iOS-PCM文件转MP3文件

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PCM音频文件转MP3音频文件，也可以是直接NSData转换。

导入Lame库

Lame库是一个开源的编码转换库，先下载Lame后，导入到项目中，并导入以下两个Framework:

AVFoundation、AudioToolbox

编码转换

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#import "lame.h"

- (void)decode{
    NSData *totalData = [NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"numb" ofType:@"pcm"]];
    int frame = 1048576 / 4;
    for(int i = 0; i < totalData.length; i += frame){
        int size = MIN(frame, (int)totalData.length - i);
        [self pcmToMp3:[totalData subdataWithRange:NSMakeRange(i, size)]];
    }
    NSLog(@"End..");
}

- (NSData*)pcmToMp3:(NSData*)pcmData
{
    int PCM_SIZE = (int)pcmData.length;
    int MP3_SIZE = (int)pcmData.length;
    short int *pcm_buffer = (short int*)pcmData.bytes;
    unsigned char mp3_buffer[MP3_SIZE];
    
    
    lame_t lame = lame_init();
    lame_set_in_samplerate(lame, 采样率);
    lame_set_VBR(lame, vbr_default);
    lame_init_params(lame);
    NSMutableData *mp3Data = [NSMutableData new];
    int result = lame_encode_buffer_interleaved(lame, pcm_buffer, PCM_SIZE, mp3_buffer, MP3_SIZE);
    lame_close(lame);
    if(result > 0){
        NSLog(@"PCM encode success:%d..", result);
        [mp3Data appendBytes:mp3_buffer length:result];
    }else{
        NSLog(@"PCM encode fail:%d..", result);
    }
    
    return mp3Data;
}

注意，修改一下采样率，每首歌的采样率不同。