FFmpeg: AC3DSPContext Struct Reference

FFmpeg

AC3DSPContext Struct Reference

#include <ac3dsp.h>

Data Fields

void(* ac3_exponent_min )(uint8_t *exp, int num_reuse_blocks, int nb_coefs)

Set each encoded exponent in a block to the minimum of itself and the exponents in the same frequency bin of up to 5 following blocks. More...

int(* ac3_max_msb_abs_int16 )(const int16_t *src, int len)

Calculate the maximum MSB of the absolute value of each element in an array of int16_t. More...

void(* ac3_lshift_int16 )(int16_t *src, unsigned int len, unsigned int shift)

Left-shift each value in an array of int16_t by a specified amount. More...

void(* ac3_rshift_int32 )(int32_t *src, unsigned int len, unsigned int shift)

Right-shift each value in an array of int32_t by a specified amount. More...

void(* float_to_fixed24 )(int32_t *dst, const float *src, unsigned int len)

Convert an array of float in range [-1.0,1.0] to int32_t with range [-(1<<24),(1<<24)]. More...

void(* bit_alloc_calc_bap )(int16_t *mask, int16_t *psd, int start, int end, int snr_offset, int floor, const uint8_t *bap_tab, uint8_t *bap)

Calculate bit allocation pointers. More...

void(* update_bap_counts )(uint16_t mant_cnt[16], uint8_t *bap, int len)

Update bap counts using the supplied array of bap. More...

int(* compute_mantissa_size )(uint16_t mant_cnt[6][16])

Calculate the number of bits needed to encode a set of mantissas. More...

void(* extract_exponents )(uint8_t *exp, int32_t *coef, int nb_coefs)

void(* sum_square_butterfly_int32 )(int64_t sum[4], const int32_t *coef0, const int32_t *coef1, int len)

void(* sum_square_butterfly_float )(float sum[4], const float *coef0, const float *coef1, int len)

void(* downmix )(float **samples, float(*matrix)[2], int out_ch, int in_ch, int len)

void(* downmix_fixed )(int32_t **samples, int16_t(*matrix)[2], int out_ch, int in_ch, int len)

void(* apply_window_int16 )(int16_t *output, const int16_t *input, const int16_t *window, unsigned int len)

Apply symmetric window in 16-bit fixed-point. More...

Detailed Description

Definition at line 33 of file ac3dsp.h.

Field Documentation

void(* AC3DSPContext::ac3_exponent_min)(uint8_t *exp, int num_reuse_blocks, int nb_coefs)

Set each encoded exponent in a block to the minimum of itself and the exponents in the same frequency bin of up to 5 following blocks.

Parameters: exp pointer to the start of the current block of exponents. constraints: align 16

num_reuse_blocks number of blocks that will reuse exponents from the current block. constraints: range 0 to 5

nb_coefs number of frequency coefficients.

Definition at line 43 of file ac3dsp.h.

Referenced by encode_exponents(), ff_ac3dsp_init(), ff_ac3dsp_init_arm(), and ff_ac3dsp_init_x86().

int(* AC3DSPContext::ac3_max_msb_abs_int16)(const int16_t *src, int len)

Calculate the maximum MSB of the absolute value of each element in an array of int16_t.

Parameters: src input array constraints: align 16. values must be in range [-32767,32767]

len number of values in the array constraints: multiple of 16 greater than 0

Returns: a value with the same MSB as max(abs(src[]))

Definition at line 54 of file ac3dsp.h.

Referenced by ff_ac3dsp_init(), ff_ac3dsp_init_arm(), ff_ac3dsp_init_x86(), and normalize_samples().

void(* AC3DSPContext::ac3_lshift_int16)(int16_t *src, unsigned int len, unsigned int shift)

Left-shift each value in an array of int16_t by a specified amount.

Parameters: src input array constraints: align 16

len number of values in the array constraints: multiple of 32 greater than 0

shift left shift amount constraints: range [0,15]

Definition at line 65 of file ac3dsp.h.

Referenced by ff_ac3dsp_init(), ff_ac3dsp_init_arm(), ff_ac3dsp_init_x86(), and normalize_samples().

void(* AC3DSPContext::ac3_rshift_int32)(int32_t *src, unsigned int len, unsigned int shift)

Right-shift each value in an array of int32_t by a specified amount.

Parameters: src input array constraints: align 16

len number of values in the array constraints: multiple of 16 greater than 0

shift right shift amount constraints: range [0,31]

Definition at line 76 of file ac3dsp.h.

Referenced by ff_ac3dsp_init(), ff_ac3dsp_init_arm(), ff_ac3dsp_init_x86(), and scale_coefficients().

void(* AC3DSPContext::float_to_fixed24)(int32_t *dst, const float *src, unsigned int len)

Convert an array of float in range [-1.0,1.0] to int32_t with range [-(1<<24),(1<<24)].

Parameters: dst destination array of int32_t. constraints: 16-byte aligned

src source array of float. constraints: 16-byte aligned

len number of elements to convert. constraints: multiple of 32 greater than zero

Definition at line 89 of file ac3dsp.h.

Referenced by apply_channel_coupling(), ff_ac3dsp_init(), ff_ac3dsp_init_arm(), ff_ac3dsp_init_mips(), ff_ac3dsp_init_x86(), and scale_coefficients().

void(* AC3DSPContext::bit_alloc_calc_bap)(int16_t *mask, int16_t *psd, int start, int end, int snr_offset, int floor, const uint8_t *bap_tab, uint8_t *bap)

Calculate bit allocation pointers.

The SNR is the difference between the masking curve and the signal. AC-3 uses this value for each frequency bin to allocate bits. The snroffset parameter is a global adjustment to the SNR for all bins.

Parameters: [in] mask masking curve

[in] psd signal power for each frequency bin

[in] start starting bin location

[in] end ending bin location

[in] snr_offset SNR adjustment

[in] floor noise floor

[in] bap_tab look-up table for bit allocation pointers

[out] bap bit allocation pointers

Definition at line 106 of file ac3dsp.h.

Referenced by bit_alloc(), decode_audio_block(), ff_ac3dsp_init(), ff_ac3dsp_init_arm(), and ff_ac3dsp_init_mips().

void(* AC3DSPContext::update_bap_counts)(uint16_t mant_cnt[16], uint8_t *bap, int len)

Update bap counts using the supplied array of bap.

Parameters: [out] mant_cnt bap counts for 1 block

[in] bap array of bap, pointing to start coef bin

[in] len number of elements to process

Definition at line 117 of file ac3dsp.h.

Referenced by count_mantissa_bits_update_ch(), ff_ac3dsp_init(), ff_ac3dsp_init_arm(), and ff_ac3dsp_init_mips().

int(* AC3DSPContext::compute_mantissa_size)(uint16_t mant_cnt[6][16])

Calculate the number of bits needed to encode a set of mantissas.

Parameters: [in] mant_cnt bap counts for all blocks

Returns: mantissa bit count

Definition at line 125 of file ac3dsp.h.

Referenced by count_mantissa_bits(), ff_ac3dsp_init(), and ff_ac3dsp_init_x86().

void(* AC3DSPContext::extract_exponents)(uint8_t *exp, int32_t *coef, int nb_coefs)

Definition at line 127 of file ac3dsp.h.

Referenced by apply_channel_coupling(), extract_exponents(), ff_ac3dsp_init(), ff_ac3dsp_init_arm(), and ff_ac3dsp_init_x86().

void(* AC3DSPContext::sum_square_butterfly_int32)(int64_t sum[4], const int32_t *coef0, const int32_t *coef1, int len)

Definition at line 129 of file ac3dsp.h.

Referenced by ff_ac3dsp_init(), ff_ac3dsp_init_arm(), and sum_square_butterfly().

void(* AC3DSPContext::sum_square_butterfly_float)(float sum[4], const float *coef0, const float *coef1, int len)

Definition at line 132 of file ac3dsp.h.

Referenced by ff_ac3dsp_init(), ff_ac3dsp_init_arm(), and sum_square_butterfly().

void(* AC3DSPContext::downmix)(float **samples, float(*matrix)[2], int out_ch, int in_ch, int len)

Definition at line 135 of file ac3dsp.h.

Referenced by decode_audio_block(), ff_ac3dsp_init(), ff_ac3dsp_init_mips(), and ff_ac3dsp_init_x86().

void(* AC3DSPContext::downmix_fixed)(int32_t **samples, int16_t(*matrix)[2], int out_ch, int in_ch, int len)

Definition at line 138 of file ac3dsp.h.

Referenced by ff_ac3dsp_init().

void(* AC3DSPContext::apply_window_int16)(int16_t *output, const int16_t *input, const int16_t *window, unsigned int len)

Apply symmetric window in 16-bit fixed-point.

Parameters: output destination array constraints: 16-byte aligned

input source array constraints: 16-byte aligned

window window array constraints: 16-byte aligned, at least len/2 elements

len full window length constraints: multiple of ? greater than zero

Definition at line 152 of file ac3dsp.h.

Referenced by apply_mdct(), ff_ac3dsp_init(), ff_ac3dsp_init_arm(), and ff_ac3dsp_init_x86().

The documentation for this struct was generated from the following file:

libavcodec/ac3dsp.h

Generated on Wed Jun 10 2015 01:57:18 for FFmpeg by doxygen 1.8.6