使用lame转换音频时遇到的杂音问题
最近项目增加了录音功能，ios端需要将WAV格式音频转换成MP3然后上传到服务器，项目中用到了lame，音频转换都成功了，但是出现了杂音的问题，经过查资料和自己研究解决了问题，新手发表，有错误请多指教。。。。。
录音代码：
_setting = [[NSDictionary alloc] initWithObjectsAndKeys:
[NSNumber numberWithFloat: 15000],AVSampleRateKey, //采样率
[NSNumber numberWithInt: kAudioFormatLinearPCM],AVFormatIDKey,
[NSNumber numberWithInt: 2], AVNumberOfChannelsKey,//通道
[NSNumber numberWithInt: AVAudioQualityMedium],AVEncoderAudioQualityKey,//音频编码质量
nil];
[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayAndRecord error:nil];
[[AVAudioSession sharedInstance] setActive:YES error:nil];
NSError *error=nil;
_recorder = [[AVAudioRecorder alloc] initWithURL:pathUrl
settings:_setting
error:&error];
[_recorder prepareToRecord];
_recorder.meteringEnabled = YES; //设置可以检测音量变化
[_recorder record];
转换代码：
+ (NSString *)audioToMP3: (NSString *)sourcePath isDeleteSourchFile:(BOOL)isDelete{
NSString *inPath = sourcePath;
NSFileManager *fm = [NSFileManager defaultManager];
if (![fm fileExistsAtPath:sourcePath]){
NSLog(@"file path error!");
return @"";
}
NSString *outPath = [[sourcePath stringByDeletingPathExtension] stringByAppendingString:@".mp3"];
@try {
int read, write;
FILE *pcm = fopen([inPath cStringUsingEncoding:1], "rb");
fseek(pcm, 4*1024, SEEK_CUR);
FILE *mp3 = fopen([outPath cStringUsingEncoding:1], "wb");
const int PCM_SIZE = 8192;
const int MP3_SIZE = 8192;
short int pcm_buffer[PCM_SIZE*2];
unsigned char mp3_buffer[MP3_SIZE];
lame_t lame = lame_init();
lame_set_VBR(lame, vbr_default);
lame_set_num_channels(lame,2);//默认为2双通道
lame_set_in_samplerate(lame, 20000);//11025.0
lame_set_brate(lame,8);
lame_set_mode(lame,3);
lame_set_quality(lame,5); /* 2=high 5 = medium 7=low 音质*/
lame_init_params(lame);
do {
read = (int)fread(pcm_buffer, 2*sizeof(short int), PCM_SIZE, pcm);
if (read == 0)
write = lame_encode_flush(lame, mp3_buffer, MP3_SIZE);
else
write = lame_encode_buffer_interleaved(lame, pcm_buffer, read, mp3_buffer, MP3_SIZE);
fwrite(mp3_buffer, write, 1, mp3);
} while (read != 0);
lame_close(lame);
fclose(mp3);
fclose(pcm);
}
@catch (NSException *exception) {
NSLog(@"%@",[exception description]);
}
@finally {
NSLog(@"mp3 build success!");
if (isDelete) {
NSError *error;
[fm removeItemAtPath:sourcePath error:&error];
if (error == nil){
NSLog(@"source file is deleted!");
}
}
return outPath;
}
}