diff options
Diffstat (limited to 'src/common/emphasis.c')
| -rw-r--r-- | src/common/emphasis.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/common/emphasis.c b/src/common/emphasis.c index 241deee..5a1453e 100644 --- a/src/common/emphasis.c +++ b/src/common/emphasis.c @@ -29,6 +29,7 @@ #define PI M_PI #define CUT_OFF_H 100.0 /* cut-off frequency for high-pass filter */ +#define CUT_OFF_L 4000.0 /* cut-off frequency for low-pass filter */ static void gen_sine(sample_t *samples, int num, int samplerate, double freq) { @@ -66,8 +67,12 @@ int init_emphasis(emphasis_t *state, int samplerate, double cut_off) state->d.factor = factor; state->d.amp = 1.0; + /* do not de-emphasis below CUT_OFF_H */ iir_highpass_init(&state->d.hp, CUT_OFF_H, samplerate, 1); + /* do not pre-emphasis above CUT_OFF_L */ + iir_lowpass_init(&state->p.lp, CUT_OFF_L, samplerate, 1); + /* calibrate amplification to be neutral at 1000 Hz */ gen_sine(test_samples, sizeof(test_samples) / sizeof(test_samples[0]), samplerate, 1000.0); pre_emphasis(state, test_samples, sizeof(test_samples) / sizeof(test_samples[0])); @@ -84,6 +89,8 @@ void pre_emphasis(emphasis_t *state, sample_t *samples, int num) double x, y, x_last, factor, amp; int i; + iir_process(&state->p.lp, samples, num); + x_last = state->p.x_last; factor = state->p.factor; amp = state->p.amp; |