libspandsp 0.0.4

ima_adpcm.h File Reference

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Classes

struct  ima_adpcm_state_t

Enumerations

enum  { IMA_ADPCM_IMA4 = 0, IMA_ADPCM_DVI4 = 1, IMA_ADPCM_VDVI = 2 }

Functions

ima_adpcm_state_tima_adpcm_init (ima_adpcm_state_t *s, int variant, int chunk_size)
int ima_adpcm_release (ima_adpcm_state_t *s)
int ima_adpcm_encode (ima_adpcm_state_t *s, uint8_t ima_data[], const int16_t amp[], int len)
int ima_adpcm_decode (ima_adpcm_state_t *s, int16_t amp[], const uint8_t ima_data[], int ima_bytes)

Detailed Description


Enumeration Type Documentation

anonymous enum
Enumerator:
IMA_ADPCM_IMA4 

IMA4 is the original IMA ADPCM variant

IMA_ADPCM_DVI4 

DVI4 is the IMA ADPCM variant defined in RFC3551

IMA_ADPCM_VDVI 

VDVI is the variable bit rate IMA ADPCM variant defined in RFC3551


Function Documentation

int ima_adpcm_decode ( ima_adpcm_state_t s,
int16_t  amp[],
const uint8_t  ima_data[],
int  ima_bytes 
)

Decode a buffer of IMA ADPCM data to linear PCM.

Parameters:
sThe IMA ADPCM context.
ampThe audio sample buffer.
ima_data
ima_bytes
Returns:
The number of samples returned.

References ima_adpcm_state_t::chunk_size, IMA_ADPCM_DVI4, IMA_ADPCM_IMA4, IMA_ADPCM_VDVI, ima_adpcm_state_t::last, and ima_adpcm_state_t::step_index.

int ima_adpcm_encode ( ima_adpcm_state_t s,
uint8_t  ima_data[],
const int16_t  amp[],
int  len 
)

Encode a buffer of linear PCM data to IMA ADPCM.

Parameters:
sThe IMA ADPCM context.
ima_dataThe IMA ADPCM data produced.
ampThe audio sample buffer.
lenThe number of samples in the buffer.
Returns:
The number of bytes of IMA ADPCM data produced.

References ima_adpcm_state_t::chunk_size, IMA_ADPCM_DVI4, IMA_ADPCM_IMA4, IMA_ADPCM_VDVI, ima_adpcm_state_t::ima_byte, ima_adpcm_state_t::last, and ima_adpcm_state_t::step_index.

ima_adpcm_state_t* ima_adpcm_init ( ima_adpcm_state_t s,
int  variant,
int  chunk_size 
)

Initialise an IMA ADPCM encode or decode context.

Parameters:
sThe IMA ADPCM context
variant???
chunk_sizeThe size of a chunk, in samples. A chunk size of zero sample samples means treat each encode or decode operation as a chunk.
Returns:
A pointer to the IMA ADPCM context, or NULL for error.

References ima_adpcm_state_t::chunk_size.

int ima_adpcm_release ( ima_adpcm_state_t s)

Free an IMA ADPCM encode or decode context.

Parameters:
sThe IMA ADPCM context.
Returns:
0 for OK.