Android上使用MP3格式录制声音

0. 下载LAME 并解压缩

http://lame.sourceforge.net/download.php

http://sourceforge.net/projects/lame/files/lame/3.99/lame-3.99.5.tar.gz

1. 创建jni/libmp3lame/src目录, 将解压缩后的lame-3.99.5/libmp3lame/ 目录下的

bitstream.c  fft.h            l3side.h                         presets.c   quantize_pvt.c  set_get.h   util.h         version.c
bitstream.h  gain_analysis.c  lame-analysis.h      machine.h           psymodel.c  quantize_pvt.h  tables.c    vbrquantize.c  version.h
encoder.c    gain_analysis.h  lame.c               mpglib_interface.c  psymodel.h  reservoir.c     tables.h    vbrquantize.h
encoder.h    id3tag.c         lame_global_flags.h  newmdct.c           quantize.c  reservoir.h     takehiro.c  VbrTag.c
fft.c        id3tag.h                     newmdct.h           quantize.h  set_get.c       util.c      VbrTag.h

基本上就是所有的.c和.h文件, 除了lameerror.h可以不用

等文件 全部复制到 jni/libmp3lame/src

将 lame-3.99.5/include/ 目录下的 lame.h 也复制到 jni/libmp3lame/src

2.创建jni/Android.mk

ROOT_PATH := $(call my-dir)

# make speex and lame
LOCAL_PATH := $(call my-dir)
include $(ROOT_PATH)/libmp3lame/Android.mk

jni/libmp3lame/Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LAME_LIBMP3_DIR := src

LOCAL_MODULE    := mp3lame
LOCAL_SRC_FILES := \
$(LAME_LIBMP3_DIR)/bitstream.c \
$(LAME_LIBMP3_DIR)/fft.c \
$(LAME_LIBMP3_DIR)/id3tag.c \
$(LAME_LIBMP3_DIR)/mpglib_interface.c \
$(LAME_LIBMP3_DIR)/presets.c \
$(LAME_LIBMP3_DIR)/quantize.c \
$(LAME_LIBMP3_DIR)/reservoir.c \
$(LAME_LIBMP3_DIR)/tables.c \
$(LAME_LIBMP3_DIR)/util.c \
$(LAME_LIBMP3_DIR)/VbrTag.c \
$(LAME_LIBMP3_DIR)/encoder.c \
$(LAME_LIBMP3_DIR)/gain_analysis.c \
$(LAME_LIBMP3_DIR)/lame.c \
$(LAME_LIBMP3_DIR)/newmdct.c \
$(LAME_LIBMP3_DIR)/psymodel.c \
$(LAME_LIBMP3_DIR)/quantize_pvt.c \
$(LAME_LIBMP3_DIR)/set_get.c \
$(LAME_LIBMP3_DIR)/takehiro.c \
$(LAME_LIBMP3_DIR)/vbrquantize.c \
$(LAME_LIBMP3_DIR)/version.c \
li_zhiwei_mp3recorder_SimpleLame.c

include $(BUILD_SHARED_LIBRARY)

jni/application.mk

APP_ABI := armeabi armeabi-v7a
APP_PLATFORM := android-8
 APP_PLATFORM := android-9
 APP_STL := stlport_static
 STLPORT_FORCE_REBUILD := true

3. 修改源代码
fft.c中去掉
//#include “vector/lame_intrin.h”

这个是用Intel CPU的特性进行优化, ARM上用不到

set_get.h中将
#include
改成
#include “lame.h”

utils.h中将
extern ieee754_float32_t fast_log2(ieee754_float32_t x);
用
extern float fast_log2(float x);
替换

4. 创建封装文件
li_zhiwei_mp3recorder_SimpleLame.c

#include "src/lame.h"
#include "li_zhiwei_mp3recorder_SimpleLame.h"

static lame_global_flags *glf = NULL;

JNIEXPORT void JNICALL Java_li_zhiwei_mp3recorder_SimpleLame_init(
		JNIEnv *env, jclass cls, jint inSamplerate, jint outChannel,
		jint outSamplerate, jint outBitrate, jint quality) {
	if (glf != NULL) {
		lame_close(glf);
		glf = NULL;
	}
	glf = lame_init();
	lame_set_in_samplerate(glf, inSamplerate);
	lame_set_num_channels(glf, outChannel);
	lame_set_out_samplerate(glf, outSamplerate);
	lame_set_brate(glf, outBitrate);
	lame_set_quality(glf, quality);
	lame_init_params(glf);
}

JNIEXPORT jint JNICALL Java_li_zhiwei_mp3recorder_SimpleLame_encode(
		JNIEnv *env, jclass cls, jshortArray buffer_l, jshortArray buffer_r,
		jint samples, jbyteArray mp3buf) {
	jshort* j_buffer_l = (*env)->GetShortArrayElements(env, buffer_l, NULL);

	jshort* j_buffer_r = (*env)->GetShortArrayElements(env, buffer_r, NULL);

	const jsize mp3buf_size = (*env)->GetArrayLength(env, mp3buf);
	jbyte* j_mp3buf = (*env)->GetByteArrayElements(env, mp3buf, NULL);

	int result = lame_encode_buffer(glf, j_buffer_l, j_buffer_r,
			samples, j_mp3buf, mp3buf_size);

	(*env)->ReleaseShortArrayElements(env, buffer_l, j_buffer_l, 0);
	(*env)->ReleaseShortArrayElements(env, buffer_r, j_buffer_r, 0);
	(*env)->ReleaseByteArrayElements(env, mp3buf, j_mp3buf, 0);

	return result;
}

JNIEXPORT jint JNICALL Java_li_zhiwei_mp3recorder_SimpleLame_flush(
		JNIEnv *env, jclass cls, jbyteArray mp3buf) {
	const jsize mp3buf_size = (*env)->GetArrayLength(env, mp3buf);
	jbyte* j_mp3buf = (*env)->GetByteArrayElements(env, mp3buf, NULL);

	int result = lame_encode_flush(glf, j_mp3buf, mp3buf_size);

	(*env)->ReleaseByteArrayElements(env, mp3buf, j_mp3buf, 0);

	return result;
}

JNIEXPORT void JNICALL Java_li_zhiwei_mp3recorder_SimpleLame_close(
		JNIEnv *env, jclass cls) {
	lame_close(glf);
	glf = NULL;
}

li_zhiwei_mp3recorder_SimpleLame.h (这个文件其实是在 javah li.zhiwei.mp3recorder.SimpleLame 命令生成的)

/* DO NOT EDIT THIS FILE - it is machine generated */
#include 
/* Header for class li_zhiwei_mp3recorder_SimpleLame */

#ifndef _Included_li_zhiwei_mp3recorder_SimpleLame
#define _Included_li_zhiwei_mp3recorder_SimpleLame
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     li_zhiwei_mp3recorder_SimpleLame
 * Method:    close
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_li_zhiwei_mp3recorder_SimpleLame_close
  (JNIEnv *, jclass);

/*
 * Class:     li_zhiwei_mp3recorder_SimpleLame
 * Method:    encode
 * Signature: ([S[SI[B)I
 */
JNIEXPORT jint JNICALL Java_li_zhiwei_mp3recorder_SimpleLame_encode
  (JNIEnv *, jclass, jshortArray, jshortArray, jint, jbyteArray);

/*
 * Class:     li_zhiwei_mp3recorder_SimpleLame
 * Method:    flush
 * Signature: ([B)I
 */
JNIEXPORT jint JNICALL Java_li_zhiwei_mp3recorder_SimpleLame_flush
  (JNIEnv *, jclass, jbyteArray);

/*
 * Class:     li_zhiwei_mp3recorder_SimpleLame
 * Method:    init
 * Signature: (IIIII)V
 */
JNIEXPORT void JNICALL Java_li_zhiwei_mp3recorder_SimpleLame_init
  (JNIEnv *, jclass, jint, jint, jint, jint, jint);

#ifdef __cplusplus
}
#endif
#endif

6. 运行 ndk_build 即可

参考资料

http://developer.samsung.com/android/technical-docs/Porting-and-using-LAME-MP3-on-Android-with-JNI

https://github.com/talzeus/AndroidMp3Recorder

http://ikinglai.blog.51cto.com/6220785/1228730