Create a public API for FFT family of functions

Originally committed as revision 22291 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 89 insertions, 0 deletions

diff --git a/libavcodec/avfft.h b/libavcodec/avfft.h
new file mode 100644
index 0000000000..d0babc0909
--- /dev/null
+++ b/libavcodec/avfft.h
@@ -0,0 +1,89 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVCODEC_AVFFT_H
+#define AVCODEC_AVFFT_H
+
+typedef float FFTSample;
+
+typedef struct FFTComplex {
+    FFTSample re, im;
+} FFTComplex;
+
+typedef struct FFTContext FFTContext;
+
+/**
+ * Set up a complex FFT.
+ * @param nbits           log2 of the length of the input array
+ * @param inverse         if 0 perform the forward transform, if 1 perform the inverse
+ */
+FFTContext *av_fft_init(int nbits, int inverse);
+
+/**
+ * Do the permutation needed BEFORE calling ff_fft_calc().
+ */
+void av_fft_permute(FFTContext *s, FFTComplex *z);
+
+/**
+ * Do a complex FFT with the parameters defined in av_fft_init(). The
+ * input data must be permuted before. No 1.0/sqrt(n) normalization is done.
+ */
+void av_fft_calc(FFTContext *s, FFTComplex *z);
+
+void av_fft_end(FFTContext *s);
+
+FFTContext *av_mdct_init(int nbits, int inverse, double scale);
+void av_imdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
+void av_imdct_half(FFTContext *s, FFTSample *output, const FFTSample *input);
+void av_mdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
+void av_mdct_end(FFTContext *s);
+
+/* Real Discrete Fourier Transform */
+
+enum RDFTransformType {
+    DFT_R2C,
+    IDFT_C2R,
+    IDFT_R2C,
+    DFT_C2R,
+};
+
+typedef struct RDFTContext RDFTContext;
+
+/**
+ * Set up a real FFT.
+ * @param nbits           log2 of the length of the input array
+ * @param trans           the type of transform
+ */
+RDFTContext *av_rdft_init(int nbits, enum RDFTransformType trans);
+void av_rdft_calc(RDFTContext *s, FFTSample *data);
+void av_rdft_end(RDFTContext *s);
+
+/* Discrete Cosine Transform */
+
+typedef struct DCTContext DCTContext;
+
+/**
+ * Set up (Inverse)DCT.
+ * @param nbits           log2 of the length of the input array
+ * @param inverse         >0 forward transform, <0 inverse transform
+ */
+DCTContext *av_dct_init(int nbits, int inverse);
+void av_dct_calc(DCTContext *s, FFTSample *data);
+void av_dct_end (DCTContext *s);
+
+#endif /* AVCODEC_AVFFT_H */