* Table of bin locations for rematrixing bands
* reference: Section 7.5.2 Rematrixing : Frequency Band Definitions
*/
-static const uint8_t rematrix_band_tbl[5] = { 13, 25, 37, 61, 253 };
+static const uint8_t rematrix_band_tab[5] = { 13, 25, 37, 61, 253 };
-/* table for exponent to scale_factor mapping
- * scale_factor[i] = 2 ^ -(i + 15)
+/**
+ * table for exponent to scale_factor mapping
+ * scale_factors[i] = 2 ^ -i
*/
static float scale_factors[25];
/** table for grouping exponents */
-static uint8_t exp_ungroup_tbl[128][3];
+static uint8_t exp_ungroup_tab[128][3];
/** tables for ungrouping mantissas */
};
/** dynamic range table. converts codes to scale factors. */
-static float dynrng_tbl[256];
+static float dynrng_tab[256];
+
+/** dialogue normalization table */
+static float dialnorm_tab[32];
-/* Adjustmens in dB gain */
+/** Adjustments in dB gain */
#define LEVEL_MINUS_3DB 0.7071067811865476
#define LEVEL_MINUS_4POINT5DB 0.5946035575013605
#define LEVEL_MINUS_6DB 0.5000000000000000
-#define LEVEL_PLUS_3DB 1.4142135623730951
-#define LEVEL_PLUS_6DB 2.0000000000000000
+#define LEVEL_MINUS_9DB 0.3535533905932738
#define LEVEL_ZERO 0.0000000000000000
+#define LEVEL_ONE 1.0000000000000000
+
+static const float gain_levels[6] = {
+ LEVEL_ZERO,
+ LEVEL_ONE,
+ LEVEL_MINUS_3DB,
+ LEVEL_MINUS_4POINT5DB,
+ LEVEL_MINUS_6DB,
+ LEVEL_MINUS_9DB
+};
+
+/**
+ * Table for center mix levels
+ * reference: Section 5.4.2.4 cmixlev
+ */
+static const uint8_t clevs[4] = { 2, 3, 4, 3 };
+
+/**
+ * Table for surround mix levels
+ * reference: Section 5.4.2.5 surmixlev
+ */
+static const uint8_t slevs[4] = { 2, 4, 0, 4 };
-static const float clevs[4] = { LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB,
- LEVEL_MINUS_6DB, LEVEL_MINUS_4POINT5DB };
+/**
+ * Table for default stereo downmixing coefficients
+ * reference: Section 7.8.2 Downmixing Into Two Channels
+ */
+static const uint8_t ac3_default_coeffs[8][5][2] = {
+ { { 1, 0 }, { 0, 1 }, },
+ { { 2, 2 }, },
+ { { 1, 0 }, { 0, 1 }, },
+ { { 1, 0 }, { 3, 3 }, { 0, 1 }, },
+ { { 1, 0 }, { 0, 1 }, { 4, 4 }, },
+ { { 1, 0 }, { 3, 3 }, { 0, 1 }, { 5, 5 }, },
+ { { 1, 0 }, { 0, 1 }, { 4, 0 }, { 0, 4 }, },
+ { { 1, 0 }, { 3, 3 }, { 0, 1 }, { 4, 0 }, { 0, 4 }, },
+};
-static const float slevs[4] = { LEVEL_MINUS_3DB, LEVEL_MINUS_6DB, LEVEL_ZERO, LEVEL_MINUS_6DB };
+/* override ac3.h to include coupling channel */
+#undef AC3_MAX_CHANNELS
+#define AC3_MAX_CHANNELS 7
+#define CPL_CH 0
#define AC3_OUTPUT_LFEON 8
typedef struct {
- int acmod;
- int cmixlev;
- int surmixlev;
- int dsurmod;
-
- int blksw[AC3_MAX_CHANNELS];
- int dithflag[AC3_MAX_CHANNELS];
- int dither_all;
- int cplinu;
- int chincpl[AC3_MAX_CHANNELS];
- int phsflginu;
- int cplcoe;
- uint32_t cplbndstrc;
- int rematstr;
- int nrematbnd;
- int rematflg[AC3_MAX_CHANNELS];
- int cplexpstr;
- int lfeexpstr;
- int chexpstr[5];
- int cplsnroffst;
- int cplfgain;
- int snroffst[5];
- int fgain[5];
- int lfesnroffst;
- int lfefgain;
- int cpldeltbae;
- int deltbae[5];
- int cpldeltnseg;
- uint8_t cpldeltoffst[8];
- uint8_t cpldeltlen[8];
- uint8_t cpldeltba[8];
- int deltnseg[5];
- uint8_t deltoffst[5][8];
- uint8_t deltlen[5][8];
- uint8_t deltba[5][8];
-
- /* Derived Attributes. */
- int sampling_rate;
- int bit_rate;
- int frame_size;
-
- int nchans; //number of total channels
- int nfchans; //number of full-bandwidth channels
- int lfeon; //lfe channel in use
- int output_mode; ///< output channel configuration
- int out_channels; ///< number of output channels
-
- float dynrng; //dynamic range gain
- float dynrng2; //dynamic range gain for 1+1 mode
- float cplco[5][18]; //coupling coordinates
- int ncplbnd; //number of coupling bands
- int ncplsubnd; //number of coupling sub bands
- int cplstrtmant; //coupling start mantissa
- int cplendmant; //coupling end mantissa
- int endmant[5]; //channel end mantissas
+ int acmod; ///< audio coding mode
+ int dsurmod; ///< dolby surround mode
+ int blksw[AC3_MAX_CHANNELS]; ///< block switch flags
+ int dithflag[AC3_MAX_CHANNELS]; ///< dither flags
+ int dither_all; ///< true if all channels are dithered
+ int cplinu; ///< coupling in use
+ int chincpl[AC3_MAX_CHANNELS]; ///< channel in coupling
+ int phsflginu; ///< phase flags in use
+ int cplbndstrc[18]; ///< coupling band structure
+ int rematstr; ///< rematrixing strategy
+ int nrematbnd; ///< number of rematrixing bands
+ int rematflg[4]; ///< rematrixing flags
+ int expstr[AC3_MAX_CHANNELS]; ///< exponent strategies
+ int snroffst[AC3_MAX_CHANNELS]; ///< signal-to-noise ratio offsets
+ int fgain[AC3_MAX_CHANNELS]; ///< fast gain values (signal-to-mask ratio)
+ int deltbae[AC3_MAX_CHANNELS]; ///< delta bit allocation exists
+ int deltnseg[AC3_MAX_CHANNELS]; ///< number of delta segments
+ uint8_t deltoffst[AC3_MAX_CHANNELS][8]; ///< delta segment offsets
+ uint8_t deltlen[AC3_MAX_CHANNELS][8]; ///< delta segment lengths
+ uint8_t deltba[AC3_MAX_CHANNELS][8]; ///< delta values for each segment
+
+ int sampling_rate; ///< sample frequency, in Hz
+ int bit_rate; ///< stream bit rate, in bits-per-second
+ int frame_size; ///< current frame size, in bytes
+
+ int nchans; ///< number of total channels
+ int nfchans; ///< number of full-bandwidth channels
+ int lfeon; ///< lfe channel in use
+ int lfe_ch; ///< index of LFE channel
+ int output_mode; ///< output channel configuration
+ int out_channels; ///< number of output channels
+
+ float downmix_coeffs[AC3_MAX_CHANNELS][2]; ///< stereo downmix coefficients
+ float dialnorm[2]; ///< dialogue normalization
+ float dynrng[2]; ///< dynamic range
+ float cplco[AC3_MAX_CHANNELS][18]; ///< coupling coordinates
+ int ncplbnd; ///< number of coupling bands
+ int ncplsubnd; ///< number of coupling sub bands
+ int startmant[AC3_MAX_CHANNELS]; ///< start frequency bin
+ int endmant[AC3_MAX_CHANNELS]; ///< end frequency bin
AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters
- int8_t dcplexps[256]; //decoded coupling exponents
- int8_t dexps[5][256]; //decoded fbw channel exponents
- int8_t dlfeexps[256]; //decoded lfe channel exponents
- uint8_t cplbap[256]; //coupling bit allocation pointers
- uint8_t bap[5][256]; //fbw channel bit allocation pointers
- uint8_t lfebap[256]; //lfe channel bit allocation pointers
+ int8_t dexps[AC3_MAX_CHANNELS][256]; ///< decoded exponents
+ uint8_t bap[AC3_MAX_CHANNELS][256]; ///< bit allocation pointers
+ int16_t psd[AC3_MAX_CHANNELS][256]; ///< scaled exponents
+ int16_t bndpsd[AC3_MAX_CHANNELS][50]; ///< interpolated exponents
+ int16_t mask[AC3_MAX_CHANNELS][50]; ///< masking curve values
- float transform_coeffs_cpl[256];
- DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][256]); //transform coefficients
+ DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][256]); ///< transform coefficients
/* For IMDCT. */
- MDCTContext imdct_512; //for 512 sample imdct transform
- MDCTContext imdct_256; //for 256 sample imdct transform
- DSPContext dsp; //for optimization
-
- DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS][256]); //output after imdct transform and windowing
- DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS][256]); //delay - added to the next block
- DECLARE_ALIGNED_16(float, tmp_imdct[256]); //temporary storage for imdct transform
- DECLARE_ALIGNED_16(float, tmp_output[512]); //temporary storage for output before windowing
- DECLARE_ALIGNED_16(float, window[256]); //window coefficients
+ MDCTContext imdct_512; ///< for 512 sample IMDCT
+ MDCTContext imdct_256; ///< for 256 sample IMDCT
+ DSPContext dsp; ///< for optimization
+ float add_bias; ///< offset for float_to_int16 conversion
+ float mul_bias; ///< scaling for float_to_int16 conversion
+
+ DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS-1][256]); ///< output after imdct transform and windowing
+ DECLARE_ALIGNED_16(short, int_output[AC3_MAX_CHANNELS-1][256]); ///< final 16-bit integer output
+ DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS-1][256]); ///< delay - added to the next block
+ DECLARE_ALIGNED_16(float, tmp_imdct[256]); ///< temporary storage for imdct transform
+ DECLARE_ALIGNED_16(float, tmp_output[512]); ///< temporary storage for output before windowing
+ DECLARE_ALIGNED_16(float, window[256]); ///< window coefficients
/* Miscellaneous. */
- GetBitContext gb;
- AVRandomState dith_state; //for dither generation
+ GetBitContext gb; ///< bitstream reader
+ AVRandomState dith_state; ///< for dither generation
+ AVCodecContext *avctx; ///< parent context
} AC3DecodeContext;
-/*********** BEGIN INIT HELPER FUNCTIONS ***********/
/**
* Generate a Kaiser-Bessel Derived Window.
*/
for (i = 0; i < 256; i++) {
tmp = i * (256 - i) * alpha2;
bessel = 1.0;
- for (j = 100; j > 0; j--) /* defaul to 100 iterations */
+ for (j = 100; j > 0; j--) /* default to 100 iterations */
bessel = bessel * tmp / (j * j) + 1;
sum += bessel;
local_window[i] = sum;
window[i] = sqrt(local_window[i] / sum);
}
+/**
+ * Symmetrical Dequantization
+ * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
+ * Tables 7.19 to 7.23
+ */
static inline float
symmetric_dequant(int code, int levels)
{
reference: Section 7.7.1 Dynamic Range Control */
for(i=0; i<256; i++) {
int v = (i >> 5) - ((i >> 7) << 3) - 5;
- dynrng_tbl[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
+ dynrng_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
+ }
+
+ /* generate dialogue normalization table
+ references: Section 5.4.2.8 dialnorm
+ Section 7.6 Dialogue Normalization */
+ for(i=1; i<32; i++) {
+ dialnorm_tab[i] = expf((i-31) * M_LN10 / 20.0f);
}
+ dialnorm_tab[0] = dialnorm_tab[31];
- //generate scale factors
+ /* generate scale factors for exponents and asymmetrical dequantization
+ reference: Section 7.3.2 Expansion of Mantissas for Asymmetric Quantization */
for (i = 0; i < 25; i++)
scale_factors[i] = pow(2.0, -i);
/* generate exponent tables
reference: Section 7.1.3 Exponent Decoding */
for(i=0; i<128; i++) {
- exp_ungroup_tbl[i][0] = i / 25;
- exp_ungroup_tbl[i][1] = (i % 25) / 5;
- exp_ungroup_tbl[i][2] = (i % 25) % 5;
+ exp_ungroup_tab[i][0] = i / 25;
+ exp_ungroup_tab[i][1] = (i % 25) / 5;
+ exp_ungroup_tab[i][2] = (i % 25) % 5;
}
}
+/**
+ * AVCodec initialization
+ */
static int ac3_decode_init(AVCodecContext *avctx)
{
AC3DecodeContext *ctx = avctx->priv_data;
+ ctx->avctx = avctx;
ac3_common_init();
ac3_tables_init();
dsputil_init(&ctx->dsp, avctx);
av_init_random(0, &ctx->dith_state);
+ /* set bias values for float to int16 conversion */
+ if(ctx->dsp.float_to_int16 == ff_float_to_int16_c) {
+ ctx->add_bias = 385.0f;
+ ctx->mul_bias = 1.0f;
+ } else {
+ ctx->add_bias = 0.0f;
+ ctx->mul_bias = 32767.0f;
+ }
+
return 0;
}
-/*********** END INIT FUNCTIONS ***********/
/**
- * Parses the 'sync info' and 'bit stream info' from the AC-3 bitstream.
+ * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
* GetBitContext within AC3DecodeContext must point to
* start of the synchronized ac3 bitstream.
*/
{
AC3HeaderInfo hdr;
GetBitContext *gb = &ctx->gb;
+ float cmixlev, surmixlev;
int err, i;
err = ff_ac3_parse_header(gb->buffer, &hdr);
/* get decoding parameters from header info */
ctx->bit_alloc_params.fscod = hdr.fscod;
ctx->acmod = hdr.acmod;
- ctx->cmixlev = hdr.cmixlev;
- ctx->surmixlev = hdr.surmixlev;
+ cmixlev = gain_levels[clevs[hdr.cmixlev]];
+ surmixlev = gain_levels[slevs[hdr.surmixlev]];
ctx->dsurmod = hdr.dsurmod;
ctx->lfeon = hdr.lfeon;
ctx->bit_alloc_params.halfratecod = hdr.halfratecod;
ctx->bit_rate = hdr.bit_rate;
ctx->nchans = hdr.channels;
ctx->nfchans = ctx->nchans - ctx->lfeon;
+ ctx->lfe_ch = ctx->nfchans + 1;
ctx->frame_size = hdr.frame_size;
/* set default output to all source channels */
ctx->output_mode |= AC3_OUTPUT_LFEON;
/* skip over portion of header which has already been read */
- skip_bits(gb, 16); //skip the sync_word, sync_info->sync_word = get_bits(gb, 16);
+ skip_bits(gb, 16); // skip the sync_word
skip_bits(gb, 16); // skip crc1
skip_bits(gb, 8); // skip fscod and frmsizecod
skip_bits(gb, 11); // skip bsid, bsmod, and acmod
/* read the rest of the bsi. read twice for dual mono mode. */
i = !(ctx->acmod);
do {
- skip_bits(gb, 5); //skip dialog normalization
+ ctx->dialnorm[i] = dialnorm_tab[get_bits(gb, 5)]; // dialogue normalization
if (get_bits1(gb))
skip_bits(gb, 8); //skip compression
if (get_bits1(gb))
skip_bits(gb, 2); //skip copyright bit and original bitstream bit
- /* FIXME: read & use the xbsi1 downmix levels */
+ /* skip the timecodes (or extra bitstream information for Alternate Syntax)
+ TODO: read & use the xbsi1 downmix levels */
if (get_bits1(gb))
- skip_bits(gb, 14); //skip timecode1
+ skip_bits(gb, 14); //skip timecode1 / xbsi1
if (get_bits1(gb))
- skip_bits(gb, 14); //skip timecode2
+ skip_bits(gb, 14); //skip timecode2 / xbsi2
+ /* skip additional bitstream info */
if (get_bits1(gb)) {
- i = get_bits(gb, 6); //additional bsi length
+ i = get_bits(gb, 6);
do {
skip_bits(gb, 8);
} while(i--);
}
+ /* set stereo downmixing coefficients
+ reference: Section 7.8.2 Downmixing Into Two Channels */
+ for(i=0; i<ctx->nfchans; i++) {
+ ctx->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[ctx->acmod][i][0]];
+ ctx->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[ctx->acmod][i][1]];
+ }
+ if(ctx->acmod > 1 && ctx->acmod & 1) {
+ ctx->downmix_coeffs[1][0] = ctx->downmix_coeffs[1][1] = cmixlev;
+ }
+ if(ctx->acmod == AC3_ACMOD_2F1R || ctx->acmod == AC3_ACMOD_3F1R) {
+ int nf = ctx->acmod - 2;
+ ctx->downmix_coeffs[nf][0] = ctx->downmix_coeffs[nf][1] = surmixlev * LEVEL_MINUS_3DB;
+ }
+ if(ctx->acmod == AC3_ACMOD_2F2R || ctx->acmod == AC3_ACMOD_3F2R) {
+ int nf = ctx->acmod - 4;
+ ctx->downmix_coeffs[nf][0] = ctx->downmix_coeffs[nf+1][1] = surmixlev;
+ }
+
return 0;
}
/**
- * Decodes the grouped exponents.
- * This function decodes the coded exponents according to exponent strategy
- * and stores them in the decoded exponents buffer.
- *
- * @param[in] gb GetBitContext which points to start of coded exponents
- * @param[in] expstr Exponent coding strategy
- * @param[in] ngrps Number of grouped exponents
- * @param[in] absexp Absolute exponent or DC exponent
- * @param[out] dexps Decoded exponents are stored in dexps
+ * Decode the grouped exponents according to exponent strategy.
+ * reference: Section 7.1.3 Exponent Decoding
*/
static void decode_exponents(GetBitContext *gb, int expstr, int ngrps,
uint8_t absexp, int8_t *dexps)
grpsize = expstr + (expstr == EXP_D45);
for(grp=0,i=0; grp<ngrps; grp++) {
expacc = get_bits(gb, 7);
- dexp[i++] = exp_ungroup_tbl[expacc][0];
- dexp[i++] = exp_ungroup_tbl[expacc][1];
- dexp[i++] = exp_ungroup_tbl[expacc][2];
+ dexp[i++] = exp_ungroup_tab[expacc][0];
+ dexp[i++] = exp_ungroup_tab[expacc][1];
+ dexp[i++] = exp_ungroup_tab[expacc][2];
}
/* convert to absolute exps and expand groups */
}
/**
- * Generates transform coefficients for each coupled channel in the coupling
+ * Generate transform coefficients for each coupled channel in the coupling
* range using the coupling coefficients and coupling coordinates.
* reference: Section 7.4.3 Coupling Coordinate Format
*/
int i, j, ch, bnd, subbnd;
subbnd = -1;
- i = ctx->cplstrtmant;
+ i = ctx->startmant[CPL_CH];
for(bnd=0; bnd<ctx->ncplbnd; bnd++) {
do {
subbnd++;
for(j=0; j<12; j++) {
for(ch=1; ch<=ctx->nfchans; ch++) {
- if(ctx->chincpl[ch-1])
- ctx->transform_coeffs[ch][i] = ctx->transform_coeffs_cpl[i] * ctx->cplco[ch-1][bnd] * 8.0f;
+ if(ctx->chincpl[ch])
+ ctx->transform_coeffs[ch][i] = ctx->transform_coeffs[CPL_CH][i] * ctx->cplco[ch][bnd] * 8.0f;
}
i++;
}
- } while((ctx->cplbndstrc >> subbnd) & 1);
+ } while(ctx->cplbndstrc[subbnd]);
}
}
-typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantization */
+/**
+ * Grouped mantissas for 3-level 5-level and 11-level quantization
+ */
+typedef struct {
float b1_mant[3];
float b2_mant[3];
float b4_mant[2];
int b4ptr;
} mant_groups;
-/* Get the transform coefficients for particular channel */
+/**
+ * Get the transform coefficients for a particular channel
+ * reference: Section 7.3 Quantization and Decoding of Mantissas
+ */
static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_groups *m)
{
GetBitContext *gb = &ctx->gb;
uint8_t *bap;
float *coeffs;
- if (ch_index >= 0) { /* fbw channels */
- exps = ctx->dexps[ch_index];
- bap = ctx->bap[ch_index];
- coeffs = ctx->transform_coeffs[ch_index + 1];
- start = 0;
- end = ctx->endmant[ch_index];
- } else if (ch_index == -1) {
- exps = ctx->dlfeexps;
- bap = ctx->lfebap;
- coeffs = ctx->transform_coeffs[0];
- start = 0;
- end = 7;
- } else {
- exps = ctx->dcplexps;
- bap = ctx->cplbap;
- coeffs = ctx->transform_coeffs_cpl;
- start = ctx->cplstrtmant;
- end = ctx->cplendmant;
- }
-
+ exps = ctx->dexps[ch_index];
+ bap = ctx->bap[ch_index];
+ coeffs = ctx->transform_coeffs[ch_index];
+ start = ctx->startmant[ch_index];
+ end = ctx->endmant[ch_index];
for (i = start; i < end; i++) {
tbap = bap[i];
switch (tbap) {
case 0:
- coeffs[i] = ((av_random(&ctx->dith_state) & 0xFFFF) * LEVEL_MINUS_3DB) / 32768.0f;
+ coeffs[i] = ((av_random(&ctx->dith_state) & 0xFFFF) / 65535.0f) - 0.5f;
break;
case 1:
break;
default:
+ /* asymmetric dequantization */
coeffs[i] = get_sbits(gb, qntztab[tbap]) * scale_factors[qntztab[tbap]-1];
break;
}
}
/**
- * Removes random dithering from coefficients with zero-bit mantissas
+ * Remove random dithering from coefficients with zero-bit mantissas
* reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
*/
static void remove_dithering(AC3DecodeContext *ctx) {
uint8_t *bap;
for(ch=1; ch<=ctx->nfchans; ch++) {
- if(!ctx->dithflag[ch-1]) {
+ if(!ctx->dithflag[ch]) {
coeffs = ctx->transform_coeffs[ch];
- bap = ctx->bap[ch-1];
- if(ctx->chincpl[ch-1])
- end = ctx->cplstrtmant;
+ bap = ctx->bap[ch];
+ if(ctx->chincpl[ch])
+ end = ctx->startmant[CPL_CH];
else
- end = ctx->endmant[ch-1];
+ end = ctx->endmant[ch];
for(i=0; i<end; i++) {
if(bap[i] == 0)
coeffs[i] = 0.0f;
}
- if(ctx->chincpl[ch-1]) {
- bap = ctx->cplbap;
- for(; i<ctx->cplendmant; i++) {
+ if(ctx->chincpl[ch]) {
+ bap = ctx->bap[CPL_CH];
+ for(; i<ctx->endmant[CPL_CH]; i++) {
if(bap[i] == 0)
coeffs[i] = 0.0f;
}
}
}
-/* Get the transform coefficients.
- * This function extracts the tranform coefficients form the ac3 bitstream.
- * This function is called after bit allocation is performed.
+/**
+ * Get the transform coefficients.
*/
static int get_transform_coeffs(AC3DecodeContext * ctx)
{
- int i, end;
+ int ch, end;
int got_cplchan = 0;
mant_groups m;
m.b1ptr = m.b2ptr = m.b4ptr = 3;
- for (i = 0; i < ctx->nfchans; i++) {
- /* transform coefficients for individual channel */
- if (get_transform_coeffs_ch(ctx, i, &m))
+ for (ch = 1; ch <= ctx->nchans; ch++) {
+ /* transform coefficients for full-bandwidth channel */
+ if (get_transform_coeffs_ch(ctx, ch, &m))
return -1;
- /* tranform coefficients for coupling channels */
- if (ctx->chincpl[i]) {
+ /* tranform coefficients for coupling channel come right after the
+ coefficients for the first coupled channel*/
+ if (ctx->chincpl[ch]) {
if (!got_cplchan) {
- if (get_transform_coeffs_ch(ctx, -2, &m)) {
- av_log(NULL, AV_LOG_ERROR, "error in decoupling channels\n");
+ if (get_transform_coeffs_ch(ctx, CPL_CH, &m)) {
+ av_log(ctx->avctx, AV_LOG_ERROR, "error in decoupling channels\n");
return -1;
}
uncouple_channels(ctx);
got_cplchan = 1;
}
- end = ctx->cplendmant;
- } else
- end = ctx->endmant[i];
+ end = ctx->endmant[CPL_CH];
+ } else {
+ end = ctx->endmant[ch];
+ }
do
- ctx->transform_coeffs[i + 1][end] = 0;
+ ctx->transform_coeffs[ch][end] = 0;
while(++end < 256);
}
- if (ctx->lfeon) {
- if (get_transform_coeffs_ch(ctx, -1, &m))
- return -1;
- for (i = 7; i < 256; i++) {
- ctx->transform_coeffs[0][i] = 0;
- }
- }
/* if any channel doesn't use dithering, zero appropriate coefficients */
if(!ctx->dither_all)
}
/**
- * Performs stereo rematrixing.
+ * Stereo rematrixing.
* reference: Section 7.5.4 Rematrixing : Decoding Technique
*/
static void do_rematrixing(AC3DecodeContext *ctx)
int end, bndend;
float tmp0, tmp1;
- end = FFMIN(ctx->endmant[0], ctx->endmant[1]);
+ end = FFMIN(ctx->endmant[1], ctx->endmant[2]);
for(bnd=0; bnd<ctx->nrematbnd; bnd++) {
if(ctx->rematflg[bnd]) {
- bndend = FFMIN(end, rematrix_band_tbl[bnd+1]);
- for(i=rematrix_band_tbl[bnd]; i<bndend; i++) {
+ bndend = FFMIN(end, rematrix_band_tab[bnd+1]);
+ for(i=rematrix_band_tab[bnd]; i<bndend; i++) {
tmp0 = ctx->transform_coeffs[1][i];
tmp1 = ctx->transform_coeffs[2][i];
ctx->transform_coeffs[1][i] = tmp0 + tmp1;
}
}
-/* This function performs the imdct on 256 sample transform
- * coefficients.
+/**
+ * Perform the 256-point IMDCT
*/
static void do_imdct_256(AC3DecodeContext *ctx, int chindex)
{
}
}
-/* IMDCT Transform. */
+/**
+ * Inverse MDCT Transform.
+ * Convert frequency domain coefficients to time-domain audio samples.
+ * reference: Section 7.9.4 Transformation Equations
+ */
static inline void do_imdct(AC3DecodeContext *ctx)
{
int ch;
+ int nchans;
- if (ctx->output_mode & AC3_OUTPUT_LFEON) {
- ctx->imdct_512.fft.imdct_calc(&ctx->imdct_512, ctx->tmp_output,
- ctx->transform_coeffs[0], ctx->tmp_imdct);
- ctx->dsp.vector_fmul_add_add(ctx->output[0], ctx->tmp_output,
- ctx->window, ctx->delay[0], 384, 256, 1);
- ctx->dsp.vector_fmul_reverse(ctx->delay[0], ctx->tmp_output+256,
- ctx->window, 256);
- }
- for (ch=1; ch<=ctx->nfchans; ch++) {
- if (ctx->blksw[ch-1])
+ /* Don't perform the IMDCT on the LFE channel unless it's used in the output */
+ nchans = ctx->nfchans;
+ if(ctx->output_mode & AC3_OUTPUT_LFEON)
+ nchans++;
+
+ for (ch=1; ch<=nchans; ch++) {
+ if (ctx->blksw[ch]) {
do_imdct_256(ctx, ch);
- else
+ } else {
ctx->imdct_512.fft.imdct_calc(&ctx->imdct_512, ctx->tmp_output,
ctx->transform_coeffs[ch],
ctx->tmp_imdct);
-
- ctx->dsp.vector_fmul_add_add(ctx->output[ch], ctx->tmp_output,
- ctx->window, ctx->delay[ch], 384, 256, 1);
- ctx->dsp.vector_fmul_reverse(ctx->delay[ch], ctx->tmp_output+256,
+ }
+ /* For the first half of the block, apply the window, add the delay
+ from the previous block, and send to output */
+ ctx->dsp.vector_fmul_add_add(ctx->output[ch-1], ctx->tmp_output,
+ ctx->window, ctx->delay[ch-1], 0, 256, 1);
+ /* For the second half of the block, apply the window and store the
+ samples to delay, to be combined with the next block */
+ ctx->dsp.vector_fmul_reverse(ctx->delay[ch-1], ctx->tmp_output+256,
ctx->window, 256);
}
}
-/* Parse the audio block from ac3 bitstream.
- * This function extract the audio block from the ac3 bitstream
- * and produces the output for the block. This function must
- * be called for each of the six audio block in the ac3 bitstream.
+/**
+ * Downmix the output to mono or stereo.
+ */
+static void ac3_downmix(float samples[AC3_MAX_CHANNELS][256], int nfchans,
+ int output_mode, float coef[AC3_MAX_CHANNELS][2])
+{
+ int i, j;
+ float v0, v1, s0, s1;
+
+ for(i=0; i<256; i++) {
+ v0 = v1 = s0 = s1 = 0.0f;
+ for(j=0; j<nfchans; j++) {
+ v0 += samples[j][i] * coef[j][0];
+ v1 += samples[j][i] * coef[j][1];
+ s0 += coef[j][0];
+ s1 += coef[j][1];
+ }
+ v0 /= s0;
+ v1 /= s1;
+ if(output_mode == AC3_ACMOD_MONO) {
+ samples[0][i] = (v0 + v1) * LEVEL_MINUS_3DB;
+ } else if(output_mode == AC3_ACMOD_STEREO) {
+ samples[0][i] = v0;
+ samples[1][i] = v1;
+ }
+ }
+}
+
+/**
+ * Parse an audio block from AC-3 bitstream.
*/
static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
{
int nfchans = ctx->nfchans;
int acmod = ctx->acmod;
- int i, bnd, seg, grpsize, ch;
+ int i, bnd, seg, ch;
GetBitContext *gb = &ctx->gb;
- int bit_alloc_flags = 0;
- int8_t *dexps;
- int mstrcplco, cplcoexp, cplcomant;
- int chbwcod, ngrps, cplabsexp, skipl;
+ uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
+
+ memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
- for (i = 0; i < nfchans; i++) /*block switch flag */
- ctx->blksw[i] = get_bits1(gb);
+ /* block switch flags */
+ for (ch = 1; ch <= nfchans; ch++)
+ ctx->blksw[ch] = get_bits1(gb);
+ /* dithering flags */
ctx->dither_all = 1;
- for (i = 0; i < nfchans; i++) { /* dithering flag */
- ctx->dithflag[i] = get_bits1(gb);
- if(!ctx->dithflag[i])
+ for (ch = 1; ch <= nfchans; ch++) {
+ ctx->dithflag[ch] = get_bits1(gb);
+ if(!ctx->dithflag[ch])
ctx->dither_all = 0;
}
- if (get_bits1(gb)) { /* dynamic range */
- ctx->dynrng = dynrng_tbl[get_bits(gb, 8)];
- } else if(blk == 0) {
- ctx->dynrng = 1.0;
- }
-
- if(acmod == AC3_ACMOD_DUALMONO) { /* dynamic range 1+1 mode */
+ /* dynamic range */
+ i = !(ctx->acmod);
+ do {
if(get_bits1(gb)) {
- ctx->dynrng2 = dynrng_tbl[get_bits(gb, 8)];
+ ctx->dynrng[i] = dynrng_tab[get_bits(gb, 8)];
} else if(blk == 0) {
- ctx->dynrng2 = 1.0;
+ ctx->dynrng[i] = 1.0f;
}
- }
+ } while(i--);
- if (get_bits1(gb)) { /* coupling strategy */
+ /* coupling strategy */
+ if (get_bits1(gb)) {
+ memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
ctx->cplinu = get_bits1(gb);
- ctx->cplbndstrc = 0;
- if (ctx->cplinu) { /* coupling in use */
+ if (ctx->cplinu) {
+ /* coupling in use */
int cplbegf, cplendf;
- for (i = 0; i < nfchans; i++)
- ctx->chincpl[i] = get_bits1(gb);
+ /* determine which channels are coupled */
+ for (ch = 1; ch <= nfchans; ch++)
+ ctx->chincpl[ch] = get_bits1(gb);
+ /* phase flags in use */
if (acmod == AC3_ACMOD_STEREO)
- ctx->phsflginu = get_bits1(gb); //phase flag in use
+ ctx->phsflginu = get_bits1(gb);
+ /* coupling frequency range and band structure */
cplbegf = get_bits(gb, 4);
cplendf = get_bits(gb, 4);
-
if (3 + cplendf - cplbegf < 0) {
- av_log(NULL, AV_LOG_ERROR, "cplendf = %d < cplbegf = %d\n", cplendf, cplbegf);
+ av_log(ctx->avctx, AV_LOG_ERROR, "cplendf = %d < cplbegf = %d\n", cplendf, cplbegf);
return -1;
}
-
ctx->ncplbnd = ctx->ncplsubnd = 3 + cplendf - cplbegf;
- ctx->cplstrtmant = cplbegf * 12 + 37;
- ctx->cplendmant = cplendf * 12 + 73;
- for (i = 0; i < ctx->ncplsubnd - 1; i++) /* coupling band structure */
+ ctx->startmant[CPL_CH] = cplbegf * 12 + 37;
+ ctx->endmant[CPL_CH] = cplendf * 12 + 73;
+ for (bnd = 0; bnd < ctx->ncplsubnd - 1; bnd++) {
if (get_bits1(gb)) {
- ctx->cplbndstrc |= 1 << i;
+ ctx->cplbndstrc[bnd] = 1;
ctx->ncplbnd--;
}
+ }
} else {
- for (i = 0; i < nfchans; i++)
- ctx->chincpl[i] = 0;
+ /* coupling not in use */
+ for (ch = 1; ch <= nfchans; ch++)
+ ctx->chincpl[ch] = 0;
}
}
+ /* coupling coordinates */
if (ctx->cplinu) {
- ctx->cplcoe = 0;
+ int cplcoe = 0;
- for (i = 0; i < nfchans; i++)
- if (ctx->chincpl[i])
- if (get_bits1(gb)) { /* coupling co-ordinates */
- ctx->cplcoe |= 1 << i;
+ for (ch = 1; ch <= nfchans; ch++) {
+ if (ctx->chincpl[ch]) {
+ if (get_bits1(gb)) {
+ int mstrcplco, cplcoexp, cplcomant;
+ cplcoe = 1;
mstrcplco = 3 * get_bits(gb, 2);
for (bnd = 0; bnd < ctx->ncplbnd; bnd++) {
cplcoexp = get_bits(gb, 4);
cplcomant = get_bits(gb, 4);
if (cplcoexp == 15)
- ctx->cplco[i][bnd] = cplcomant / 16.0f;
+ ctx->cplco[ch][bnd] = cplcomant / 16.0f;
else
- ctx->cplco[i][bnd] = (cplcomant + 16.0f) / 32.0f;
- ctx->cplco[i][bnd] *= scale_factors[cplcoexp + mstrcplco];
+ ctx->cplco[ch][bnd] = (cplcomant + 16.0f) / 32.0f;
+ ctx->cplco[ch][bnd] *= scale_factors[cplcoexp + mstrcplco];
}
}
-
- if (acmod == AC3_ACMOD_STEREO && ctx->phsflginu && (ctx->cplcoe & 1 || ctx->cplcoe & 2))
- for (bnd = 0; bnd < ctx->ncplbnd; bnd++)
+ }
+ }
+ /* phase flags */
+ if (acmod == AC3_ACMOD_STEREO && ctx->phsflginu && cplcoe) {
+ for (bnd = 0; bnd < ctx->ncplbnd; bnd++) {
if (get_bits1(gb))
- ctx->cplco[1][bnd] = -ctx->cplco[1][bnd];
+ ctx->cplco[2][bnd] = -ctx->cplco[2][bnd];
+ }
+ }
}
- if (acmod == AC3_ACMOD_STEREO) {/* rematrixing */
+ /* stereo rematrixing strategy and band structure */
+ if (acmod == AC3_ACMOD_STEREO) {
ctx->rematstr = get_bits1(gb);
if (ctx->rematstr) {
ctx->nrematbnd = 4;
- if(ctx->cplinu && ctx->cplstrtmant <= 61)
- ctx->nrematbnd -= 1 + (ctx->cplstrtmant == 37);
+ if(ctx->cplinu && ctx->startmant[CPL_CH] <= 61)
+ ctx->nrematbnd -= 1 + (ctx->startmant[CPL_CH] == 37);
for(bnd=0; bnd<ctx->nrematbnd; bnd++)
ctx->rematflg[bnd] = get_bits1(gb);
}
}
- ctx->cplexpstr = EXP_REUSE;
- ctx->lfeexpstr = EXP_REUSE;
- if (ctx->cplinu) /* coupling exponent strategy */
- ctx->cplexpstr = get_bits(gb, 2);
- for (i = 0; i < nfchans; i++) /* channel exponent strategy */
- ctx->chexpstr[i] = get_bits(gb, 2);
- if (ctx->lfeon) /* lfe exponent strategy */
- ctx->lfeexpstr = get_bits1(gb);
-
- for (i = 0; i < nfchans; i++) /* channel bandwidth code */
- if (ctx->chexpstr[i] != EXP_REUSE) {
- if (ctx->chincpl[i])
- ctx->endmant[i] = ctx->cplstrtmant;
+ /* exponent strategies for each channel */
+ ctx->expstr[CPL_CH] = EXP_REUSE;
+ ctx->expstr[ctx->lfe_ch] = EXP_REUSE;
+ for (ch = !ctx->cplinu; ch <= ctx->nchans; ch++) {
+ if(ch == ctx->lfe_ch)
+ ctx->expstr[ch] = get_bits(gb, 1);
+ else
+ ctx->expstr[ch] = get_bits(gb, 2);
+ if(ctx->expstr[ch] != EXP_REUSE)
+ bit_alloc_stages[ch] = 3;
+ }
+
+ /* channel bandwidth */
+ for (ch = 1; ch <= nfchans; ch++) {
+ ctx->startmant[ch] = 0;
+ if (ctx->expstr[ch] != EXP_REUSE) {
+ int prev = ctx->endmant[ch];
+ if (ctx->chincpl[ch])
+ ctx->endmant[ch] = ctx->startmant[CPL_CH];
else {
- chbwcod = get_bits(gb, 6);
+ int chbwcod = get_bits(gb, 6);
if (chbwcod > 60) {
- av_log(NULL, AV_LOG_ERROR, "chbwcod = %d > 60", chbwcod);
+ av_log(ctx->avctx, AV_LOG_ERROR, "chbwcod = %d > 60", chbwcod);
return -1;
}
- ctx->endmant[i] = chbwcod * 3 + 73;
+ ctx->endmant[ch] = chbwcod * 3 + 73;
}
+ if(blk > 0 && ctx->endmant[ch] != prev)
+ memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
}
-
- if (ctx->cplexpstr != EXP_REUSE) {/* coupling exponents */
- bit_alloc_flags = 64;
- cplabsexp = get_bits(gb, 4) << 1;
- ngrps = (ctx->cplendmant - ctx->cplstrtmant) / (3 << (ctx->cplexpstr - 1));
- decode_exponents(gb, ctx->cplexpstr, ngrps, cplabsexp, ctx->dcplexps + ctx->cplstrtmant);
}
-
- for (i = 0; i < nfchans; i++) /* fbw channel exponents */
- if (ctx->chexpstr[i] != EXP_REUSE) {
- bit_alloc_flags |= 1 << i;
- grpsize = 3 << (ctx->chexpstr[i] - 1);
- ngrps = (ctx->endmant[i] + grpsize - 4) / grpsize;
- dexps = ctx->dexps[i];
- dexps[0] = get_bits(gb, 4);
- decode_exponents(gb, ctx->chexpstr[i], ngrps, dexps[0], dexps + 1);
- skip_bits(gb, 2); /* skip gainrng */
+ ctx->startmant[ctx->lfe_ch] = 0;
+ ctx->endmant[ctx->lfe_ch] = 7;
+
+ /* decode exponents for each channel */
+ for (ch = !ctx->cplinu; ch <= ctx->nchans; ch++) {
+ if (ctx->expstr[ch] != EXP_REUSE) {
+ int grpsize, ngrps;
+ grpsize = 3 << (ctx->expstr[ch] - 1);
+ if(ch == CPL_CH)
+ ngrps = (ctx->endmant[ch] - ctx->startmant[ch]) / grpsize;
+ else if(ch == ctx->lfe_ch)
+ ngrps = 2;
+ else
+ ngrps = (ctx->endmant[ch] + grpsize - 4) / grpsize;
+ ctx->dexps[ch][0] = get_bits(gb, 4) << !ch;
+ decode_exponents(gb, ctx->expstr[ch], ngrps, ctx->dexps[ch][0],
+ &ctx->dexps[ch][ctx->startmant[ch]+!!ch]);
+ if(ch != CPL_CH && ch != ctx->lfe_ch)
+ skip_bits(gb, 2); /* skip gainrng */
}
-
- if (ctx->lfeexpstr != EXP_REUSE) { /* lfe exponents */
- bit_alloc_flags |= 32;
- ctx->dlfeexps[0] = get_bits(gb, 4);
- decode_exponents(gb, ctx->lfeexpstr, 2, ctx->dlfeexps[0], ctx->dlfeexps + 1);
}
- if (get_bits1(gb)) { /* bit allocation information */
- bit_alloc_flags = 127;
- ctx->bit_alloc_params.sdecay = ff_sdecaytab[get_bits(gb, 2)];
- ctx->bit_alloc_params.fdecay = ff_fdecaytab[get_bits(gb, 2)];
+ /* bit allocation information */
+ if (get_bits1(gb)) {
+ ctx->bit_alloc_params.sdecay = ff_sdecaytab[get_bits(gb, 2)] >> ctx->bit_alloc_params.halfratecod;
+ ctx->bit_alloc_params.fdecay = ff_fdecaytab[get_bits(gb, 2)] >> ctx->bit_alloc_params.halfratecod;
ctx->bit_alloc_params.sgain = ff_sgaintab[get_bits(gb, 2)];
ctx->bit_alloc_params.dbknee = ff_dbkneetab[get_bits(gb, 2)];
ctx->bit_alloc_params.floor = ff_floortab[get_bits(gb, 3)];
+ for(ch=!ctx->cplinu; ch<=ctx->nchans; ch++) {
+ bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
+ }
}
- if (get_bits1(gb)) { /* snroffset */
+ /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
+ if (get_bits1(gb)) {
int csnr;
- bit_alloc_flags = 127;
csnr = (get_bits(gb, 6) - 15) << 4;
- if (ctx->cplinu) { /* coupling fine snr offset and fast gain code */
- ctx->cplsnroffst = (csnr + get_bits(gb, 4)) << 2;
- ctx->cplfgain = ff_fgaintab[get_bits(gb, 3)];
- }
- for (i = 0; i < nfchans; i++) { /* channel fine snr offset and fast gain code */
- ctx->snroffst[i] = (csnr + get_bits(gb, 4)) << 2;
- ctx->fgain[i] = ff_fgaintab[get_bits(gb, 3)];
- }
- if (ctx->lfeon) { /* lfe fine snr offset and fast gain code */
- ctx->lfesnroffst = (csnr + get_bits(gb, 4)) << 2;
- ctx->lfefgain = ff_fgaintab[get_bits(gb, 3)];
+ for (ch = !ctx->cplinu; ch <= ctx->nchans; ch++) { /* snr offset and fast gain */
+ ctx->snroffst[ch] = (csnr + get_bits(gb, 4)) << 2;
+ ctx->fgain[ch] = ff_fgaintab[get_bits(gb, 3)];
}
+ memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
}
- if (ctx->cplinu && get_bits1(gb)) { /* coupling leak information */
- bit_alloc_flags |= 64;
+ /* coupling leak information */
+ if (ctx->cplinu && get_bits1(gb)) {
ctx->bit_alloc_params.cplfleak = get_bits(gb, 3);
ctx->bit_alloc_params.cplsleak = get_bits(gb, 3);
+ bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
}
- if (get_bits1(gb)) { /* delta bit allocation information */
- bit_alloc_flags = 127;
-
- if (ctx->cplinu) {
- ctx->cpldeltbae = get_bits(gb, 2);
- if (ctx->cpldeltbae == DBA_RESERVED) {
- av_log(NULL, AV_LOG_ERROR, "coupling delta bit allocation strategy reserved\n");
- return -1;
- }
- }
-
- for (i = 0; i < nfchans; i++) {
- ctx->deltbae[i] = get_bits(gb, 2);
- if (ctx->deltbae[i] == DBA_RESERVED) {
- av_log(NULL, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
+ /* delta bit allocation information */
+ if (get_bits1(gb)) {
+ /* delta bit allocation exists (strategy) */
+ for (ch = !ctx->cplinu; ch <= nfchans; ch++) {
+ ctx->deltbae[ch] = get_bits(gb, 2);
+ if (ctx->deltbae[ch] == DBA_RESERVED) {
+ av_log(ctx->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
return -1;
}
+ bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
}
-
- if (ctx->cplinu)
- if (ctx->cpldeltbae == DBA_NEW) { /*coupling delta offset, len and bit allocation */
- ctx->cpldeltnseg = get_bits(gb, 3);
- for (seg = 0; seg <= ctx->cpldeltnseg; seg++) {
- ctx->cpldeltoffst[seg] = get_bits(gb, 5);
- ctx->cpldeltlen[seg] = get_bits(gb, 4);
- ctx->cpldeltba[seg] = get_bits(gb, 3);
- }
- }
-
- for (i = 0; i < nfchans; i++)
- if (ctx->deltbae[i] == DBA_NEW) {/*channel delta offset, len and bit allocation */
- ctx->deltnseg[i] = get_bits(gb, 3);
- for (seg = 0; seg <= ctx->deltnseg[i]; seg++) {
- ctx->deltoffst[i][seg] = get_bits(gb, 5);
- ctx->deltlen[i][seg] = get_bits(gb, 4);
- ctx->deltba[i][seg] = get_bits(gb, 3);
+ /* channel delta offset, len and bit allocation */
+ for (ch = !ctx->cplinu; ch <= nfchans; ch++) {
+ if (ctx->deltbae[ch] == DBA_NEW) {
+ ctx->deltnseg[ch] = get_bits(gb, 3);
+ for (seg = 0; seg <= ctx->deltnseg[ch]; seg++) {
+ ctx->deltoffst[ch][seg] = get_bits(gb, 5);
+ ctx->deltlen[ch][seg] = get_bits(gb, 4);
+ ctx->deltba[ch][seg] = get_bits(gb, 3);
}
}
+ }
} else if(blk == 0) {
- if(ctx->cplinu)
- ctx->cpldeltbae = DBA_NONE;
- for(i=0; i<nfchans; i++) {
- ctx->deltbae[i] = DBA_NONE;
+ for(ch=0; ch<=ctx->nchans; ch++) {
+ ctx->deltbae[ch] = DBA_NONE;
}
}
- if (bit_alloc_flags) {
- if (ctx->cplinu && (bit_alloc_flags & 64))
- ac3_parametric_bit_allocation(&ctx->bit_alloc_params, ctx->cplbap,
- ctx->dcplexps, ctx->cplstrtmant,
- ctx->cplendmant, ctx->cplsnroffst,
- ctx->cplfgain, 0,
- ctx->cpldeltbae, ctx->cpldeltnseg,
- ctx->cpldeltoffst, ctx->cpldeltlen,
- ctx->cpldeltba);
- for (i = 0; i < nfchans; i++)
- if ((bit_alloc_flags >> i) & 1)
- ac3_parametric_bit_allocation(&ctx->bit_alloc_params,
- ctx->bap[i], ctx->dexps[i], 0,
- ctx->endmant[i], ctx->snroffst[i],
- ctx->fgain[i], 0, ctx->deltbae[i],
- ctx->deltnseg[i], ctx->deltoffst[i],
- ctx->deltlen[i], ctx->deltba[i]);
- if (ctx->lfeon && (bit_alloc_flags & 32))
- ac3_parametric_bit_allocation(&ctx->bit_alloc_params, ctx->lfebap,
- ctx->dlfeexps, 0, 7, ctx->lfesnroffst,
- ctx->lfefgain, 1,
- DBA_NONE, 0, NULL, NULL, NULL);
+ /* Bit allocation */
+ for(ch=!ctx->cplinu; ch<=ctx->nchans; ch++) {
+ if(bit_alloc_stages[ch] > 2) {
+ /* Exponent mapping into PSD and PSD integration */
+ ff_ac3_bit_alloc_calc_psd(ctx->dexps[ch],
+ ctx->startmant[ch], ctx->endmant[ch],
+ ctx->psd[ch], ctx->bndpsd[ch]);
+ }
+ if(bit_alloc_stages[ch] > 1) {
+ /* Compute excitation function, Compute masking curve, and
+ Apply delta bit allocation */
+ ff_ac3_bit_alloc_calc_mask(&ctx->bit_alloc_params, ctx->bndpsd[ch],
+ ctx->startmant[ch], ctx->endmant[ch],
+ ctx->fgain[ch], (ch == ctx->lfe_ch),
+ ctx->deltbae[ch], ctx->deltnseg[ch],
+ ctx->deltoffst[ch], ctx->deltlen[ch],
+ ctx->deltba[ch], ctx->mask[ch]);
+ }
+ if(bit_alloc_stages[ch] > 0) {
+ /* Compute bit allocation */
+ ff_ac3_bit_alloc_calc_bap(ctx->mask[ch], ctx->psd[ch],
+ ctx->startmant[ch], ctx->endmant[ch],
+ ctx->snroffst[ch],
+ ctx->bit_alloc_params.floor,
+ ctx->bap[ch]);
+ }
}
- if (get_bits1(gb)) { /* unused dummy data */
- skipl = get_bits(gb, 9);
+ /* unused dummy data */
+ if (get_bits1(gb)) {
+ int skipl = get_bits(gb, 9);
while(skipl--)
skip_bits(gb, 8);
}
+
/* unpack the transform coefficients
- * * this also uncouples channels if coupling is in use.
- */
+ this also uncouples channels if coupling is in use. */
if (get_transform_coeffs(ctx)) {
- av_log(NULL, AV_LOG_ERROR, "Error in routine get_transform_coeffs\n");
+ av_log(ctx->avctx, AV_LOG_ERROR, "Error in routine get_transform_coeffs\n");
return -1;
}
if(ctx->acmod == AC3_ACMOD_STEREO)
do_rematrixing(ctx);
- /* apply scaling to coefficients (headroom, dynrng) */
- if(ctx->lfeon) {
- for(i=0; i<7; i++) {
- ctx->transform_coeffs[0][i] *= 2.0f * ctx->dynrng;
- }
- }
- for(ch=1; ch<=ctx->nfchans; ch++) {
- float gain = 2.0f;
- if(ctx->acmod == AC3_ACMOD_DUALMONO && ch == 2) {
- gain *= ctx->dynrng2;
+ /* apply scaling to coefficients (headroom, dialnorm, dynrng) */
+ for(ch=1; ch<=ctx->nchans; ch++) {
+ float gain = 2.0f * ctx->mul_bias;
+ if(ctx->acmod == AC3_ACMOD_DUALMONO) {
+ gain *= ctx->dialnorm[ch-1] * ctx->dynrng[ch-1];
} else {
- gain *= ctx->dynrng;
+ gain *= ctx->dialnorm[0] * ctx->dynrng[0];
}
- for(i=0; i<ctx->endmant[ch-1]; i++) {
+ for(i=0; i<ctx->endmant[ch]; i++) {
ctx->transform_coeffs[ch][i] *= gain;
}
}
do_imdct(ctx);
- return 0;
-}
+ /* downmix output if needed */
+ if(ctx->nchans != ctx->out_channels && !((ctx->output_mode & AC3_OUTPUT_LFEON) &&
+ ctx->nfchans == ctx->out_channels)) {
+ ac3_downmix(ctx->output, ctx->nfchans, ctx->output_mode,
+ ctx->downmix_coeffs);
+ }
-static inline int16_t convert(int32_t i)
-{
- if (i > 0x43c07fff)
- return 32767;
- else if (i <= 0x43bf8000)
- return -32768;
- else
- return (i - 0x43c00000);
+ /* convert float to 16-bit integer */
+ for(ch=0; ch<ctx->out_channels; ch++) {
+ for(i=0; i<256; i++) {
+ ctx->output[ch][i] += ctx->add_bias;
+ }
+ ctx->dsp.float_to_int16(ctx->int_output[ch], ctx->output[ch], 256);
+ }
+
+ return 0;
}
-/* Decode ac3 frame.
- *
- * @param avctx Pointer to AVCodecContext
- * @param data Pointer to pcm smaples
- * @param data_size Set to number of pcm samples produced by decoding
- * @param buf Data to be decoded
- * @param buf_size Size of the buffer
+/**
+ * Decode a single AC-3 frame.
*/
static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
{
AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
int16_t *out_samples = (int16_t *)data;
- int i, j, k, start;
- int32_t *int_ptr[6];
+ int i, blk, ch, err;
- for (i = 0; i < 6; i++)
- int_ptr[i] = (int32_t *)(&ctx->output[i]);
-
- //Initialize the GetBitContext with the start of valid AC3 Frame.
+ /* initialize the GetBitContext with the start of valid AC-3 Frame */
init_get_bits(&ctx->gb, buf, buf_size * 8);
- //Parse the syncinfo.
- if (ac3_parse_header(ctx)) {
- av_log(avctx, AV_LOG_ERROR, "\n");
- *data_size = 0;
- return buf_size;
+ /* parse the syncinfo */
+ err = ac3_parse_header(ctx);
+ if(err) {
+ switch(err) {
+ case AC3_PARSE_ERROR_SYNC:
+ av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
+ break;
+ case AC3_PARSE_ERROR_BSID:
+ av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
+ break;
+ case AC3_PARSE_ERROR_SAMPLE_RATE:
+ av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
+ break;
+ case AC3_PARSE_ERROR_FRAME_SIZE:
+ av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
+ break;
+ default:
+ av_log(avctx, AV_LOG_ERROR, "invalid header\n");
+ break;
+ }
+ return -1;
}
avctx->sample_rate = ctx->sampling_rate;
avctx->bit_rate = ctx->bit_rate;
+ /* check that reported frame size fits in input buffer */
+ if(ctx->frame_size > buf_size) {
+ av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
+ return -1;
+ }
+
/* channel config */
+ ctx->out_channels = ctx->nchans;
if (avctx->channels == 0) {
avctx->channels = ctx->out_channels;
+ } else if(ctx->out_channels < avctx->channels) {
+ av_log(avctx, AV_LOG_ERROR, "Cannot upmix AC3 from %d to %d channels.\n",
+ ctx->out_channels, avctx->channels);
+ return -1;
}
- if(avctx->channels != ctx->out_channels) {
- av_log(avctx, AV_LOG_ERROR, "Cannot mix AC3 to %d channels.\n",
- avctx->channels);
+ if(avctx->channels == 2) {
+ ctx->output_mode = AC3_ACMOD_STEREO;
+ } else if(avctx->channels == 1) {
+ ctx->output_mode = AC3_ACMOD_MONO;
+ } else if(avctx->channels != ctx->out_channels) {
+ av_log(avctx, AV_LOG_ERROR, "Cannot downmix AC3 from %d to %d channels.\n",
+ ctx->out_channels, avctx->channels);
return -1;
}
+ ctx->out_channels = avctx->channels;
- //av_log(avctx, AV_LOG_INFO, "channels = %d \t bit rate = %d \t sampling rate = %d \n", avctx->channels, avctx->bit_rate * 1000, avctx->sample_rate);
-
- //Parse the Audio Blocks.
- for (i = 0; i < NB_BLOCKS; i++) {
- if (ac3_parse_audio_block(ctx, i)) {
+ /* parse the audio blocks */
+ for (blk = 0; blk < NB_BLOCKS; blk++) {
+ if (ac3_parse_audio_block(ctx, blk)) {
av_log(avctx, AV_LOG_ERROR, "error parsing the audio block\n");
*data_size = 0;
return ctx->frame_size;
}
- start = (ctx->output_mode & AC3_OUTPUT_LFEON) ? 0 : 1;
- for (k = 0; k < 256; k++)
- for (j = start; j <= ctx->nfchans; j++)
- *(out_samples++) = convert(int_ptr[j][k]);
+ for (i = 0; i < 256; i++)
+ for (ch = 0; ch < ctx->out_channels; ch++)
+ *(out_samples++) = ctx->int_output[ch][i];
}
*data_size = NB_BLOCKS * 256 * avctx->channels * sizeof (int16_t);
return ctx->frame_size;
}
-/* Uninitialize ac3 decoder.
+/**
+ * Uninitialize the AC-3 decoder.
*/
static int ac3_decode_end(AVCodecContext *avctx)
{
.close = ac3_decode_end,
.decode = ac3_decode_frame,
};
-
projects / ffmpeg / blobdiff