Wie konvertiert man wav zu mp3 für Samplerate 16000?

Question

Ich versuche, Konvertierung von WAV-Datei in MP3 mit Samplerate 16000. Nach der Konvertierung der Qualität des Audio ist nicht gut und seine Geschwindigkeit scheint wie eine erhöhte. Wo, wie es funktionierte gut, wenn die Audio-Konvertierungs-Abtastrate auf 8000. ich die Methode für Wav zu mp3 erstellt haben:

+(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

Denn für mp3 Verwendung Umwandlung Welle können die ExtAudioFileConverter verwenden Klasse: https://github.com/lixing123/ExtAudioFileConverter

für mP3-Abtastrate 16000 Umwandlung:

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];