iOS使用AVAudioRecorder录音时实时pcm转码mp3。

设置audiorecorder参数问题这里就不多说了，网上有很多例子。我们要做的是把录出来的比较大的pcm音频文件实时压缩转码成mp3文件，这样在播放时能更加快速，并且与安卓、h5播放器也好做到统一。设置好audiorecorder，开始录音，也就是record后，开一个线程，插入我们的转码代码。

[self.audioRecorderrecord]

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

[selfconventToMp3];

});

- (void)conventToMp3 {

NSString*cafFilePath = [selfgetSavePath1];

NSString*mp3FilePath = [selfgetmp3SavePath1];

@try{

intread, write;

FILE*pcm =fopen([cafFilePathcStringUsingEncoding:NSASCIIStringEncoding],"rb");

FILE*mp3 =fopen([mp3FilePathcStringUsingEncoding:NSASCIIStringEncoding],"wb");

constintPCM_SIZE = 8192;

constintMP3_SIZE = 8192;

shortintpcm_buffer[PCM_SIZE * 2];

unsignedcharmp3_buffer[MP3_SIZE];

lame_tlame =lame_init();

lame_set_num_channels(lame,1);//设置1为单通道，默认为2双通道

lame_set_in_samplerate(lame, 44100.0);//11025.0

//lame_set_VBR(lame, vbr_default);

lame_set_brate(lame,32);

lame_set_mode(lame,3);

lame_set_quality(lame,2);

lame_init_params(lame);

longcurpos;

BOOLisSkipPCMHeader =NO;

do{

curpos =ftell(pcm);

longstartPos =ftell(pcm);

fseek(pcm, 0,SEEK_END);

longendPos =ftell(pcm);

longlength = endPos - startPos;

fseek(pcm, curpos,SEEK_SET);

if(length > PCM_SIZE * 2 *sizeof(shortint)) {

if(!isSkipPCMHeader) {

//Uump audio file header, If you do not skip file header

//you will heard some noise at the beginning!!!

fseek(pcm, 4 * 1024,SEEK_SET);

isSkipPCMHeader =YES;

}

read = (int)fread(pcm_buffer, 2 *sizeof(shortint), PCM_SIZE, pcm);

write =lame_encode_buffer_interleaved(lame, pcm_buffer, read, mp3_buffer, MP3_SIZE);

fwrite(mp3_buffer, write, 1, mp3);

}

else{

[NSThreadsleepForTimeInterval:0.05];

}

}while(!self.isStopRecorde);

read = (int)fread(pcm_buffer, 2 *sizeof(shortint), PCM_SIZE, pcm);

write =lame_encode_flush(lame, mp3_buffer, MP3_SIZE);

lame_close(lame);

fclose(mp3);

fclose(pcm);

//self.isFinishConvert = YES;

}

@catch(NSException *exception) {

//DWDLog(@"%@", [exception description]);

}

@finally{

//DWDLog(@"convert mp3 finish!!!");

}

}

//获取pcm地址

-(NSString*)getSavePath1{

NSString*urlStr=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES)lastObject];

urlStr=[urlStrstringByAppendingPathComponent:SPRecordAudioFile];

returnurlStr;

}

//获取转化后的mp3地址

-(NSString*)getmp3SavePath1{

NSString*urlStr=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES)lastObject];

urlStr=[urlStrstringByAppendingPathComponent:SPMP3RecordAudioFile];

returnurlStr;

}