1、README
前言
本demo是使用开源项目lame来将PCM数据编码成MP3数据。（环境：x86_64 Ubuntu16.04 64位）
a. 编译使用
lame的编译： (源码下载地址：https://sourceforge.net/projects/lame/files/lame/)
bash
tar xzf lame-3.100.tar.gz
cd lame-3.100/
./configure --prefix=$PWD/_install
make
make install本demo的编译与使用：
bash
$ make clean && make
$
$ ./pcm2mp3
Usage:
./pcm2mp3 <in pcm file> <smaplerate> <channels> <out mp3 file>
Examples:
./pcm2mp3 audio/test1_44100_16bit_stereo.pcm 44100 2 out1_44100_stereo.mp3
./pcm2mp3 audio/test2_22050_16bit_stereo.pcm 22050 2 out2_22050_stereo.mp3
./pcm2mp3 audio/test3_22050_16bit_mono.pcm 22050 1 out3_22050_mono.mp3
./pcm2mp3 audio/test4_8000_16bit_mono.pcm 8000 1 out4_8000_mono.mp3b. 参考文章
c. demo目录架构
bash
$ tree
.
├── audio
│ ├── out1_44100_stereo.mp3
│ ├── out2_22050_stereo.mp3
│ ├── out3_22050_mono.mp3
│ ├── out4_8000_mono.mp3
│ ├── test1_44100_16bit_stereo.pcm
│ ├── test2_22050_16bit_stereo.pcm
│ ├── test3_22050_16bit_mono.pcm
│ └── test4_8000_16bit_mono.pcm
├── docs
│ ├── c++ - 使用 libmp3lame_liblame_lame 将单声道 PCM 文件编码为 MP3 - IT工具网.mhtml
│ ├── Is there any LAME C++ wrapper_simplifier (working on Linux Mac and Win from pure code)_ - Stack Overflow.mhtml
│ └── 使用libmp3lame库编码mp3_太上绝情的博客-CSDN博客_libmp3lame.mhtml
├── include
│ └── lame
│ └── lame.h
├── lib
│ └── libmp3lame.a
├── main.c
├── Makefile
└── README.md2、主要代码片段
main.c
c
#include <stdio.h>
#include <stdlib.h>
#include "lame/lame.h"
#define PCM_SAMPLE_CNT (4096)
#define PCM_BUF_SIZE (PCM_SAMPLE_CNT * sizeof(short))
#define MP3_BUF_SIZE (PCM_SAMPLE_CNT * sizeof(short))
int main(int argc, char *argv[])
{
char *pcmFileName = NULL;
char *mp3FileName = NULL;
FILE *fpPcm = NULL;
FILE *fpMp3 = NULL;
int readSampleCnt = -1;
int encBytes = -1;
int samplerate = -1;
int channels = -1;
short pcmBuf[PCM_BUF_SIZE];
unsigned char mp3Buf[MP3_BUF_SIZE];
lame_t mp3EncHandler = NULL;
if(argc != 5)
{
printf("Usage: \n"
" %s <in pcm file> <smaplerate> <channels> <out mp3 file>\n"
"Examples: \n"
" %s audio/test1_44100_16bit_stereo.pcm 44100 2 out1_44100_stereo.mp3\n"
" %s audio/test2_22050_16bit_stereo.pcm 22050 2 out2_22050_stereo.mp3\n"
" %s audio/test3_22050_16bit_mono.pcm 22050 1 out3_22050_mono.mp3\n"
" %s audio/test4_8000_16bit_mono.pcm 8000 1 out4_8000_mono.mp3\n",
argv[0], argv[0], argv[0], argv[0], argv[0]);
return -1;
}
else
{
pcmFileName = argv[1];
samplerate = atoi(argv[2]);
channels = atoi(argv[3]);
mp3FileName = argv[4];
}
/* open file */
fpPcm = fopen(pcmFileName, "rb");
fpMp3 = fopen(mp3FileName, "wb");
if(!fpPcm || !fpMp3)
{
printf("[%s:%d]: open %s or %s failed!\n", __FUNCTION__, __LINE__, pcmFileName, mp3FileName);
return -1;
}
/* mp3 encode 1/5 : open encoder */
mp3EncHandler = lame_init();
if(!mp3EncHandler)
{
printf("[%s:%d] open MP3 encoder failed!\n", __FUNCTION__, __LINE__);
goto exit;
}
/* mp3 encode 2/5 : configure encoder params */
lame_set_in_samplerate(mp3EncHandler, samplerate); /* default = 44100hz */
//lame_set_out_samplerate(mp3EncHandler, samplerate); /* if not set, it will be auto configured */
lame_set_num_channels(mp3EncHandler, channels); /* number of channels in input stream. default=2 */
//lame_set_mode(mp3EncHandler, STEREO); /* if not set, it will be auto configured */
lame_set_VBR(mp3EncHandler, vbr_mtrh); /* Types of VBR. vbr_default=vbr_mtrh */
//lame_set_brate(mp3EncHandler, 160; /* for CBR */
//lame_set_VBR_mean_bitrate_kbps(mp3EncHandler, 160); /* Ignored except for VBR=vbr_abr (ABR mode) */
lame_init_params(mp3EncHandler);
while(1)
{
readSampleCnt = fread(pcmBuf, sizeof(short)/* 16bit */, PCM_SAMPLE_CNT, fpPcm);
if(readSampleCnt == PCM_SAMPLE_CNT)
{
if(channels == 1)
{
/* mp3 encode 3/5 : encode(mono) */
//encBytes = lame_encode_buffer(mp3EncHandler, NULL, pcmBuf, readSampleCnt/channels, mp3Buf, MP3_BUF_SIZE); /* R */
encBytes = lame_encode_buffer(mp3EncHandler, pcmBuf, NULL, readSampleCnt/channels, mp3Buf, MP3_BUF_SIZE); /* L */
}
else if(channels == 2)
{
/* mp3 encode 3/5 : encode(stereo) */
encBytes = lame_encode_buffer_interleaved(mp3EncHandler, pcmBuf, readSampleCnt/channels, /* number of samples per channel, not number of samples in pcmBuf*/
mp3Buf, MP3_BUF_SIZE);
}
else
{
printf("[%s:%d] Unknown channels(%d)!\n", __FUNCTION__, __LINE__, channels);
goto exit;
}
if(encBytes > 0)
{
/* save to file */
fwrite(mp3Buf, 1, encBytes, fpMp3);
printf("<in> [pcm bytes: %d] | <out> [mp3 bytes: %d]\n", (int)(readSampleCnt * sizeof(short)), encBytes);
}
else
{
printf("[%s:%d] encode failed!\n", __FUNCTION__, __LINE__);
goto exit;
}
}
else
{
break;
}
}
/* mp3 encode 4/5 : flush to file */
encBytes = lame_encode_flush(mp3EncHandler, mp3Buf, MP3_BUF_SIZE);
if(encBytes > 0)
{
/* save to file */
fwrite(mp3Buf, 1, encBytes, fpMp3);
printf("<in> [pcm bytes: %d] | <out> [mp3 bytes: %d]\n", (int)(readSampleCnt * sizeof(short)), encBytes);
}
else
{
printf("[%s:%d] encode failed!\n", __FUNCTION__, __LINE__);
goto exit;
}
printf("\e[32m%s -> %s success!\e[0m\n", argv[1], argv[4]);
exit:
/* mp3 encode 5/5 : close encoder */
if(mp3EncHandler) lame_close(mp3EncHandler);
if(mp3EncHandler) {fflush(fpMp3); fclose(fpMp3);}
if(mp3EncHandler) fclose(fpPcm);
return 0;
}