音頻錄製

 

原生音視頻編碼  https://github.com/loyinglin/LearnVideoToolBox/tree/master

 

基於 AVFoundation 進行音頻錄製

@interface ViewController ()<AVAudioRecorderDelegate>
{
    AVAudioRecorder *recorder;
    AVAudioPlayer *player;
}

@property (weak, nonatomic) IBOutlet UILabel *label;
 
@end


- (IBAction)record:(id)sender {
    
    if (recorder == nil) {
//        路徑拼接
        NSString *filePath =
        [NSString stringWithFormat:@"%@/rec_audio.caf", [self documentsDirectory]];
//        構建URL
        NSURL *fileUrl = [NSURL fileURLWithPath:filePath];
        
        NSError *error = nil;
//        AVAudioSession類提供了Audio Session服務，Audio Session是指定應用於音頻系統如何交互。AVAudioSession經過指定一個音頻類別實現的，音頻類別描述了應用使用音頻的方式
//        下面是設置音頻回話類別
//        AVAudioSessionCategoryRecord表明只能輸入音頻，即錄製音頻，其效果是中止其餘音頻播放，開始錄製音頻，         AVAudioSessionCategoryPlayback表明只能輸出音頻，即進行音頻播放。
        [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryRecord
                                               error:&error];
//        設置是否「活躍」，這會把系統的任何聲音關閉
        [[AVAudioSession sharedInstance] setActive:YES error:&error];
//        設置settings參數
        NSMutableDictionary *settings = [NSMutableDictionary dictionary];
//        AVFormatIDKey鍵是設置錄製音頻編碼格式，kAudioFormatLinearPCM表明線性PCM編碼格式，PCM（pulse code modulation）線性脈衝編碼調製，它是一種非壓縮格式。
//        注意：編碼格式與文件格式不一樣，例如WAV是音頻文件格式，它採用線性PCM音頻編碼
        [settings setValue:[NSNumber numberWithInt:kAudioFormatLinearPCM]
                    forKey:AVFormatIDKey];
//        AVSampleRateKey鍵是設置音頻採樣頻率，44100.0是音頻CD，VCD，SVCD和MP3所用的採樣頻率。
        [settings setValue:[NSNumber numberWithFloat:44100.0]
                    forKey:AVSampleRateKey];
//        AVNumberOfChannelsKey設置聲道數量，值爲1或者2
        [settings setValue:[NSNumber numberWithInt:1]
                    forKey:AVNumberOfChannelsKey];
//        AVLinearPCMBitDepthKey這是採樣位數，取值爲8，16，24，32，16是默認值
        [settings setValue:[NSNumber numberWithInt:16]
                    forKey:AVLinearPCMBitDepthKey];
//        AVLinearPCMIsBigEndianKey設置音頻解碼是大字節序仍是小字節序，大字節序，YES，不然爲NO
        [settings setValue:[NSNumber numberWithBool:NO]
                    forKey:AVLinearPCMIsBigEndianKey];
//        AVLinearPCMIsFloatKey設置音頻解碼是否爲浮點數，若是是則設置爲YES，不然爲NO
        [settings setValue:[NSNumber numberWithBool:NO]
                    forKey:AVLinearPCMIsFloatKey];
//        實例化recorder對象
        recorder = [[AVAudioRecorder alloc]
                    initWithURL:fileUrl
                    settings:settings
                    error:&error];
//        設置代理
        recorder.delegate = self;
    }
    
//    若是正在錄製，return
    if(recorder.isRecording) {
        return;
    }
//若是正在播放，中止
    if(player && player.isPlaying) {
        [player stop];
    }
//    開始錄製
    [recorder record];
    
    self.label.text = @"錄製中...";
}

- (IBAction)stop:(id)sender {
    self.label.text = @"中止...";
//    是否正在錄製
    if(recorder.isRecording) {
        [recorder stop];//中止
        recorder.delegate = nil;
        recorder = nil;
    }
    if(player.isPlaying) {
        [player stop];
    }
}

- (IBAction)play:(id)sender {
    
    if(recorder.isRecording) {
        [recorder stop];
        recorder.delegate = nil;
        recorder = nil;
    }
    if(player.isPlaying) {
        [player stop];
    }
    
    NSString *filePath =
    [NSString stringWithFormat:@"%@/rec_audio.caf", [self documentsDirectory]];
    NSURL *fileUrl = [NSURL fileURLWithPath:filePath];
    
    NSError *error = nil;
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback
                                           error:&error];
    [[AVAudioSession sharedInstance] setActive:YES error:&error];
    player = [[AVAudioPlayer alloc] initWithContentsOfURL:fileUrl error:&error];
    
    if(error) {
        NSLog(@"%@",[error description]);
    } else {
        [player play];
        self.label.text = @"播放...";
    }
    
}
-(NSString *)documentsDirectory{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
                                                         NSUserDomainMask, YES);
    return [paths objectAtIndex:0];
}

#pragma mark--實現AVAudioRecorderDelegate協議方法
- (void)audioRecorderDidFinishRecording:(AVAudioRecorder *)recorder successfully:(BOOL)flag{   
    NSLog(@"錄製完成。");
}
- (void)audioRecorderEncodeErrorDidOccur:(AVAudioRecorder *)recorder error:(NSError *)error{
    NSLog(@"錄製錯誤發生: %@", [error localizedDescription]);
}
- (void)audioRecorderBeginInterruption:(AVAudioRecorder *)recorder{
    NSLog(@"播放中斷。");
}
- (void)audioRecorderEndInterruption:(AVAudioRecorder *)recorder withOptions:(NSUInteger)flags{
    NSLog(@"中斷返回。");
}