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author | Ramiro Polla <ramiro.polla@gmail.com> | 2008-08-16 17:18:20 +0000 |
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committer | Ramiro Polla <ramiro.polla@gmail.com> | 2008-08-16 17:18:20 +0000 |
commit | c50da3ad6c5ee316bafd38170172dcc6c3163764 (patch) | |
tree | a14e1737b60d336d2a498bd8dc3a689b17f33fb4 /libavcodec/flacenc.c | |
parent | 51c796d012b6494f4937e794db9ed05e05d970c4 (diff) | |
download | ffmpeg-streaming-c50da3ad6c5ee316bafd38170172dcc6c3163764.zip ffmpeg-streaming-c50da3ad6c5ee316bafd38170172dcc6c3163764.tar.gz |
flacenc, lpc: Move LPC code from flacenc.c to new lpc.[ch] files.
Originally committed as revision 14790 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/flacenc.c')
-rw-r--r-- | libavcodec/flacenc.c | 191 |
1 files changed, 2 insertions, 189 deletions
diff --git a/libavcodec/flacenc.c b/libavcodec/flacenc.c index 2750209..4876895 100644 --- a/libavcodec/flacenc.c +++ b/libavcodec/flacenc.c @@ -25,6 +25,7 @@ #include "bitstream.h" #include "dsputil.h" #include "golomb.h" +#include "lpc.h" #define FLAC_MAX_CH 8 #define FLAC_MIN_BLOCKSIZE 16 @@ -41,17 +42,8 @@ #define FLAC_CHMODE_RIGHT_SIDE 9 #define FLAC_CHMODE_MID_SIDE 10 -#define ORDER_METHOD_EST 0 -#define ORDER_METHOD_2LEVEL 1 -#define ORDER_METHOD_4LEVEL 2 -#define ORDER_METHOD_8LEVEL 3 -#define ORDER_METHOD_SEARCH 4 -#define ORDER_METHOD_LOG 5 - #define FLAC_STREAMINFO_SIZE 34 -#define MIN_LPC_ORDER 1 -#define MAX_LPC_ORDER 32 #define MAX_FIXED_ORDER 4 #define MAX_PARTITION_ORDER 8 #define MAX_PARTITIONS (1 << MAX_PARTITION_ORDER) @@ -635,185 +627,6 @@ void ff_flac_compute_autocorr(const int32_t *data, int len, int lag, } } -/** - * Levinson-Durbin recursion. - * Produces LPC coefficients from autocorrelation data. - */ -static void compute_lpc_coefs(const double *autoc, int max_order, - double lpc[][MAX_LPC_ORDER], double *ref) -{ - int i, j, i2; - double r, err, tmp; - double lpc_tmp[MAX_LPC_ORDER]; - - for(i=0; i<max_order; i++) lpc_tmp[i] = 0; - err = autoc[0]; - - for(i=0; i<max_order; i++) { - r = -autoc[i+1]; - for(j=0; j<i; j++) { - r -= lpc_tmp[j] * autoc[i-j]; - } - r /= err; - ref[i] = fabs(r); - - err *= 1.0 - (r * r); - - i2 = (i >> 1); - lpc_tmp[i] = r; - for(j=0; j<i2; j++) { - tmp = lpc_tmp[j]; - lpc_tmp[j] += r * lpc_tmp[i-1-j]; - lpc_tmp[i-1-j] += r * tmp; - } - if(i & 1) { - lpc_tmp[j] += lpc_tmp[j] * r; - } - - for(j=0; j<=i; j++) { - lpc[i][j] = -lpc_tmp[j]; - } - } -} - -/** - * Quantize LPC coefficients - */ -static void quantize_lpc_coefs(double *lpc_in, int order, int precision, - int32_t *lpc_out, int *shift, int max_shift, int zero_shift) -{ - int i; - double cmax, error; - int32_t qmax; - int sh; - - /* define maximum levels */ - qmax = (1 << (precision - 1)) - 1; - - /* find maximum coefficient value */ - cmax = 0.0; - for(i=0; i<order; i++) { - cmax= FFMAX(cmax, fabs(lpc_in[i])); - } - - /* if maximum value quantizes to zero, return all zeros */ - if(cmax * (1 << max_shift) < 1.0) { - *shift = zero_shift; - memset(lpc_out, 0, sizeof(int32_t) * order); - return; - } - - /* calculate level shift which scales max coeff to available bits */ - sh = max_shift; - while((cmax * (1 << sh) > qmax) && (sh > 0)) { - sh--; - } - - /* since negative shift values are unsupported in decoder, scale down - coefficients instead */ - if(sh == 0 && cmax > qmax) { - double scale = ((double)qmax) / cmax; - for(i=0; i<order; i++) { - lpc_in[i] *= scale; - } - } - - /* output quantized coefficients and level shift */ - error=0; - for(i=0; i<order; i++) { - error += lpc_in[i] * (1 << sh); - lpc_out[i] = av_clip(lrintf(error), -qmax, qmax); - error -= lpc_out[i]; - } - *shift = sh; -} - -static int estimate_best_order(double *ref, int max_order) -{ - int i, est; - - est = 1; - for(i=max_order-1; i>=0; i--) { - if(ref[i] > 0.10) { - est = i+1; - break; - } - } - return est; -} - -/** - * Calculate LPC coefficients for multiple orders - */ -static int lpc_calc_coefs(DSPContext *s, - const int32_t *samples, int blocksize, int max_order, - int precision, int32_t coefs[][MAX_LPC_ORDER], - int *shift, int use_lpc, int omethod, int max_shift, int zero_shift) -{ - double autoc[MAX_LPC_ORDER+1]; - double ref[MAX_LPC_ORDER]; - double lpc[MAX_LPC_ORDER][MAX_LPC_ORDER]; - int i, j, pass; - int opt_order; - - assert(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER); - - if(use_lpc == 1){ - s->flac_compute_autocorr(samples, blocksize, max_order, autoc); - - compute_lpc_coefs(autoc, max_order, lpc, ref); - }else{ - LLSModel m[2]; - double var[MAX_LPC_ORDER+1], weight; - - for(pass=0; pass<use_lpc-1; pass++){ - av_init_lls(&m[pass&1], max_order); - - weight=0; - for(i=max_order; i<blocksize; i++){ - for(j=0; j<=max_order; j++) - var[j]= samples[i-j]; - - if(pass){ - double eval, inv, rinv; - eval= av_evaluate_lls(&m[(pass-1)&1], var+1, max_order-1); - eval= (512>>pass) + fabs(eval - var[0]); - inv = 1/eval; - rinv = sqrt(inv); - for(j=0; j<=max_order; j++) - var[j] *= rinv; - weight += inv; - }else - weight++; - - av_update_lls(&m[pass&1], var, 1.0); - } - av_solve_lls(&m[pass&1], 0.001, 0); - } - - for(i=0; i<max_order; i++){ - for(j=0; j<max_order; j++) - lpc[i][j]= m[(pass-1)&1].coeff[i][j]; - ref[i]= sqrt(m[(pass-1)&1].variance[i] / weight) * (blocksize - max_order) / 4000; - } - for(i=max_order-1; i>0; i--) - ref[i] = ref[i-1] - ref[i]; - } - opt_order = max_order; - - if(omethod == ORDER_METHOD_EST) { - opt_order = estimate_best_order(ref, max_order); - i = opt_order-1; - quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift); - } else { - for(i=0; i<max_order; i++) { - quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift); - } - } - - return opt_order; -} - static void encode_residual_verbatim(int32_t *res, int32_t *smp, int n) { @@ -1042,7 +855,7 @@ static int encode_residual(FlacEncodeContext *ctx, int ch) } /* LPC */ - opt_order = lpc_calc_coefs(&ctx->dsp, smp, n, max_order, precision, coefs, + opt_order = ff_lpc_calc_coefs(&ctx->dsp, smp, n, max_order, precision, coefs, shift, ctx->options.use_lpc, omethod, MAX_LPC_SHIFT, 0); if(omethod == ORDER_METHOD_2LEVEL || |