Compandor: Remove unused option for unaffected level
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@ -32,7 +32,7 @@
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#define EXPAND_ATTACK_FACTOR 1.145 /* about 0.57 after 6 dB step up */
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#define EXPAND_RECOVERY_FACTOR 0.753 /* about 1.51 after 6 dB step down */
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/* Minimum level value to keep state */
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/* Minimum level value to keep state (-60 dB) */
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#define ENVELOPE_MIN 0.001
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/* Maximum level, to prevent sqrt_tab to overflow */
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@ -46,7 +46,7 @@ static double sqrt_tab[10000];
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* Hopefully this is correct
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*
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*/
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void init_compandor(compandor_t *state, double samplerate, double attack_ms, double recovery_ms, double unaffected_level)
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void init_compandor(compandor_t *state, double samplerate, double attack_ms, double recovery_ms)
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{
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int i;
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@ -60,8 +60,6 @@ void init_compandor(compandor_t *state, double samplerate, double attack_ms, dou
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state->c.step_down = pow(COMPRESS_RECOVERY_FACTOR, 1000.0 / recovery_ms / samplerate);
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state->e.step_up = pow(EXPAND_ATTACK_FACTOR, 1000.0 / attack_ms / samplerate);
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state->e.step_down = pow(EXPAND_RECOVERY_FACTOR, 1000.0 / recovery_ms / samplerate);
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state->c.unaffected = unaffected_level;
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state->e.unaffected = unaffected_level;
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// FIXME: make global, not at instance
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for (i = 0; i < 10000; i++)
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@ -70,19 +68,17 @@ void init_compandor(compandor_t *state, double samplerate, double attack_ms, dou
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void compress_audio(compandor_t *state, sample_t *samples, int num)
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{
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double value, peak, envelope, step_up, step_down, unaffected;
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double value, peak, envelope, step_up, step_down;
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int i;
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step_up = state->c.step_up;
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step_down = state->c.step_down;
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peak = state->c.peak;
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envelope = state->c.envelope;
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unaffected = state->c.unaffected;
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// printf("envelope=%.4f\n", envelope);
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for (i = 0; i < num; i++) {
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/* normalize sample value to unaffected level */
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value = *samples / unaffected;
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value = *samples;
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/* 'peak' is the level that raises directly with the signal
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* level, but falls with specified recovery rate. */
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@ -101,11 +97,9 @@ void compress_audio(compandor_t *state, sample_t *samples, int num)
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if (envelope > ENVELOPE_MAX)
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envelope = ENVELOPE_MAX;
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value = value / sqrt_tab[(int)(envelope / 0.001)];
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*samples++ = value / sqrt_tab[(int)(envelope / 0.001)];
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//if (i > 47000.0 && i < 48144)
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//printf("time=%.4f envelope=%.4fdb, value=%.4f\n", (double)i/48000.0, 20*log10(envelope), value);
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*samples++ = value * unaffected;
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}
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//exit(0);
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@ -115,18 +109,16 @@ void compress_audio(compandor_t *state, sample_t *samples, int num)
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void expand_audio(compandor_t *state, sample_t *samples, int num)
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{
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double value, peak, envelope, step_up, step_down, unaffected;
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double value, peak, envelope, step_up, step_down;
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int i;
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step_up = state->e.step_up;
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step_down = state->e.step_down;
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peak = state->e.peak;
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envelope = state->e.envelope;
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unaffected = state->e.unaffected;
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for (i = 0; i < num; i++) {
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/* normalize sample value to 0 DB level */
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value = *samples / unaffected;
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value = *samples;
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/* for comments: see compress_audio() */
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if (fabs(value) > peak)
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@ -140,9 +132,7 @@ void expand_audio(compandor_t *state, sample_t *samples, int num)
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if (envelope < ENVELOPE_MIN)
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envelope = ENVELOPE_MIN;
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value = value * envelope;
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*samples++ = value * unaffected;
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*samples++ = value * envelope;
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}
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state->e.envelope = envelope;
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@ -1,14 +1,12 @@
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typedef struct compandor {
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struct {
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double unaffected;
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double step_up;
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double step_down;
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double peak;
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double envelope;
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} c;
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struct {
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double unaffected;
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double step_up;
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double step_down;
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double peak;
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@ -16,7 +14,7 @@ typedef struct compandor {
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} e;
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} compandor_t;
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void init_compandor(compandor_t *state, double samplerate, double attack_ms, double recovery_ms, double unaffected_level);
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void init_compandor(compandor_t *state, double samplerate, double attack_ms, double recovery_ms);
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void compress_audio(compandor_t *state, sample_t *samples, int num);
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void expand_audio(compandor_t *state, sample_t *samples, int num);
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