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@ -50,36 +50,6 @@ SINTABLE_CONST FFTSample * const ff_sin_tabs[] = { |
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ff_sin_2048, ff_sin_4096, ff_sin_8192, ff_sin_16384, ff_sin_32768, ff_sin_65536, |
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}; |
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static void ff_rdft_calc_c(RDFTContext* s, FFTSample* data); |
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av_cold int ff_rdft_init(RDFTContext *s, int nbits, enum RDFTransformType trans) |
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{ |
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int n = 1 << nbits; |
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int i; |
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const double theta = (trans == DFT_R2C || trans == DFT_C2R ? -1 : 1)*2*M_PI/n; |
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s->nbits = nbits; |
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s->inverse = trans == IDFT_C2R || trans == DFT_C2R; |
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s->sign_convention = trans == IDFT_R2C || trans == DFT_C2R ? 1 : -1; |
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if (nbits < 4 || nbits > 16) |
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return -1; |
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if (ff_fft_init(&s->fft, nbits-1, trans == IDFT_C2R || trans == IDFT_R2C) < 0) |
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return -1; |
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ff_init_ff_cos_tabs(nbits); |
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s->tcos = ff_cos_tabs[nbits]; |
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s->tsin = ff_sin_tabs[nbits]+(trans == DFT_R2C || trans == DFT_C2R)*(n>>2); |
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#if !CONFIG_HARDCODED_TABLES |
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for (i = 0; i < (n>>2); i++) { |
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s->tsin[i] = sin(i*theta); |
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} |
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#endif |
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s->rdft_calc = ff_rdft_calc_c; |
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return 0; |
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} |
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/** Map one real FFT into two parallel real even and odd FFTs. Then interleave
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* the two real FFTs into one complex FFT. Unmangle the results. |
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* ref: http://www.engineeringproductivitytools.com/stuff/T0001/PT10.HTM
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@ -126,6 +96,34 @@ static void ff_rdft_calc_c(RDFTContext* s, FFTSample* data) |
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} |
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} |
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av_cold int ff_rdft_init(RDFTContext *s, int nbits, enum RDFTransformType trans) |
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{ |
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int n = 1 << nbits; |
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int i; |
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const double theta = (trans == DFT_R2C || trans == DFT_C2R ? -1 : 1)*2*M_PI/n; |
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s->nbits = nbits; |
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s->inverse = trans == IDFT_C2R || trans == DFT_C2R; |
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s->sign_convention = trans == IDFT_R2C || trans == DFT_C2R ? 1 : -1; |
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if (nbits < 4 || nbits > 16) |
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return -1; |
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if (ff_fft_init(&s->fft, nbits-1, trans == IDFT_C2R || trans == IDFT_R2C) < 0) |
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return -1; |
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ff_init_ff_cos_tabs(nbits); |
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s->tcos = ff_cos_tabs[nbits]; |
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s->tsin = ff_sin_tabs[nbits]+(trans == DFT_R2C || trans == DFT_C2R)*(n>>2); |
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#if !CONFIG_HARDCODED_TABLES |
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for (i = 0; i < (n>>2); i++) { |
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s->tsin[i] = sin(i*theta); |
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} |
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#endif |
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s->rdft_calc = ff_rdft_calc_c; |
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return 0; |
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} |
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av_cold void ff_rdft_end(RDFTContext *s) |
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{ |
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ff_fft_end(&s->fft); |
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