mirror of
https://github.com/cookiengineer/audacity
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51 lines
2.0 KiB
Plaintext
51 lines
2.0 KiB
Plaintext
(TAPV-ALG
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(NAME "tapv")
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(ARGUMENTS ("sound_type" "s1") ("double" "offset") ("sound_type" "vardelay")
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("double" "maxdelay"))
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(INTERNAL-SCALING vardelay)
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(START (MAX s1 vardelay))
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(TERMINATE (MIN s1 vardelay))
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(LOGICAL-STOP (MIN s1))
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(STATE ("double" "offset" "offset * s1->sr")
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("double" "vdscale" "vardelay->scale * s1->sr")
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("double" "maxdelay" "maxdelay * s1->sr")
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("long" "bufflen" "max(2, (long) (susp->maxdelay + 1.5))")
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("long" "index" "susp->bufflen")
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("sample_type *" "buffer"
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"(sample_type *) calloc(susp->bufflen + 1, sizeof(sample_type))"))
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(SAMPLE-RATE (MAX s1))
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(CONSTANT "maxdelay" "offset" "vdscale" "buffer")
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(INNER-LOOP-LOCALS " double phase;
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long i;
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")
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(INNER-LOOP "phase = vardelay * vdscale + offset;
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/* now phase should give number of samples of delay */
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if (phase < 0) phase = 0;
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else if (phase > maxdelay) phase = maxdelay;
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phase = (double) index - phase;
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/* now phase is a location in the buffer (before modulo) */
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/* Time out to update the buffer:
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* this is a tricky buffer: buffer[0] == buffer[bufflen]
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* the logical length is bufflen, but the actual length
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* is bufflen + 1 to allow for a repeated sample at the
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* end. This allows for efficient interpolation.
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*/
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buffer[index++] = s1;
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if (index > bufflen) {
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buffer[0] = buffer[bufflen];
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index = 1;
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}
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/* back to the phase calculation:
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* use conditional instead of modulo
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*/
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if (phase < 0) phase += bufflen;
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i = (long) phase; /* put integer part in i */
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phase -= (double) i; /* put fractional part in phase */
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output = (sample_type) (buffer[i] * (1.0 - phase) +
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buffer[i + 1] * phase)")
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(FINALIZATION " free(susp->buffer);\n")
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)
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