mirror of https://git.ffmpeg.org/ffmpeg.git
AC-3 decoder, soc revision 71, Sep 4 09:47:12 2006 UTC by cloud9
Redundant code cleanup. Optimized dither generation. Minor optimization in bit allocation. Comments. Originally committed as revision 9669 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles
parent
860fe8c908
commit
c7cfc48f37
|
|
@ -13,8 +13,6 @@
|
|||
*
|
||||
* Thanks Makoto Matsumoto and Takuji Nishimura for the Mersenne Twister.
|
||||
*
|
||||
* Kaiser-Bessel derived window by Justin Ruggles.
|
||||
*
|
||||
* Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com).
|
||||
* Something is wrong up on cloud # 9!
|
||||
*
|
||||
|
|
@ -95,7 +93,6 @@ typedef struct {
|
|||
/* Mersenne Twister */
|
||||
|
||||
typedef struct {
|
||||
uint32_t flags;
|
||||
uint16_t crc1;
|
||||
uint8_t fscod;
|
||||
|
||||
|
|
@ -148,74 +145,81 @@ typedef struct {
|
|||
int bit_rate;
|
||||
int frame_size;
|
||||
|
||||
int nfchans;
|
||||
int lfeon;
|
||||
int nfchans; //number of channels
|
||||
int lfeon; //lfe channel in use
|
||||
|
||||
float dynrng;
|
||||
float dynrng2;
|
||||
float chcoeffs[6];
|
||||
float cplco[5][18];
|
||||
int ncplbnd;
|
||||
int ncplsubnd;
|
||||
int cplstrtmant;
|
||||
int cplendmant;
|
||||
int endmant[5];
|
||||
uint8_t dcplexps[256];
|
||||
uint8_t dexps[5][256];
|
||||
uint8_t dlfeexps[256];
|
||||
uint8_t cplbap[256];
|
||||
uint8_t bap[5][256];
|
||||
uint8_t lfebap[256];
|
||||
int blkoutput;
|
||||
float dynrng; //dynamic range gain
|
||||
float dynrng2; //dynamic range gain for 1+1 mode
|
||||
float chcoeffs[6]; //normalized channel coefficients
|
||||
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
|
||||
|
||||
DECLARE_ALIGNED_16(float, transform_coeffs[MAX_CHANNELS][BLOCK_SIZE]);
|
||||
uint8_t dcplexps[256]; //decoded coupling exponents
|
||||
uint8_t dexps[5][256]; //decoded fbw channel exponents
|
||||
uint8_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
|
||||
|
||||
int blkoutput; //output configuration for block
|
||||
|
||||
DECLARE_ALIGNED_16(float, transform_coeffs[MAX_CHANNELS][BLOCK_SIZE]); //transform coefficients
|
||||
|
||||
/* For IMDCT. */
|
||||
MDCTContext imdct_512; //N/8 point IFFT context
|
||||
MDCTContext imdct_256; //N/4 point IFFT context
|
||||
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[MAX_CHANNELS][BLOCK_SIZE]);
|
||||
DECLARE_ALIGNED_16(float, delay[MAX_CHANNELS][BLOCK_SIZE]);
|
||||
DECLARE_ALIGNED_16(float, tmp_imdct[BLOCK_SIZE]);
|
||||
DECLARE_ALIGNED_16(float, tmp_output[BLOCK_SIZE * 2]);
|
||||
DECLARE_ALIGNED_16(float, window[BLOCK_SIZE]);
|
||||
|
||||
DECLARE_ALIGNED_16(float, output[MAX_CHANNELS][BLOCK_SIZE]); //output after imdct transform and windowing
|
||||
DECLARE_ALIGNED_16(float, delay[MAX_CHANNELS][BLOCK_SIZE]); //delay - added to the next block
|
||||
DECLARE_ALIGNED_16(float, tmp_imdct[BLOCK_SIZE]); //temporary storage for imdct transform
|
||||
DECLARE_ALIGNED_16(float, tmp_output[BLOCK_SIZE * 2]); //temporary storage for output before windowing
|
||||
DECLARE_ALIGNED_16(float, window[BLOCK_SIZE]); //window coefficients
|
||||
|
||||
/* Miscellaneous. */
|
||||
GetBitContext gb;
|
||||
dither_state dith_state;
|
||||
dither_state dith_state; //for dither generation
|
||||
} AC3DecodeContext;
|
||||
|
||||
|
||||
/* BEGIN Mersenne Twister Code. */
|
||||
static void dither_seed(dither_state *state, uint32_t seed)
|
||||
{
|
||||
if (seed == 0) seed = 0x1f2e3d4c;
|
||||
static const uint32_t mag01[2] = { 0x00, MATRIX_A };
|
||||
uint32_t y;
|
||||
int kk;
|
||||
|
||||
if (seed == 0)
|
||||
seed = 0x7ba05e; //default seed to my birthday!
|
||||
|
||||
state->mt[0] = seed;
|
||||
for (state->mti = 1; state->mti < NMT; state->mti++)
|
||||
state->mt[state->mti] = ((69069 * state->mt[state->mti - 1]) + 1);
|
||||
|
||||
for (kk = 0; kk < NMT - MMT; kk++) {
|
||||
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
|
||||
state->mt[kk] = state->mt[kk + MMT] ^ (y >> 1) ^ mag01[y & 0x01];
|
||||
}
|
||||
for (;kk < NMT - 1; kk++) {
|
||||
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
|
||||
state->mt[kk] = state->mt[kk + (MMT - NMT)] ^ (y >> 1) ^ mag01[y & 0x01];
|
||||
}
|
||||
y = (state->mt[NMT - 1] & UPPER_MASK) | (state->mt[0] & LOWER_MASK);
|
||||
state->mt[NMT - 1] = state->mt[MMT - 1] ^ (y >> 1) ^ mag01[y & 0x01];
|
||||
|
||||
state->mti = 0;
|
||||
}
|
||||
|
||||
static uint32_t dither_uint32(dither_state *state)
|
||||
static int16_t dither_int16(dither_state *state)
|
||||
{
|
||||
uint32_t y;
|
||||
static const uint32_t mag01[2] = { 0x00, MATRIX_A };
|
||||
int kk;
|
||||
|
||||
if (state->mti >= NMT) {
|
||||
for (kk = 0; kk < NMT - MMT; kk++) {
|
||||
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
|
||||
state->mt[kk] = state->mt[kk + MMT] ^ (y >> 1) ^ mag01[y & 0x01];
|
||||
}
|
||||
for (;kk < NMT - 1; kk++) {
|
||||
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
|
||||
state->mt[kk] = state->mt[kk + (MMT - NMT)] ^ (y >> 1) ^ mag01[y & 0x01];
|
||||
}
|
||||
y = (state->mt[NMT - 1] & UPPER_MASK) | (state->mt[0] & LOWER_MASK);
|
||||
state->mt[NMT - 1] = state->mt[MMT - 1] ^ (y >> 1) ^ mag01[y & 0x01];
|
||||
|
||||
if (state->mti >= NMT)
|
||||
state->mti = 0;
|
||||
}
|
||||
|
||||
y = state->mt[state->mti++];
|
||||
y ^= (y >> 11);
|
||||
|
|
@ -223,16 +227,11 @@ static uint32_t dither_uint32(dither_state *state)
|
|||
y ^= ((y << 15) & 0xefc60000);
|
||||
y ^= (y >> 18);
|
||||
|
||||
return y;
|
||||
return ((y << 16) >> 16);
|
||||
}
|
||||
|
||||
static inline int16_t dither_int16(dither_state *state)
|
||||
{
|
||||
return ((dither_uint32(state) << 16) >> 16);
|
||||
}
|
||||
|
||||
/* END Mersenne Twister */
|
||||
|
||||
/*********** BEGIN INIT HELPER FUNCTIONS ***********/
|
||||
/**
|
||||
* Generate a Kaiser-Bessel Derived Window.
|
||||
*/
|
||||
|
|
@ -257,6 +256,9 @@ static void ac3_window_init(float *window)
|
|||
window[i] = sqrt(local_window[i] / sum);
|
||||
}
|
||||
|
||||
/*
|
||||
* Generate quantizer tables.
|
||||
*/
|
||||
static void generate_quantizers_table(int16_t quantizers[], int level, int length)
|
||||
{
|
||||
int i;
|
||||
|
|
@ -308,6 +310,9 @@ static void generate_quantizers_table_3(int16_t quantizers[], int level, int len
|
|||
quantizers[i] = 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Initialize tables at runtime.
|
||||
*/
|
||||
static void ac3_tables_init(void)
|
||||
{
|
||||
int i, j, k, l, v;
|
||||
|
|
@ -323,6 +328,10 @@ static void ac3_tables_init(void)
|
|||
masktab[253] = masktab[254] = masktab[255] = 0;
|
||||
bndtab[50] = 0;
|
||||
|
||||
/* PSD Table For Mapping Exponents To PSD. */
|
||||
for (i = 0; i < 25; i++)
|
||||
psdtab[i] = 3072 - (i << 7);
|
||||
|
||||
/* Exponent Decoding Tables */
|
||||
for (i = 0; i < 5; i++) {
|
||||
v = i - 2;
|
||||
|
|
@ -366,6 +375,11 @@ static void ac3_tables_init(void)
|
|||
|
||||
//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));
|
||||
}
|
||||
|
||||
|
||||
|
|
@ -376,14 +390,21 @@ static int ac3_decode_init(AVCodecContext *avctx)
|
|||
ac3_tables_init();
|
||||
ff_mdct_init(&ctx->imdct_256, 8, 1);
|
||||
ff_mdct_init(&ctx->imdct_512, 9, 1);
|
||||
/* Kaiser-Bessel derived window. */
|
||||
ac3_window_init(ctx->window);
|
||||
dsputil_init(&ctx->dsp, avctx);
|
||||
dither_seed(&ctx->dith_state, 0);
|
||||
|
||||
return 0;
|
||||
}
|
||||
/*********** END INIT FUNCTIONS ***********/
|
||||
|
||||
/* Synchronize to ac3 bitstream.
|
||||
* This function searches for the syncword '0xb77'.
|
||||
*
|
||||
* @param buf Pointer to "probable" ac3 bitstream buffer
|
||||
* @param buf_size Size of buffer
|
||||
* @return Returns the position where syncword is found, -1 if no syncword is found
|
||||
*/
|
||||
static int ac3_synchronize(uint8_t *buf, int buf_size)
|
||||
{
|
||||
int i;
|
||||
|
|
@ -395,7 +416,14 @@ static int ac3_synchronize(uint8_t *buf, int buf_size)
|
|||
return -1;
|
||||
}
|
||||
|
||||
//Returns -1 when 'fscod' is not valid;
|
||||
/* Parse the 'sync_info' from the ac3 bitstream.
|
||||
* This function extracts the sync_info from ac3 bitstream.
|
||||
* GetBitContext within AC3DecodeContext must point to
|
||||
* start of the synchronized ac3 bitstream.
|
||||
*
|
||||
* @param ctx AC3DecodeContext
|
||||
* @return Returns framesize, returns 0 if fscod, frmsizecod or bsid is not valid
|
||||
*/
|
||||
static int ac3_parse_sync_info(AC3DecodeContext *ctx)
|
||||
{
|
||||
GetBitContext *gb = &ctx->gb;
|
||||
|
|
@ -434,6 +462,11 @@ static int ac3_parse_sync_info(AC3DecodeContext *ctx)
|
|||
return 0;
|
||||
}
|
||||
|
||||
/* Parse bsi from ac3 bitstream.
|
||||
* This function extracts the bitstream information (bsi) from ac3 bitstream.
|
||||
*
|
||||
* @param ctx AC3DecodeContext after processed by ac3_parse_sync_info
|
||||
*/
|
||||
static void ac3_parse_bsi(AC3DecodeContext *ctx)
|
||||
{
|
||||
GetBitContext *gb = &ctx->gb;
|
||||
|
|
@ -490,10 +523,16 @@ static void ac3_parse_bsi(AC3DecodeContext *ctx)
|
|||
}
|
||||
}
|
||||
|
||||
/* Decodes the grouped exponents and stores them
|
||||
* in decoded exponents (dexps).
|
||||
* The code is derived from liba52.
|
||||
* Uses liba52 tables.
|
||||
/* Decodes the grouped exponents.
|
||||
* This function decodes the coded exponents according to exponent strategy
|
||||
* and stores them in the decoded exponents buffer.
|
||||
*
|
||||
* @param gb GetBitContext which points to start of coded exponents
|
||||
* @param expstr Exponent coding strategy
|
||||
* @param ngrps Number of grouped exponetns
|
||||
* @param absexp Absolute exponent
|
||||
* @param dexps Decoded exponents are stored in dexps
|
||||
* @return Returns 0 if exponents are decoded successfully, -1 if error occurs
|
||||
*/
|
||||
static int decode_exponents(GetBitContext *gb, int expstr, int ngrps, uint8_t absexp, uint8_t *dexps)
|
||||
{
|
||||
|
|
@ -551,6 +590,7 @@ static int decode_exponents(GetBitContext *gb, int expstr, int ngrps, uint8_t ab
|
|||
return 0;
|
||||
}
|
||||
|
||||
/*********** HELPER FUNCTIONS FOR BIT ALLOCATION ***********/
|
||||
static inline int logadd(int a, int b)
|
||||
{
|
||||
int c = a - b;
|
||||
|
|
@ -583,11 +623,10 @@ static inline int calc_lowcomp(int a, int b0, int b1, int bin)
|
|||
|
||||
return a;
|
||||
}
|
||||
/*********** END HELPER FUNCTIONS FOR BIT ALLOCATION ***********/
|
||||
|
||||
/* do the bit allocation for chnl.
|
||||
* chnl = 0 to 4 - fbw channel
|
||||
* chnl = 5 coupling channel
|
||||
* chnl = 6 lfe channel
|
||||
/* Performs bit allocation.
|
||||
* This function performs bit allocation for the requested chanenl.
|
||||
*/
|
||||
static void do_bit_allocation(AC3DecodeContext *ctx, int chnl)
|
||||
{
|
||||
|
|
@ -655,7 +694,7 @@ static void do_bit_allocation(AC3DecodeContext *ctx, int chnl)
|
|||
}
|
||||
|
||||
for (bin = start; bin < end; bin++) /* exponent mapping into psd */
|
||||
psd[bin] = (3072 - (exps[bin] << 7));
|
||||
psd[bin] = psdtab[exps[bin]];
|
||||
|
||||
/* psd integration */
|
||||
j = start;
|
||||
|
|
@ -972,6 +1011,10 @@ static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_gro
|
|||
return 0;
|
||||
}
|
||||
|
||||
/* Get the transform coefficients.
|
||||
* This function extracts the tranform coefficients form the ac3 bitstream.
|
||||
* This function is called after bit allocation is performed.
|
||||
*/
|
||||
static int get_transform_coeffs(AC3DecodeContext * ctx)
|
||||
{
|
||||
int i, end;
|
||||
|
|
@ -1011,6 +1054,7 @@ static int get_transform_coeffs(AC3DecodeContext * ctx)
|
|||
return 0;
|
||||
}
|
||||
|
||||
/* Rematrixing routines. */
|
||||
static void do_rematrixing1(AC3DecodeContext *ctx, int start, int end)
|
||||
{
|
||||
float tmp0, tmp1;
|
||||
|
|
@ -1050,6 +1094,10 @@ static void do_rematrixing(AC3DecodeContext *ctx)
|
|||
}
|
||||
}
|
||||
|
||||
/* This function sets the normalized channel coefficients.
|
||||
* Transform coefficients are multipllied by the channel
|
||||
* coefficients to get normalized transform coefficients.
|
||||
*/
|
||||
static void get_downmix_coeffs(AC3DecodeContext *ctx)
|
||||
{
|
||||
int from = ctx->acmod;
|
||||
|
|
@ -1217,6 +1265,7 @@ static void get_downmix_coeffs(AC3DecodeContext *ctx)
|
|||
}
|
||||
}
|
||||
|
||||
/*********** BEGIN DOWNMIX FUNCTIONS ***********/
|
||||
static inline void mix_dualmono_to_mono(AC3DecodeContext *ctx)
|
||||
{
|
||||
int i;
|
||||
|
|
@ -1433,12 +1482,20 @@ static inline void mix_3f_2r_to_dolby(AC3DecodeContext *ctx)
|
|||
memset(output[4], 0, sizeof(output[4]));
|
||||
memset(output[5], 0, sizeof(output[5]));
|
||||
}
|
||||
/*********** END DOWNMIX FUNCTIONS ***********/
|
||||
|
||||
/* Downmix the output.
|
||||
* This function downmixes the output when the number of input
|
||||
* channels is not equal to the number of output channels requested.
|
||||
*/
|
||||
static void do_downmix(AC3DecodeContext *ctx)
|
||||
{
|
||||
int from = ctx->acmod;
|
||||
int to = ctx->blkoutput;
|
||||
|
||||
if (to == AC3_OUTPUT_UNMODIFIED)
|
||||
return;
|
||||
|
||||
switch (from) {
|
||||
case AC3_INPUT_DUALMONO:
|
||||
switch (to) {
|
||||
|
|
@ -1545,16 +1602,9 @@ static void dump_floats(const char *name, int prec, const float *tab, int n)
|
|||
av_log(NULL, AV_LOG_INFO, "\n");
|
||||
}
|
||||
|
||||
#define CMUL(pre, pim, are, aim, bre, bim) \
|
||||
{\
|
||||
float _are = (are);\
|
||||
float _aim = (aim);\
|
||||
float _bre = (bre);\
|
||||
float _bim = (bim);\
|
||||
(pre) = _are * _bre - _aim * _bim;\
|
||||
(pim) = _are * _bim + _aim * _bre;\
|
||||
}
|
||||
|
||||
/* This function performs the imdct on 256 sample transform
|
||||
* coefficients.
|
||||
*/
|
||||
static void do_imdct_256(AC3DecodeContext *ctx, int chindex)
|
||||
{
|
||||
int k;
|
||||
|
|
@ -1575,6 +1625,9 @@ static void do_imdct_256(AC3DecodeContext *ctx, int chindex)
|
|||
ctx->dsp.vector_fmul_reverse(ptr, ctx->tmp_output + 256, ctx->window, BLOCK_SIZE);
|
||||
}
|
||||
|
||||
/* This function performs the imdct on 512 sample transform
|
||||
* coefficients.
|
||||
*/
|
||||
static void do_imdct_512(AC3DecodeContext *ctx, int chindex)
|
||||
{
|
||||
float *ptr;
|
||||
|
|
@ -1587,6 +1640,7 @@ static void do_imdct_512(AC3DecodeContext *ctx, int chindex)
|
|||
ctx->dsp.vector_fmul_reverse(ptr, ctx->tmp_output + 256, ctx->window, BLOCK_SIZE);
|
||||
}
|
||||
|
||||
/* IMDCT Transform. */
|
||||
static inline void do_imdct(AC3DecodeContext *ctx)
|
||||
{
|
||||
int i;
|
||||
|
|
@ -1602,6 +1656,11 @@ static inline void do_imdct(AC3DecodeContext *ctx)
|
|||
}
|
||||
}
|
||||
|
||||
/* 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.
|
||||
*/
|
||||
static int ac3_parse_audio_block(AC3DecodeContext * ctx)
|
||||
{
|
||||
int nfchans = ctx->nfchans;
|
||||
|
|
@ -1609,7 +1668,6 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
|
|||
int i, bnd, rbnd, seg, grpsize;
|
||||
GetBitContext *gb = &ctx->gb;
|
||||
int bit_alloc_flags = 0;
|
||||
float drange;
|
||||
uint8_t *dexps;
|
||||
int mstrcplco, cplcoexp, cplcomant;
|
||||
int dynrng, chbwcod, ngrps, cplabsexp, skipl;
|
||||
|
|
@ -1879,16 +1937,6 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
|
|||
return 0;
|
||||
}
|
||||
|
||||
/*static inline int16_t convert(float f)
|
||||
{
|
||||
if (f >= 1.0)
|
||||
return 32767;
|
||||
else if (f <= -1.0)
|
||||
return -32768;
|
||||
else
|
||||
return (lrintf(f * 32767.0));
|
||||
}*/
|
||||
|
||||
static inline int16_t convert(int32_t i)
|
||||
{
|
||||
if (i > 0x43c07fff)
|
||||
|
|
@ -1901,6 +1949,14 @@ static inline int16_t convert(int32_t i)
|
|||
|
||||
static int frame_count = 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
|
||||
*/
|
||||
static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
|
||||
{
|
||||
AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
|
||||
|
|
@ -1981,8 +2037,14 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
|
|||
return ctx->frame_size;
|
||||
}
|
||||
|
||||
static int ac3_decode_end(AVCodecContext *ctx)
|
||||
/* Uninitialize ac3 decoder.
|
||||
*/
|
||||
static int ac3_decode_end(AVCodecContext *avctx)
|
||||
{
|
||||
AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
|
||||
ff_mdct_end(&ctx->imdct_512);
|
||||
ff_mdct_end(&ctx->imdct_256);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue