仅录制设备声音而静音麦克风录制的声音。

要仅录制设备声音而静音麦克风录制的声音，可以使用以下方法：

在Windows上使用C#：

using System;
using NAudio.Wave;

class Program
{
    static void Main()
    {
        WasapiLoopbackCapture capture = new WasapiLoopbackCapture();
        using (WaveFileWriter writer = new WaveFileWriter("output.wav", capture.WaveFormat))
        {
            capture.DataAvailable += (sender, e) =>
            {
                writer.Write(e.Buffer, 0, e.BytesRecorded);
            };

            capture.RecordingStopped += (sender, e) =>
            {
                capture.Dispose();
                writer.Dispose();
            };

            capture.StartRecording();

            Console.WriteLine("Press Enter to stop recording...");
            Console.ReadLine();

            capture.StopRecording();
        }
    }
}

在Mac上使用Objective-C：

#import <Foundation/Foundation.h>
#import <AVFoundation/AVFoundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSURL *outputURL = [NSURL fileURLWithPath:@"output.caf"];
        
        AVAudioSession *session = [AVAudioSession sharedInstance];
        NSError *error;
        [session setCategory:AVAudioSessionCategoryRecord error:&error];
        if (error) {
            NSLog(@"Error setting audio session category: %@", error.localizedDescription);
            return 1;
        }
        
        NSMutableDictionary *recordSettings = [[NSMutableDictionary alloc] init];
        [recordSettings setValue:[NSNumber numberWithInt:kAudioFormatAppleLossless] forKey:AVFormatIDKey];
        [recordSettings setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey];
        [recordSettings setValue:[NSNumber numberWithInt:2] forKey:AVNumberOfChannelsKey];
        
        AVAssetWriterInput *input = [[AVAssetWriterInput alloc] initWithMediaType:AVMediaTypeAudio outputSettings:recordSettings];
        
        AVAssetWriter *writer = [[AVAssetWriter alloc] initWithURL:outputURL fileType:AVFileTypeAppleM4A error:&error];
        if (error) {
            NSLog(@"Error creating asset writer: %@", error.localizedDescription);
            return 1;
        }
        
        [writer addInput:input];
        [writer startWriting];
        [writer startSessionAtSourceTime:kCMTimeZero];
        
        AVAudioEngine *audioEngine = [[AVAudioEngine alloc] init];
        AVAudioInputNode *inputNode = audioEngine.inputNode;
        
        AVAudioFormat *inputFormat = [inputNode outputFormatForBus:0];
        [inputNode installTapOnBus:0 bufferSize:4096 format:inputFormat block:^(AVAudioPCMBuffer *buffer, AVAudioTime *when) {
            [input appendSampleBuffer:buffer];
        }];
        
        [audioEngine prepare];
        [audioEngine startAndReturnError:&error];
        if (error) {
            NSLog(@"Error starting audio engine: %@", error.localizedDescription);
            return 1;
        }
        
        NSLog(@"Recording started. Press Enter to stop...");
        getchar();
        
        [inputNode removeTapOnBus:0];
        [input markAsFinished];
        [writer finishWritingWithCompletionHandler:^{
            if (writer.status == AVAssetWriterStatusFailed) {
                NSLog(@"Error writing audio file: %@", writer.error.localizedDescription);
            } else {
                NSLog(@"Recording finished.");
            }
        }];
        
        [audioEngine stop];
    }
    return 0;
}

这些示例代码演示了如何使用C#和Objective-C在Windows和Mac上分别录制设备声音而静音麦克风录制的声音。这些代码使用了NAudio库（C#）和AVFoundation库（Objective-C）来处理音频输入和输出。