安卓如何压缩音频文件，压缩声音的方法，Speex工具的使用，音频压缩工具Speex的使用实例源码。Android开发中需要录音并发送到对方设备上。然而手机常会是GPRS、3G等方式上网，节省流量是非常重要的，使用Speex来压缩音频文件，可音频压文件小数倍。

1.到Speex官网下载最新Speex源码。

2.创建一个新的应用（我创建的应用名为Audio），并创建一个jni目录（$project/jni）。

3.把speex源码目录下的libspeex和include目录及其子目录文件全部拷贝到$project/jni目录下（$project/jni/libspeex and $project/jni/include）。

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)

LOCAL_MODULE  := libspeex

LOCAL_CFLAGS = -DFIXED_POINT -DUSE_KISS_FFT -DEXPORT=”" -UHAVE_CONFIG_H

LOCAL_C_INCLUDES := $(LOCAL_PATH)/include

LOCAL_SRC_FILES := \

./speex_jni.cpp \

./libspeex/bits.c \

./libspeex/buffer.c \

./libspeex/cb_search.c \

./libspeex/exc_10_16_table.c \

./libspeex/exc_10_32_table.c \

./libspeex/exc_20_32_table.c \

./libspeex/exc_5_256_table.c \

./libspeex/exc_5_64_table.c \

./libspeex/exc_8_128_table.c \

./libspeex/fftwrap.c \

./libspeex/filterbank.c \

./libspeex/filters.c \

./libspeex/gain_table.c \

./libspeex/gain_table_lbr.c \

./libspeex/hexc_10_32_table.c \

./libspeex/hexc_table.c \

./libspeex/high_lsp_tables.c \

./libspeex/jitter.c \

./libspeex/kiss_fft.c \

./libspeex/kiss_fftr.c \

./libspeex/lpc.c \

./libspeex/lsp.c \

./libspeex/lsp_tables_nb.c \

./libspeex/ltp.c \

./libspeex/mdf.c \

./libspeex/modes.c \

./libspeex/modes_wb.c \

./libspeex/nb_celp.c \

./libspeex/preprocess.c \

./libspeex/quant_lsp.c \

./libspeex/resample.c \

./libspeex/sb_celp.c \

./libspeex/scal.c \

./libspeex/smallft.c \

./libspeex/speex.c \

./libspeex/speex_callbacks.c \

./libspeex/speex_header.c \

./libspeex/stereo.c \

./libspeex/vbr.c \

./libspeex/vq.c \

./libspeex/window.c

include $(BUILD_SHARED_LIBRARY)

 

5.在jni目录下新增Application.mk文件，编辑内容如下

APP_ABI := armeabi armeabi-v7a

6.在$project/jni/include/speex/目录下新增speex_config_types.h文件，编辑内容如下

#ifndef __SPEEX_TYPES_H__

#define __SPEEX_TYPES_H__

typedef short spx_int16_t;

typedef unsigned short spx_uint16_t;

typedef int spx_int32_t;

typedef unsigned int spx_uint32_t;

#endif

 

7.创建JNI包装类speex_jni.cpp，用来调用Speex中的C代码函数，编辑内容如下

#include

#include

#include

#include

static int codec_open = 0;

static int dec_frame_size;

static int enc_frame_size;

static SpeexBits ebits, dbits;

void *enc_state;

void *dec_state;

static JavaVM *gJavaVM;

 

extern “C”

JNIEXPORT jint JNICALL Java_com_audio_Speex_open

  (JNIEnv *env, jobject obj, jint compression) {

int tmp;

 

if (codec_open++ != 0)

return (jint)0;

 

speex_bits_init(&ebits);

speex_bits_init(&dbits);

 

enc_state = speex_encoder_init(&speex_nb_mode);

dec_state = speex_decoder_init(&speex_nb_mode);

tmp = compression;

speex_encoder_ctl(enc_state, SPEEX_SET_QUALITY, &tmp);

speex_encoder_ctl(enc_state, SPEEX_GET_FRAME_SIZE, &enc_frame_size);

speex_decoder_ctl(dec_state, SPEEX_GET_FRAME_SIZE, &dec_frame_size);

 

return (jint)0;

}

 

extern “C”

JNIEXPORT jint Java_com_audio_Speex_encode

    (JNIEnv *env, jobject obj, jshortArray lin, jint offset, jbyteArray encoded, jint size) {

 

        jshort buffer[enc_frame_size];

        jbyte output_buffer[enc_frame_size];

int nsamples = (size-1)/enc_frame_size + 1;

int i, tot_bytes = 0;

 

if (!codec_open)

return 0;

 

speex_bits_reset(&ebits);

 

for (i = 0; i < nsamples; i++) {

env->GetShortArrayRegion(lin, offset + i*enc_frame_size, enc_frame_size, buffer);

speex_encode_int(enc_state, buffer, &ebits);

}

//env->GetShortArrayRegion(lin, offset, enc_frame_size, buffer);

//speex_encode_int(enc_state, buffer, &ebits);

 

tot_bytes = speex_bits_write(&ebits, (char *)output_buffer,

    enc_frame_size);

env->SetByteArrayRegion(encoded, 0, tot_bytes,

output_buffer);

 

        return (jint)tot_bytes;

}

 

extern “C”

JNIEXPORT jint JNICALL Java_com_audio_Speex_decode

    (JNIEnv *env, jobject obj, jbyteArray encoded, jshortArray lin, jint size) {

 

        jbyte buffer[dec_frame_size];

        jshort output_buffer[dec_frame_size];

        jsize encoded_length = size;

 

if (!codec_open)

return 0;

 env->GetByteArrayRegion(encoded, 0, encoded_length, buffer);

speex_bits_read_from(&dbits, (char *)buffer, encoded_length);

speex_decode_int(dec_state, &dbits, output_buffer);

env->SetShortArrayRegion(lin, 0, dec_frame_size,

output_buffer);

 

return (jint)dec_frame_size;

}

 extern “C”

JNIEXPORT jint JNICALL Java_com_audio_getFrameSize

    (JNIEnv *env, jobject obj) {

 if (!codec_open)

return 0;

return (jint)enc_frame_size;

 

}

 

extern “C”

JNIEXPORT void JNICALL Java_com_audio_Speex_close

    (JNIEnv *env, jobject obj) {

 if (–codec_open != 0)

return;

 speex_bits_destroy(&ebits);

speex_bits_destroy(&dbits);

speex_decoder_destroy(dec_state);

speex_encoder_destroy(enc_state);

}