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resample: use fixed point for resample phase and input rate

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If phase is float, calculations in impl_native_in_len/out_len can
produce wrong results due to rounding error.

It's probably better to not be in the business of predicting
floating-point rounding, so replace this by fixed-point arithmetic.

Also make sure `offset+1` cannot overflow data->filter array in
do_resample_inter* due to float multiplication possibly rounding up.
This commit is contained in:
Pauli Virtanen 2025-07-26 17:23:44 +03:00 • committed by Wim Taymans
parent 3cade43cf3
commit 244d5a1cc1
3 changed files with 61 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

45
spa/plugins/audioconvert/resample-native-impl.h
View file

@ -12,6 +12,18 @@ typedef void (*resample_func_t)(struct resample *r,
const void * SPA_RESTRICT src[], uint32_t ioffs, uint32_t *in_len,
void * SPA_RESTRICT dst[], uint32_t ooffs, uint32_t *out_len);
#define FIXP_SHIFT 32
#define FIXP_SCALE ((uint64_t)1 << FIXP_SHIFT)
#define FIXP_MASK (FIXP_SCALE - 1)
#define UINT32_TO_FIXP(v) ((struct fixp) { (uint64_t)((uint32_t)(v)) << FIXP_SHIFT })
#define FLOAT_TO_FIXP(d) ((struct fixp) { (uint64_t)((d) * (float)FIXP_SCALE) })
#define FIXP_TO_UINT32(f) ((f).value >> FIXP_SHIFT)
#define FIXP_TO_FLOAT(f) ((f).value / (float)FIXP_SCALE)
struct fixp {
uint64_t value;
};
struct resample_info {
uint32_t format;
resample_func_t process_copy;
@ -29,10 +41,10 @@ struct native_data {
uint32_t n_phases;
uint32_t in_rate;
uint32_t out_rate;
float phase;
struct fixp phase;
float pm;
uint32_t inc;
uint32_t frac;
struct fixp frac;
uint32_t filter_stride;
uint32_t filter_stride_os;
uint32_t gcd;
@ -86,25 +98,26 @@ DEFINE_RESAMPLER(full,arch) \
{ \
struct native_data *data = r->data; \
uint32_t n_taps = data->n_taps, stride = data->filter_stride_os; \
uint32_t index, phase, out_rate = data->out_rate; \
uint32_t index; \
uint32_t c, o, olen = *out_len, ilen = *in_len; \
uint32_t inc = data->inc, frac = data->frac, ch = r->channels; \
uint32_t inc = data->inc, ch = r->channels; \
uint64_t frac = data->frac.value, phase = data->phase.value; \
uint64_t denom = UINT32_TO_FIXP(data->out_rate).value; \
\
index = ioffs; \
phase = (uint32_t)data->phase; \
for (o = ooffs; o < olen && index + n_taps <= ilen; o++) { \
float *filter = &data->filter[phase * stride]; \
float *filter = &data->filter[(phase >> FIXP_SHIFT) * stride]; \
for (c = 0; c < ch; c++) { \
const float *s = src[c]; \
float *d = dst[c]; \
inner_product_##arch(&d[o], &s[index], \
filter, n_taps); \
} \
INC(index, phase, out_rate); \
INC(index, phase, denom); \
} \
*in_len = index; \
*out_len = o; \
data->phase = phase; \
data->phase.value = phase; \
}
#define MAKE_RESAMPLER_INTER(arch) \
@ -112,16 +125,18 @@ DEFINE_RESAMPLER(inter,arch) \
{ \
struct native_data *data = r->data; \
uint32_t index, stride = data->filter_stride; \
uint32_t n_taps = data->n_taps, out_rate = data->out_rate; \
uint32_t n_taps = data->n_taps; \
uint32_t c, o, olen = *out_len, ilen = *in_len; \
uint32_t inc = data->inc, frac = data->frac, ch = r->channels; \
float phase, pm = data->pm; \
uint32_t inc = data->inc, ch = r->channels; \
uint32_t ph_max = data->n_phases - 1; \
uint64_t frac = data->frac.value, phase = data->phase.value; \
uint64_t denom = UINT32_TO_FIXP(data->out_rate).value; \
float pm = data->pm; \
\
index = ioffs; \
phase = data->phase; \
for (o = ooffs; o < olen && index + n_taps <= ilen; o++) { \
float ph = phase * pm; \
uint32_t offset = (uint32_t)floorf(ph); \
uint32_t offset = SPA_MIN((uint32_t)floorf(ph), ph_max); \
float *filter0 = &data->filter[(offset+0) * stride]; \
float *filter1 = &data->filter[(offset+1) * stride]; \
float pho = ph - offset; \
@ -131,11 +146,11 @@ DEFINE_RESAMPLER(inter,arch) \
inner_product_ip_##arch(&d[o], &s[index], \
filter0, filter1, pho, n_taps); \
} \
INC(index, phase, out_rate); \
INC(index, phase, denom); \
} \
*in_len = index; \
*out_len = o; \
data->phase = phase; \
data->phase.value = phase; \
}