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Formalized Real 16-bit FFT for APM.

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It also prepares for introducing Real 16-bit FFT Neon code from Openmax to SPL. CL https://webrtc-codereview.appspot.com/1819004/ takes care of that, but this CL is a prerequisite of that one.
Tested audioproc with an offline file. Bit exact.

R=andrew@webrtc.org, rtoy@google.com

Review URL: https://webrtc-codereview.appspot.com/1830004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4390 4adac7df-926f-26a2-2b94-8c16560cd09d
This commit is contained in:
kma@webrtc.org
2013-07-24 17:38:23 +00:00
parent b63c29f48c
commit fc8aaf02e1
10 changed files with 285 additions and 473 deletions
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96
webrtc/common_audio/signal_processing/include/real_fft.h
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@ -13,70 +13,112 @@
#include "webrtc/typedefs.h"
// For ComplexFFT(), the maximum fft order is 10;
// for OpenMax FFT in ARM, it is 12;
// WebRTC APM uses orders of only 7 and 8.
enum {kMaxFFTOrder = 10};
struct RealFFT;
#ifdef __cplusplus
extern "C" {
#endif
typedef struct RealFFT* (*CreateRealFFT)(int order);
typedef void (*FreeRealFFT)(struct RealFFT* self);
typedef int (*RealForwardFFT)(struct RealFFT* self,
const int16_t* data_in,
int16_t* data_out);
const int16_t* real_data_in,
int16_t* complex_data_out);
typedef int (*RealInverseFFT)(struct RealFFT* self,
const int16_t* data_in,
int16_t* data_out);
const int16_t* complex_data_in,
int16_t* real_data_out);
extern CreateRealFFT WebRtcSpl_CreateRealFFT;
extern FreeRealFFT WebRtcSpl_FreeRealFFT;
extern RealForwardFFT WebRtcSpl_RealForwardFFT;
extern RealInverseFFT WebRtcSpl_RealInverseFFT;
struct RealFFT* WebRtcSpl_CreateRealFFT(int order);
void WebRtcSpl_FreeRealFFT(struct RealFFT* self);
struct RealFFT* WebRtcSpl_CreateRealFFTC(int order);
void WebRtcSpl_FreeRealFFTC(struct RealFFT* self);
// TODO(kma): Implement FFT functions for real signals.
#if (defined WEBRTC_DETECT_ARM_NEON) || (defined WEBRTC_ARCH_ARM_NEON)
struct RealFFT* WebRtcSpl_CreateRealFFTNeon(int order);
void WebRtcSpl_FreeRealFFTNeon(struct RealFFT* self);
#endif
// Compute the forward FFT for a complex signal of length 2^order.
// Compute an FFT for a real-valued signal of length of 2^order,
// where 1 < order <= MAX_FFT_ORDER. Transform length is determined by the
// specification structure, which must be initialized prior to calling the FFT
// function with WebRtcSpl_CreateRealFFT().
// The relationship between the input and output sequences can
// be expressed in terms of the DFT, i.e.:
// x[n] = (2^(-scalefactor)/N) . SUM[k=0,...,N-1] X[k].e^(jnk.2.pi/N)
// n=0,1,2,...N-1
// N=2^order.
// The conjugate-symmetric output sequence is represented using a CCS vector,
// which is of length N+2, and is organized as follows:
// Index: 0 1 2 3 4 5 . . . N-2 N-1 N N+1
// Component: R0 0 R1 I1 R2 I2 . . . R[N/2-1] I[N/2-1] R[N/2] 0
// where R[n] and I[n], respectively, denote the real and imaginary components
// for FFT bin 'n'. Bins are numbered from 0 to N/2, where N is the FFT length.
// Bin index 0 corresponds to the DC component, and bin index N/2 corresponds to
// the foldover frequency.
//
// Input Arguments:
// self - pointer to preallocated and initialized FFT specification structure.
// data_in - the input signal.
// real_data_in - the input signal. For an ARM Neon platform, it must be
// aligned on a 32-byte boundary.
//
// Output Arguments:
// data_out - the output signal; must be different to data_in.
// complex_data_out - the output complex signal with (2^order + 2) 16-bit
// elements. For an ARM Neon platform, it must be different
// from real_data_in, and aligned on a 32-byte boundary.
//
// Return Value:
// 0 - FFT calculation is successful.
// -1 - Error
//
// -1 - Error with bad arguments (NULL pointers).
int WebRtcSpl_RealForwardFFTC(struct RealFFT* self,
const int16_t* data_in,
int16_t* data_out);
const int16_t* real_data_in,
int16_t* complex_data_out);
#if (defined WEBRTC_DETECT_ARM_NEON) || (defined WEBRTC_ARCH_ARM_NEON)
int WebRtcSpl_RealForwardFFTNeon(struct RealFFT* self,
const int16_t* data_in,
int16_t* data_out);
const int16_t* real_data_in,
int16_t* complex_data_out);
#endif
// Compute the inverse FFT for a complex signal of length 2^order.
// Compute the inverse FFT for a conjugate-symmetric input sequence of length of
// 2^order, where 1 < order <= MAX_FFT_ORDER. Transform length is determined by
// the specification structure, which must be initialized prior to calling the
// FFT function with WebRtcSpl_CreateRealFFT().
// For a transform of length M, the input sequence is represented using a packed
// CCS vector of length M+2, which is explained in the comments for
// WebRtcSpl_RealForwardFFTC above.
//
// Input Arguments:
// self - pointer to preallocated and initialized FFT specification structure.
// data_in - the input signal.
// complex_data_in - the input complex signal with (2^order + 2) 16-bit
// elements. For an ARM Neon platform, it must be aligned on
// a 32-byte boundary.
//
// Output Arguments:
// data_out - the output signal; must be different to data_in.
// real_data_out - the output real signal. For an ARM Neon platform, it must
// be different to complex_data_in, and aligned on a 32-byte
// boundary.
//
// Return Value:
// 0 or a positive number - a value that the elements in the |data_out| should
// be shifted left with in order to get correct
// physical values.
// -1 - Error
// 0 or a positive number - a value that the elements in the |real_data_out|
// should be shifted left with in order to get
// correct physical values.
// -1 - Error with bad arguments (NULL pointers).
int WebRtcSpl_RealInverseFFTC(struct RealFFT* self,
const int16_t* data_in,
int16_t* data_out);
const int16_t* complex_data_in,
int16_t* real_data_out);
#if (defined WEBRTC_DETECT_ARM_NEON) || (defined WEBRTC_ARCH_ARM_NEON)
int WebRtcSpl_RealInverseFFTNeon(struct RealFFT* self,
const int16_t* data_in,
int16_t* data_out);
const int16_t* complex_data_in,
int16_t* real_data_out);
#endif
#ifdef __cplusplus