diff options
| -rw-r--r-- | nncmpp.c | 29 |
1 files changed, 21 insertions, 8 deletions
@@ -638,13 +638,13 @@ spectrum_decode_8 (struct spectrum *s, int sample) { size_t n = s->useful_bins; float *data = s->data + n; - int8_t *p = (int8_t *) s->buffer + sample * n * s->channels; - while (n--) + for (int8_t *p = (int8_t *) s->buffer + sample * n * s->channels; + n--; p += s->channels) { int32_t acc = 0; for (int ch = 0; ch < s->channels; ch++) - acc += *p++; - *data++ = (float) acc / -INT8_MIN / s->channels; + acc += p[ch]; + *data++ = (float) acc / s->channels / -INT8_MIN; } } @@ -653,16 +653,25 @@ spectrum_decode_16 (struct spectrum *s, int sample) { size_t n = s->useful_bins; float *data = s->data + n; - int16_t *p = (int16_t *) s->buffer + sample * n * s->channels; - while (n--) + for (int16_t *p = (int16_t *) s->buffer + sample * n * s->channels; + n--; p += s->channels) { int32_t acc = 0; for (int ch = 0; ch < s->channels; ch++) - acc += *p++; - *data++ = (float) acc / -INT16_MIN / s->channels; + acc += p[ch]; + *data++ = (float) acc / s->channels / -INT16_MIN; } } +static void +spectrum_decode_16_2 (struct spectrum *s, int sample) +{ + size_t n = s->useful_bins; + float *data = s->data + n; + for (int16_t *p = (int16_t *) s->buffer + sample * n * 2; n--; p += 2) + *data++ = ((int32_t) p[0] + p[1]) / 2. / -INT16_MIN; +} + // - - Spectrum analysis - - - - - - - - - - - - - - - - - - - - - - - - - - - - static const char *spectrum_bars[] = @@ -803,6 +812,10 @@ spectrum_init (struct spectrum *s, char *format, int bars, struct error **e) if (s->bits == 8) s->decode = spectrum_decode_8; if (s->bits == 16) s->decode = spectrum_decode_16; + // Micro-optimize to achieve some piece of mind; it's weak but measurable + if (s->bits == 16 && s->channels == 2) + s->decode = spectrum_decode_16_2; + s->buffer_size = s->samples * s->useful_bins * s->bits / 8 * s->channels; s->buffer = xcalloc (1, s->buffer_size); |