应用过滤器（AVAudioUnitEQ）后保存音频文件，最后保存为mp3？ [复制]

Question

应用过滤器后保存音频文件让我非常沮丧。该过滤器仅适用于 AVAudioPlayerNode，这意味着在播放器中播放期间过滤器非常适合应用，但我该如何保存呢？过去 3 天我很挣扎，请任何帮助将不胜感激。 我使用了以下这些代码，

engine = [[AVAudioEngine alloc] init];

 - (void)setupEQ
{
      NSLog(@"setupEQ");

      unitEq = [[AVAudioUnitEQ alloc] initWithNumberOfBands:12];
      unitEq.globalGain = 3.0;
      AVAudioUnitEQFilterParameters *filterParameters;
      filterParameters = unitEq.bands[0];
      filterParameters.filterType = AVAudioUnitEQFilterTypeParametric;
      filterParameters.frequency = 31;
      filterParameters.bandwidth = 1.0;
      filterParameters.gain = [[[filter_arr objectAtIndex:index_filter] objectForKey:@"filter_freq_31.5hz"] floatValue];
      filterParameters.bypass = FALSE;

      filterParameters = unitEq.bands[1];
      filterParameters.filterType = AVAudioUnitEQFilterTypeParametric;
      filterParameters.frequency = 63;
      filterParameters.bandwidth = 1.0;
      filterParameters.gain = [[[filter_arr objectAtIndex:index_filter] objectForKey:@"filter_freq_63hz"] floatValue];
      filterParameters.bypass = FALSE;

      filterParameters = unitEq.bands[2];
      filterParameters.filterType = AVAudioUnitEQFilterTypeParametric;
      filterParameters.frequency = 125;
      filterParameters.bandwidth = 1.0;
      filterParameters.gain = [[[filter_arr objectAtIndex:index_filter] objectForKey:@"filter_freq_125hz"] floatValue];
      filterParameters.bypass = FALSE;

      filterParameters = unitEq.bands[3];
      filterParameters.filterType = AVAudioUnitEQFilterTypeParametric;
      filterParameters.frequency = 250;
      filterParameters.bandwidth = 1.0;
      filterParameters.gain = [[[filter_arr objectAtIndex:index_filter] objectForKey:@"filter_freq_250hz"] floatValue];
      filterParameters.bypass = FALSE;

      filterParameters = unitEq.bands[4];
      filterParameters.filterType = AVAudioUnitEQFilterTypeParametric;
      filterParameters.frequency = 500;
      filterParameters.bandwidth = 1.0;
      filterParameters.gain = [[[filter_arr objectAtIndex:index_filter] objectForKey:@"filter_freq_500hz"] floatValue];
      filterParameters.bypass = FALSE;

      filterParameters = unitEq.bands[5];
      filterParameters.filterType = AVAudioUnitEQFilterTypeParametric;
      filterParameters.frequency = 1000;
      filterParameters.bandwidth = 1.0;
      filterParameters.gain = [[[filter_arr objectAtIndex:index_filter] objectForKey:@"filter_freq_1khz"] floatValue];
      filterParameters.bypass = FALSE;

      filterParameters = unitEq.bands[6];
      filterParameters.filterType = AVAudioUnitEQFilterTypeParametric;
      filterParameters.frequency = 2000;
      filterParameters.bandwidth = 1.0;
      filterParameters.gain = [[[filter_arr objectAtIndex:index_filter] objectForKey:@"filter_freq_2khz"] floatValue];
      filterParameters.bypass = FALSE;

      filterParameters = unitEq.bands[7];
      filterParameters.filterType = AVAudioUnitEQFilterTypeParametric;
      filterParameters.frequency = 4000;
      filterParameters.bandwidth = 1.0;
      filterParameters.gain =[[[filter_arr objectAtIndex:index_filter] objectForKey:@"filter_freq_4khz"] floatValue];
      filterParameters.bypass = FALSE;

      filterParameters = unitEq.bands[8];
      filterParameters.filterType = AVAudioUnitEQFilterTypeParametric;
      filterParameters.frequency = 8000;
      filterParameters.bandwidth = 1.0;
      filterParameters.gain = [[[filter_arr objectAtIndex:index_filter] objectForKey:@"filter_freq_8khz"] floatValue];
      filterParameters.bypass = FALSE;

      filterParameters = unitEq.bands[9];
      filterParameters.filterType = AVAudioUnitEQFilterTypeParametric;
      filterParameters.frequency = 16000;
      filterParameters.bandwidth = 1.0;
      filterParameters.gain =[[[filter_arr objectAtIndex:index_filter] objectForKey:@"filter_freq_16khz"] floatValue];
      filterParameters.bypass = FALSE;


      filterParameters = unitEq.bands[10];
      filterParameters.filterType = AVAudioUnitEQFilterTypeLowPass;
      filterParameters.frequency = 16857;
      filterParameters.bypass = FALSE;

      filterParameters = unitEq.bands[11];
      filterParameters.filterType = AVAudioUnitEQFilterTypeHighPass;
      filterParameters.frequency = 205;
      filterParameters.bypass = FALSE;

      [engine attachNode:unitEq];
}







audioFile = [[AVAudioFile alloc] initForReading:[NSURL fileURLWithPath:[NSString stringWithFormat:@"%@",[self audio_file_path:mp3FileName]]] error:&playerError];
            [self setupPlayer];
            [self setupEQ];

            AVAudioMixerNode *mixerNode = [engine mainMixerNode];
            [engine connect:audio_player_node to:unitEq format:audio_file.processingFormat];
            [engine connect:unitEq to:mixerNode format:audio_file.processingFormat];

这些是可以正常工作的示例。但是我如何存储具有相同频率的音频文件？音频文件应为 mp3 格式。在苹果中，他们只将保存文件定位为 m4a。

Answer 1

试试这个，当你播放文件时，你必须再次播放整个文件才能保存效果。

AVAudioFormat  * commonFormat = [[AVAudioFormat alloc] initWithCommonFormat:AVAudioPCMFormatFloat32 sampleRate:44100 channels:2 interleaved:NO];


AVAudioFile *outputFile = [[AVAudioFile alloc] initForWriting:[NSURL URLWithString:[self filePath1]] settings:commonFormat.settings error:&error];


[unitEq  installTapOnBus:0 bufferSize:4096 format:commonFormat block:^(AVAudioPCMBuffer *buffer, AVAudioTime *when)
 {

     if (outputFile.length < file.length)
     {//Let us know when to stop saving the file, otherwise saving infinitely
         NSError *error;

         NSAssert([outputFile writeFromBuffer:buffer error:&error], @"error writing buffer data to file, %@", [error localizedDescription]);

     }else{
         audioEngine = nil;
         [unitEq removeTapOnBus:0];//if we dont remove it, will keep on tapping infinitely

     }

 }
];