Question

我正在尝试使用Samplerate 16000将wav文件转换为mp3。转换后音频质量不佳，速度似乎有所增加。如果音频转换采样率设置为8000，它的效果很好。我已经为Wav创建了mp3方法：

+(void)convertFromWavToMp3:(NSString *)filePath FileName:(NSString *)kFileName SampleRate:(int)kSampleRate failAction:(WavToMp3CompletionBlock)failBlock successAction:(WavToMp3CompletionBlock)successBlock

{

NSLog(@"%@", [filePath stringByDeletingLastPathComponent]);

NSString *mp3FileName = kFileName;
mp3FileName = [mp3FileName stringByAppendingString:@".mp3"];
NSString *mp3FilePath = [[filePath stringByDeletingLastPathComponent] stringByAppendingPathComponent:mp3FileName];

NSLog(@"%@", mp3FilePath);

@try {
    int read, write;

    NSFileManager *filemgr;
    filemgr = [NSFileManager defaultManager];
    char const *path_cstr = [filemgr fileSystemRepresentationWithPath:filePath];

    FILE *pcm = fopen(path_cstr, "rb");  //source
    fseek(pcm, 4*1024, SEEK_CUR);                                   //skip file header
    FILE *mp3 = fopen([mp3FilePath cStringUsingEncoding:1], "wb");  //output

    const int PCM_SIZE = 16384;
    const int MP3_SIZE = 16384;
    short int pcm_buffer[PCM_SIZE*2];
    unsigned char mp3_buffer[MP3_SIZE];

    lame_t lame = lame_init();
    lame_set_in_samplerate(lame, 8000);
    lame_set_num_channels(lame, 1);
    lame_set_VBR(lame, vbr_default);
   // lame_set_brate(lame, 128);

    lame_set_quality(lame, 0);
    lame_set_brate(lame, 128);

    lame_set_num_samples(lame, 8000);
    lame_set_out_samplerate(lame, 8000);
    lame_set_mode(lame, 3);

    lame_init_params(lame);

    lame_print_config(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);
    successBlock(true);
}
@catch (NSException *exception) {
    NSLog(@"%@",[exception description]);
    failBlock(false);
}
@finally {

}

Answer 1

要将wave转换为mp3，可以使用ExtAudioFileConverter类： https://github.com/lixing123/ExtAudioFileConverter

用于转换mp3采样率16000：

ExtAudioConverter* converter = [[ExtAudioConverter alloc] init];
converter.outputSampleRate = 16000;
converter.outputNumberChannels = 2;
converter.outputBitDepth = BitDepth_16;
converter.outputFormatID = kAudioFormatLinearPCM;
converter.outputFileType = kAudioFileMP3Type;

converter.inputFile =  @"Desktop/input.wav";
converter.outputFile = @"Desktop/output.mp3";
[converter convert];

如何将wav转换为mp3为samplerate 16000？

1 个答案: