mirror of https://git.ffmpeg.org/ffmpeg.git
new generic FFT/MDCT code for audio codecs
Originally committed as revision 1088 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Fabrice Bellard
parent
6d29182097
commit
bb6f569072
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@ -221,5 +221,52 @@ struct unaligned_32 { uint32_t l; } __attribute__((packed));
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void get_psnr(UINT8 *orig_image[3], UINT8 *coded_image[3],
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int orig_linesize[3], int coded_linesize,
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AVCodecContext *avctx);
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/* FFT computation */
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/* NOTE: soon integer code will be added, so you must use the
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FFTSample type */
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typedef float FFTSample;
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typedef struct FFTComplex {
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FFTSample re, im;
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} FFTComplex;
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typedef struct FFTContext {
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int nbits;
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int inverse;
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uint16_t *revtab;
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FFTComplex *exptab;
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FFTComplex *exptab1; /* only used by SSE code */
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void (*fft_calc)(struct FFTContext *s, FFTComplex *z);
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} FFTContext;
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int fft_init(FFTContext *s, int nbits, int inverse);
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void fft_permute(FFTContext *s, FFTComplex *z);
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void fft_calc_c(FFTContext *s, FFTComplex *z);
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void fft_calc_sse(FFTContext *s, FFTComplex *z);
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static inline void fft_calc(FFTContext *s, FFTComplex *z)
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{
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s->fft_calc(s, z);
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}
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void fft_end(FFTContext *s);
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/* MDCT computation */
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typedef struct MDCTContext {
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int n; /* size of MDCT (i.e. number of input data * 2) */
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int nbits; /* n = 2^nbits */
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/* pre/post rotation tables */
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FFTSample *tcos;
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FFTSample *tsin;
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FFTContext fft;
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} MDCTContext;
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int mdct_init(MDCTContext *s, int nbits, int inverse);
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void imdct_calc(MDCTContext *s, FFTSample *output,
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const FFTSample *input, FFTSample *tmp);
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void mdct_calc(MDCTContext *s, FFTSample *out,
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const FFTSample *input, FFTSample *tmp);
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void mdct_end(MDCTContext *s);
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#endif
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@ -0,0 +1,294 @@
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/* FFT and MDCT tests */
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#include "dsputil.h"
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#include <math.h>
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#include <getopt.h>
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#include <sys/time.h>
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int mm_flags;
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void *av_malloc(int size)
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{
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void *ptr;
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ptr = malloc(size);
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return ptr;
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}
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void av_free(void *ptr)
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{
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/* XXX: this test should not be needed on most libcs */
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if (ptr)
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free(ptr);
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}
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/* cannot call it directly because of 'void **' casting is not automatic */
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void __av_freep(void **ptr)
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{
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av_free(*ptr);
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*ptr = NULL;
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}
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/* reference fft */
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#define MUL16(a,b) ((a) * (b))
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#define CMAC(pre, pim, are, aim, bre, bim) \
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{\
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pre += (MUL16(are, bre) - MUL16(aim, bim));\
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pim += (MUL16(are, bim) + MUL16(bre, aim));\
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}
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FFTComplex *exptab;
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void fft_ref_init(int nbits, int inverse)
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{
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int n, i;
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float c1, s1, alpha;
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n = 1 << nbits;
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exptab = av_malloc((n / 2) * sizeof(FFTComplex));
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for(i=0;i<(n/2);i++) {
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alpha = 2 * M_PI * (float)i / (float)n;
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c1 = cos(alpha);
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s1 = sin(alpha);
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if (!inverse)
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s1 = -s1;
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exptab[i].re = c1;
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exptab[i].im = s1;
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}
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}
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void fft_ref(FFTComplex *tabr, FFTComplex *tab, int nbits)
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{
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int n, i, j, k, n2;
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float tmp_re, tmp_im, s, c;
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FFTComplex *q;
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n = 1 << nbits;
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n2 = n >> 1;
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for(i=0;i<n;i++) {
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tmp_re = 0;
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tmp_im = 0;
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q = tab;
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for(j=0;j<n;j++) {
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k = (i * j) & (n - 1);
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if (k >= n2) {
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c = -exptab[k - n2].re;
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s = -exptab[k - n2].im;
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} else {
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c = exptab[k].re;
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s = exptab[k].im;
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}
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CMAC(tmp_re, tmp_im, c, s, q->re, q->im);
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q++;
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}
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tabr[i].re = tmp_re;
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tabr[i].im = tmp_im;
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}
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}
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void imdct_ref(float *out, float *in, int n)
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{
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int k, i, a;
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float sum, f;
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for(i=0;i<n;i++) {
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sum = 0;
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for(k=0;k<n/2;k++) {
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a = (2 * i + 1 + (n / 2)) * (2 * k + 1);
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f = cos(M_PI * a / (double)(2 * n));
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sum += f * in[k];
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}
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out[i] = -sum;
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}
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}
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/* NOTE: no normalisation by 1 / N is done */
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void mdct_ref(float *output, float *input, int n)
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{
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int k, i;
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float a, s;
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/* do it by hand */
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for(k=0;k<n/2;k++) {
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s = 0;
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for(i=0;i<n;i++) {
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a = (2*M_PI*(2*i+1+n/2)*(2*k+1) / (4 * n));
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s += input[i] * cos(a);
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}
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output[k] = s;
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}
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}
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float frandom(void)
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{
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return (float)((random() & 0xffff) - 32768) / 32768.0;
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}
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INT64 gettime(void)
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{
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struct timeval tv;
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gettimeofday(&tv,NULL);
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return (INT64)tv.tv_sec * 1000000 + tv.tv_usec;
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}
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void check_diff(float *tab1, float *tab2, int n)
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{
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int i;
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for(i=0;i<n;i++) {
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if (fabsf(tab1[i] - tab2[i]) >= 1e-3) {
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printf("ERROR %d: %f %f\n",
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i, tab1[i], tab2[i]);
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}
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}
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}
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void help(void)
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{
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printf("usage: fft-test [-h] [-s] [-i] [-n b]\n"
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"-h print this help\n"
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"-s speed test\n"
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"-m (I)MDCT test\n"
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"-i inverse transform test\n"
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"-n b set the transform size to 2^b\n"
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);
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exit(1);
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}
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int main(int argc, char **argv)
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{
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FFTComplex *tab, *tab1, *tab_ref;
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FFTSample *tabtmp, *tab2;
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int it, i, c;
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int do_speed = 0;
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int do_mdct = 0;
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int do_inverse = 0;
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FFTContext s1, *s = &s1;
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MDCTContext m1, *m = &m1;
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int fft_nbits, fft_size;
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mm_flags = 0;
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fft_nbits = 9;
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for(;;) {
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c = getopt(argc, argv, "hsimn:");
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if (c == -1)
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break;
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switch(c) {
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case 'h':
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help();
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break;
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case 's':
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do_speed = 1;
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break;
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case 'i':
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do_inverse = 1;
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break;
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case 'm':
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do_mdct = 1;
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break;
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case 'n':
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fft_nbits = atoi(optarg);
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break;
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}
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}
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fft_size = 1 << fft_nbits;
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tab = av_malloc(fft_size * sizeof(FFTComplex));
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tab1 = av_malloc(fft_size * sizeof(FFTComplex));
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tab_ref = av_malloc(fft_size * sizeof(FFTComplex));
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tabtmp = av_malloc(fft_size / 2 * sizeof(FFTSample));
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tab2 = av_malloc(fft_size * sizeof(FFTSample));
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if (do_mdct) {
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if (do_inverse)
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printf("IMDCT");
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else
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printf("MDCT");
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mdct_init(m, fft_nbits, do_inverse);
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} else {
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if (do_inverse)
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printf("IFFT");
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else
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printf("FFT");
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fft_init(s, fft_nbits, do_inverse);
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fft_ref_init(fft_nbits, do_inverse);
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}
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printf(" %d test\n", fft_size);
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/* generate random data */
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for(i=0;i<fft_size;i++) {
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tab1[i].re = frandom();
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tab1[i].im = frandom();
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}
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/* checking result */
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printf("Checking...\n");
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if (do_mdct) {
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if (do_inverse) {
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imdct_ref((float *)tab_ref, (float *)tab1, fft_size);
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imdct_calc(m, tab2, (float *)tab1, tabtmp);
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check_diff((float *)tab_ref, tab2, fft_size);
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} else {
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mdct_ref((float *)tab_ref, (float *)tab1, fft_size);
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mdct_calc(m, tab2, (float *)tab1, tabtmp);
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check_diff((float *)tab_ref, tab2, fft_size / 2);
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}
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} else {
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memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
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fft_permute(s, tab);
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fft_calc(s, tab);
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fft_ref(tab_ref, tab1, fft_nbits);
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check_diff((float *)tab_ref, (float *)tab, fft_size * 2);
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}
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/* do a speed test */
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if (do_speed) {
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INT64 time_start, duration;
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int nb_its;
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printf("Speed test...\n");
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/* we measure during about 1 seconds */
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nb_its = 1;
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for(;;) {
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time_start = gettime();
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for(it=0;it<nb_its;it++) {
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if (do_mdct) {
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if (do_inverse) {
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imdct_calc(m, (float *)tab, (float *)tab1, tabtmp);
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} else {
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mdct_calc(m, (float *)tab, (float *)tab1, tabtmp);
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}
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} else {
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memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
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fft_calc(s, tab);
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}
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}
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duration = gettime() - time_start;
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if (duration >= 1000000)
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break;
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nb_its *= 2;
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}
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printf("time: %0.1f us/transform [total time=%0.2f s its=%d]\n",
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(double)duration / nb_its,
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(double)duration / 1000000.0,
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nb_its);
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}
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if (do_mdct) {
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mdct_end(m);
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} else {
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fft_end(s);
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}
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return 0;
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}
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@ -0,0 +1,229 @@
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/*
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* FFT/IFFT transforms
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* Copyright (c) 2002 Fabrice Bellard.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "dsputil.h"
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/**
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* The size of the FFT is 2^nbits. If inverse is TRUE, inverse FFT is
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* done
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*/
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int fft_init(FFTContext *s, int nbits, int inverse)
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{
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int i, j, m, n;
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float alpha, c1, s1, s2;
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s->nbits = nbits;
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n = 1 << nbits;
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s->exptab = av_malloc((n / 2) * sizeof(FFTComplex));
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if (!s->exptab)
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goto fail;
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s->revtab = av_malloc(n * sizeof(uint16_t));
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if (!s->revtab)
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goto fail;
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s->inverse = inverse;
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s2 = inverse ? 1.0 : -1.0;
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for(i=0;i<(n/2);i++) {
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alpha = 2 * M_PI * (float)i / (float)n;
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c1 = cos(alpha);
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s1 = sin(alpha) * s2;
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s->exptab[i].re = c1;
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s->exptab[i].im = s1;
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}
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s->fft_calc = fft_calc_c;
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s->exptab1 = NULL;
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/* compute constant table for HAVE_SSE version */
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#if defined(HAVE_MMX) && 0
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if (mm_flags & MM_SSE) {
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int np, nblocks, np2, l;
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FFTComplex *q;
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np = 1 << nbits;
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nblocks = np >> 3;
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np2 = np >> 1;
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s->exptab1 = av_malloc(np * 2 * sizeof(FFTComplex));
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if (!s->exptab1)
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goto fail;
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q = s->exptab1;
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do {
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for(l = 0; l < np2; l += 2 * nblocks) {
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*q++ = s->exptab[l];
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*q++ = s->exptab[l + nblocks];
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q->re = -s->exptab[l].im;
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q->im = s->exptab[l].re;
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q++;
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q->re = -s->exptab[l + nblocks].im;
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q->im = s->exptab[l + nblocks].re;
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q++;
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}
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nblocks = nblocks >> 1;
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} while (nblocks != 0);
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av_freep(&s->exptab);
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}
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#endif
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/* compute bit reverse table */
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for(i=0;i<n;i++) {
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m=0;
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for(j=0;j<nbits;j++) {
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m |= ((i >> j) & 1) << (nbits-j-1);
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}
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s->revtab[i]=m;
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}
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return 0;
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fail:
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av_freep(&s->revtab);
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av_freep(&s->exptab);
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av_freep(&s->exptab1);
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return -1;
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}
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/* butter fly op */
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#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
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{\
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FFTSample ax, ay, bx, by;\
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bx=pre1;\
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by=pim1;\
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ax=qre1;\
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ay=qim1;\
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pre = (bx + ax);\
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pim = (by + ay);\
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qre = (bx - ax);\
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qim = (by - ay);\
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}
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#define MUL16(a,b) ((a) * (b))
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#define CMUL(pre, pim, are, aim, bre, bim) \
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{\
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pre = (MUL16(are, bre) - MUL16(aim, bim));\
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pim = (MUL16(are, bim) + MUL16(bre, aim));\
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}
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/**
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* Do a complex FFT with the parameters defined in fft_init(). The
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* input data must be permuted before with s->revtab table. No
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* 1.0/sqrt(n) normalization is done.
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*/
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void fft_calc_c(FFTContext *s, FFTComplex *z)
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{
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int ln = s->nbits;
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int j, np, np2;
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int nblocks, nloops;
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register FFTComplex *p, *q;
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FFTComplex *exptab = s->exptab;
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int l;
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FFTSample tmp_re, tmp_im;
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np = 1 << ln;
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/* pass 0 */
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p=&z[0];
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j=(np >> 1);
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do {
|
||||
BF(p[0].re, p[0].im, p[1].re, p[1].im,
|
||||
p[0].re, p[0].im, p[1].re, p[1].im);
|
||||
p+=2;
|
||||
} while (--j != 0);
|
||||
|
||||
/* pass 1 */
|
||||
|
||||
|
||||
p=&z[0];
|
||||
j=np >> 2;
|
||||
if (s->inverse) {
|
||||
do {
|
||||
BF(p[0].re, p[0].im, p[2].re, p[2].im,
|
||||
p[0].re, p[0].im, p[2].re, p[2].im);
|
||||
BF(p[1].re, p[1].im, p[3].re, p[3].im,
|
||||
p[1].re, p[1].im, -p[3].im, p[3].re);
|
||||
p+=4;
|
||||
} while (--j != 0);
|
||||
} else {
|
||||
do {
|
||||
BF(p[0].re, p[0].im, p[2].re, p[2].im,
|
||||
p[0].re, p[0].im, p[2].re, p[2].im);
|
||||
BF(p[1].re, p[1].im, p[3].re, p[3].im,
|
||||
p[1].re, p[1].im, p[3].im, -p[3].re);
|
||||
p+=4;
|
||||
} while (--j != 0);
|
||||
}
|
||||
/* pass 2 .. ln-1 */
|
||||
|
||||
nblocks = np >> 3;
|
||||
nloops = 1 << 2;
|
||||
np2 = np >> 1;
|
||||
do {
|
||||
p = z;
|
||||
q = z + nloops;
|
||||
for (j = 0; j < nblocks; ++j) {
|
||||
BF(p->re, p->im, q->re, q->im,
|
||||
p->re, p->im, q->re, q->im);
|
||||
|
||||
p++;
|
||||
q++;
|
||||
for(l = nblocks; l < np2; l += nblocks) {
|
||||
CMUL(tmp_re, tmp_im, exptab[l].re, exptab[l].im, q->re, q->im);
|
||||
BF(p->re, p->im, q->re, q->im,
|
||||
p->re, p->im, tmp_re, tmp_im);
|
||||
p++;
|
||||
q++;
|
||||
}
|
||||
|
||||
p += nloops;
|
||||
q += nloops;
|
||||
}
|
||||
nblocks = nblocks >> 1;
|
||||
nloops = nloops << 1;
|
||||
} while (nblocks != 0);
|
||||
}
|
||||
|
||||
/**
|
||||
* Do the permutation needed BEFORE calling fft_calc()
|
||||
*/
|
||||
void fft_permute(FFTContext *s, FFTComplex *z)
|
||||
{
|
||||
int j, k, np;
|
||||
FFTComplex tmp;
|
||||
const uint16_t *revtab = s->revtab;
|
||||
|
||||
/* reverse */
|
||||
np = 1 << s->nbits;
|
||||
for(j=0;j<np;j++) {
|
||||
k = revtab[j];
|
||||
if (k < j) {
|
||||
tmp = z[k];
|
||||
z[k] = z[j];
|
||||
z[j] = tmp;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
void fft_end(FFTContext *s)
|
||||
{
|
||||
av_freep(&s->revtab);
|
||||
av_freep(&s->exptab);
|
||||
av_freep(&s->exptab1);
|
||||
}
|
||||
|
||||
|
|
@ -0,0 +1,128 @@
|
|||
/*
|
||||
* FFT/MDCT transform with SSE optimizations
|
||||
* Copyright (c) 2002 Fabrice Bellard.
|
||||
*
|
||||
* This library is free software; you can redistribute it and/or
|
||||
* modify it under the terms of the GNU Lesser General Public
|
||||
* License as published by the Free Software Foundation; either
|
||||
* version 2 of the License, or (at your option) any later version.
|
||||
*
|
||||
* This library is distributed in the hope that it will be useful,
|
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
* Lesser General Public License for more details.
|
||||
*
|
||||
* You should have received a copy of the GNU Lesser General Public
|
||||
* License along with this library; if not, write to the Free Software
|
||||
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
||||
*/
|
||||
#include "../dsputil.h"
|
||||
#include <math.h>
|
||||
|
||||
#include <xmmintrin.h>
|
||||
|
||||
static const float p1p1p1m1[4] __attribute__((aligned(16))) =
|
||||
{ 1.0, 1.0, 1.0, -1.0 };
|
||||
|
||||
static const float p1p1m1m1[4] __attribute__((aligned(16))) =
|
||||
{ 1.0, 1.0, -1.0, -1.0 };
|
||||
|
||||
#if 0
|
||||
static void print_v4sf(const char *str, __m128 a)
|
||||
{
|
||||
float *p = (float *)&a;
|
||||
printf("%s: %f %f %f %f\n",
|
||||
str, p[0], p[1], p[2], p[3]);
|
||||
}
|
||||
#endif
|
||||
|
||||
/* XXX: handle reverse case */
|
||||
void fft_calc_sse(FFTContext *s, FFTComplex *z)
|
||||
{
|
||||
int ln = s->nbits;
|
||||
int j, np, np2;
|
||||
int nblocks, nloops;
|
||||
register FFTComplex *p, *q;
|
||||
FFTComplex *cptr, *cptr1;
|
||||
int k;
|
||||
|
||||
np = 1 << ln;
|
||||
|
||||
{
|
||||
__m128 *r, a, b, a1, c1, c2;
|
||||
|
||||
r = (__m128 *)&z[0];
|
||||
c1 = *(__m128 *)p1p1m1m1;
|
||||
c2 = *(__m128 *)p1p1p1m1;
|
||||
j = (np >> 2);
|
||||
do {
|
||||
a = r[0];
|
||||
b = _mm_shuffle_ps(a, a, _MM_SHUFFLE(1, 0, 3, 2));
|
||||
a = _mm_mul_ps(a, c1);
|
||||
/* do the pass 0 butterfly */
|
||||
a = _mm_add_ps(a, b);
|
||||
|
||||
a1 = r[1];
|
||||
b = _mm_shuffle_ps(a1, a1, _MM_SHUFFLE(1, 0, 3, 2));
|
||||
a1 = _mm_mul_ps(a1, c1);
|
||||
/* do the pass 0 butterfly */
|
||||
b = _mm_add_ps(a1, b);
|
||||
|
||||
/* multiply third by -i */
|
||||
b = _mm_shuffle_ps(b, b, _MM_SHUFFLE(2, 3, 1, 0));
|
||||
b = _mm_mul_ps(b, c2);
|
||||
|
||||
/* do the pass 1 butterfly */
|
||||
r[0] = _mm_add_ps(a, b);
|
||||
r[1] = _mm_sub_ps(a, b);
|
||||
r += 2;
|
||||
} while (--j != 0);
|
||||
}
|
||||
/* pass 2 .. ln-1 */
|
||||
|
||||
nblocks = np >> 3;
|
||||
nloops = 1 << 2;
|
||||
np2 = np >> 1;
|
||||
|
||||
cptr1 = s->exptab1;
|
||||
do {
|
||||
p = z;
|
||||
q = z + nloops;
|
||||
j = nblocks;
|
||||
do {
|
||||
cptr = cptr1;
|
||||
k = nloops >> 1;
|
||||
do {
|
||||
__m128 a, b, c, t1, t2;
|
||||
|
||||
a = *(__m128 *)p;
|
||||
b = *(__m128 *)q;
|
||||
|
||||
/* complex mul */
|
||||
c = *(__m128 *)cptr;
|
||||
/* cre*re cim*re */
|
||||
t1 = _mm_mul_ps(c,
|
||||
_mm_shuffle_ps(b, b, _MM_SHUFFLE(2, 2, 0, 0)));
|
||||
c = *(__m128 *)(cptr + 2);
|
||||
/* -cim*im cre*im */
|
||||
t2 = _mm_mul_ps(c,
|
||||
_mm_shuffle_ps(b, b, _MM_SHUFFLE(3, 3, 1, 1)));
|
||||
b = _mm_add_ps(t1, t2);
|
||||
|
||||
/* butterfly */
|
||||
*(__m128 *)p = _mm_add_ps(a, b);
|
||||
*(__m128 *)q = _mm_sub_ps(a, b);
|
||||
|
||||
p += 2;
|
||||
q += 2;
|
||||
cptr += 4;
|
||||
} while (--k);
|
||||
|
||||
p += nloops;
|
||||
q += nloops;
|
||||
} while (--j);
|
||||
cptr1 += nloops * 2;
|
||||
nblocks = nblocks >> 1;
|
||||
nloops = nloops << 1;
|
||||
} while (nblocks != 0);
|
||||
}
|
||||
|
|
@ -0,0 +1,170 @@
|
|||
/*
|
||||
* MDCT/IMDCT transforms
|
||||
* Copyright (c) 2002 Fabrice Bellard.
|
||||
*
|
||||
* This library is free software; you can redistribute it and/or
|
||||
* modify it under the terms of the GNU Lesser General Public
|
||||
* License as published by the Free Software Foundation; either
|
||||
* version 2 of the License, or (at your option) any later version.
|
||||
*
|
||||
* This library is distributed in the hope that it will be useful,
|
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
* Lesser General Public License for more details.
|
||||
*
|
||||
* You should have received a copy of the GNU Lesser General Public
|
||||
* License along with this library; if not, write to the Free Software
|
||||
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
||||
*/
|
||||
#include "dsputil.h"
|
||||
|
||||
/*
|
||||
* init MDCT or IMDCT computation
|
||||
*/
|
||||
int mdct_init(MDCTContext *s, int nbits, int inverse)
|
||||
{
|
||||
int n, n4, i;
|
||||
float alpha;
|
||||
|
||||
memset(s, 0, sizeof(*s));
|
||||
n = 1 << nbits;
|
||||
s->nbits = nbits;
|
||||
s->n = n;
|
||||
n4 = n >> 2;
|
||||
s->tcos = malloc(n4 * sizeof(FFTSample));
|
||||
if (!s->tcos)
|
||||
goto fail;
|
||||
s->tsin = malloc(n4 * sizeof(FFTSample));
|
||||
if (!s->tsin)
|
||||
goto fail;
|
||||
|
||||
for(i=0;i<n4;i++) {
|
||||
alpha = 2 * M_PI * (i + 1.0 / 8.0) / n;
|
||||
s->tcos[i] = -cos(alpha);
|
||||
s->tsin[i] = -sin(alpha);
|
||||
}
|
||||
if (fft_init(&s->fft, s->nbits - 2, inverse) < 0)
|
||||
goto fail;
|
||||
return 0;
|
||||
fail:
|
||||
av_freep(&s->tcos);
|
||||
av_freep(&s->tsin);
|
||||
return -1;
|
||||
}
|
||||
|
||||
/* complex multiplication: p = a * b */
|
||||
#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;\
|
||||
}
|
||||
|
||||
/**
|
||||
* Compute inverse MDCT of size N = 2^nbits
|
||||
* @param output N samples
|
||||
* @param input N/2 samples
|
||||
* @param tmp N/2 samples
|
||||
*/
|
||||
void imdct_calc(MDCTContext *s, FFTSample *output,
|
||||
const FFTSample *input, FFTSample *tmp)
|
||||
{
|
||||
int k, n8, n4, n2, n, j;
|
||||
const uint16_t *revtab = s->fft.revtab;
|
||||
const FFTSample *tcos = s->tcos;
|
||||
const FFTSample *tsin = s->tsin;
|
||||
const FFTSample *in1, *in2;
|
||||
FFTComplex *z = (FFTComplex *)tmp;
|
||||
|
||||
n = 1 << s->nbits;
|
||||
n2 = n >> 1;
|
||||
n4 = n >> 2;
|
||||
n8 = n >> 3;
|
||||
|
||||
/* pre rotation */
|
||||
in1 = input;
|
||||
in2 = input + n2 - 1;
|
||||
for(k = 0; k < n4; k++) {
|
||||
j=revtab[k];
|
||||
CMUL(z[j].re, z[j].im, *in2, *in1, tcos[k], tsin[k]);
|
||||
in1 += 2;
|
||||
in2 -= 2;
|
||||
}
|
||||
fft_calc(&s->fft, z);
|
||||
|
||||
/* post rotation + reordering */
|
||||
/* XXX: optimize */
|
||||
for(k = 0; k < n4; k++) {
|
||||
CMUL(z[k].re, z[k].im, z[k].re, z[k].im, tcos[k], tsin[k]);
|
||||
}
|
||||
for(k = 0; k < n8; k++) {
|
||||
output[2*k] = -z[n8 + k].im;
|
||||
output[n2-1-2*k] = z[n8 + k].im;
|
||||
|
||||
output[2*k+1] = z[n8-1-k].re;
|
||||
output[n2-1-2*k-1] = -z[n8-1-k].re;
|
||||
|
||||
output[n2 + 2*k]=-z[k+n8].re;
|
||||
output[n-1- 2*k]=-z[k+n8].re;
|
||||
|
||||
output[n2 + 2*k+1]=z[n8-k-1].im;
|
||||
output[n-2 - 2 * k] = z[n8-k-1].im;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Compute MDCT of size N = 2^nbits
|
||||
* @param input N samples
|
||||
* @param out N/2 samples
|
||||
* @param tmp temporary storage of N/2 samples
|
||||
*/
|
||||
void mdct_calc(MDCTContext *s, FFTSample *out,
|
||||
const FFTSample *input, FFTSample *tmp)
|
||||
{
|
||||
int i, j, n, n8, n4, n2, n3;
|
||||
FFTSample re, im, re1, im1;
|
||||
const uint16_t *revtab = s->fft.revtab;
|
||||
const FFTSample *tcos = s->tcos;
|
||||
const FFTSample *tsin = s->tsin;
|
||||
FFTComplex *x = (FFTComplex *)tmp;
|
||||
|
||||
n = 1 << s->nbits;
|
||||
n2 = n >> 1;
|
||||
n4 = n >> 2;
|
||||
n8 = n >> 3;
|
||||
n3 = 3 * n4;
|
||||
|
||||
/* pre rotation */
|
||||
for(i=0;i<n8;i++) {
|
||||
re = -input[2*i+3*n4] - input[n3-1-2*i];
|
||||
im = -input[n4+2*i] + input[n4-1-2*i];
|
||||
j = revtab[i];
|
||||
CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]);
|
||||
|
||||
re = input[2*i] - input[n2-1-2*i];
|
||||
im = -(input[n2+2*i] + input[n-1-2*i]);
|
||||
j = revtab[n8 + i];
|
||||
CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);
|
||||
}
|
||||
|
||||
fft_calc(&s->fft, x);
|
||||
|
||||
/* post rotation */
|
||||
for(i=0;i<n4;i++) {
|
||||
re = x[i].re;
|
||||
im = x[i].im;
|
||||
CMUL(re1, im1, re, im, -tsin[i], -tcos[i]);
|
||||
out[2*i] = im1;
|
||||
out[n2-1-2*i] = re1;
|
||||
}
|
||||
}
|
||||
|
||||
void mdct_end(MDCTContext *s)
|
||||
{
|
||||
av_freep(&s->tcos);
|
||||
av_freep(&s->tsin);
|
||||
fft_end(&s->fft);
|
||||
}
|
||||
Loading…
Reference in New Issue