iOS 录音文件格式转换 lame库_如何将音频编码转换为lame编码-优快云博客

本文链接：https://blog.youkuaiyun.com/flover5724059/article/details/77948694

本文介绍了一种使用lame库将PCM音频文件转换为MP3格式的方法，并提供了详细的源代码实现。通过调整采样率和VBR设置，确保了转换过程的质量。此外，该方法还包括了在转换完成后删除原始PCM文件的功能。

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导入 lame 库文件，引入lame.h 头文件

下面方法实现了格式转换并删除原文件

(NSString*)audio_PCM_to_MP3:(NSString *)recordFilePath changeName:(BOOL)isChange audioTime:(NSInteger)audioTime{

NSString *wavFileName = [recordFilePath lastPathComponent];

if (isChange) {
wavFileName = [wavFileName stringByReplacingOccurrencesOfString:[NSString stringWithFormat:@”%d”,PerRecordFileLimitCount - 1] withString:[NSString stringWithFormat:@”%ld”,audioTime]];

}

NSString *wavFilePath = [recordFilePath stringByDeletingLastPathComponent];

NSString *mp3FilePath = [wavFilePath stringByAppendingPathComponent:[NSString stringWithFormat:@”%@.mp3”,[wavFileName componentsSeparatedByString:@”.”].firstObject]];

@try {

int read, write;



FILE *pcm = fopen([recordFilePath cStringUsingEncoding:1], "rb");  //source 被转换的音频文件位置
if (!pcm)return nil;
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);

lame_set_VBR(lame, vbr_default);

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 {

if ([[NSFileManager defaultManager]fileExistsAtPath:recordFilePath]) {
    [[NSFileManager defaultManager] removeItemAtURL:[NSURL fileURLWithPath:recordFilePath] error:nil]; // 生成文件移除原文件
    NSLog(@"MP3生成成功: %@",mp3FilePath);
    return mp3FilePath;
}
return nil;

}
}