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Allow arch-specific mdct code to request interleaving of cos/sin tables 

Originally committed as revision 19939 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Måns Rullgård 2009-09-21 02:56:06 +00:00
parent 670bd2005a
commit 94274b82f6
2 changed files with 25 additions and 10 deletions
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3
libavcodec/dsputil.h
View File

@ -687,6 +687,9 @@ typedef struct FFTContext {
void (*imdct_half)(struct FFTContext *s, FFTSample *output, const FFTSample *input);
void (*mdct_calc)(struct FFTContext *s, FFTSample *output, const FFTSample *input);
int split_radix;
int permutation;
#define FF_MDCT_PERM_NONE 0
#define FF_MDCT_PERM_INTERLEAVE 1
} FFTContext;
extern FFTSample* const ff_cos_tabs[13];

32
libavcodec/mdct.c
View File

@ -76,32 +76,45 @@ av_cold int ff_mdct_init(FFTContext *s, int nbits, int inverse, double scale)
{
int n, n4, i;
double alpha, theta;
int tstep;
memset(s, 0, sizeof(*s));
n = 1 << nbits;
s->mdct_bits = nbits;
s->mdct_size = n;
n4 = n >> 2;
s->tcos = av_malloc(n4 * sizeof(FFTSample));
s->permutation = FF_MDCT_PERM_NONE;
if (ff_fft_init(s, s->mdct_bits - 2, inverse) < 0)
goto fail;
s->tcos = av_malloc(n/2 * sizeof(FFTSample));
if (!s->tcos)
goto fail;
s->tsin = av_malloc(n4 * sizeof(FFTSample));
if (!s->tsin)
switch (s->permutation) {
case FF_MDCT_PERM_NONE:
s->tsin = s->tcos + n4;
tstep = 1;
break;
case FF_MDCT_PERM_INTERLEAVE:
s->tsin = s->tcos + 1;
tstep = 2;
break;
default:
goto fail;
}
theta = 1.0 / 8.0 + (scale < 0 ? n4 : 0);
scale = sqrt(fabs(scale));
for(i=0;i<n4;i++) {
alpha = 2 * M_PI * (i + theta) / n;
s->tcos[i] = -cos(alpha) * scale;
s->tsin[i] = -sin(alpha) * scale;
s->tcos[i*tstep] = -cos(alpha) * scale;
s->tsin[i*tstep] = -sin(alpha) * scale;
}
if (ff_fft_init(s, s->mdct_bits - 2, inverse) < 0)
goto fail;
return 0;
fail:
av_freep(&s->tcos);
av_freep(&s->tsin);
ff_mdct_end(s);
return -1;
}
@ -229,6 +242,5 @@ void ff_mdct_calc_c(FFTContext *s, FFTSample *out, const FFTSample *input)
av_cold void ff_mdct_end(FFTContext *s)
{
av_freep(&s->tcos);
av_freep(&s->tsin);
ff_fft_end(s);
}