s->sdecaycod);
- put_bits(&s->pb, 2, s->fdecaycod);
- put_bits(&s->pb, 2, s->sgaincod);
- put_bits(&s->pb, 2, s->dbkneecod);
- put_bits(&s->pb, 3, s->floorcod);
- }
-
- /* snr offset */
- put_bits(&s->pb, 1, baie); /* always present with bai */
- if (baie) {
- put_bits(&s->pb, 6, s->csnroffst);
- for(ch=0;ch<s->nb_all_channels;ch++) {
- put_bits(&s->pb, 4, s->fsnroffst[ch]);
- put_bits(&s->pb, 3, s->fgaincod[ch]);
- }
- }
-
- put_bits(&s->pb, 1, 0); /* no delta bit allocation */
- put_bits(&s->pb, 1, 0); /* no data to skip */
-
- /* mantissa encoding : we use two passes to handle the grouping. A
- one pass method may be faster, but it would necessitate to
- modify the output stream. */
-
- /* first pass: quantize */
- mant1_cnt = mant2_cnt = mant4_cnt = 0;
- qmant1_ptr = qmant2_ptr = qmant4_ptr = NULL;
-
- for (ch = 0; ch < s->nb_all_channels; ch++) {
- int b, c, e, v;
-
- for(i=0;i<s->nb_coefs[ch];i++) {
- c = mdct_coefs[ch][i];
- e = encoded_exp[ch][i] - global_exp[ch];
- b = bap[ch][i];
- switch(b) {
- case 0:
- v = 0;
- break;
- case 1:
- v = sym_quant(c, e, 3);
- switch(mant1_cnt) {
- case 0:
- qmant1_ptr = &qmant[ch][i];
- v = 9 * v;
- mant1_cnt = 1;
- break;
- case 1:
- *qmant1_ptr += 3 * v;
- mant1_cnt = 2;
- v = 128;
- break;
- default:
- *qmant1_ptr += v;
- mant1_cnt = 0;
- v = 128;
- break;
- }
- break;
- case 2:
- v = sym_quant(c, e, 5);
- switch(mant2_cnt) {
- case 0:
- qmant2_ptr = &qmant[ch][i];
- v = 25 * v;
- mant2_cnt = 1;
- break;
- case 1:
- *qmant2_ptr += 5 * v;
- mant2_cnt = 2;
- v = 128;
- break;
- default:
- *qmant2_ptr += v;
- mant2_cnt = 0;
- v = 128;
- break;
- }
- break;
- case 3:
- v = sym_quant(c, e, 7);
- break;
- case 4:
- v = sym_quant(c, e, 11);
- switch(mant4_cnt) {
- case 0:
- qmant4_ptr = &qmant[ch][i];
- v = 11 * v;
- mant4_cnt = 1;
- break;
- default:
- *qmant4_ptr += v;
- mant4_cnt = 0;
- v = 128;
- break;
- }
- break;
- case 5:
- v = sym_quant(c, e, 15);
- break;
- case 14:
- v = asym_quant(c, e, 14);
- break;
- case 15:
- v = asym_quant(c, e, 16);
- break;
- default:
- v = asym_quant(c, e, b - 1);
- break;
- }
- qmant[ch][i] = v;
- }
- }
-
- /* second pass : output the values */
- for (ch = 0; ch < s->nb_all_channels; ch++) {
- int b, q;
-
- for(i=0;i<s->nb_coefs[ch];i++) {
- q = qmant[ch][i];
- b = bap[ch][i];
- switch(b) {
- case 0:
- break;
- case 1:
- if (q != 128)
- put_bits(&s->pb, 5, q);
- break;
- case 2:
- if (q != 128)
- put_bits(&s->pb, 7, q);
- break;
- case 3:
- put_bits(&s->pb, 3, q);
- break;
- case 4:
- if (q != 128)
- put_bits(&s->pb, 7, q);
- break;
- case 14:
- put_bits(&s->pb, 14, q);
- break;
- case 15:
- put_bits(&s->pb, 16, q);
- break;
- default:
- put_bits(&s->pb, b - 1, q);
- break;
- }
- }
- }
-}
-
-#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
-
-static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
-{
- unsigned int c;
-
- c = 0;
- while (a) {
- if (a & 1)
- c ^= b;
- a = a >> 1;
- b = b << 1;
- if (b & (1 << 16))
- b ^= poly;
- }
- return c;
-}
-
-static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
-{
- unsigned int r;
- r = 1;
- while (n) {
- if (n & 1)
- r = mul_poly(r, a, poly);
- a = mul_poly(a, a, poly);
- n >>= 1;
- }
- return r;
-}
-
-
-/* compute log2(max(abs(tab[]))) */
-static int log2_tab(int16_t *tab, int n)
-{
- int i, v;
-
- v = 0;
- for(i=0;i<n;i++) {
- v |= abs(tab[i]);
- }
- return av_log2(v);
-}
-
-static void lshift_tab(int16_t *tab, int n, int lshift)
-{
- int i;
-
- if (lshift > 0) {
- for(i=0;i<n;i++) {
- tab[i] <<= lshift;
- }
- } else if (lshift < 0) {
- lshift = -lshift;
- for(i=0;i<n;i++) {
- tab[i] >>= lshift;
- }
- }
-}
-
-/* fill the end of the frame and compute the two crcs */
-static int output_frame_end(AC3EncodeContext *s)
-{
- int frame_size, frame_size_58, n, crc1, crc2, crc_inv;
- uint8_t *frame;
-
- frame_size = s->frame_size; /* frame size in words */
- /* align to 8 bits */
- flush_put_bits(&s->pb);
- /* add zero bytes to reach the frame size */
- frame = s->pb.buf;
- n = 2 * s->frame_size - (pbBufPtr(&s->pb) - frame) - 2;
- assert(n >= 0);
- if(n>0)
- memset(pbBufPtr(&s->pb), 0, n);
-
- /* Now we must compute both crcs : this is not so easy for crc1
- because it is at the beginning of the data... */
- frame_size_58 = (frame_size >> 1) + (frame_size >> 3);
- crc1 = bswap_16(av_crc(av_crc8005, 0, frame + 4, 2 * frame_size_58 - 4));
- /* XXX: could precompute crc_inv */
- crc_inv = pow_poly((CRC16_POLY >> 1), (16 * frame_size_58) - 16, CRC16_POLY);
- crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
- frame[2] = crc1 >> 8;
- frame[3] = crc1;
-
- crc2 = bswap_16(av_crc(av_crc8005, 0, frame + 2 * frame_size_58, (frame_size - frame_size_58) * 2 - 2));
- frame[2*frame_size - 2] = crc2 >> 8;
- frame[2*frame_size - 1] = crc2;
-
- // printf("n=%d frame_size=%d\n", n, frame_size);
- return frame_size * 2;
-}
-
-static int AC3_encode_frame(AVCodecContext *avctx,
- unsigned char *frame, int buf_size, void *data)
-{
- AC3EncodeContext *s = avctx->priv_data;
- int16_t *samples = data;
- int i, j, k, v, ch;
- int16_t input_samples[N];
- int32_t mdct_coef[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
- uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
- uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS];
- uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
- uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
- int8_t exp_samples[NB_BLOCKS][AC3_MAX_CHANNELS];
- int frame_bits;
-
- frame_bits = 0;
- for(ch=0;ch<s->nb_all_channels;ch++) {
- /* fixed mdct to the six sub blocks & exponent computation */
- for(i=0;i<NB_BLOCKS;i++) {
- int16_t *sptr;
- int sinc;
-
- /* compute input samples */
- memcpy(input_samples, s->last_samples[ch], N/2 * sizeof(int16_t));
- sinc = s->nb_all_channels;
- sptr = samples + (sinc * (N/2) * i) + ch;
- for(j=0;j<N/2;j++) {
- v = *sptr;
- input_samples[j + N/2] = v;
- s->last_samples[ch][j] = v;
- sptr += sinc;
- }
-
- /* apply the MDCT window */
- for(j=0;j<N/2;j++) {
- input_samples[j] = MUL16(input_samples[j],
- ac3_window[j]) >> 15;
- input_samples[N-j-1] = MUL16(input_samples[N-j-1],
- ac3_window[j]) >> 15;
- }
-
- /* Normalize the samples to use the maximum available
- precision */
- v = 14 - log2_tab(input_samples, N);
- if (v < 0)
- v = 0;
- exp_samples[i][ch] = v - 10;
- lshift_tab(input_samples, N, v);
-
- /* do the MDCT */
- mdct512(mdct_coef[i][ch], input_samples);
-
- /* compute "exponents". We take into account the
- normalization there */
- for(j=0;j<N/2;j++) {
- int e;
- v = abs(mdct_coef[i][ch][j]);
- if (v == 0)
- e = 24;
- else {
- e = 23 - av_log2(v) + exp_samples[i][ch];
- if (e >= 24) {
- e = 24;
- mdct_coef[i][ch][j] = 0;
- }
- }
- exp[i][ch][j] = e;
- }
- }
-
- compute_exp_strategy(exp_strategy, exp, ch, ch == s->lfe_channel);
-
- /* compute the exponents as the decoder will see them. The
- EXP_REUSE case must be handled carefully : we select the
- min of the exponents */
- i = 0;
- while (i < NB_BLOCKS) {
- j = i + 1;
- while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE) {
- 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],
- 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],
- s->nb_coefs[ch] * sizeof(uint8_t));
- }
- i = j;
- }
- }
-
- /* adjust for fractional frame sizes */
- while(s->bits_written >= s->bit_rate*1000 && s->samples_written >= s->sample_rate) {
- s->bits_written -= s->bit_rate*1000;
- s->samples_written -= s->sample_rate;
- }
- s->frame_size = s->frame_size_min + (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate*1000);
- s->bits_written += s->frame_size * 16;
- s->samples_written += AC3_FRAME_SIZE;
-
- compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits);
- /* everything is known... let's output the frame */
- output_frame_header(s, frame);
-
- for(i=0;i<NB_BLOCKS;i++) {
- output_audio_block(s, exp_strategy[i], encoded_exp[i],
- bap[i], mdct_coef[i], exp_samples[i], i);
- }
- return output_frame_end(s);
-}
-
-static int AC3_encode_close(AVCodecContext *avctx)
-{
- av_freep(&avctx->coded_frame);
- return 0;
-}
-
-#if 0
-/*************************************************************************/
-/* TEST */
-
-#define FN (N/4)
-
-void fft_test(void)
-{
- IComplex in[FN], in1[FN];
- int k, n, i;
- float sum_re, sum_im, a;
-
- /* FFT test */
-
- for(i=0;i<FN;i++) {
- in[i].re = random() % 65535 - 32767;
- in[i].im = random() % 65535 - 32767;
- in1[i] = in[i];
- }
- fft(in, 7);
-
- /* do it by hand */
- for(k=0;k<FN;k++) {
- sum_re = 0;
- sum_im = 0;
- for(n=0;n<FN;n++) {
- a = -2 * M_PI * (n * k) / FN;
- sum_re += in1[n].re * cos(a) - in1[n].im * sin(a);
- sum_im += in1[n].re * sin(a) + in1[n].im * cos(a);
- }
- printf("%3d: %6d,%6d %6.0f,%6.0f\n",
- k, in[k].re, in[k].im, sum_re / FN, sum_im / FN);
- }
-}
-
-void mdct_test(void)
-{
- int16_t input[N];
- int32_t output[N/2];
- float input1[N];
- float output1[N/2];
- float s, a, err, e, emax;
- int i, k, n;
-
- for(i=0;i<N;i++) {
- input[i] = (random() % 65535 - 32767) * 9 / 10;
- input1[i] = input[i];
- }
-
- mdct512(output, input);
-
- /* do it by hand */
- for(k=0;k<N/2;k++) {
- s = 0;
- for(n=0;n<N;n++) {
- a = (2*M_PI*(2*n+1+N/2)*(2*k+1) / (4 * N));
- s += input1[n] * cos(a);
- }
- output1[k] = -2 * s / N;
- }
-
- err = 0;
- emax = 0;
- for(i=0;i<N/2;i++) {
- printf("%3d: %7d %7.0f\n", i, output[i], output1[i]);
- e = output[i] - output1[i];
- if (e > emax)
- emax = e;
- err += e * e;
- }
- printf("err2=%f emax=%f\n", err / (N/2), emax);
-}
-
-void test_ac3(void)
-{
- AC3EncodeContext ctx;
- unsigned char frame[AC3_MAX_CODED_FRAME_SIZE];
- short samples[AC3_FRAME_SIZE];
- int ret, i;
-
- AC3_encode_init(&ctx, 44100, 64000, 1);
-
- fft_test();
- mdct_test();
-
- for(i=0;i<AC3_FRAME_SIZE;i++)
- samples[i] = (int)(sin(2*M_PI*i*1000.0/44100) * 10000);
- ret = AC3_encode_frame(&ctx, frame, samples);
- printf("ret=%d\n", ret);
-}
-#endif
-
-AVCodec ac3_encoder = {
- "ac3",
- CODEC_TYPE_AUDIO,
- CODEC_ID_AC3,
- sizeof(AC3EncodeContext),
- AC3_encode_init,
- AC3_encode_frame,
- AC3_encode_close,
- NULL,
-};
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