iOS疯狂详解之录制音频转换成Mp3

使用第三方 lame
,Mp3音频编码器.   

使用 AVAudioRecorder 进行音频录制之前,进行参数设置:

NSString *recordTemporaryPathString = [NSString stringWithFormat:@"%@/temporary",self.audioTemporarySavePath];

//LinearPCM 是iOS的一种无损编码格式,但是体积较为庞大

//录音设置

NSMutableDictionary *recordSettings = [[NSMutableDictionary alloc] init];

//录音格式 无法使用

[recordSettings setValue :[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey: AVFormatIDKey];

//采样率

[recordSettings setValue :[NSNumber numberWithFloat:11025.0] forKey: AVSampleRateKey];//44100.0

//通道数

[recordSettings setValue :[NSNumber numberWithInt:2] forKey: AVNumberOfChannelsKey];

//线性采样位数

//[recordSettings setValue :[NSNumber numberWithInt:16] forKey: AVLinearPCMBitDepthKey];

//音频质量,采样质量

[recordSettings setValue:[NSNumber numberWithInt:AVAudioQualityMin] forKey:AVEncoderAudioQualityKey];

#include "lame.h"

- (void)audio_PCMtoMP3

{

    NSString *mp3FileName = [self.audioFileSavePath lastPathComponent];

    mp3FileName = [mp3FileName stringByAppendingString:@".mp3"];

    NSString *mp3FilePath = [self.audioTemporarySavePath stringByAppendingPathComponent:mp3FileName];

    

    @try {

        int read, write;

        

        FILE *pcm = fopen([self.audioFileSavePath cStringUsingEncoding:1], "rb");  //source 被转换的音频文件位置

        fseek(pcm, 4*1024, SEEK_CUR);                                   //skip file header

        FILE *mp3 = fopen([mp3FilePath cStringUsingEncoding:1], "wb");  //output 输出生成的Mp3文件位置

        

        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_in_samplerate(lame, 11025.0);

        lame_set_VBR(lame, vbr_default);

        lame_init_params(lame);

        

        do {

            read = 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 {

        self.audioFileSavePath = mp3FilePath;

        NSLog(@"MP3生成成功: %@",self.audioFileSavePath);

    }

}

更多iOS疯狂详解:http://blog.csdn.net/wanglongblog

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