-
-#define FRAC_BITS 16
-#define FRAC (1 << FRAC_BITS)
-
-static void init_mono_resample(ReSampleChannelContext *s, float ratio)
-{
- ratio = 1.0 / ratio;
- s->iratio = (int)floorf(ratio);
- if (s->iratio == 0)
- s->iratio = 1;
- s->incr = (int)((ratio / s->iratio) * FRAC);
- s->frac = FRAC;
- s->last_sample = 0;
- s->icount = s->iratio;
- s->isum = 0;
- s->inv = (FRAC / s->iratio);
-}
-
-/* fractional audio resampling */
-static int fractional_resample(ReSampleChannelContext *s, short *output, short *input, int nb_samples)
-{
- unsigned int frac, incr;
- int l0, l1;
- short *q, *p, *pend;
-
- l0 = s->last_sample;
- incr = s->incr;
- frac = s->frac;
-
- p = input;
- pend = input + nb_samples;
- q = output;
-
- l1 = *p++;
- for(;;) {
- /* interpolate */
- *q++ = (l0 * (FRAC - frac) + l1 * frac) >> FRAC_BITS;
- frac = frac + s->incr;
- while (frac >= FRAC) {
- frac -= FRAC;
- if (p >= pend)
- goto the_end;
- l0 = l1;
- l1 = *p++;
- }
- }
- the_end:
- s->last_sample = l1;
- s->frac = frac;
- return q - output;
-}
-
-static int integer_downsample(ReSampleChannelContext *s, short *output, short *input, int nb_samples)
-{
- short *q, *p, *pend;
- int c, sum;
-
- p = input;
- pend = input + nb_samples;
- q = output;
-
- c = s->icount;
- sum = s->isum;
-
- for(;;) {
- sum += *p++;
- if (--c == 0) {
- *q++ = (sum * s->inv) >> FRAC_BITS;
- c = s->iratio;
- sum = 0;
- }
- if (p >= pend)
- break;
- }
- s->isum = sum;
- s->icount = c;
- return q - output;
-}
-