Silk编解码是Skype向第三方开发人员和硬件制造商提供免版税认证(RF)的Silk宽带音频编码器。Skype已将其开源，可以访问[http://developer.skype.com/silk](http://developer.skype.com/silk)获取最新动向。SILK Codec是一个语音和音频编解码算法, 对于音频带宽、网络带宽和算法复杂度都具有很好的弹性。支持4种采样率：8KHz、12KHz、16KHz、24KHz；三种复杂度：低、中、高。编码码率在 6~40kbps（不同采样率具有不同的码率范围）以及还支持VAD、DTX、FEC等模块，感觉还是比较全面。最重要的一点是提供了定点C代码，非常有利于向ARM、DSP移植和优化。这一篇主要参考了pjsip中的silk实现。
1、获取silk源码（[http://developer.skype.com/silk](http://developer.skype.com/silk)）
2、创建新的android工程，并创建jni文件夹。
3、将silk源码拷贝到jni目录
4、在jni目录下新增Android.mk文件，编辑内容如下：
~~~
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
SILK := silk
LOCAL_MODULE := silkcommon
LOCAL_SRC_FILES := $(SILK)/src/SKP_Silk_A2NLSF.c \
$(SILK)/src/SKP_Silk_CNG.c \
$(SILK)/src/SKP_Silk_HP_variable_cutoff_FIX.c \
$(SILK)/src/SKP_Silk_LBRR_reset.c \
$(SILK)/src/SKP_Silk_LPC_inv_pred_gain.c \
$(SILK)/src/SKP_Silk_LPC_stabilize.c \
$(SILK)/src/SKP_Silk_LPC_synthesis_filter.c \
$(SILK)/src/SKP_Silk_LPC_synthesis_order16.c \
$(SILK)/src/SKP_Silk_LP_variable_cutoff.c \
$(SILK)/src/SKP_Silk_LSF_cos_table.c \
$(SILK)/src/SKP_Silk_LTP_analysis_filter_FIX.c \
$(SILK)/src/SKP_Silk_LTP_scale_ctrl_FIX.c \
$(SILK)/src/SKP_Silk_MA.c \
$(SILK)/src/SKP_Silk_NLSF2A.c \
$(SILK)/src/SKP_Silk_NLSF2A_stable.c \
$(SILK)/src/SKP_Silk_NLSF_MSVQ_decode.c \
$(SILK)/src/SKP_Silk_NLSF_MSVQ_encode_FIX.c \
$(SILK)/src/SKP_Silk_NLSF_VQ_rate_distortion_FIX.c \
$(SILK)/src/SKP_Silk_NLSF_VQ_sum_error_FIX.c \
$(SILK)/src/SKP_Silk_NLSF_VQ_weights_laroia.c \
$(SILK)/src/SKP_Silk_NLSF_stabilize.c \
$(SILK)/src/SKP_Silk_NSQ.c \
$(SILK)/src/SKP_Silk_NSQ_del_dec.c \
$(SILK)/src/SKP_Silk_PLC.c \
$(SILK)/src/SKP_Silk_VAD.c \
$(SILK)/src/SKP_Silk_VQ_nearest_neighbor_FIX.c \
$(SILK)/src/SKP_Silk_allpass_int.c \
$(SILK)/src/SKP_Silk_ana_filt_bank_1.c \
$(SILK)/src/SKP_Silk_apply_sine_window.c \
$(SILK)/src/SKP_Silk_array_maxabs.c \
$(SILK)/src/SKP_Silk_autocorr.c \
$(SILK)/src/SKP_Silk_biquad.c \
$(SILK)/src/SKP_Silk_biquad_alt.c \
$(SILK)/src/SKP_Silk_burg_modified.c \
$(SILK)/src/SKP_Silk_bwexpander.c \
$(SILK)/src/SKP_Silk_bwexpander_32.c \
$(SILK)/src/SKP_Silk_code_signs.c \
$(SILK)/src/SKP_Silk_control_codec_FIX.c \
$(SILK)/src/SKP_Silk_corrMatrix_FIX.c \
$(SILK)/src/SKP_Silk_create_init_destroy.c \
$(SILK)/src/SKP_Silk_dec_API.c \
$(SILK)/src/SKP_Silk_decode_core.c \
$(SILK)/src/SKP_Silk_decode_frame.c \
$(SILK)/src/SKP_Silk_decode_indices_v4.c \
$(SILK)/src/SKP_Silk_decode_parameters.c \
$(SILK)/src/SKP_Silk_decode_parameters_v4.c \
$(SILK)/src/SKP_Silk_decode_pulses.c \
$(SILK)/src/SKP_Silk_decoder_set_fs.c \
$(SILK)/src/SKP_Silk_detect_SWB_input.c \
$(SILK)/src/SKP_Silk_enc_API.c \
$(SILK)/src/SKP_Silk_encode_frame_FIX.c \
$(SILK)/src/SKP_Silk_encode_parameters.c \
$(SILK)/src/SKP_Silk_encode_parameters_v4.c \
$(SILK)/src/SKP_Silk_encode_pulses.c \
$(SILK)/src/SKP_Silk_find_LPC_FIX.c \
$(SILK)/src/SKP_Silk_find_LTP_FIX.c \
$(SILK)/src/SKP_Silk_find_pitch_lags_FIX.c \
$(SILK)/src/SKP_Silk_find_pred_coefs_FIX.c \
$(SILK)/src/SKP_Silk_gain_quant.c \
$(SILK)/src/SKP_Silk_init_encoder_FIX.c \
$(SILK)/src/SKP_Silk_inner_prod_aligned.c \
$(SILK)/src/SKP_Silk_interpolate.c \
$(SILK)/src/SKP_Silk_k2a.c \
$(SILK)/src/SKP_Silk_k2a_Q16.c \
$(SILK)/src/SKP_Silk_lin2log.c \
$(SILK)/src/SKP_Silk_log2lin.c \
$(SILK)/src/SKP_Silk_lowpass_int.c \
$(SILK)/src/SKP_Silk_lowpass_short.c \
$(SILK)/src/SKP_Silk_noise_shape_analysis_FIX.c \
$(SILK)/src/SKP_Silk_pitch_analysis_core.c \
$(SILK)/src/SKP_Silk_pitch_est_tables.c \
$(SILK)/src/SKP_Silk_prefilter_FIX.c \
$(SILK)/src/SKP_Silk_process_NLSFs_FIX.c \
$(SILK)/src/SKP_Silk_process_gains_FIX.c \
$(SILK)/src/SKP_Silk_pulses_to_bytes.c \
$(SILK)/src/SKP_Silk_quant_LTP_gains_FIX.c \
$(SILK)/src/SKP_Silk_range_coder.c \
$(SILK)/src/SKP_Silk_regularize_correlations_FIX.c \
$(SILK)/src/SKP_Silk_resample_1_2.c \
$(SILK)/src/SKP_Silk_resample_1_2_coarse.c \
$(SILK)/src/SKP_Silk_resample_1_2_coarsest.c \
$(SILK)/src/SKP_Silk_resample_1_3.c \
$(SILK)/src/SKP_Silk_resample_2_1_coarse.c \
$(SILK)/src/SKP_Silk_resample_2_3.c \
$(SILK)/src/SKP_Silk_resample_2_3_coarse.c \
$(SILK)/src/SKP_Silk_resample_2_3_coarsest.c \
$(SILK)/src/SKP_Silk_resample_2_3_rom.c \
$(SILK)/src/SKP_Silk_resample_3_1.c \
$(SILK)/src/SKP_Silk_resample_3_2.c \
$(SILK)/src/SKP_Silk_resample_3_2_rom.c \
$(SILK)/src/SKP_Silk_resample_3_4.c \
$(SILK)/src/SKP_Silk_resample_4_3.c \
$(SILK)/src/SKP_Silk_residual_energy16_FIX.c \
$(SILK)/src/SKP_Silk_residual_energy_FIX.c \
$(SILK)/src/SKP_Silk_scale_copy_vector16.c \
$(SILK)/src/SKP_Silk_scale_vector.c \
$(SILK)/src/SKP_Silk_schur.c \
$(SILK)/src/SKP_Silk_schur64.c \
$(SILK)/src/SKP_Silk_shell_coder.c \
$(SILK)/src/SKP_Silk_sigm_Q15.c \
$(SILK)/src/SKP_Silk_solve_LS_FIX.c \
$(SILK)/src/SKP_Silk_sort.c \
$(SILK)/src/SKP_Silk_sum_sqr_shift.c \
$(SILK)/src/SKP_Silk_tables_LTP.c \
$(SILK)/src/SKP_Silk_tables_NLSF_CB0_10.c \
$(SILK)/src/SKP_Silk_tables_NLSF_CB0_16.c \
$(SILK)/src/SKP_Silk_tables_NLSF_CB1_10.c \
$(SILK)/src/SKP_Silk_tables_NLSF_CB1_16.c \
$(SILK)/src/SKP_Silk_tables_gain.c \
$(SILK)/src/SKP_Silk_tables_other.c \
$(SILK)/src/SKP_Silk_tables_pitch_lag.c \
$(SILK)/src/SKP_Silk_tables_pulses_per_block.c \
$(SILK)/src/SKP_Silk_tables_sign.c \
$(SILK)/src/SKP_Silk_tables_type_offset.c
LOCAL_ARM_MODE := arm
LOCAL_CFLAGS = -O3
LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog
LOCAL_C_INCLUDES += $(LOCAL_PATH)/$(SILK)/src $(LOCAL_PATH)/$(SILK)/interface
include $(BUILD_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := silk8_jni
LOCAL_SRC_FILES := silk8_jni.cpp
LOCAL_C_INCLUDES += $(LOCAL_PATH)/$(SILK)/src $(LOCAL_PATH)/$(SILK)/interface
LOCAL_CFLAGS = -O3
LOCAL_STATIC_LIBRARIES := silkcommon
LOCAL_ARM_MODE := arm
LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog
include $(BUILD_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := silk16_jni
LOCAL_SRC_FILES := silk16_jni.cpp
LOCAL_C_INCLUDES += $(LOCAL_PATH)/$(SILK)/src $(LOCAL_PATH)/$(SILK)/interface
LOCAL_CFLAGS = -O3
LOCAL_STATIC_LIBRARIES := silkcommon
LOCAL_ARM_MODE := arm
LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog
include $(BUILD_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := silk24_jni
LOCAL_SRC_FILES := silk24_jni.cpp
LOCAL_C_INCLUDES += $(LOCAL_PATH)/$(SILK)/src $(LOCAL_PATH)/$(SILK)/interface
LOCAL_CFLAGS = -O3
LOCAL_STATIC_LIBRARIES := silkcommon
LOCAL_ARM_MODE := arm
LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog
include $(BUILD_SHARED_LIBRARY)
~~~
5、创建JNI包装类silk8_jni.cpp、silk16_jni.cpp、silk24_jni.cpp，用来调用Silk中的C代码函数，编辑内容如下
silk8_jni.cpp:
~~~
#include <jni.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
/* Define codec specific settings */
#define MAX_BYTES_ENC_PER_FRAME 250 // Equals peak bitrate of 100 kbps
#define MAX_BYTES_DEC_PER_FRAME 1024
#define MAX_INPUT_FRAMES 5
#define MAX_LBRR_DELAY 2
#define MAX_FRAME_LENGTH 480
#define MAX_FRAME 160
#include <android/log.h>
#define LOG_TAG "silk" // text for log tag
#include "SKP_Silk_SDK_API.h"
#include "SKP_Silk_SigProc_FIX.h"
#undef DEBUG_SILK8
// the header length of the RTP frame (must skip when en/decoding)
#define RTP_HDR_SIZE 12
static int codec_open = 0;
static JavaVM *gJavaVM;
const char *kInterfacePath = "org/sipdroid/pjlib/silk8";
/* encoder parameters */
SKP_int32 encSizeBytes;
void *psEnc;
/* default settings */
SKP_int fs_kHz = 8;
SKP_int targetRate_bps = 20000;
SKP_int packetSize_ms = 20;
SKP_int frameSizeReadFromFile_ms = 20;
SKP_int packetLoss_perc = 0, smplsSinceLastPacket;
SKP_int INBandFec_enabled = 0, DTX_enabled = 0, quiet = 0;
SKP_SILK_SDK_EncControlStruct encControl; // Struct for input to encoder
/* decoder parameters */
jbyte payloadToDec[ MAX_BYTES_DEC_PER_FRAME * MAX_INPUT_FRAMES * ( MAX_LBRR_DELAY + 1 ) ];
jshort out[ ( MAX_FRAME_LENGTH << 1 ) * MAX_INPUT_FRAMES ], *outPtr;
SKP_int32 decSizeBytes;
void *psDec;
SKP_SILK_SDK_DecControlStruct DecControl;
extern "C"
JNIEXPORT jint JNICALL Java_com_trunkbow_silk_SILK8_open
(JNIEnv *env, jobject obj, jint compression) {
int ret;
if (codec_open++ != 0)
return (jint)0;
/* Set the samplingrate that is requested for the output */
DecControl.sampleRate = 8000;
/* Create decoder */
ret = SKP_Silk_SDK_Get_Decoder_Size( &decSizeBytes );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_SDK_Get_Decoder_Size returned %d", ret );
}
#ifdef DEBUG_SILK8
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"### INIT Decoder decSizeBytes = %d\n", decSizeBytes);
#endif
psDec = malloc( decSizeBytes );
/* Reset decoder */
ret = SKP_Silk_SDK_InitDecoder( psDec );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_InitDecoder returned %d", ret );
}
/* Create Encoder */
ret = SKP_Silk_SDK_Get_Encoder_Size( &encSizeBytes );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_SDK_Get_Encoder_Size returned %d", ret );
}
#ifdef DEBUG_SILK8
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"### INIT Encoder encSizeBytes = %d\n", encSizeBytes);
#endif
psEnc = malloc( encSizeBytes );
/* Reset Encoder */
ret = SKP_Silk_SDK_InitEncoder( psEnc, &encControl );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_SDK_InitEncoder returned %d", ret );
}
/* Set Encoder parameters */
encControl.sampleRate = fs_kHz * 1000;
encControl.packetSize = packetSize_ms * fs_kHz;
encControl.packetLossPercentage = packetLoss_perc;
encControl.useInBandFEC = INBandFec_enabled;
encControl.useDTX = DTX_enabled;
encControl.complexity = compression;
encControl.bitRate = targetRate_bps;
return (jint)0;
}
void Print_Decode_Error_Msg(int errcode) {
switch (errcode) {
case SKP_SILK_DEC_WRONG_SAMPLING_FREQUENCY:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nOutput sampling frequency lower than internal decoded sampling frequency\n", errcode);
break;
case SKP_SILK_DEC_PAYLOAD_TOO_LARGE:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nPayload size exceeded the maximum allowed 1024 bytes\n", errcode);
break;
case SKP_SILK_DEC_PAYLOAD_ERROR:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nPayload has bit errors\n", errcode);
break;
}
}
void Print_Encode_Error_Msg(int errcode) {
switch (errcode) {
case SKP_SILK_ENC_INPUT_INVALID_NO_OF_SAMPLES:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nInput length is not a multiplum of 10 ms, or length is longer than the packet length\n", errcode);
break;
case SKP_SILK_ENC_FS_NOT_SUPPORTED:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nSampling frequency not 8000, 12000, 16000 or 24000 Hertz \n", errcode);
break;
case SKP_SILK_ENC_PACKET_SIZE_NOT_SUPPORTED:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nPacket size not 20, 40, 60, 80 or 100 ms\n", errcode);
break;
case SKP_SILK_ENC_PAYLOAD_BUF_TOO_SHORT:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nAllocated payload buffer too short \n", errcode);
break;
case SKP_SILK_ENC_WRONG_LOSS_RATE:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nLoss rate not between 0 and 100 percent\n", errcode);
break;
case SKP_SILK_ENC_WRONG_COMPLEXITY_SETTING:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nComplexity setting not valid, use 0, 1 or 2\n", errcode);
break;
case SKP_SILK_ENC_WRONG_INBAND_FEC_SETTING:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nInband FEC setting not valid, use 0 or 1\n", errcode);
break;
case SKP_SILK_ENC_WRONG_DTX_SETTING:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nDTX setting not valid, use 0 or 1\n", errcode);
break;
case SKP_SILK_ENC_INTERNAL_ERROR:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nInternal encoder error\n", errcode);
break;
}
}
extern "C"
JNIEXPORT jint JNICALL Java_com_trunkbow_silk_SILK8_encode
(JNIEnv *env, jobject obj, jshortArray lin, jint offset, jbyteArray encoded, jint size) {
jbyte enc_payload[ MAX_BYTES_DEC_PER_FRAME * MAX_INPUT_FRAMES ];
jshort in[ MAX_FRAME_LENGTH * MAX_INPUT_FRAMES ];
int ret,i,frsz=MAX_FRAME;
SKP_int16 nBytes;
unsigned int lin_pos = 0;
if (!codec_open)
return 0;
#ifdef DEBUG_SILK8
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"encoding frame size: %d\toffset: %d\n", size, offset);
#endif
for (i = 0; i < size; i+=MAX_FRAME) {
#ifdef DEBUG_SILK8
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"encoding frame size: %d\toffset: %d i: %d\n", size, offset, i);
#endif
env->GetShortArrayRegion(lin, offset + i,frsz, in);
/* max payload size */
nBytes = MAX_BYTES_ENC_PER_FRAME * MAX_INPUT_FRAMES;
ret = SKP_Silk_SDK_Encode( psEnc, &encControl, in, (SKP_int16)frsz, (SKP_uint8 *)enc_payload, &nBytes );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!! SKP_Silk_Encode returned: %d\n", ret);
Print_Encode_Error_Msg(ret);
break;
}
#ifdef DEBUG_SILK8
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"Enocded nBytes: %d\n", nBytes);
#endif
/* Write payload */
env->SetByteArrayRegion(encoded, RTP_HDR_SIZE+ lin_pos, nBytes, enc_payload);
lin_pos += nBytes;
}
#ifdef DEBUG_SILK8
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"encoding **END** frame size: %d\toffset: %d i: %d lin_pos: %d\n", size, offset, i, lin_pos);
#endif
return (jint)lin_pos;
}
extern "C"
JNIEXPORT jint JNICALL Java_com_trunkbow_silk_SILK8_decode
(JNIEnv *env, jobject obj, jbyteArray encoded, jshortArray lin, jint size) {
jbyte buffer [MAX_BYTES_DEC_PER_FRAME * MAX_INPUT_FRAMES * ( MAX_LBRR_DELAY + 1 ) ];
jshort output_buffer[( MAX_FRAME_LENGTH << 1 ) * MAX_INPUT_FRAMES ];
// SKP_int16 *outPtr;
int ret;
SKP_int16 len;
// int tot_len,frames;
if (!codec_open)
return 0;
#ifdef DEBUG_SILK8
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"##### BEGIN DECODE ******** decoding frame size: %d\n", size);
#endif
env->GetByteArrayRegion(encoded, RTP_HDR_SIZE, size, buffer);
// outPtr = output_buffer;
// tot_len = 0;
// frames = 0;
// do {
ret = SKP_Silk_SDK_Decode( psDec, &DecControl, 0,(SKP_uint8 *) buffer, size, output_buffer,&len );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!! SKP_Silk_SDK_Decode returned: %d\n", ret);
Print_Decode_Error_Msg(ret);
}
#ifdef DEBUG_SILK8
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"##### DECODED length: %d\n\t Frame #: %d", len);
#endif
// frames++;
// outPtr += len;
// tot_len += len;
// } while( DecControl.moreInternalDecoderFrames );
env->SetShortArrayRegion(lin, 0, len,output_buffer);
return (jint)len;
}
extern "C"
JNIEXPORT void JNICALL Java_com_trunkbow_silk_SILK8_close
(JNIEnv *env, jobject obj) {
if (--codec_open != 0)
return;
/* Free decoder */
free( psDec );
/* Free Encoder */
free( psEnc );
}
~~~
silk_16.cpp:
~~~
#include <jni.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
/* Define codec specific settings */
#define MAX_BYTES_ENC_PER_FRAME 250 // Equals peak bitrate of 100 kbps
#define MAX_BYTES_DEC_PER_FRAME 1024
#define MAX_INPUT_FRAMES 5
#define MAX_LBRR_DELAY 2
#define MAX_FRAME_LENGTH 480
#define MAX_FRAME 320
#include <android/log.h>
#define LOG_TAG "silk" // text for log tag
#include "SKP_Silk_SDK_API.h"
#include "SKP_Silk_SigProc_FIX.h"
#undef DEBUG_SILK16
// the header length of the RTP frame (must skip when en/decoding)
#define RTP_HDR_SIZE 12
static int codec_open = 0;
static JavaVM *gJavaVM;
const char *kInterfacePath = "org/sipdroid/pjlib/silk16";
/* encoder parameters */
SKP_int32 encSizeBytes;
void *psEnc;
/* default settings */
SKP_int fs_kHz = 16;
SKP_int targetRate_bps = 20000;
SKP_int packetSize_ms = 20;
SKP_int frameSizeReadFromFile_ms = 20;
SKP_int packetLoss_perc = 0, smplsSinceLastPacket;
SKP_int INBandFec_enabled = 0, DTX_enabled = 0, quiet = 0;
SKP_SILK_SDK_EncControlStruct encControl; // Struct for input to encoder
/* decoder parameters */
jbyte payloadToDec[ MAX_BYTES_DEC_PER_FRAME * MAX_INPUT_FRAMES * ( MAX_LBRR_DELAY + 1 ) ];
jshort out[ ( MAX_FRAME_LENGTH << 1 ) * MAX_INPUT_FRAMES ], *outPtr;
SKP_int32 decSizeBytes;
void *psDec;
SKP_SILK_SDK_DecControlStruct DecControl;
extern "C"
JNIEXPORT jint JNICALL Java_com_trunkbow_silk_SILK16_open
(JNIEnv *env, jobject obj, jint compression) {
int ret;
if (codec_open++ != 0)
return (jint)0;
/* Set the samplingrate that is requested for the output */
DecControl.sampleRate = 16000;
/* Create decoder */
ret = SKP_Silk_SDK_Get_Decoder_Size( &decSizeBytes );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_SDK_Get_Decoder_Size returned %d", ret );
}
#ifdef DEBUG_SILK16
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"### INIT Decoder decSizeBytes = %d\n", decSizeBytes);
#endif
psDec = malloc( decSizeBytes );
/* Reset decoder */
ret = SKP_Silk_SDK_InitDecoder( psDec );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_InitDecoder returned %d", ret );
}
/* Create Encoder */
ret = SKP_Silk_SDK_Get_Encoder_Size( &encSizeBytes );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_SDK_Get_Encoder_Size returned %d", ret );
}
#ifdef DEBUG_SILK16
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"### INIT Encoder encSizeBytes = %d\n", encSizeBytes);
#endif
psEnc = malloc( encSizeBytes );
/* Reset Encoder */
ret = SKP_Silk_SDK_InitEncoder( psEnc, &encControl );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_SDK_InitEncoder returned %d", ret );
}
/* Set Encoder parameters */
encControl.sampleRate = fs_kHz * 1000;
encControl.packetSize = packetSize_ms * fs_kHz;
encControl.packetLossPercentage = packetLoss_perc;
encControl.useInBandFEC = INBandFec_enabled;
encControl.useDTX = DTX_enabled;
encControl.complexity = compression;
encControl.bitRate = targetRate_bps;
return (jint)0;
}
void Print_Decode_Error_Msg(int errcode) {
switch (errcode) {
case SKP_SILK_DEC_WRONG_SAMPLING_FREQUENCY:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nOutput sampling frequency lower than internal decoded sampling frequency\n", errcode);
break;
case SKP_SILK_DEC_PAYLOAD_TOO_LARGE:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nPayload size exceeded the maximum allowed 1024 bytes\n", errcode);
break;
case SKP_SILK_DEC_PAYLOAD_ERROR:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nPayload has bit errors\n", errcode);
break;
}
}
void Print_Encode_Error_Msg(int errcode) {
switch (errcode) {
case SKP_SILK_ENC_INPUT_INVALID_NO_OF_SAMPLES:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nInput length is not a multiplum of 10 ms, or length is longer than the packet length\n", errcode);
break;
case SKP_SILK_ENC_FS_NOT_SUPPORTED:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nSampling frequency not 8000, 12000, 16000 or 24000 Hertz \n", errcode);
break;
case SKP_SILK_ENC_PACKET_SIZE_NOT_SUPPORTED:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nPacket size not 20, 40, 60, 80 or 100 ms\n", errcode);
break;
case SKP_SILK_ENC_PAYLOAD_BUF_TOO_SHORT:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nAllocated payload buffer too short \n", errcode);
break;
case SKP_SILK_ENC_WRONG_LOSS_RATE:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nLoss rate not between 0 and 100 percent\n", errcode);
break;
case SKP_SILK_ENC_WRONG_COMPLEXITY_SETTING:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nComplexity setting not valid, use 0, 1 or 2\n", errcode);
break;
case SKP_SILK_ENC_WRONG_INBAND_FEC_SETTING:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nInband FEC setting not valid, use 0 or 1\n", errcode);
break;
case SKP_SILK_ENC_WRONG_DTX_SETTING:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nDTX setting not valid, use 0 or 1\n", errcode);
break;
case SKP_SILK_ENC_INTERNAL_ERROR:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nInternal encoder error\n", errcode);
break;
}
}
extern "C"
JNIEXPORT jint JNICALL Java_com_trunkbow_silk_SILK16_encode
(JNIEnv *env, jobject obj, jshortArray lin, jint offset, jbyteArray encoded, jint size) {
jbyte enc_payload[ MAX_BYTES_DEC_PER_FRAME * MAX_INPUT_FRAMES ];
jshort in[ MAX_FRAME_LENGTH * MAX_INPUT_FRAMES ];
int ret,i,frsz=MAX_FRAME;
SKP_int16 nBytes;
unsigned int lin_pos = 0;
if (!codec_open)
return 0;
#ifdef DEBUG_SILK16
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"encoding frame size: %d\toffset: %d\n", size, offset);
#endif
for (i = 0; i < size; i+=MAX_FRAME) {
#ifdef DEBUG_SILK16
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"encoding frame size: %d\toffset: %d i: %d\n", size, offset, i);
#endif
env->GetShortArrayRegion(lin, offset + i,frsz, in);
/* max payload size */
nBytes = MAX_BYTES_ENC_PER_FRAME * MAX_INPUT_FRAMES;
ret = SKP_Silk_SDK_Encode( psEnc, &encControl, in, (SKP_int16)frsz, (SKP_uint8 *)enc_payload, &nBytes );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!! SKP_Silk_Encode returned: %d\n", ret);
Print_Encode_Error_Msg(ret);
break;
}
#ifdef DEBUG_SILK16
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"Enocded nBytes: %d\n", nBytes);
#endif
/* Write payload */
env->SetByteArrayRegion(encoded, RTP_HDR_SIZE+ lin_pos, nBytes, enc_payload);
lin_pos += nBytes;
}
#ifdef DEBUG_SILK16
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"encoding **END** frame size: %d\toffset: %d i: %d lin_pos: %d\n", size, offset, i, lin_pos);
#endif
return (jint)lin_pos;
}
extern "C"
JNIEXPORT jint JNICALL Java_com_trunkbow_silk_SILK16_decode
(JNIEnv *env, jobject obj, jbyteArray encoded, jshortArray lin, jint size) {
jbyte buffer [MAX_BYTES_DEC_PER_FRAME * MAX_INPUT_FRAMES * ( MAX_LBRR_DELAY + 1 ) ];
jshort output_buffer[( MAX_FRAME_LENGTH << 1 ) * MAX_INPUT_FRAMES ];
// SKP_int16 *outPtr;
int ret;
SKP_int16 len;
// int tot_len,frames;
if (!codec_open)
return 0;
#ifdef DEBUG_SILK16
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"##### BEGIN DECODE ******** decoding frame size: %d\n", size);
#endif
env->GetByteArrayRegion(encoded, RTP_HDR_SIZE, size, buffer);
// outPtr = output_buffer;
// tot_len = 0;
// frames = 0;
// do {
ret = SKP_Silk_SDK_Decode( psDec, &DecControl, 0,(SKP_uint8 *) buffer, size, output_buffer,&len );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!! SKP_Silk_SDK_Decode returned: %d\n", ret);
Print_Decode_Error_Msg(ret);
}
#ifdef DEBUG_SILK16
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"##### DECODED length: %d\n\t Frame #: %d", len);
#endif
// frames++;
// outPtr += len;
// tot_len += len;
// } while( DecControl.moreInternalDecoderFrames );
env->SetShortArrayRegion(lin, 0, len,output_buffer);
return (jint)len;
}
extern "C"
JNIEXPORT void JNICALL Java_com_trunkbow_silk_SILK16_close
(JNIEnv *env, jobject obj) {
if (--codec_open != 0)
return;
/* Free decoder */
free( psDec );
/* Free Encoder */
free( psEnc );
}
~~~
silk24_jni.cpp
~~~
#include <jni.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
/* Define codec specific settings */
#define MAX_BYTES_ENC_PER_FRAME 250 // Equals peak bitrate of 100 kbps
#define MAX_BYTES_DEC_PER_FRAME 1024
#define MAX_INPUT_FRAMES 5
#define MAX_LBRR_DELAY 2
#define MAX_FRAME_LENGTH 480
#define MAX_FRAME 480
#include <android/log.h>
#define LOG_TAG "silk" // text for log tag
#include "SKP_Silk_SDK_API.h"
#include "SKP_Silk_SigProc_FIX.h"
#undef DEBUG_SILK24
// the header length of the RTP frame (must skip when en/decoding)
#define RTP_HDR_SIZE 12
static int codec_open = 0;
static JavaVM *gJavaVM;
const char *kInterfacePath = "org/sipdroid/pjlib/SILK24";
/* encoder parameters */
SKP_int32 encSizeBytes;
void *psEnc;
/* default settings */
SKP_int fs_kHz = 24;
SKP_int targetRate_bps = 20000;
SKP_int packetSize_ms = 20;
SKP_int frameSizeReadFromFile_ms = 20;
SKP_int packetLoss_perc = 0, smplsSinceLastPacket;
SKP_int INBandFec_enabled = 0, DTX_enabled = 0, quiet = 0;
SKP_SILK_SDK_EncControlStruct encControl; // Struct for input to encoder
/* decoder parameters */
jbyte payloadToDec[ MAX_BYTES_DEC_PER_FRAME * MAX_INPUT_FRAMES * ( MAX_LBRR_DELAY + 1 ) ];
jshort out[ ( MAX_FRAME_LENGTH << 1 ) * MAX_INPUT_FRAMES ], *outPtr;
SKP_int32 decSizeBytes;
void *psDec;
SKP_SILK_SDK_DecControlStruct DecControl;
extern "C"
JNIEXPORT jint JNICALL Java_com_trunkbow_silk_SILK24_open
(JNIEnv *env, jobject obj, jint compression) {
int ret;
if (codec_open++ != 0)
return (jint)0;
/* Set the samplingrate that is requested for the output */
DecControl.sampleRate = 24000;
/* Create decoder */
ret = SKP_Silk_SDK_Get_Decoder_Size( &decSizeBytes );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_SDK_Get_Decoder_Size returned %d", ret );
}
#ifdef DEBUG_SILK24
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"### INIT Decoder decSizeBytes = %d\n", decSizeBytes);
#endif
psDec = malloc( decSizeBytes );
/* Reset decoder */
ret = SKP_Silk_SDK_InitDecoder( psDec );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_InitDecoder returned %d", ret );
}
/* Create Encoder */
ret = SKP_Silk_SDK_Get_Encoder_Size( &encSizeBytes );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_SDK_Get_Encoder_Size returned %d", ret );
}
#ifdef DEBUG_SILK24
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"### INIT Encoder encSizeBytes = %d\n", encSizeBytes);
#endif
psEnc = malloc( encSizeBytes );
/* Reset Encoder */
ret = SKP_Silk_SDK_InitEncoder( psEnc, &encControl );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"\n!!!!!!!! SKP_Silk_SDK_InitEncoder returned %d", ret );
}
/* Set Encoder parameters */
encControl.sampleRate = fs_kHz * 1000;
encControl.packetSize = packetSize_ms * fs_kHz;
encControl.packetLossPercentage = packetLoss_perc;
encControl.useInBandFEC = INBandFec_enabled;
encControl.useDTX = DTX_enabled;
encControl.complexity = compression;
encControl.bitRate = targetRate_bps;
return (jint)0;
}
void Print_Decode_Error_Msg(int errcode) {
switch (errcode) {
case SKP_SILK_DEC_WRONG_SAMPLING_FREQUENCY:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nOutput sampling frequency lower than internal decoded sampling frequency\n", errcode);
break;
case SKP_SILK_DEC_PAYLOAD_TOO_LARGE:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nPayload size exceeded the maximum allowed 1024 bytes\n", errcode);
break;
case SKP_SILK_DEC_PAYLOAD_ERROR:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nPayload has bit errors\n", errcode);
break;
}
}
void Print_Encode_Error_Msg(int errcode) {
switch (errcode) {
case SKP_SILK_ENC_INPUT_INVALID_NO_OF_SAMPLES:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nInput length is not a multiplum of 10 ms, or length is longer than the packet length\n", errcode);
break;
case SKP_SILK_ENC_FS_NOT_SUPPORTED:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nSampling frequency not 8000, 12000, 16000 or 24000 Hertz \n", errcode);
break;
case SKP_SILK_ENC_PACKET_SIZE_NOT_SUPPORTED:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nPacket size not 20, 40, 60, 80 or 100 ms\n", errcode);
break;
case SKP_SILK_ENC_PAYLOAD_BUF_TOO_SHORT:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nAllocated payload buffer too short \n", errcode);
break;
case SKP_SILK_ENC_WRONG_LOSS_RATE:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nLoss rate not between 0 and 100 percent\n", errcode);
break;
case SKP_SILK_ENC_WRONG_COMPLEXITY_SETTING:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nComplexity setting not valid, use 0, 1 or 2\n", errcode);
break;
case SKP_SILK_ENC_WRONG_INBAND_FEC_SETTING:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nInband FEC setting not valid, use 0 or 1\n", errcode);
break;
case SKP_SILK_ENC_WRONG_DTX_SETTING:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nDTX setting not valid, use 0 or 1\n", errcode);
break;
case SKP_SILK_ENC_INTERNAL_ERROR:
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!!!!! Decode_Error_Message: %d\nInternal encoder error\n", errcode);
break;
}
}
extern "C"
JNIEXPORT jint JNICALL Java_com_trunkbow_silk_SILK24_encode
(JNIEnv *env, jobject obj, jshortArray lin, jint offset, jbyteArray encoded, jint size) {
jbyte enc_payload[ MAX_BYTES_DEC_PER_FRAME * MAX_INPUT_FRAMES ];
jshort in[ MAX_FRAME_LENGTH * MAX_INPUT_FRAMES ];
int ret,i,frsz=MAX_FRAME;
SKP_int16 nBytes;
unsigned int lin_pos = 0;
if (!codec_open)
return 0;
#ifdef DEBUG_SILK24
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"encoding frame size: %d\toffset: %d\n", size, offset);
#endif
for (i = 0; i < size; i+=MAX_FRAME) {
#ifdef DEBUG_SILK24
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"encoding frame size: %d\toffset: %d i: %d\n", size, offset, i);
#endif
env->GetShortArrayRegion(lin, offset + i,frsz, in);
/* max payload size */
nBytes = MAX_BYTES_ENC_PER_FRAME * MAX_INPUT_FRAMES;
ret = SKP_Silk_SDK_Encode( psEnc, &encControl, in, (SKP_int16)frsz, (SKP_uint8 *)enc_payload, &nBytes );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!! SKP_Silk_Encode returned: %d\n", ret);
Print_Encode_Error_Msg(ret);
break;
}
#ifdef DEBUG_SILK24
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"Enocded nBytes: %d\n", nBytes);
#endif
/* Write payload */
env->SetByteArrayRegion(encoded, RTP_HDR_SIZE+ lin_pos, nBytes, enc_payload);
lin_pos += nBytes;
}
#ifdef DEBUG_SILK24
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"encoding **END** frame size: %d\toffset: %d i: %d lin_pos: %d\n", size, offset, i, lin_pos);
#endif
return (jint)lin_pos;
}
extern "C"
JNIEXPORT jint JNICALL Java_com_trunkbow_silk_SILK24_decode
(JNIEnv *env, jobject obj, jbyteArray encoded, jshortArray lin, jint size) {
jbyte buffer [MAX_BYTES_DEC_PER_FRAME * MAX_INPUT_FRAMES * ( MAX_LBRR_DELAY + 1 ) ];
jshort output_buffer[( MAX_FRAME_LENGTH << 1 ) * MAX_INPUT_FRAMES ];
// SKP_int16 *outPtr;
int ret;
SKP_int16 len;
// int tot_len,frames;
if (!codec_open)
return 0;
#ifdef DEBUG_SILK24
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"##### BEGIN DECODE ******** decoding frame size: %d\n", size);
#endif
env->GetByteArrayRegion(encoded, RTP_HDR_SIZE, size, buffer);
// outPtr = output_buffer;
// tot_len = 0;
// frames = 0;
// do {
ret = SKP_Silk_SDK_Decode( psDec, &DecControl, 0,(SKP_uint8 *) buffer, size, output_buffer,&len );
if( ret ) {
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"!!!!!!!! SKP_Silk_SDK_Decode returned: %d\n", ret);
Print_Decode_Error_Msg(ret);
}
#ifdef DEBUG_SILK24
__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG,
"##### DECODED length: %d\n\t Frame #: %d", len);
#endif
// frames++;
// outPtr += len;
// tot_len += len;
// } while( DecControl.moreInternalDecoderFrames );
env->SetShortArrayRegion(lin, 0, len,output_buffer);
return (jint)len;
}
extern "C"
JNIEXPORT void JNICALL Java_com_trunkbow_silk_SILK24_close
(JNIEnv *env, jobject obj) {
if (--codec_open != 0)
return;
/* Free decoder */
free( psDec );
/* Free Encoder */
free( psEnc );
}
~~~
6、在Java层创建Speex工具类，内容如下：
Silk8.java：
~~~
class SILK8{
/*
* | fs (Hz) | BR (kbps)
* ----------------+---------+---------
* Narrowband | 8000 | 6 -20
* Mediumband | 12000 | 7 -25
* Wideband | 16000 | 8 -30
* Super Wideband | 24000 | 12 -40
*
* Table 1: fs specifies the audio sampling frequency in Hertz (Hz); BR
* specifies the adaptive bit rate range in kilobits per second (kbps).
*
* Complexity can be scaled to optimize for CPU resources in real-time,
* mostly in trade-off to network bit rate. 0 is least CPU demanding and
* highest bit rate.
*/
private static final int DEFAULT_COMPLEXITY = 0;
void load() {
System.loadLibrary("silk8_jni");
}
public native int open(int compression);
public native int decode(byte encoded[], short lin[], int size);
public native int encode(short lin[], int offset, byte encoded[], int size);
public native void close();
}
~~~
Silk16.java：
~~~
class SILK16 {
/*
* | fs (Hz) | BR (kbps)
* ----------------+---------+---------
* Narrowband | 8000 | 6 -20
* Mediumband | 12000 | 7 -25
* Wideband | 16000 | 8 -30
* Super Wideband | 24000 | 12 -40
*
* Table 1: fs specifies the audio sampling frequency in Hertz (Hz); BR
* specifies the adaptive bit rate range in kilobits per second (kbps).
*
* Complexity can be scaled to optimize for CPU resources in real-time,
* mostly in trade-off to network bit rate. 0 is least CPU demanding and
* highest bit rate.
*/
private static final int DEFAULT_COMPLEXITY = 0;
void load() {
System.loadLibrary("silk16_jni");
}
public native int open(int compression);
public native int decode(byte encoded[], short lin[], int size);
public native int encode(short lin[], int offset, byte encoded[], int size);
public native void close();
}
~~~
Silk24.java：
~~~
class SILK24 {
/*
* | fs (Hz) | BR (kbps)
* ----------------+---------+---------
* Narrowband | 8000 | 6 -20
* Mediumband | 12000 | 7 -25
* Wideband | 16000 | 8 -30
* Super Wideband | 24000 | 12 -40
*
* Table 1: fs specifies the audio sampling frequency in Hertz (Hz); BR
* specifies the adaptive bit rate range in kilobits per second (kbps).
*
* Complexity can be scaled to optimize for CPU resources in real-time,
* mostly in trade-off to network bit rate. 0 is least CPU demanding and
* highest bit rate.
*/
private static final int DEFAULT_COMPLEXITY = 0;
void load() {
System.loadLibrary("silk24_jni");
}
public native int open(int compression);
public native int decode(byte encoded[], short lin[], int size);
public native int encode(short lin[], int offset, byte encoded[], int size);
public native void close();
}
~~~
7、使用cygwin编译，生成so文件。
参考：http://developer.skype.com/silk
http://blog.csdn.net/wanggp_2007/article/details/5540686 Skype SILK vs. iLBC vs. Speex
