CMSIS-DSP  
CMSIS DSP Software Library
 
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Functions

void arm_dct4_f32 (const arm_dct4_instance_f32 *S, float32_t *pState, float32_t *pInlineBuffer)
 Processing function for the floating-point DCT4/IDCT4.
 
arm_status arm_dct4_init_f32 (arm_dct4_instance_f32 *S, arm_rfft_instance_f32 *S_RFFT, arm_cfft_radix4_instance_f32 *S_CFFT, uint16_t N, uint16_t Nby2, float32_t normalize)
 Initialization function for the floating-point DCT4/IDCT4.
 

Description

Function Documentation

◆ arm_dct4_f32()

void arm_dct4_f32 ( const arm_dct4_instance_f32 S,
float32_t pState,
float32_t pInlineBuffer 
)

Processing function for the floating-point DCT4/IDCT4.

Deprecated:
Do not use this function. It is using a deprecated version of the RFFT.
Parameters
[in]Spoints to an instance of the floating-point DCT4/IDCT4 structure
[in]pStatepoints to state buffer
[in,out]pInlineBufferpoints to the in-place input and output buffer

◆ arm_dct4_init_f32()

arm_status arm_dct4_init_f32 ( arm_dct4_instance_f32 S,
arm_rfft_instance_f32 S_RFFT,
arm_cfft_radix4_instance_f32 S_CFFT,
uint16_t  N,
uint16_t  Nby2,
float32_t  normalize 
)

Initialization function for the floating-point DCT4/IDCT4.

Deprecated:
Do not use this function. It is using a deprecated version of the RFFT.
Parameters
[in,out]Spoints to an instance of floating-point DCT4/IDCT4 structure
[in]S_RFFTpoints to an instance of floating-point RFFT/RIFFT structure
[in]S_CFFTpoints to an instance of floating-point CFFT/CIFFT structure
[in]Nlength of the DCT4
[in]Nby2half of the length of the DCT4
[in]normalizenormalizing factor.
Returns
execution status
Normalizing factor
The normalizing factor is sqrt(2/N), which depends on the size of transform N. Floating-point normalizing factors are mentioned in the table below for different DCT sizes:
DCT Size Normalizing factor value
2048 0.03125
512 0.0625
128 0.125