Clean up FFT related comments.

Originally committed as revision 16721 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/dsputil.h

@@ -674,6 +674,11 @@ typedef struct FFTContext {
     void (*imdct_half)(struct MDCTContext *s, FFTSample *output, const FFTSample *input);
 } FFTContext;
 
+/**
+ * Sets 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
+ */
 int ff_fft_init(FFTContext *s, int nbits, int inverse);
 void ff_fft_permute_c(FFTContext *s, FFTComplex *z);
 void ff_fft_permute_sse(FFTContext *s, FFTComplex *z);
@@ -683,10 +688,17 @@ void ff_fft_calc_3dn(FFTContext *s, FFTComplex *z);
 void ff_fft_calc_3dn2(FFTContext *s, FFTComplex *z);
 void ff_fft_calc_altivec(FFTContext *s, FFTComplex *z);
 
+/**
+ * Do the permutation needed BEFORE calling ff_fft_calc().
+ */
 static inline void ff_fft_permute(FFTContext *s, FFTComplex *z)
 {
     s->fft_permute(s, z);
 }
+/**
+ * Do a complex FFT with the parameters defined in ff_fft_init(). The
+ * input data must be permuted before. No 1.0/sqrt(n) normalization is done.
+ */
 static inline void ff_fft_calc(FFTContext *s, FFTComplex *z)
 {
     s->fft_calc(s, z);

libavcodec/fft.c

@@ -58,10 +58,6 @@ static int split_radix_permutation(int i, int n, int inverse)
     else                  return split_radix_permutation(i, m, inverse)*4 - 1;
 }
 
-/**
- * The size of the FFT is 2^nbits. If inverse is TRUE, inverse FFT is
- * done
- */
 int ff_fft_init(FFTContext *s, int nbits, int inverse)
 {
     int i, j, m, n;
@@ -185,9 +181,6 @@ int ff_fft_init(FFTContext *s, int nbits, int inverse)
     return -1;
 }
 
-/**
- * Do the permutation needed BEFORE calling ff_fft_calc()
- */
 void ff_fft_permute_c(FFTContext *s, FFTComplex *z)
 {
     int j, k, np;
@@ -374,11 +367,6 @@ static void (*fft_dispatch[])(FFTComplex*) = {
     fft2048, fft4096, fft8192, fft16384, fft32768, fft65536,
 };
 
-/**
- * Do a complex FFT with the parameters defined in ff_fft_init(). The
- * input data must be permuted before with s->revtab table. No
- * 1.0/sqrt(n) normalization is done.
- */
 void ff_fft_calc_c(FFTContext *s, FFTComplex *z)
 {
     fft_dispatch[s->nbits-2](z);