EVS

Decodes Enhanced Voice Service (EVS) audio data streams into pulse code modulation (PCM) streams. It supports 8 kHz sampling rate and 5.9, 7.2, 8.0, 9.6, 13.2, 16.4, and 24.4 kbit/s bit rates.

The function is called as follows:

Obtain the size of the memory to be applied for decoding (DstBufLen).
Initialize the structure by calling Init.
Call the main function HMPPA_Evs_Decode_8u16s for decoding.
Call Release to release the memory allocated to the structure.

The function interface is declared as follows:

Obtaining the size of the memory to be applied for decoding:
HmppResult HMPPA_Evs_GetDecodeDstBufLen_8u16s(const uint8_t *src, int32_t len, int32_t *dstBufLen);
Initialization:
HmppResult HMPPA_Evs_DecodeInit_8u16s(HmppaEvsDecodePolicy_16s** policy);
Decoding:
HmppResult HMPPA_Evs_Decode_8u16s(uint8_t *src, int32_t len, int16_t *dst, HmppaEvsDecodePolicy_16s*policy, int32_t *bytesConsumed, int64_t *byteDecoded);
Release:
HmppResult HMPPA_Evs_DecodeRelease_8u16s(HmppaEvsDecodePolicy_16s* policy);

Parameters

Parameter	Description	Value Range	Input/Output
src	Pointer to the EVS stream to be decoded	Not null	Input
len	Length of the data stream to be decoded, in bytes	(0, INT_MAX]	Input
dst	Pointer to the destination vector	Not null	Output
policy	Pointer to the special structure	Not null	Input/Output
bytesConsumed	Pointer to the data stream length (in bytes) actually consumed for decoding	[0, len]	Output
bytesDecoded	Pointer to the data stream length (in bytes) of the actual decoded output	[0, Theoretical output data stream length after decoding]	Output
dstBufLen	Pointer to the required destination vector length (in duel-bytes)	Not null	Output

Return Value

Success: HMPP_STS_NO_ERR
Failure: An error code is returned.

Error Codes

Error Code	Description
HMPP_STS_NULL_PTR_ERR	The value of src, dst, or policy is NULL.
HMPP_STS_MALLOC_FAILED	Memory allocation failed.
HMPP_STS_SIZE_WRN	The input data stream is not completely decoded.
HMPP_STS_BAD_ARG_ERR	The format of the input data stream is incorrect. The protocol or bit rate is not supported.

Example

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <hmppa.h>

int main(int argc, char *argv[]) {
    FILE* in;
    FILE* out;
    int32_t re;
    int32_t bytesConsumed = 0;
    int64_t bytesDecoded = 0;
    if (argc < 3) {
        fprintf(stderr, "%s in.evs out.pcm\n", argv[0]);
        return 1;
    }

    in = fopen(argv[1], "rb");
    out = fopen(argv[2], "w+");
    if (!in) {
        perror(argv[1]);
        return 1;
    }

    fseek(in, 0, SEEK_END);
    int32_t srcLen = ftell(in);
    fseek(in, 0, SEEK_SET);
  
    uint8_t* src = (uint8_t*)malloc(srcLen * sizeof(uint8_t));
    int32_t n = fread(src, sizeof(uint8_t), srcLen, in);
    if (n != srcLen) {
        return -1;
    }

    HmppaEvsDecodePolicy_16s *policy;
    re = HMPPA_Evs_DecodeInit_8u16s(&policy);

    int32_t dstLen;
    re = HMPPA_Evs_GetDecodeDstBufLen_8u16s(src, srcLen, &dstLen);
    int16_t* dst = (int16_t*)malloc(dstLen * sizeof(int16_t));

    if (re != HMPP_STS_NO_ERR) {
        return 0;
    }
    re = HMPPA_Evs_Decode_8u16s(src, srcLen, dst, policy, &bytesConsumed, &bytesDecoded);
    if (re == HMPP_STS_NO_ERR) {
        fwrite(dst, sizeof(int16_t), dstLen, out);
        printf("SUCCESS: srcLen:%d, HmppResult:%d, bytesConsumed:%d, bytesDecoded:%d\n", srcLen, re, bytesConsumed, bytesDecoded);
    } else {
        printf("WRONG: srcLen:%d, HmppResult:%d, bytesConsumed:%d, bytesDecoded:%d\n", srcLen, re, bytesConsumed, bytesDecoded);
    }

    re = HMPPA_Evs_DecodeRelease_8u16s(policy);
    fclose(in);
    fclose(out);:q

    return 0;
}

Output:

SUCCESS: srcLen:25296, HmppResult:0, bytesConsumed:50592, bytesDecoded:130560

Parent topic: Audio Decoding