26 lines
807 B
C
26 lines
807 B
C
/* SoX Resampler Library Copyright (c) 2007-12 robs@users.sourceforge.net
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* Licence for this file: LGPL v2.1 See LICENCE for details. */
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/* Down-sample by a factor of 2 using a FIR with odd length (LEN).*/
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/* Input must be preceded and followed by LEN >> 1 samples. */
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#define _ sum += (input[-(2*j +1)] + input[(2*j +1)]) * COEFS[j], ++j;
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static void FUNCTION(stage_t * p, fifo_t * output_fifo)
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{
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sample_t const * input = stage_read_p(p);
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int i, num_out = (stage_occupancy(p) + 1) / 2;
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sample_t * output = fifo_reserve(output_fifo, num_out);
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for (i = 0; i < num_out; ++i, input += 2) {
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int j = 0;
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sample_t sum = input[0] * .5f;
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CONVOLVE
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output[i] = sum;
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}
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fifo_read(&p->fifo, 2 * num_out, NULL);
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}
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#undef _
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#undef COEFS
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#undef CONVOLVE
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#undef FUNCTION
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