#include "avcodec.h"
#include "ac3_parser.h"
#include "bitstream.h"
+#include "crc.h"
#include "dsputil.h"
#include "random.h"
* 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 };
-
-/* table for exponent to scale_factor mapping
- * scale_factor[i] = 2 ^ -(i + 15)
- */
-static float scale_factors[25];
+static const uint8_t rematrix_band_tab[5] = { 13, 25, 37, 61, 253 };
/** table for grouping exponents */
-static uint8_t exp_ungroup_tbl[128][3];
-
-static int16_t l3_quantizers_1[32];
-static int16_t l3_quantizers_2[32];
-static int16_t l3_quantizers_3[32];
+static uint8_t exp_ungroup_tab[128][3];
-static int16_t l5_quantizers_1[128];
-static int16_t l5_quantizers_2[128];
-static int16_t l5_quantizers_3[128];
-static int16_t l7_quantizers[7];
+/** tables for ungrouping mantissas */
+static int b1_mantissas[32][3];
+static int b2_mantissas[128][3];
+static int b3_mantissas[8];
+static int b4_mantissas[128][2];
+static int b5_mantissas[16];
-static int16_t l11_quantizers_1[128];
-static int16_t l11_quantizers_2[128];
-
-static int16_t l15_quantizers[15];
+/**
+ * Quantization table: levels for symmetric. bits for asymmetric.
+ * reference: Table 7.18 Mapping of bap to Quantizer
+ */
+static const uint8_t quantization_tab[16] = {
+ 0, 3, 5, 7, 11, 15,
+ 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
+};
-static const uint8_t qntztab[16] = { 0, 5, 7, 3, 7, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16 };
+/** dynamic range table. converts codes to scale factors. */
+static float dynamic_range_tab[256];
-/* 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 center_levels[4] = { 2, 3, 4, 3 };
+
+/**
+ * Table for surround mix levels
+ * reference: Section 5.4.2.5 surmixlev
+ */
+static const uint8_t surround_levels[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 channel_mode; ///< channel mode (acmod)
+ int block_switch[AC3_MAX_CHANNELS]; ///< block switch flags
+ int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags
+ int dither_all; ///< true if all channels are dithered
+ int cpl_in_use; ///< coupling in use
+ int channel_in_cpl[AC3_MAX_CHANNELS]; ///< channel in coupling
+ int phase_flags_in_use; ///< phase flags in use
+ int phase_flags[18]; ///< phase flags
+ int cpl_band_struct[18]; ///< coupling band structure
+ int num_rematrixing_bands; ///< number of rematrixing bands
+ int rematrixing_flags[4]; ///< rematrixing flags
+ int exp_strategy[AC3_MAX_CHANNELS]; ///< exponent strategies
+ int snr_offset[AC3_MAX_CHANNELS]; ///< signal-to-noise ratio offsets
+ int fast_gain[AC3_MAX_CHANNELS]; ///< fast gain values (signal-to-mask ratio)
+ int dba_mode[AC3_MAX_CHANNELS]; ///< delta bit allocation mode
+ int dba_nsegs[AC3_MAX_CHANNELS]; ///< number of delta segments
+ uint8_t dba_offsets[AC3_MAX_CHANNELS][8]; ///< delta segment offsets
+ uint8_t dba_lengths[AC3_MAX_CHANNELS][8]; ///< delta segment lengths
+ uint8_t dba_values[AC3_MAX_CHANNELS][8]; ///< delta values for each segment
+
+ int sample_rate; ///< sample frequency, in Hz
+ int bit_rate; ///< stream bit rate, in bits-per-second
+ int frame_size; ///< current frame size, in bytes
+
+ int channels; ///< number of total channels
+ int fbw_channels; ///< number of full-bandwidth channels
+ int lfe_on; ///< lfe channel in use
+ int lfe_ch; ///< index of LFE channel
+ int output_mode; ///< output channel configuration
+ int out_channels; ///< number of output channels
+
+ int center_mix_level; ///< Center mix level index
+ int surround_mix_level; ///< Surround mix level index
+ float downmix_coeffs[AC3_MAX_CHANNELS][2]; ///< stereo downmix coefficients
+ float downmix_coeff_adjust[2]; ///< adjustment needed for each output channel when downmixing
+ float dynamic_range[2]; ///< dynamic range
+ int cpl_coords[AC3_MAX_CHANNELS][18]; ///< coupling coordinates
+ int num_cpl_bands; ///< number of coupling bands
+ int num_cpl_subbands; ///< number of coupling sub bands
+ int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin
+ int end_freq[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 band_psd[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
+ int fixed_coeffs[AC3_MAX_CHANNELS][256]; ///> fixed-point transform coefficients
+ DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][256]); ///< transform coefficients
+ int downmixed; ///< indicates if coeffs are currently downmixed
/* 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][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][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 gbc; ///< bitstream reader
+ AVRandomState dith_state; ///< for dither generation
+ AVCodecContext *avctx; ///< parent context
} AC3DecodeContext;
-/*********** BEGIN INIT HELPER FUNCTIONS ***********/
/**
- * Generate a Kaiser-Bessel Derived Window.
+ * Symmetrical Dequantization
+ * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
+ * Tables 7.19 to 7.23
*/
-static void ac3_window_init(float *window)
+static inline int
+symmetric_dequant(int code, int levels)
{
- int i, j;
- double sum = 0.0, bessel, tmp;
- double local_window[256];
- double alpha2 = (5.0 * M_PI / 256.0) * (5.0 * M_PI / 256.0);
-
- for (i = 0; i < 256; i++) {
- tmp = i * (256 - i) * alpha2;
- bessel = 1.0;
- for (j = 100; j > 0; j--) /* defaul to 100 iterations */
- bessel = bessel * tmp / (j * j) + 1;
- sum += bessel;
- local_window[i] = sum;
- }
-
- sum++;
- for (i = 0; i < 256; i++)
- window[i] = sqrt(local_window[i] / sum);
+ return ((code - (levels >> 1)) << 24) / levels;
}
/*
- * Generate quantizer tables.
+ * Initialize tables at runtime.
*/
-static void generate_quantizers_table(int16_t quantizers[], int level, int length)
+static av_cold void ac3_tables_init(void)
{
int i;
- for (i = 0; i < length; i++)
- quantizers[i] = ((2 * i - level + 1) << 15) / level;
-}
-
-static void generate_quantizers_table_1(int16_t quantizers[], int level, int length1, int length2, int size)
-{
- int i, j;
- int16_t v;
-
- for (i = 0; i < length1; i++) {
- v = ((2 * i - level + 1) << 15) / level;
- for (j = 0; j < length2; j++)
- quantizers[i * length2 + j] = v;
+ /* generate grouped mantissa tables
+ reference: Section 7.3.5 Ungrouping of Mantissas */
+ for(i=0; i<32; i++) {
+ /* bap=1 mantissas */
+ b1_mantissas[i][0] = symmetric_dequant( i / 9 , 3);
+ b1_mantissas[i][1] = symmetric_dequant((i % 9) / 3, 3);
+ b1_mantissas[i][2] = symmetric_dequant((i % 9) % 3, 3);
}
-
- for (i = length1 * length2; i < size; i++)
- quantizers[i] = 0;
-}
-
-static void generate_quantizers_table_2(int16_t quantizers[], int level, int length1, int length2, int size)
-{
- int i, j;
- int16_t v;
-
- for (i = 0; i < length1; i++) {
- v = ((2 * (i % level) - level + 1) << 15) / level;
- for (j = 0; j < length2; j++)
- quantizers[i * length2 + j] = v;
+ for(i=0; i<128; i++) {
+ /* bap=2 mantissas */
+ b2_mantissas[i][0] = symmetric_dequant( i / 25 , 5);
+ b2_mantissas[i][1] = symmetric_dequant((i % 25) / 5, 5);
+ b2_mantissas[i][2] = symmetric_dequant((i % 25) % 5, 5);
+
+ /* bap=4 mantissas */
+ b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
+ b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
+ }
+ /* generate ungrouped mantissa tables
+ reference: Tables 7.21 and 7.23 */
+ for(i=0; i<7; i++) {
+ /* bap=3 mantissas */
+ b3_mantissas[i] = symmetric_dequant(i, 7);
+ }
+ for(i=0; i<15; i++) {
+ /* bap=5 mantissas */
+ b5_mantissas[i] = symmetric_dequant(i, 15);
}
- for (i = length1 * length2; i < size; i++)
- quantizers[i] = 0;
-
-}
-
-static void generate_quantizers_table_3(int16_t quantizers[], int level, int length1, int length2, int size)
-{
- int i, j;
-
- for (i = 0; i < length1; i++)
- for (j = 0; j < length2; j++)
- quantizers[i * length2 + j] = ((2 * (j % level) - level + 1) << 15) / level;
-
- for (i = length1 * length2; i < size; i++)
- quantizers[i] = 0;
-}
-
-/*
- * Initialize tables at runtime.
- */
-static void ac3_tables_init(void)
-{
- int i;
-
- /* Quantizer ungrouping tables. */
- // for level-3 quantizers
- generate_quantizers_table_1(l3_quantizers_1, 3, 3, 9, 32);
- generate_quantizers_table_2(l3_quantizers_2, 3, 9, 3, 32);
- generate_quantizers_table_3(l3_quantizers_3, 3, 9, 3, 32);
-
- //for level-5 quantizers
- generate_quantizers_table_1(l5_quantizers_1, 5, 5, 25, 128);
- generate_quantizers_table_2(l5_quantizers_2, 5, 25, 5, 128);
- generate_quantizers_table_3(l5_quantizers_3, 5, 25, 5, 128);
-
- //for level-7 quantizers
- generate_quantizers_table(l7_quantizers, 7, 7);
-
- //for level-4 quantizers
- generate_quantizers_table_2(l11_quantizers_1, 11, 11, 11, 128);
- generate_quantizers_table_3(l11_quantizers_2, 11, 11, 11, 128);
-
- //for level-15 quantizers
- generate_quantizers_table(l15_quantizers, 15, 15);
- /* End Quantizer ungrouping tables. */
-
- //generate scale factors
- for (i = 0; i < 25; i++)
- scale_factors[i] = pow(2.0, -(i + 15));
+ /* generate dynamic range table
+ reference: Section 7.7.1 Dynamic Range Control */
+ for(i=0; i<256; i++) {
+ int v = (i >> 5) - ((i >> 7) << 3) - 5;
+ dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
+ }
/* 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;
}
}
-static int ac3_decode_init(AVCodecContext *avctx)
+/**
+ * AVCodec initialization
+ */
+static av_cold int ac3_decode_init(AVCodecContext *avctx)
{
- AC3DecodeContext *ctx = avctx->priv_data;
+ AC3DecodeContext *s = avctx->priv_data;
+ s->avctx = avctx;
ac3_common_init();
ac3_tables_init();
- ff_mdct_init(&ctx->imdct_256, 8, 1);
- ff_mdct_init(&ctx->imdct_512, 9, 1);
- ac3_window_init(ctx->window);
- dsputil_init(&ctx->dsp, avctx);
- av_init_random(0, &ctx->dith_state);
+ ff_mdct_init(&s->imdct_256, 8, 1);
+ ff_mdct_init(&s->imdct_512, 9, 1);
+ ff_kbd_window_init(s->window, 5.0, 256);
+ dsputil_init(&s->dsp, avctx);
+ av_init_random(0, &s->dith_state);
+
+ /* set bias values for float to int16 conversion */
+ if(s->dsp.float_to_int16 == ff_float_to_int16_c) {
+ s->add_bias = 385.0f;
+ s->mul_bias = 1.0f;
+ } else {
+ s->add_bias = 0.0f;
+ s->mul_bias = 32767.0f;
+ }
+
+ /* allow downmixing to stereo or mono */
+ if (avctx->channels > 0 && avctx->request_channels > 0 &&
+ avctx->request_channels < avctx->channels &&
+ avctx->request_channels <= 2) {
+ avctx->channels = avctx->request_channels;
+ }
+ s->downmixed = 1;
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.
*/
-static int ac3_parse_header(AC3DecodeContext *ctx)
+static int ac3_parse_header(AC3DecodeContext *s)
{
AC3HeaderInfo hdr;
- GetBitContext *gb = &ctx->gb;
+ GetBitContext *gbc = &s->gbc;
int err, i;
- err = ff_ac3_parse_header(gb->buffer, &hdr);
+ err = ff_ac3_parse_header(gbc->buffer, &hdr);
if(err)
return err;
+ if(hdr.bitstream_id > 10)
+ return AC3_PARSE_ERROR_BSID;
+
/* 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;
- ctx->dsurmod = hdr.dsurmod;
- ctx->lfeon = hdr.lfeon;
- ctx->bit_alloc_params.halfratecod = hdr.halfratecod;
- ctx->sampling_rate = hdr.sample_rate;
- ctx->bit_rate = hdr.bit_rate;
- ctx->nchans = hdr.channels;
- ctx->nfchans = ctx->nchans - ctx->lfeon;
- ctx->frame_size = hdr.frame_size;
+ s->bit_alloc_params.sr_code = hdr.sr_code;
+ s->channel_mode = hdr.channel_mode;
+ s->lfe_on = hdr.lfe_on;
+ s->bit_alloc_params.sr_shift = hdr.sr_shift;
+ s->sample_rate = hdr.sample_rate;
+ s->bit_rate = hdr.bit_rate;
+ s->channels = hdr.channels;
+ s->fbw_channels = s->channels - s->lfe_on;
+ s->lfe_ch = s->fbw_channels + 1;
+ s->frame_size = hdr.frame_size;
/* set default output to all source channels */
- ctx->out_channels = ctx->nchans;
- ctx->output_mode = ctx->acmod;
- if(ctx->lfeon)
- ctx->output_mode |= AC3_OUTPUT_LFEON;
+ s->out_channels = s->channels;
+ s->output_mode = s->channel_mode;
+ if(s->lfe_on)
+ s->output_mode |= AC3_OUTPUT_LFEON;
+
+ /* set default mix levels */
+ s->center_mix_level = 3; // -4.5dB
+ s->surround_mix_level = 4; // -6.0dB
/* 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 crc1
- skip_bits(gb, 8); // skip fscod and frmsizecod
- skip_bits(gb, 11); // skip bsid, bsmod, and acmod
- if(ctx->acmod == AC3_ACMOD_STEREO) {
- skip_bits(gb, 2); // skip dsurmod
+ skip_bits(gbc, 16); // skip the sync_word
+ skip_bits(gbc, 16); // skip crc1
+ skip_bits(gbc, 8); // skip fscod and frmsizecod
+ skip_bits(gbc, 11); // skip bsid, bsmod, and acmod
+ if(s->channel_mode == AC3_CHMODE_STEREO) {
+ skip_bits(gbc, 2); // skip dsurmod
} else {
- if((ctx->acmod & 1) && ctx->acmod != AC3_ACMOD_MONO)
- skip_bits(gb, 2); // skip cmixlev
- if(ctx->acmod & 4)
- skip_bits(gb, 2); // skip surmixlev
+ if((s->channel_mode & 1) && s->channel_mode != AC3_CHMODE_MONO)
+ s->center_mix_level = center_levels[get_bits(gbc, 2)];
+ if(s->channel_mode & 4)
+ s->surround_mix_level = surround_levels[get_bits(gbc, 2)];
}
- skip_bits1(gb); // skip lfeon
+ skip_bits1(gbc); // skip lfeon
/* read the rest of the bsi. read twice for dual mono mode. */
- i = !(ctx->acmod);
+ i = !(s->channel_mode);
do {
- skip_bits(gb, 5); //skip dialog normalization
- if (get_bits1(gb))
- skip_bits(gb, 8); //skip compression
- if (get_bits1(gb))
- skip_bits(gb, 8); //skip language code
- if (get_bits1(gb))
- skip_bits(gb, 7); //skip audio production information
+ skip_bits(gbc, 5); // skip dialog normalization
+ if (get_bits1(gbc))
+ skip_bits(gbc, 8); //skip compression
+ if (get_bits1(gbc))
+ skip_bits(gbc, 8); //skip language code
+ if (get_bits1(gbc))
+ skip_bits(gbc, 7); //skip audio production information
} while (i--);
- skip_bits(gb, 2); //skip copyright bit and original bitstream bit
+ skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
- /* FIXME: read & use the xbsi1 downmix levels */
- if (get_bits1(gb))
- skip_bits(gb, 14); //skip timecode1
- if (get_bits1(gb))
- skip_bits(gb, 14); //skip timecode2
+ /* skip the timecodes (or extra bitstream information for Alternate Syntax)
+ TODO: read & use the xbsi1 downmix levels */
+ if (get_bits1(gbc))
+ skip_bits(gbc, 14); //skip timecode1 / xbsi1
+ if (get_bits1(gbc))
+ skip_bits(gbc, 14); //skip timecode2 / xbsi2
- if (get_bits1(gb)) {
- i = get_bits(gb, 6); //additional bsi length
+ /* skip additional bitstream info */
+ if (get_bits1(gbc)) {
+ i = get_bits(gbc, 6);
do {
- skip_bits(gb, 8);
+ skip_bits(gbc, 8);
} while(i--);
}
}
/**
- * 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
+ * Set stereo downmixing coefficients based on frame header info.
+ * reference: Section 7.8.2 Downmixing Into Two Channels
*/
-static void decode_exponents(GetBitContext *gb, int expstr, int ngrps,
+static void set_downmix_coeffs(AC3DecodeContext *s)
+{
+ int i;
+ float cmix = gain_levels[s->center_mix_level];
+ float smix = gain_levels[s->surround_mix_level];
+
+ for(i=0; i<s->fbw_channels; i++) {
+ s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
+ s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
+ }
+ if(s->channel_mode > 1 && s->channel_mode & 1) {
+ s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
+ }
+ if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
+ int nf = s->channel_mode - 2;
+ s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
+ }
+ if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
+ int nf = s->channel_mode - 4;
+ s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
+ }
+
+ /* calculate adjustment needed for each channel to avoid clipping */
+ s->downmix_coeff_adjust[0] = s->downmix_coeff_adjust[1] = 0.0f;
+ for(i=0; i<s->fbw_channels; i++) {
+ s->downmix_coeff_adjust[0] += s->downmix_coeffs[i][0];
+ s->downmix_coeff_adjust[1] += s->downmix_coeffs[i][1];
+ }
+ s->downmix_coeff_adjust[0] = 1.0f / s->downmix_coeff_adjust[0];
+ s->downmix_coeff_adjust[1] = 1.0f / s->downmix_coeff_adjust[1];
+}
+
+/**
+ * Decode the grouped exponents according to exponent strategy.
+ * reference: Section 7.1.3 Exponent Decoding
+ */
+static void decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
uint8_t absexp, int8_t *dexps)
{
- int i, j, grp, grpsize;
+ int i, j, grp, group_size;
int dexp[256];
int expacc, prevexp;
/* unpack groups */
- grpsize = expstr + (expstr == EXP_D45);
+ group_size = exp_strategy + (exp_strategy == 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];
+ expacc = get_bits(gbc, 7);
+ 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 */
prevexp = absexp;
for(i=0; i<ngrps*3; i++) {
prevexp = av_clip(prevexp + dexp[i]-2, 0, 24);
- for(j=0; j<grpsize; j++) {
- dexps[(i*grpsize)+j] = prevexp;
+ for(j=0; j<group_size; j++) {
+ dexps[(i*group_size)+j] = prevexp;
}
}
}
/**
- * 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
*/
-static void uncouple_channels(AC3DecodeContext *ctx)
+static void uncouple_channels(AC3DecodeContext *s)
{
int i, j, ch, bnd, subbnd;
subbnd = -1;
- i = ctx->cplstrtmant;
- for(bnd=0; bnd<ctx->ncplbnd; bnd++) {
+ i = s->start_freq[CPL_CH];
+ for(bnd=0; bnd<s->num_cpl_bands; 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];
+ for(ch=1; ch<=s->fbw_channels; ch++) {
+ if(s->channel_in_cpl[ch]) {
+ s->fixed_coeffs[ch][i] = ((int64_t)s->fixed_coeffs[CPL_CH][i] * (int64_t)s->cpl_coords[ch][bnd]) >> 23;
+ if (ch == 2 && s->phase_flags[bnd])
+ s->fixed_coeffs[ch][i] = -s->fixed_coeffs[ch][i];
+ }
}
i++;
}
- } while((ctx->cplbndstrc >> subbnd) & 1);
+ } while(s->cpl_band_struct[subbnd]);
}
}
-typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantization */
- int16_t l3_quantizers[3];
- int16_t l5_quantizers[3];
- int16_t l11_quantizers[2];
- int l3ptr;
- int l5ptr;
- int l11ptr;
+/**
+ * Grouped mantissas for 3-level 5-level and 11-level quantization
+ */
+typedef struct {
+ int b1_mant[3];
+ int b2_mant[3];
+ int b4_mant[2];
+ int b1ptr;
+ int b2ptr;
+ int b4ptr;
} mant_groups;
-/* Get the transform coefficients for particular channel */
-static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_groups *m)
+/**
+ * Get the transform coefficients for a particular channel
+ * reference: Section 7.3 Quantization and Decoding of Mantissas
+ */
+static int get_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
{
- GetBitContext *gb = &ctx->gb;
+ GetBitContext *gbc = &s->gbc;
int i, gcode, tbap, start, end;
uint8_t *exps;
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;
- }
+ int *coeffs;
+ exps = s->dexps[ch_index];
+ bap = s->bap[ch_index];
+ coeffs = s->fixed_coeffs[ch_index];
+ start = s->start_freq[ch_index];
+ end = s->end_freq[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;
+ coeffs[i] = (av_random(&s->dith_state) & 0x7FFFFF) - 4194304;
break;
case 1:
- if (m->l3ptr > 2) {
- gcode = get_bits(gb, 5);
- m->l3_quantizers[0] = l3_quantizers_1[gcode];
- m->l3_quantizers[1] = l3_quantizers_2[gcode];
- m->l3_quantizers[2] = l3_quantizers_3[gcode];
- m->l3ptr = 0;
+ if(m->b1ptr > 2) {
+ gcode = get_bits(gbc, 5);
+ m->b1_mant[0] = b1_mantissas[gcode][0];
+ m->b1_mant[1] = b1_mantissas[gcode][1];
+ m->b1_mant[2] = b1_mantissas[gcode][2];
+ m->b1ptr = 0;
}
- coeffs[i] = m->l3_quantizers[m->l3ptr++];
+ coeffs[i] = m->b1_mant[m->b1ptr++];
break;
case 2:
- if (m->l5ptr > 2) {
- gcode = get_bits(gb, 7);
- m->l5_quantizers[0] = l5_quantizers_1[gcode];
- m->l5_quantizers[1] = l5_quantizers_2[gcode];
- m->l5_quantizers[2] = l5_quantizers_3[gcode];
- m->l5ptr = 0;
+ if(m->b2ptr > 2) {
+ gcode = get_bits(gbc, 7);
+ m->b2_mant[0] = b2_mantissas[gcode][0];
+ m->b2_mant[1] = b2_mantissas[gcode][1];
+ m->b2_mant[2] = b2_mantissas[gcode][2];
+ m->b2ptr = 0;
}
- coeffs[i] = m->l5_quantizers[m->l5ptr++];
+ coeffs[i] = m->b2_mant[m->b2ptr++];
break;
case 3:
- coeffs[i] = l7_quantizers[get_bits(gb, 3)];
+ coeffs[i] = b3_mantissas[get_bits(gbc, 3)];
break;
case 4:
- if (m->l11ptr > 1) {
- gcode = get_bits(gb, 7);
- m->l11_quantizers[0] = l11_quantizers_1[gcode];
- m->l11_quantizers[1] = l11_quantizers_2[gcode];
- m->l11ptr = 0;
+ if(m->b4ptr > 1) {
+ gcode = get_bits(gbc, 7);
+ m->b4_mant[0] = b4_mantissas[gcode][0];
+ m->b4_mant[1] = b4_mantissas[gcode][1];
+ m->b4ptr = 0;
}
- coeffs[i] = m->l11_quantizers[m->l11ptr++];
+ coeffs[i] = m->b4_mant[m->b4ptr++];
break;
case 5:
- coeffs[i] = l15_quantizers[get_bits(gb, 4)];
+ coeffs[i] = b5_mantissas[get_bits(gbc, 4)];
break;
- default:
- coeffs[i] = get_sbits(gb, qntztab[tbap]) << (16 - qntztab[tbap]);
+ default: {
+ /* asymmetric dequantization */
+ int qlevel = quantization_tab[tbap];
+ coeffs[i] = get_sbits(gbc, qlevel) << (24 - qlevel);
break;
+ }
}
- coeffs[i] *= scale_factors[exps[i]];
+ coeffs[i] >>= exps[i];
}
return 0;
}
/**
- * 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) {
+static void remove_dithering(AC3DecodeContext *s) {
int ch, i;
int end=0;
- float *coeffs;
+ int *coeffs;
uint8_t *bap;
- for(ch=1; ch<=ctx->nfchans; ch++) {
- if(!ctx->dithflag[ch-1]) {
- coeffs = ctx->transform_coeffs[ch];
- bap = ctx->bap[ch-1];
- if(ctx->chincpl[ch-1])
- end = ctx->cplstrtmant;
+ for(ch=1; ch<=s->fbw_channels; ch++) {
+ if(!s->dither_flag[ch]) {
+ coeffs = s->fixed_coeffs[ch];
+ bap = s->bap[ch];
+ if(s->channel_in_cpl[ch])
+ end = s->start_freq[CPL_CH];
else
- end = ctx->endmant[ch-1];
+ end = s->end_freq[ch];
for(i=0; i<end; i++) {
- if(bap[i] == 0)
- coeffs[i] = 0.0f;
+ if(!bap[i])
+ coeffs[i] = 0;
}
- if(ctx->chincpl[ch-1]) {
- bap = ctx->cplbap;
- for(; i<ctx->cplendmant; i++) {
- if(bap[i] == 0)
- coeffs[i] = 0.0f;
+ if(s->channel_in_cpl[ch]) {
+ bap = s->bap[CPL_CH];
+ for(; i<s->end_freq[CPL_CH]; i++) {
+ if(!bap[i])
+ coeffs[i] = 0;
}
}
}
}
}
-/* 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)
+static int get_transform_coeffs(AC3DecodeContext *s)
{
- int i, end;
+ int ch, end;
int got_cplchan = 0;
mant_groups m;
- m.l3ptr = m.l5ptr = m.l11ptr = 3;
+ 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 <= s->channels; ch++) {
+ /* transform coefficients for full-bandwidth channel */
+ if (get_transform_coeffs_ch(s, 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 (s->channel_in_cpl[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(s, CPL_CH, &m)) {
+ av_log(s->avctx, AV_LOG_ERROR, "error in decoupling channels\n");
return -1;
}
- uncouple_channels(ctx);
+ uncouple_channels(s);
got_cplchan = 1;
}
- end = ctx->cplendmant;
- } else
- end = ctx->endmant[i];
+ end = s->end_freq[CPL_CH];
+ } else {
+ end = s->end_freq[ch];
+ }
do
- ctx->transform_coeffs[i + 1][end] = 0;
+ s->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)
- remove_dithering(ctx);
+ if(!s->dither_all)
+ remove_dithering(s);
return 0;
}
/**
- * Performs stereo rematrixing.
+ * Stereo rematrixing.
* reference: Section 7.5.4 Rematrixing : Decoding Technique
*/
-static void do_rematrixing(AC3DecodeContext *ctx)
+static void do_rematrixing(AC3DecodeContext *s)
{
int bnd, i;
int end, bndend;
- float tmp0, tmp1;
-
- end = FFMIN(ctx->endmant[0], ctx->endmant[1]);
-
- 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++) {
- tmp0 = ctx->transform_coeffs[1][i];
- tmp1 = ctx->transform_coeffs[2][i];
- ctx->transform_coeffs[1][i] = tmp0 + tmp1;
- ctx->transform_coeffs[2][i] = tmp0 - tmp1;
+ int tmp0, tmp1;
+
+ end = FFMIN(s->end_freq[1], s->end_freq[2]);
+
+ for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
+ if(s->rematrixing_flags[bnd]) {
+ bndend = FFMIN(end, rematrix_band_tab[bnd+1]);
+ for(i=rematrix_band_tab[bnd]; i<bndend; i++) {
+ tmp0 = s->fixed_coeffs[1][i];
+ tmp1 = s->fixed_coeffs[2][i];
+ s->fixed_coeffs[1][i] = tmp0 + tmp1;
+ s->fixed_coeffs[2][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)
+static void do_imdct_256(AC3DecodeContext *s, int chindex)
{
int i, k;
DECLARE_ALIGNED_16(float, x[128]);
FFTComplex z[2][64];
- float *o_ptr = ctx->tmp_output;
+ float *o_ptr = s->tmp_output;
for(i=0; i<2; i++) {
/* de-interleave coefficients */
for(k=0; k<128; k++) {
- x[k] = ctx->transform_coeffs[chindex][2*k+i];
+ x[k] = s->transform_coeffs[chindex][2*k+i];
}
/* run standard IMDCT */
- ctx->imdct_256.fft.imdct_calc(&ctx->imdct_256, o_ptr, x, ctx->tmp_imdct);
+ s->imdct_256.fft.imdct_calc(&s->imdct_256, o_ptr, x, s->tmp_imdct);
/* reverse the post-rotation & reordering from standard IMDCT */
for(k=0; k<32; k++) {
}
}
-/* IMDCT Transform. */
-static inline void do_imdct(AC3DecodeContext *ctx)
+/**
+ * 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 *s, int channels)
{
int ch;
- 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])
- do_imdct_256(ctx, ch);
- 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,
- ctx->window, 256);
+ for (ch=1; ch<=channels; ch++) {
+ if (s->block_switch[ch]) {
+ do_imdct_256(s, ch);
+ } else {
+ s->imdct_512.fft.imdct_calc(&s->imdct_512, s->tmp_output,
+ s->transform_coeffs[ch], s->tmp_imdct);
+ }
+ /* For the first half of the block, apply the window, add the delay
+ from the previous block, and send to output */
+ s->dsp.vector_fmul_add_add(s->output[ch-1], s->tmp_output,
+ s->window, s->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 */
+ s->dsp.vector_fmul_reverse(s->delay[ch-1], s->tmp_output+256,
+ s->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 int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
+static void ac3_downmix(AC3DecodeContext *s,
+ float samples[AC3_MAX_CHANNELS][256], int ch_offset)
{
- int nfchans = ctx->nfchans;
- int acmod = ctx->acmod;
- int i, bnd, seg, grpsize, ch;
- GetBitContext *gb = &ctx->gb;
- int bit_alloc_flags = 0;
- int8_t *dexps;
- int mstrcplco, cplcoexp, cplcomant;
- int dynrng, chbwcod, ngrps, cplabsexp, skipl;
-
- for (i = 0; i < nfchans; i++) /*block switch flag */
- ctx->blksw[i] = get_bits1(gb);
-
- ctx->dither_all = 1;
- for (i = 0; i < nfchans; i++) { /* dithering flag */
- ctx->dithflag[i] = get_bits1(gb);
- if(!ctx->dithflag[i])
- ctx->dither_all = 0;
- }
-
- if (get_bits1(gb)) { /* dynamic range */
- dynrng = get_sbits(gb, 8);
- ctx->dynrng = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
- } else if(blk == 0) {
- ctx->dynrng = 1.0;
- }
+ int i, j;
+ float v0, v1;
- if(acmod == AC3_ACMOD_DUALMONO) { /* dynamic range 1+1 mode */
- if(get_bits1(gb)) {
- dynrng = get_sbits(gb, 8);
- ctx->dynrng2 = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
- } else if(blk == 0) {
- ctx->dynrng2 = 1.0;
+ for(i=0; i<256; i++) {
+ v0 = v1 = 0.0f;
+ for(j=0; j<s->fbw_channels; j++) {
+ v0 += samples[j+ch_offset][i] * s->downmix_coeffs[j][0];
+ v1 += samples[j+ch_offset][i] * s->downmix_coeffs[j][1];
+ }
+ v0 *= s->downmix_coeff_adjust[0];
+ v1 *= s->downmix_coeff_adjust[1];
+ if(s->output_mode == AC3_CHMODE_MONO) {
+ samples[ch_offset][i] = (v0 + v1) * LEVEL_MINUS_3DB;
+ } else if(s->output_mode == AC3_CHMODE_STEREO) {
+ samples[ ch_offset][i] = v0;
+ samples[1+ch_offset][i] = v1;
}
}
+}
- if (get_bits1(gb)) { /* coupling strategy */
- ctx->cplinu = get_bits1(gb);
- ctx->cplbndstrc = 0;
- if (ctx->cplinu) { /* coupling in use */
- int cplbegf, cplendf;
-
- for (i = 0; i < nfchans; i++)
- ctx->chincpl[i] = get_bits1(gb);
+/**
+ * Upmix delay samples from stereo to original channel layout.
+ */
+static void ac3_upmix_delay(AC3DecodeContext *s)
+{
+ int channel_data_size = sizeof(s->delay[0]);
+ switch(s->channel_mode) {
+ case AC3_CHMODE_DUALMONO:
+ case AC3_CHMODE_STEREO:
+ /* upmix mono to stereo */
+ memcpy(s->delay[1], s->delay[0], channel_data_size);
+ break;
+ case AC3_CHMODE_2F2R:
+ memset(s->delay[3], 0, channel_data_size);
+ case AC3_CHMODE_2F1R:
+ memset(s->delay[2], 0, channel_data_size);
+ break;
+ case AC3_CHMODE_3F2R:
+ memset(s->delay[4], 0, channel_data_size);
+ case AC3_CHMODE_3F1R:
+ memset(s->delay[3], 0, channel_data_size);
+ case AC3_CHMODE_3F:
+ memcpy(s->delay[2], s->delay[1], channel_data_size);
+ memset(s->delay[1], 0, channel_data_size);
+ break;
+ }
+}
- if (acmod == AC3_ACMOD_STEREO)
- ctx->phsflginu = get_bits1(gb); //phase flag in use
+/**
+ * Parse an audio block from AC-3 bitstream.
+ */
+static int ac3_parse_audio_block(AC3DecodeContext *s, int blk)
+{
+ int fbw_channels = s->fbw_channels;
+ int channel_mode = s->channel_mode;
+ int i, bnd, seg, ch;
+ int different_transforms;
+ int downmix_output;
+ GetBitContext *gbc = &s->gbc;
+ uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
+
+ memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
+
+ /* block switch flags */
+ different_transforms = 0;
+ for (ch = 1; ch <= fbw_channels; ch++) {
+ s->block_switch[ch] = get_bits1(gbc);
+ if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
+ different_transforms = 1;
+ }
- cplbegf = get_bits(gb, 4);
- cplendf = get_bits(gb, 4);
+ /* dithering flags */
+ s->dither_all = 1;
+ for (ch = 1; ch <= fbw_channels; ch++) {
+ s->dither_flag[ch] = get_bits1(gbc);
+ if(!s->dither_flag[ch])
+ s->dither_all = 0;
+ }
- if (3 + cplendf - cplbegf < 0) {
- av_log(NULL, AV_LOG_ERROR, "cplendf = %d < cplbegf = %d\n", cplendf, cplbegf);
+ /* dynamic range */
+ i = !(s->channel_mode);
+ do {
+ if(get_bits1(gbc)) {
+ s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
+ s->avctx->drc_scale)+1.0;
+ } else if(blk == 0) {
+ s->dynamic_range[i] = 1.0f;
+ }
+ } while(i--);
+
+ /* coupling strategy */
+ if (get_bits1(gbc)) {
+ memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
+ s->cpl_in_use = get_bits1(gbc);
+ if (s->cpl_in_use) {
+ /* coupling in use */
+ int cpl_begin_freq, cpl_end_freq;
+
+ /* determine which channels are coupled */
+ for (ch = 1; ch <= fbw_channels; ch++)
+ s->channel_in_cpl[ch] = get_bits1(gbc);
+
+ /* phase flags in use */
+ if (channel_mode == AC3_CHMODE_STEREO)
+ s->phase_flags_in_use = get_bits1(gbc);
+
+ /* coupling frequency range and band structure */
+ cpl_begin_freq = get_bits(gbc, 4);
+ cpl_end_freq = get_bits(gbc, 4);
+ if (3 + cpl_end_freq - cpl_begin_freq < 0) {
+ av_log(s->avctx, AV_LOG_ERROR, "3+cplendf = %d < cplbegf = %d\n", 3+cpl_end_freq, cpl_begin_freq);
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 */
- if (get_bits1(gb)) {
- ctx->cplbndstrc |= 1 << i;
- ctx->ncplbnd--;
+ s->num_cpl_bands = s->num_cpl_subbands = 3 + cpl_end_freq - cpl_begin_freq;
+ s->start_freq[CPL_CH] = cpl_begin_freq * 12 + 37;
+ s->end_freq[CPL_CH] = cpl_end_freq * 12 + 73;
+ for (bnd = 0; bnd < s->num_cpl_subbands - 1; bnd++) {
+ if (get_bits1(gbc)) {
+ s->cpl_band_struct[bnd] = 1;
+ s->num_cpl_bands--;
}
+ }
+ s->cpl_band_struct[s->num_cpl_subbands-1] = 0;
} else {
- for (i = 0; i < nfchans; i++)
- ctx->chincpl[i] = 0;
+ /* coupling not in use */
+ for (ch = 1; ch <= fbw_channels; ch++)
+ s->channel_in_cpl[ch] = 0;
}
}
- if (ctx->cplinu) {
- ctx->cplcoe = 0;
-
- for (i = 0; i < nfchans; i++)
- if (ctx->chincpl[i])
- if (get_bits1(gb)) { /* coupling co-ordinates */
- ctx->cplcoe |= 1 << i;
- 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)
- cplcomant <<= 14;
+ /* coupling coordinates */
+ if (s->cpl_in_use) {
+ int cpl_coords_exist = 0;
+
+ for (ch = 1; ch <= fbw_channels; ch++) {
+ if (s->channel_in_cpl[ch]) {
+ if (get_bits1(gbc)) {
+ int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
+ cpl_coords_exist = 1;
+ master_cpl_coord = 3 * get_bits(gbc, 2);
+ for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
+ cpl_coord_exp = get_bits(gbc, 4);
+ cpl_coord_mant = get_bits(gbc, 4);
+ if (cpl_coord_exp == 15)
+ s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
else
- cplcomant = (cplcomant | 0x10) << 13;
- ctx->cplco[i][bnd] = cplcomant * scale_factors[cplcoexp + mstrcplco];
+ s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
+ s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
}
}
-
- if (acmod == AC3_ACMOD_STEREO && ctx->phsflginu && (ctx->cplcoe & 1 || ctx->cplcoe & 2))
- for (bnd = 0; bnd < ctx->ncplbnd; bnd++)
- if (get_bits1(gb))
- ctx->cplco[1][bnd] = -ctx->cplco[1][bnd];
+ }
+ }
+ /* phase flags */
+ if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
+ for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
+ s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
+ }
+ }
}
- if (acmod == AC3_ACMOD_STEREO) {/* rematrixing */
- ctx->rematstr = get_bits1(gb);
- if (ctx->rematstr) {
- ctx->nrematbnd = 4;
- if(ctx->cplinu && ctx->cplstrtmant <= 61)
- ctx->nrematbnd -= 1 + (ctx->cplstrtmant == 37);
- for(bnd=0; bnd<ctx->nrematbnd; bnd++)
- ctx->rematflg[bnd] = get_bits1(gb);
+ /* stereo rematrixing strategy and band structure */
+ if (channel_mode == AC3_CHMODE_STEREO) {
+ if (get_bits1(gbc)) {
+ s->num_rematrixing_bands = 4;
+ if(s->cpl_in_use && s->start_freq[CPL_CH] <= 61)
+ s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
+ for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
+ s->rematrixing_flags[bnd] = get_bits1(gbc);
}
}
- 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 */
+ s->exp_strategy[CPL_CH] = EXP_REUSE;
+ s->exp_strategy[s->lfe_ch] = EXP_REUSE;
+ for (ch = !s->cpl_in_use; ch <= s->channels; ch++) {
+ if(ch == s->lfe_ch)
+ s->exp_strategy[ch] = get_bits(gbc, 1);
+ else
+ s->exp_strategy[ch] = get_bits(gbc, 2);
+ if(s->exp_strategy[ch] != EXP_REUSE)
+ bit_alloc_stages[ch] = 3;
+ }
+
+ /* channel bandwidth */
+ for (ch = 1; ch <= fbw_channels; ch++) {
+ s->start_freq[ch] = 0;
+ if (s->exp_strategy[ch] != EXP_REUSE) {
+ int prev = s->end_freq[ch];
+ if (s->channel_in_cpl[ch])
+ s->end_freq[ch] = s->start_freq[CPL_CH];
else {
- chbwcod = get_bits(gb, 6);
- if (chbwcod > 60) {
- av_log(NULL, AV_LOG_ERROR, "chbwcod = %d > 60", chbwcod);
+ int bandwidth_code = get_bits(gbc, 6);
+ if (bandwidth_code > 60) {
+ av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60", bandwidth_code);
return -1;
}
- ctx->endmant[i] = chbwcod * 3 + 73;
+ s->end_freq[ch] = bandwidth_code * 3 + 73;
}
+ if(blk > 0 && s->end_freq[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 */
+ s->start_freq[s->lfe_ch] = 0;
+ s->end_freq[s->lfe_ch] = 7;
+
+ /* decode exponents for each channel */
+ for (ch = !s->cpl_in_use; ch <= s->channels; ch++) {
+ if (s->exp_strategy[ch] != EXP_REUSE) {
+ int group_size, num_groups;
+ group_size = 3 << (s->exp_strategy[ch] - 1);
+ if(ch == CPL_CH)
+ num_groups = (s->end_freq[ch] - s->start_freq[ch]) / group_size;
+ else if(ch == s->lfe_ch)
+ num_groups = 2;
+ else
+ num_groups = (s->end_freq[ch] + group_size - 4) / group_size;
+ s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
+ decode_exponents(gbc, s->exp_strategy[ch], num_groups, s->dexps[ch][0],
+ &s->dexps[ch][s->start_freq[ch]+!!ch]);
+ if(ch != CPL_CH && ch != s->lfe_ch)
+ skip_bits(gbc, 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)];
- 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)];
+ /* bit allocation information */
+ if (get_bits1(gbc)) {
+ s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
+ s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
+ s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
+ s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
+ s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
+ for(ch=!s->cpl_in_use; ch<=s->channels; 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(gbc)) {
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)];
+ csnr = (get_bits(gbc, 6) - 15) << 4;
+ for (ch = !s->cpl_in_use; ch <= s->channels; ch++) { /* snr offset and fast gain */
+ s->snr_offset[ch] = (csnr + get_bits(gbc, 4)) << 2;
+ s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
}
+ memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
}
- if (ctx->cplinu && get_bits1(gb)) { /* coupling leak information */
- bit_alloc_flags |= 64;
- ctx->bit_alloc_params.cplfleak = get_bits(gb, 3);
- ctx->bit_alloc_params.cplsleak = get_bits(gb, 3);
+ /* coupling leak information */
+ if (s->cpl_in_use && get_bits1(gbc)) {
+ s->bit_alloc_params.cpl_fast_leak = get_bits(gbc, 3);
+ s->bit_alloc_params.cpl_slow_leak = get_bits(gbc, 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");
+ /* delta bit allocation information */
+ if (get_bits1(gbc)) {
+ /* delta bit allocation exists (strategy) */
+ for (ch = !s->cpl_in_use; ch <= fbw_channels; ch++) {
+ s->dba_mode[ch] = get_bits(gbc, 2);
+ if (s->dba_mode[ch] == DBA_RESERVED) {
+ av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
return -1;
}
+ bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
}
-
- 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");
- return -1;
- }
- }
-
- 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 = !s->cpl_in_use; ch <= fbw_channels; ch++) {
+ if (s->dba_mode[ch] == DBA_NEW) {
+ s->dba_nsegs[ch] = get_bits(gbc, 3);
+ for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
+ s->dba_offsets[ch][seg] = get_bits(gbc, 5);
+ s->dba_lengths[ch][seg] = get_bits(gbc, 4);
+ s->dba_values[ch][seg] = get_bits(gbc, 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<=s->channels; ch++) {
+ s->dba_mode[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=!s->cpl_in_use; ch<=s->channels; ch++) {
+ if(bit_alloc_stages[ch] > 2) {
+ /* Exponent mapping into PSD and PSD integration */
+ ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
+ s->start_freq[ch], s->end_freq[ch],
+ s->psd[ch], s->band_psd[ch]);
+ }
+ if(bit_alloc_stages[ch] > 1) {
+ /* Compute excitation function, Compute masking curve, and
+ Apply delta bit allocation */
+ ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
+ s->start_freq[ch], s->end_freq[ch],
+ s->fast_gain[ch], (ch == s->lfe_ch),
+ s->dba_mode[ch], s->dba_nsegs[ch],
+ s->dba_offsets[ch], s->dba_lengths[ch],
+ s->dba_values[ch], s->mask[ch]);
+ }
+ if(bit_alloc_stages[ch] > 0) {
+ /* Compute bit allocation */
+ ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
+ s->start_freq[ch], s->end_freq[ch],
+ s->snr_offset[ch],
+ s->bit_alloc_params.floor,
+ s->bap[ch]);
+ }
}
- if (get_bits1(gb)) { /* unused dummy data */
- skipl = get_bits(gb, 9);
+ /* unused dummy data */
+ if (get_bits1(gbc)) {
+ int skipl = get_bits(gbc, 9);
while(skipl--)
- skip_bits(gb, 8);
+ skip_bits(gbc, 8);
}
+
/* unpack the transform coefficients
- * * 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");
+ this also uncouples channels if coupling is in use. */
+ if (get_transform_coeffs(s)) {
+ av_log(s->avctx, AV_LOG_ERROR, "Error in routine get_transform_coeffs\n");
return -1;
}
/* recover coefficients if rematrixing is in use */
- if(ctx->acmod == AC3_ACMOD_STEREO)
- do_rematrixing(ctx);
+ if(s->channel_mode == AC3_CHMODE_STEREO)
+ do_rematrixing(s);
/* 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<=s->channels; ch++) {
+ float gain = s->mul_bias / 4194304.0f;
+ if(s->channel_mode == AC3_CHMODE_DUALMONO) {
+ gain *= s->dynamic_range[ch-1];
+ } else {
+ gain *= s->dynamic_range[0];
+ }
+ for(i=0; i<256; i++) {
+ s->transform_coeffs[ch][i] = s->fixed_coeffs[ch][i] * gain;
}
}
- for(ch=1; ch<=ctx->nfchans; ch++) {
- float gain = 2.0f;
- if(ctx->acmod == AC3_ACMOD_DUALMONO && ch == 2) {
- gain *= ctx->dynrng2;
- } else {
- gain *= ctx->dynrng;
+
+ /* downmix and MDCT. order depends on whether block switching is used for
+ any channel in this block. this is because coefficients for the long
+ and short transforms cannot be mixed. */
+ downmix_output = s->channels != s->out_channels &&
+ !((s->output_mode & AC3_OUTPUT_LFEON) &&
+ s->fbw_channels == s->out_channels);
+ if(different_transforms) {
+ /* the delay samples have already been downmixed, so we upmix the delay
+ samples in order to reconstruct all channels before downmixing. */
+ if(s->downmixed) {
+ s->downmixed = 0;
+ ac3_upmix_delay(s);
+ }
+
+ do_imdct(s, s->channels);
+
+ if(downmix_output) {
+ ac3_downmix(s, s->output, 0);
+ }
+ } else {
+ if(downmix_output) {
+ ac3_downmix(s, s->transform_coeffs, 1);
}
- for(i=0; i<ctx->endmant[ch-1]; i++) {
- ctx->transform_coeffs[ch][i] *= gain;
+
+ if(!s->downmixed) {
+ s->downmixed = 1;
+ ac3_downmix(s, s->delay, 0);
}
+
+ do_imdct(s, s->out_channels);
}
- do_imdct(ctx);
+ /* convert float to 16-bit integer */
+ for(ch=0; ch<s->out_channels; ch++) {
+ for(i=0; i<256; i++) {
+ s->output[ch][i] += s->add_bias;
+ }
+ s->dsp.float_to_int16(s->int_output[ch], s->output[ch], 256);
+ }
return 0;
}
-static inline int16_t convert(int32_t i)
-{
- if (i > 0x43c07fff)
- return 32767;
- else if (i <= 0x43bf8000)
- return -32768;
- else
- return (i - 0x43c00000);
-}
-
-/* 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)
+static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
+ const uint8_t *buf, int buf_size)
{
- AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
+ AC3DecodeContext *s = 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 AC-3 Frame */
+ init_get_bits(&s->gbc, buf, buf_size * 8);
- //Initialize the GetBitContext with the start of valid AC3 Frame.
- init_get_bits(&ctx->gb, buf, buf_size * 8);
+ /* parse the syncinfo */
+ err = ac3_parse_header(s);
+ 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;
+ }
+
+ /* check that reported frame size fits in input buffer */
+ if(s->frame_size > buf_size) {
+ av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
+ return -1;
+ }
- //Parse the syncinfo.
- if (ac3_parse_header(ctx)) {
- av_log(avctx, AV_LOG_ERROR, "\n");
- *data_size = 0;
- return buf_size;
+ /* check for crc mismatch */
+ if(avctx->error_resilience >= FF_ER_CAREFUL) {
+ if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
+ av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
+ return -1;
+ }
+ /* TODO: error concealment */
}
- avctx->sample_rate = ctx->sampling_rate;
- avctx->bit_rate = ctx->bit_rate;
+ avctx->sample_rate = s->sample_rate;
+ avctx->bit_rate = s->bit_rate;
/* channel config */
- if (avctx->channels == 0) {
- avctx->channels = ctx->out_channels;
- }
- if(avctx->channels != ctx->out_channels) {
- av_log(avctx, AV_LOG_ERROR, "Cannot mix AC3 to %d channels.\n",
- avctx->channels);
- return -1;
+ s->out_channels = s->channels;
+ if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
+ avctx->request_channels < s->channels) {
+ s->out_channels = avctx->request_channels;
+ s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
}
+ avctx->channels = s->out_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);
+ /* set downmixing coefficients if needed */
+ if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
+ s->fbw_channels == s->out_channels)) {
+ set_downmix_coeffs(s);
+ }
- //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(s, blk)) {
av_log(avctx, AV_LOG_ERROR, "error parsing the audio block\n");
*data_size = 0;
- return ctx->frame_size;
+ return s->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 < s->out_channels; ch++)
+ *(out_samples++) = s->int_output[ch][i];
}
*data_size = NB_BLOCKS * 256 * avctx->channels * sizeof (int16_t);
- return ctx->frame_size;
+ return s->frame_size;
}
-/* Uninitialize ac3 decoder.
+/**
+ * Uninitialize the AC-3 decoder.
*/
-static int ac3_decode_end(AVCodecContext *avctx)
+static av_cold int ac3_decode_end(AVCodecContext *avctx)
{
- AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
- ff_mdct_end(&ctx->imdct_512);
- ff_mdct_end(&ctx->imdct_256);
+ AC3DecodeContext *s = avctx->priv_data;
+ ff_mdct_end(&s->imdct_512);
+ ff_mdct_end(&s->imdct_256);
return 0;
}
.close = ac3_decode_end,
.decode = ac3_decode_frame,
};
-
projects / ffmpeg / blobdiff